REVIEW | doi:10.20944/preprints201705.0176.v1
Online: 24 May 2017 (08:48:15 CEST)
Micronutrient homeostasis is a key factor in maintaining a healthy immune system. Zinc is an essential micronutrient that is involved in the regulation of the innate and adaptive immune responses. The main cause of zinc deficiency is malnutrition. Zinc deficiency leads to cell-mediated immune dysfunctions among other manifestations. Consequently, such dysfunctions lead to a worse outcome in the response towards bacterial infection and sepsis. For instance, zinc is an essential component of the pathogen-eliminating signal transduction pathways leading to neutrophil extracellular traps formation, as well as inducing cell-mediated immunity over humoral immunity by regulating specific factors or differentiation. Additionally, zinc deficiency plays a role in inflammation, mainly elevating inflammatory response as well as damage to host tissue. Zinc is involved in the modulation of the proinflammatory response by targeting Nuclear Factor Kappa B, a transcription factor that is the master regulator of proinflammatory responses. It is also involved in controlling oxidative stress and regulating inflammatory cytokines. Zinc plays an intricate function during an immune response and its homeostasis is critical for sustaining proper immune function. This review will summarize the latest findings concerning the role of this micronutrient during the course of infections and inflammatory response and how the immune system modulates zinc depending on different stimuli.
ARTICLE | doi:10.20944/preprints201901.0096.v1
Subject: Life Sciences, Endocrinology & Metabolomics Keywords: calcium diet content; mineral homeostasis; skeletal homeostasis; trabecular bone; PTH(1-34); rat
Online: 10 January 2019 (11:38:42 CET)
The present study is the second step (concerning the normal-diet restoration) of the our previous one (concerning the calcium-free diet) to determine whether the normal-diet restoration, with/without concomitant PTH(1-34) administration, can influence amounts and deposition sites of the total bone mass. Histomorphometric evaluations and immunohistochemical analysis for Sclerostin expression were conducted on the vertebral bodies and femurs in rat model. The final goals are: i) to define timing and manners of bone mass changes when calcium is restored in the diet; ii) to analyze the different involvement of the two bony architectures having different metabolism (i.e. trabecular versus cortical bone); iii) to verify the eventual role of PTH(1-34) administration. Results evidenced the greater involvement of the trabecular bone with respect to the cortical one, in answering to different calcium diet content, and the effect of PTH mostly in the recovery of trabecular bony architecture. The main findings emerged from the present study are: i) the importance of the interplay between mineral homeostasis and skeletal homeostasis in modulating and guiding bone answers to dietary/metabolic alterations and ii) the evidence that the more involved bony architecture is the trabecular one, the most susceptible to the dynamical balance of the two homeostases.
REVIEW | doi:10.20944/preprints202010.0447.v1
Subject: Medicine & Pharmacology, Oncology & Oncogenics Keywords: Iron homeostasis; Cancer; Prognostic; Diagnostic; Therapy
Online: 22 October 2020 (08:56:33 CEST)
Iron (Fe) is a trace element that plays essential roles in various biological processes such as DNA synthesis and repair, as well as cellular energy production, or oxygen transport, and it is currently widely recognized that iron homeostasis is dysregulated in many cancers. Indeed, several iron homeostasis proteins may be responsible for malignant tumor initiation, proliferation, and for metastatic spread of tumors. A large number of studies demonstrated the potential clinical value of turning these deregulated proteins as prognostic and/or predictive biomarkers of malignancy and /or response to anticancer treatments. Additionally, the iron addiction of cancer cells and the importance of iron in ferroptosis cell death signaling pathways prompted the development of therapeutic strategies against advanced stage or resistant cancers. In this review, we selected relevant and promising studies in the field of iron metabolism in cancer research and clinical oncology. Besides, we discuss some co-existing discrepant findings. We will also present and discuss the latest lines of research related to targeting iron, or its regulatory pathways, as potential promising anti-cancer strategies for human therapy. Iron chelators, such as deferoxamine or iron-oxide based nanoparticles, which are already tested in clinical trials, alone or in combination with chemotherapy will also be reported.
REVIEW | doi:10.20944/preprints202010.0353.v1
Subject: Medicine & Pharmacology, Oncology & Oncogenics Keywords: Copper homeostasis; Cancer; Prognostic; Diagnostic; Therapy
Online: 16 October 2020 (14:32:16 CEST)
In the human body, Copper (Cu) is a major and essential player in a large number of cellular mechanisms and signaling pathways. The involvement of Cu in oxidation-reduction reactions requires close regulation of copper metabolism in order to avoid toxic effects. In many types of cancer, variations in copper protein levels have been demonstrated. These variations result in increased concentrations of intra-tumoral Cu and alterations in the systemic distribution of copper. Such alterations in Cu homeostasis may promote tumor growth or invasiveness, or even confer resistance to treatments. Once characterized, the dysregulated Cu metabolism is pinpointing several promising biomarkers for clinical use, with prognostic or predictive capabilities. The altered Cu metabolism in cancer cells and the different responses of tumor cells to Cu are strongly supporting the development of treatments to disrupt, deplete or increase Cu levels in tumors. The metallic nature of Cu, as a chemical element, is key for the development of anticancer agents via the synthesis of nanoparticles or copper-based complexes with antineoplastic properties for therapy. Finally, some of these new therapeutic strategies such as chelators or ionophores have shown promising results in a preclinical setting, while others are already in the clinic.
HYPOTHESIS | doi:10.20944/preprints201904.0210.v1
Subject: Life Sciences, Biochemistry Keywords: homeostasis; membrane; glycerophospholipid; composition; chemical activity
Online: 19 April 2019 (07:38:21 CEST)
Is unclear how mammalian cells maintain the complex glycerophospholipid (GPL) compositions of their various membranes. Here we propose the first comprehensive model that suggests how this could be accomplished. The model is based on the idea that there are a limited number of GPL compositions that are energetically more favorable than the other compositions, i.e., those (optimal) compositions represent local free energy minima. Thus, the GPL composition of a membrane has a natural tendency to settle in one of the optimal composition. When the mole fraction of an GPL class exceeds that in an optimal composition, its chemical activity abruptly increases, which (i) increases its propensity to efflux from the membranes thus making it susceptible for hydrolysis by homeostatic phospholipases; (ii) increases its potency to inhibit its own biosynthesis via a feedback mechanism; (iii) enhances its conversion to another GPL class via “head group remodeling” or (iv) enhances its translocation to another membrane. These four processes may act separately or simultaneously to maintain GPL homeostasis.
ARTICLE | doi:10.20944/preprints201901.0176.v1
Subject: Biology, Physiology Keywords: homeostasis, energy, neuronal networks, behavior, emergent properties
Online: 17 January 2019 (11:58:15 CET)
A major goal of neuroscience is understanding how neurons arrange themselves into neural networks that result in behavior. Most theoretical and experimental efforts have focused on a top-down approach which seeks to identify neuronal correlates of behaviors. This has been accomplished by effectively mapping specific behaviors to distinct neural patterns, or by creating computational models that produce a desired behavioral outcome. Nonetheless, these approaches have only implicitly considered the fact that neural tissue, like any other physical system, is subjected to several restrictions and boundaries of operations.Here, we propose a new, bottom-up conceptual paradigm: The Energy Homeostasis Principle, where the balance between energy income, expenditure, and availability are the key parameters in determining the dynamics of the found neuronal phenomena from molecular to behavioral levels. Neurons display high energy consumption relative to other cells, with metabolic consumption of the brain representing 20% of the whole-body oxygen uptake, contrasting with this organ representing only 2% of the body weight. Also, neurons have specialized surrounding tissue providing the necessary energy which, in the case of the brain, is provided by astrocytes. Moreover, and unlike other cell types with high energy demands such as muscle cells, neurons have strict aerobic metabolism. These facts indicate that neurons are highly sensitive to energy limitations, with Gibb’s free energy dictating the direction of all cellular metabolic processes. From this activity, the largest energy, by far, is expended by action potentials and post-synaptic potentials; therefore, plasticity can be reinterpreted in terms of their energy context. Consequently, neurons, through their synapses, impose energy demands over post-synaptic neurons in a close loop-manner, modulating the dynamics of local circuits. Subsequently, the energy dynamics end up impacting the homeostatic mechanisms of neuronal networks. Furthermore, local energy management also emerges as a neural population property, where most of the energy expenses are triggered by sensory or other modulatory inputs. Local energy management in neurons may be sufficient to explain the emergence of behavior, enabling the assessment of which properties arise in neural circuits and how. Essentially, the proposal of the Energy Homeostasis Principle is also readily testable for simple neuronal networks.
REVIEW | doi:10.20944/preprints201809.0148.v1
Subject: Life Sciences, Biochemistry Keywords: NCOA4, ferritinophagy, iron homeostasis, erythropoiesis, ferroptosis, cancer
Online: 9 September 2018 (16:13:18 CEST)
Nuclear receptor coactivator 4 (NCOA4) is a selective cargo receptor that mediates the autophagic degradation of ferritin (“ferritinophagy”), the cytosolic iron storage complex. NCOA4-mediated ferritinophagy maintains intracellular iron homeostasis by facilitating ferritin iron storage or release according to demand. Ferritinophagy is involved in iron-dependent physiological processes such as erythropoiesis, where NCOA4 mediates ferritin iron release for mitochondrial heme synthesis. Recently, ferritinophagy has been shown to regulate ferroptosis, a newly described form of iron-dependent cell death mediated by excess lipid peroxidation. Dysregulation of iron metabolism and ferroptosis have been described in neurodegeneration, cancer, and infection, but little is known about the role of ferritinophagy in the pathogenesis of these diseases. Here, we will review the biochemical regulation of NCOA4, its contribution to physiological processes and its role in disease. Finally, we will discuss the potential of activating or inhibiting ferritinophagy and ferroptosis for therapeutic purposes.
REVIEW | doi:10.20944/preprints202209.0282.v1
Subject: Medicine & Pharmacology, Oncology & Oncogenics Keywords: Zinc homeostasis; cancer; therapy; prognostic; diagnostic; nanoparticles; biomarkers
Online: 19 September 2022 (14:05:29 CEST)
Zinc (Zn) is a trace element crucial for oxidative stress, apoptosis, the immune response, and more globally for various processes involved in cellular homeostasis. In some cancers, Zn homeostasis is dysregulated. In this review, the role of Zn in cancer and all the components associated to Zn, the use of Zn and Zn -related proteins as biomarkers and Zn-based strategies for the treatment of tumors will be described. ZIP and ZnT are proteins related to Zn metabolism in normal conditions. In cancer, the level of expression of Zn related proteins is abnormal. These Zn proteins may act as prognostic or diagnostic biomarkers, and may be helpful for detecting early-stage cancers or monitoring the course of the disease. Additionally, Zn and its pathways may also be targeted to treat cancers. Indeed, the use of metals for binding Zn cations allows to regulate the biodistribution of Zn within cells, and will control several downstream signaling pathways. Zinc may also be directly used as a therapeutic substance to improve the prognosis of cancer patients, especially with the supplementation of zinc or the use of Zn oxide nanoparticles.
ARTICLE | doi:10.20944/preprints202209.0235.v1
Subject: Biology, Physiology Keywords: lipid homeostasis; APOE4; Alzheimer’s Disease; Aβ peptide; tau
Online: 16 September 2022 (02:57:37 CEST)
The association of the APOE4 (vs APOE3) isoform with an increased risk of Alzheimer’s Disease (AD) is unequivocal, but the underlying mechanisms remain incompletely elu-cidated. A prevailing hypothesis incriminates the impaired ability of APOE4 to clear neurotoxic amyloid-β peptides (Aβ) from the brain as the main mechanism linking apolipoprotein isoform to disease aetiology. APOE protein mediates lipid transport both within the brain and from the brain to the periphery, suggesting that lipids may be potential co-factors in APOE4-associated physiopathology. The present study reveals several alterations in pathways of lipid homeostasis in the brains of mice expressing the human APOE4 versus APOE3 isoform. Carriers of APOE4 had deficient cholesterol turnover, an imbalance in the ratio of specific classes of phospholipids, lower levels of phosphatidylethanolamines bearing poly-unsaturated fatty acids and an overall eleva-tion in levels of monounsaturated fatty acids. These modifications in lipid homeostasis were related with increased production of Aβ peptides as well as augmented levels of tau and phosphorylated tau in primary neuronal cultures. This suite of AP-OE4-associated anomalies in lipid homeostasis and neurotoxic protein levels may be related to the accrued risk for AD in APOE4 carriers and provides novel insights into potential strategies for therapeutic intervention.
REVIEW | doi:10.20944/preprints202207.0309.v1
Subject: Biology, Plant Sciences Keywords: ubiquitin; E3 ligase; chloroplast; stress; photosynthesis; homeostasis; enzymes
Online: 21 July 2022 (03:20:20 CEST)
Chloroplasts are ancient organelles responsible for photosynthesis and various biosynthetic functions essential to most life on Earth. Many of these functions require tightly controlled regulatory processes to maintain homeostasis at the protein level. One such regulatory mechanism is the ubiquitin-proteasome system whose fundamental role is increasingly emerging in chloroplasts. In particular, the role of E3 ubiquitin ligases as determinants in the ubiquitination and degradation of specific intra-chloroplast proteins. Here, we highlight recent advances in understanding the roles of plant E3 ubiquitin ligases in chloroplast function.
CONCEPT PAPER | doi:10.20944/preprints202109.0530.v1
Subject: Biology, Other Keywords: energy; homeostasis; neural network; behavior; free energy principle
Online: 30 September 2021 (17:49:37 CEST)
Explaining the emergence of behavior and understanding on the basis of neuronal mechanisms is still elusive. One renowned proposal is the Free Energy Principle (FEP), which uses an information-theoretic framework derived from thermodynamic considerations to describe how behavior and understanding would emerge. FEP starts from a whole organism approach, based on mental states and phenomena, mapping them into the neuronal substrate. An alternative approach, the Energy Homeostasis Principle (EHP), initiates a similar explanatory effort, but starting from single neuron phenomena and building up to the whole organism’s behavior and understanding. In this work, we develop the EHP as an alternative but complementary vision to FEP and try to explain how behavior and understanding would emerge from the local requirements of the neurons. Based on EHP and a strict naturalist approach that sees living beings as physical and deterministic systems, we explain scenarios where learning would emerge without the need for volition or goals. Given these starting points, we state several considerations of how we see the nervous system, particularly the role of function, purpose, and the conception of goal-oriented behaviors. We problematize these conceptions, giving an alternative teleology-free framework in which behavior and, ultimately, understanding would still emerge. We reinterpret neural processing explaining basic learning situations up to simple anticipatory behavior. Finally, we end the work with an evolutionary perspective of how this non-goal-oriented behavior appears. We acknowledge that in the current form of our proposal, we are still far from explaining the emergence of understanding. Still, we set the ground for an alternative neuron-based framework to ultimately explain understanding.
ARTICLE | doi:10.20944/preprints202008.0610.v1
Online: 27 August 2020 (10:32:16 CEST)
Signaling through GPR109a, the putative receptor for the endogenous ligand β-OH butyrate, inhibits adipose tissue lipolysis. Niacin, an anti-atherosclerotic drug that can induce insulin resistance, activates GPR109a at nM concentrations. GPR109a is not essential for niacin to improve serum lipid profiles. To better understand the involvement of GPR109a signaling in regulating glucose and lipid metabolism, we treated GPR109a wildtype (+/+) and knockout (-/-) mice with repeated overnight injections of saline or niacin in physiological states characterized by low (ad libitum fed) or high (16h fasted) concentrations of the endogenous ligand, β-OH butyrate. In the fed state, niacin increased expression of PEPCK mRNA independent of genotype, while increasing CPT1 mRNA only in GPR109a -/- mice. Niacin decreased fasting serum non-esterified fatty acid concentrations in both GPR109a +/+ and -/- mice. Independent of GPR109a expression, niacin blunted fast-induced hepatic triglyceride accumulation and peroxisome proliferator activated receptor α (PPARα) mRNA expression. Surprisingly, GPR109a knockout did not affect glucose or lipid homeostasis or hepatic gene expression in either fed or fasted mice. In turn, GPR109a does not appear to be essential for the metabolic response to the ketogenic state or the pharmacological benefits associated with niacin.
CONCEPT PAPER | doi:10.20944/preprints201911.0372.v1
Subject: Biology, Plant Sciences Keywords: arabinogalactan proteins; phyllotaxis; Hechtian Oscillator; calcium homeostasis; auxin
Online: 29 November 2019 (08:22:04 CET)
Sixty years ago in the lab adjacent to Fred Sanger (1958 Nobel Prize for protein chemistry), I discovered the cell surface hydroxyproline-rich glycoproteins. Nature keeps some of her secrets longer than others. It has taken many years to dissect the molecular function and biological role of extensins and arabinogalactan proteins (AGPs). Extensins template the formation of new cell walls. AGPs remained baffling and enigmatic until a Eureka moment when computer prediction of AGP calcium binding depicted paired glucuronic acid residues and thus the likely role of a cell surface AGP-Ca2+capacitor: In conjunction with the auxin-activated proton pump that releases bound Ca2+ it led us to formulate the Hechtian Growth Oscillator as A Global Paradigm with a pivotal role in Ca2+ homeostasis. The ramifications are profound. They cannot be shrugged off with sceptical disdain but demand critical reappraisal of current dogma. Phyllotaxis is an ancient problem; it involves an essential role for auxin and the auxin efflux “PIN” proteins together with mechanotransduction of stress-strain as phyllotactic determinants. However, a general explanation remains elusive despite much effort, particularly by mathematicians. Here we propose a novel biochemical algorithm: Hechtian oscillator transduction of cell wall stress generates phyllotactic patterns quite independent of a mathematical approach. Plants simply use different rules and follow a different route.
REVIEW | doi:10.20944/preprints201706.0121.v1
Subject: Life Sciences, Immunology Keywords: autophagy； immune system； cancer；cell death；metabolic homeostasis
Online: 27 June 2017 (06:30:17 CEST)
Autophagy is a highly conserved catabolic mechanism that mediates the degradation of damaged cellular components by inducing their fusion with lysosomes. This process provides cells with an alternative source of energy for the synthesis of new proteins and the maintenance of metabolic homeostasis in stressful environments. Numerous studies have demonstrated beneficial roles for the induction as well as the suppression of autophagy in cancer cells. Autophagy may induce either survival or death depending on the cell/tissue type. Radiation therapy is widely used therapeutic option to treat cancer, and it induces autophagy in human cancer cell line. Also, melatonin seems to affect cancer cell death via regulation of programmed cell death. In this review, we summarize the current understanding of autophagy and its regulation in cancer.
Subject: Life Sciences, Other Keywords: deep sleep; slow-wave activity; evolution; comparative; physiology; homeostasis
Online: 2 August 2022 (04:46:33 CEST)
A modern definition of “deep sleep” is elusive despite being ubiquitously appreciated as an important physiological state supporting health and homeostasis. In modern times, human deep sleep is identified by specific bioelectric signatures in the electroencephalogram (EEG) emerging somewhere between periods of wakefulness. However, deep sleep has been used to describe states of quiescence well before the first electrical brain recordings in the late 1800s, highlighting its own evolution in both lay and medical literature. Furthermore, EEG states are not only ill-defined in most mammals outside of humans and laboratory rodents, but non-existent in some invertebrates. Given that all organisms rest and do so with seemingly well-defined utility, it remains a challenge linguistically, scientifically, and comparatively define what “deep sleep” means—or what it should—in a research context. Here, I explore standard definitions of deep sleep from a modern, comparative perspective, and discuss potential problems of using a strict and narrow definition of such a fleeting concept that has historically undergone significant updates. Finally, I suggest a path towards resolving inconsistencies around the meaning of “deep sleep” and consider whether it is truly reflected by any one measure.
REVIEW | doi:10.20944/preprints202209.0021.v1
Subject: Medicine & Pharmacology, Other Keywords: herbal drugs; gut microbiota; antibiotic stewardship, uncomplicated infection, NSAID, homeostasis.
Online: 1 September 2022 (10:35:01 CEST)
Epithelial surfaces in humans are home to symbiotic microbes (i.e., microbiota) that influence the defensive function against pathogens depending on the health of the microbiota. Healthy microbiota contribute to the well-being of their host in general (e.g., via the gut-brain-axis), and their respective anatomical site in particular (e.g., oral, urogenital, skin or respiratory microbiota). Despite efforts towards a more responsible use of antibiotics, they are often prescribed for uncomplicated, self-limiting infections and can have a substantial negative impact on the gut microbiota. Treatment alternatives such as non-steroidal anti-inflammatory drugs may also influence the microbiota and thus can have lasting adverse effects. Herbal drugs offer a generally safe treatment option for uncomplicated infections of the urinary or respiratory tract. Additionally, their microbiota preserving properties allow for a more appropriate therapy of uncomplicated infections without contributing to an increase in antibiotic resistance or disturbing the gut microbiota. Here, herbal treatments may be a more appropriate therapy with a generally favorable safety profile.
ARTICLE | doi:10.20944/preprints201908.0063.v1
Subject: Biology, Physiology Keywords: matreotype; proteomics; transcriptomics; lifespan; extracellular matrix; ECM; collagen; MMP; homeostasis
Online: 5 August 2019 (14:22:17 CEST)
Accumulation of damage is generally considered the cause of aging. Interventions that delay aging mobilize mechanisms that protect and repair cellular components. Consequently, research has been focused on studying the protective and homeostatic mechanisms within cells. However, in humans and other multicellular organisms, cells are surrounded by extracellular matrices (ECM), which are important for tissue structure, function and intercellular communication. During aging, components of the ECM become damaged through fragmentation, glycation, crosslinking, and accumulation of protein aggregation, all of which contribute to age-related pathologies. Interestingly, placing senescent cells into a young ECM rejuvenates them and we found that many longevity-assurances pathways re-activate de-novosynthesis of ECM proteins during aging. This raises the question of what constitutes a young ECM to reverse aging or maintain health? In order to make inroads to answering this question, I suggest a systems-level approach of quantifying the matrisome or ECM compositions reflecting health, pathology, or phenotype and propose a novel term, the “matreotype”, to describe this. The matreotype is defined as the composition and modification of ECM or matrisome proteins associated with or caused by a phenotype, such as longevity, or a distinct and acute physiological state, as observed during aging or disease. Every cell type produces its unique ECM. Interestingly, cancer-cell types can even be identified based on their unique ECM composition. Thus, the matreotype reflects cellular identity and physiological status. Defined matreotypes could be used as biomarkers or prognostic factors for disease or health status during aging with potential relevance for personalized medicine. Treatment with biologics that alter ECM-to-cell mechanotransduction might be a strategy to reverse age-associated pathologies. An understanding of how to reverse from an old to a young matreotype might point towards novel strategies to rejuvenate cells and help maintain tissue homeostasis to promote health during aging.
ARTICLE | doi:10.20944/preprints201805.0451.v2
Subject: Medicine & Pharmacology, Psychiatry & Mental Health Studies Keywords: pain; depression; treatment; meditation; synaptic plasticity and homeostasis; nerve stimulation
Online: 31 May 2018 (09:56:35 CEST)
Major depressive disorder (MDD) is a common mental disorder, which results in seriously impaired condition in the patients and great global disability burden. In light of its quite diverse etiologies, comorbidity with many other diseases, and complex underlying pathology, it has been a great challenge to understand the physiological basis of MDD, which may be a complex of related diseases, rather than a single one. In addition to the partial understanding of MDD, the individual heterogeneities among patients may render the development of a universal treatment an elusive goal. But studying how each of currently available treatments affects the disease can generate useful information to stratify patients into different subtypes for individualized treatments. In this case report, we present the first report of repeated success of using meditation as the only treatment of MDD, compared to initial success but no remission with other conventional antidepressants on the same patient. We hypothesized that the short but continuous natural pain during one-hour meditation sittings has the therapeutic effect to treat depression in the case of this patient and potentially others with MDD. This special opportunity of eliminating tremendous heterogeneity among different individuals has enabled us to probe deeply into the potential mechanism of depression treatments and the complex physiology of depression itself, both of which have likely profound implications in the treatment of other MDD patients as well. More importantly, this case report helps us dissect one specific component of meditation for its long-known and well-established benefit against depression.
ARTICLE | doi:10.20944/preprints202001.0185.v1
Subject: Biology, Plant Sciences Keywords: Abiotic stress; Antioxidant defense; Glyoxalase; Ion homeostasis; Organic acid; Osmotic stress
Online: 17 January 2020 (10:02:34 CET)
Salinity is a serious environmental hazard which limits world agricultural production by adversely affects plant physiology and biochemistry. Hence increase tolerance against salt stress is very important. In this study, we explored the function of β-aminobutyric acid (BABA) in enhancing salt stress tolerance in rapeseed (Brassica napus L.). After pretreatment with BABA, seedlings were exposed to NaCl (100 mM and 150 mM) for 2 days. Salt stress increased Na content and decreased K content in shoot and root. It disrupted the antioxidant defense system by producing reactive oxygen species (ROS; H2O2 and O2•−), methylglyoxal (MG) content and causing oxidative stress. It also reduced the growth and photosynthetic pigments of seedlings but increased proline (Pro) content. However, BABA pretreatment in salt-stressed seedlings increased ascorbate (AsA) and glutathione (GSH) contents; GSH/GSSG ratio; and the activities of ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), glutathione reductase (GR), glutathione peroxidase (GPX), superoxide dismutase (SOD), catalase (CAT), glyoxalase I (Gly I), and glyoxalase II (Gly II) as well as growth and photosynthetic pigments of plants. In addition, compared to salt stress alone BABA increased Pro content, reduced the H2O2, MDA and MG contents and decreased Na content in root and increased K content in shoot and root of rapeseed seedlings.
ARTICLE | doi:10.20944/preprints202001.0153.v1
Subject: Biology, Plant Sciences Keywords: antioxidant system; chilling stress; mineral homeostasis; nitric oxide; oxidative stress; rice
Online: 15 January 2020 (12:32:41 CET)
Being a chilling-sensitive staple crop, rice (Oryza sativa L.) is vulnerable to climate change. The competence of rice to withstand chilling stress should, therefore, be enhanced through technological tools. The present study employed chemical intervention like application of sodium nitroprusside (SNP) as nitric oxide (NO) donor and elucidated the underlying molecular mechanisms of NO-mediated chilling tolerance in rice. At germination stage, germination indicators were interrupted by chilling stress (5.0 ± 1.0°C for 8 h day‒1), while pretreatment with 100 μM SNP markedly improved the indicators. At seedling stage (14-day-old), chilling stress caused stunted growth with visible toxicity along with alteration of biochemical markers, for example, increase in oxidative stress markers (superoxide, hydrogen peroxide, and malondialdehyde) and osmolytes (total soluble sugar; proline and soluble protein content, SPC), and decrease in chlorophyll (Chl), relative water content (RWC), and antioxidants. However, NO application attenuated toxicity symptoms with improving growth performance which might be attributed to enhanced activities of antioxidants, mineral contents, Chl, RWC and SPC. Furthermore, principal component analysis indicated that water imbalance and increased oxidative damage were the main contributors to chilling injury, whereas NO-mediated mineral homeostasis and antioxidant defense were the critical determinants for chilling tolerance in rice. Collectively, our findings revealed that NO protects against chilling stress through valorizing cellular defense mechanisms, suggesting that exogenous application of NO could be a potential tool to evolve cold tolerance as well as climate resilience in rice.
ARTICLE | doi:10.20944/preprints201805.0411.v2
Subject: Medicine & Pharmacology, Psychiatry & Mental Health Studies Keywords: pain; depression; treatment; meditation; synaptic plasticity and homeostasis; DNA damage response
Online: 31 May 2018 (09:51:27 CEST)
The correlation and comorbidity between depression and chronic pain have been observed for a long time. Generally, it is considered that the two conditions reinforce each other, whereas the causal relationship between them is not clear. However, some evidence suggested that chronic pain may reverse the progression of depression in some cases. This article presents a selective review of clinical and pharmacological relationship between depression and pain, and their interactions at neurochemical and neurobiological levels. In addition, we open a discussion on a recent case report of repeated success of using short but continuous pain (SCP) during meditation as the only treatment for depression, compared to initial success but no remission with other conventional antidepressants on the same patient. Together this review proposes an updated model for depression and its various treatments that is based on synaptic and system homeostasis. More importantly, it suggests that SCP may benefit depression recovery through its properties that are different from either acute or chronic pain and represents a novel research area that has been largely neglected to date.
Subject: Medicine & Pharmacology, Nutrition Keywords: Iron, Zinc, Interactions, DMT1, ZIP4, Pancreas, Metabolism, Homeostasis, Intestine, Caco-2 cells
Online: 9 July 2019 (14:32:11 CEST)
Iron and zinc are essential micronutrients required for growth and health. Deficiencies of these nutrients are highly prevalent among populations, but can be alleviated by supplementation. Cross-sectional studies in humans showed positive association of serum zinc levels with hemoglobin and markers of iron status. Dietary restriction of zinc or intestinal specific conditional knock out of ZIP4 (SLC39A4), an intestinal zinc transporter, in experimental animals demonstrated iron deficiency anemia and tissue iron accumulation. Similarly increased iron accumulation has been observed in cultured cells exposed to zinc deficient media. These results together suggest a potential role of zinc in modulating whole body iron metabolism. Studies in intestinal cell culture models demonstrate that zinc induces iron uptake and transcellular transport via induction of divalent metal iron transporter-1 (DMT1) and ferroportin (FPN) expression, respectively. It is interesting to note that intestinal cells are exposed to very high levels of zinc through pancreatic secretions, which is a major route of zinc excretion from the body. Therefore, zinc appears to be modulating the iron metabolism possibly via regulating the DMT1 and FPN1 levels. Herein we critically reviewed the available evidence to hypothesize novel mechanism of Zinc-DMT1/FPN axis in regulating intestinal iron absorption and tissue iron accumulation to facilitate future research aimed at understanding the yet elusive mechanisms of iron and zinc interactions.
REVIEW | doi:10.20944/preprints201611.0099.v1
Subject: Medicine & Pharmacology, General Medical Research Keywords: pneumonia; acute respiratory distress syndrome; pathogenesis; protein-homeostasis-system; corticosteroid; intravenous immunoglobulin
Online: 18 November 2016 (10:18:58 CET)
Acute respiratory distress syndrome (ARDS) is caused by infectious insults, such as pneumonia from various pathogens or related to other noninfectious events. Clinical and histopathologic characteristics are similar across severely affected patients, suggesting that a common mode of immune reaction may be involved in the immunopathogenesis of ARDS. There may be etiologic substances that have an affinity for respiratory cells and induce lung cell injury in cases of ARDS. These substances originate not only from pathogens, but also from injured host cells. At the molecular level, these substances have various sizes and biochemical characteristics, classifying them as protein substances and non-protein substances. Immune cells and immune proteins may recognize and act on these substances, including pathogenic proteins and peptides, depending upon the size and biochemical properties of the substances (this theory is known as the protein-homeostasis-system hypothesis). The severity or chronicity of ARDS depends on the amount of etiologic substances with corresponding immune reactions, the duration of the appearance of specific immune cells, or the repertoire of specific immune cells that control the substances. Therefore, treatment with early systemic immune modulators (corticosteroids and/or intravenous immunoglobulin) as soon as possible may reduce aberrant immune responses in the potential stage of ARDS.
REVIEW | doi:10.20944/preprints202209.0069.v1
Subject: Medicine & Pharmacology, Psychiatry & Mental Health Studies Keywords: acetylated E2F4; synapsis; tissue homeostasis; Alzheimer’s disease; 5xFAD mice; neuroinflammation; microgliosis; reactive astrocytes.
Online: 5 September 2022 (13:52:27 CEST)
E2F4 was initially described as a transcription factor with a key function in the regulation of cell quiescence. Nevertheless, a number of recent studies have established that E2F4 can also play a relevant role in cell and tissue homeostasis as well as tissue regeneration. For these non-canonical functions, E2F4 can also act in the cytoplasm, where it is able to interact with many homeostatic and synaptic regulators. Since E2F4 is expressed in the nervous system, it may fulfill a crucial role in brain function and homeostasis, being a promising multifactorial target for neurodegenerative diseases and brain aging. The regulation of E2F4 is complex as it can be chemically modified through acetylation, from which we present evidence in the brain, as well as methylation, and phosphorylation. The phosphorylation of E2F4 within a conserved threonine motif induces cell cycle re-entry in neurons, while a dominant negative form of E2F4 (E2F4DN), in which the conserved threonines have been substituted by alanines, has been shown to act as a multifactorial therapeutic agent for Alzheimer’s disease (AD). We have generated transgenic mice neuronally expressing E2F4DN. We have recently shown using this mouse strain that expression of E2F4DN in 5xFAD mice, a known murine model of AD, improved cognitive function, reduced neuronal tetraploidization, and induced a transcriptional program consistent with modulation of amyloid-beta (Abeta) peptide proteostasis and brain homeostasis recovery. 5xFAD/E2F4DN mice also showed reduced microgliosis and astrogliosis in both cerebral cortex and hippocampus at 3-6 months of age. Here we have analyzed the immune response in 1 year-old 5xFAD/E2F4DN mice, concluding that reduced microgliosis and astrogliosis is maintained at this late stage. In addition, the expression of E2F4DN also reduced age-associated microgliosis in wild-type mice, thus stressing its role as a brain homeostatic agent. We conclude that E2F4DN transgenic mice represent a promising tool for the evaluation of E2F4 as a therapeutic target in neuropathology and brain aging.
REVIEW | doi:10.20944/preprints202106.0227.v1
Subject: Medicine & Pharmacology, Allergology Keywords: endoplasmic reticulum; endoplasmic reticulum stress; apoptosis; homeostasis; unfolded protein response; type II diabetes
Online: 8 June 2021 (13:07:30 CEST)
The endoplasmic reticulum (ER) plays a multifunctional role in lipid biosynthesis, calcium storage, protein folding, and processing. Thus, maintaining ER homeostasis in insulin-secreting beta-cells is essential. Several pathophysiological conditions and pharmacological agents disrupt the ER homeostasis, thereby causing ER stress. The cells react to ER stress by initiating an adaptive signaling process called the unfolded protein response (UPR). However, the ER initiates death signaling pathways whenever the ER stress persists. ER stress has been linked to several diseases, such as cancers, obesity, and diabetes. Thus, the regulation of ER stress may provide possible therapeutic targets for many diseases. Current evidence suggests that chronic hyperglycemia and hyperlipidemia linked to type II diabetes disrupt ER homeostasis, resulting in irreversible UPR activation and cells death. Despite much progress in understanding the pathophysiology of UPR and ER stress, to date, the mechanisms of ER stress in relation to type II diabetes remain unclear. This review provided up-to-date information regarding the current status of UPR, ER stress mechanisms, insulin dysfunction, oxidative stress, and the therapeutic potential of targeting specific ER stress pathways.
Subject: Arts & Humanities, Philosophy Keywords: complexity; uncertainty; cognition; allostasis; homeostasis; free energy principle; active inference; environmental complexity thesis; adaptation; representation; interoception; biorhythms; life-mind continuity
Online: 29 February 2020 (12:33:12 CET)
What is the function of cognition? On one influential account, cognition evolved to co-ordinate behaviour with environmental change or complexity (Godfrey-Smith 1996). Liberal interpretations of this view ascribe cognition to an extraordinarily broad set of biological systems – even bacteria, which modulate their activity in response to salient external cues, would seem to qualify as cognitive agents. However, equating cognition with adaptive flexibility per se glosses over important distinctions in the way biological organisms deal with environmental complexity. Drawing on contemporary advances in theoretical biology and computational neuroscience, we cash these distinctions out in terms of different kinds of generative models, and the representational and uncertainty-resolving capacities they afford. This analysis leads us to propose a formal criterion for delineating cognition from other, more pervasive forms of adaptive plasticity. On this view, biological cognition is rooted in a particular kind of functional organisation; namely, that which enables the agent to detach from the present and engage in counterfactual (active) inference.
REVIEW | doi:10.20944/preprints201906.0269.v1
Subject: Behavioral Sciences, Behavioral Neuroscience Keywords: subjective paranormal experience, homeostasis, trauma, dissociation, depersonalisation, compartmentalisation, fantasy proneness, safety, control, survival
Online: 26 June 2019 (13:59:44 CEST)
Subjective paranormal experience (SPE) has been a notable part of the human historical narrative. Alleged miracles, telepathy, clairvoyance, precognition, witchcraft, spiritualism, monsters and ghosts have received a supernatural interpretation. The incidence and prevalence of reported SPE remains at high levels in all populations investigated to date. Previous research on SPE has focused on the cognitive and social factors that facilitate paranormal beliefs and experiences. I consider here developmental factors in the brain’s responses to trauma that appear to predispose certain individuals towards SPE. The theory draws upon the established mechanisms of dissociation and fantasy generation to describe and explain the origins of paranormal experience. The theory hypothesizes that childhood abuse and victimization trigger autonomic responses of dissociation, depersonalization and compartmentalization. Freezing and associated releases of fantasy serve as a survival strategy in the homeostatic regaining of safety and control. The predictions from the homeostasis theory are consistent with the findings of multiple studies and falsifying evidence has yet to be identified.
REVIEW | doi:10.20944/preprints201904.0155.v1
Subject: Biology, Physiology Keywords: Rho GTPases; metabolism; glucose homeostasis; GLUT4 translocation; skeletal muscle; pancreas; insulin; diabetes; ageing
Online: 13 April 2019 (05:20:35 CEST)
Rho guanosine triphosphatases (GTPases) are key regulators in a number of cellular functions, including actin cytoskeleton remodeling and vesicle traffic. Traditionally, Rho GTPases are studied because of their function in cell migration and cancer, while their roles in metabolism are less documented. However, emerging evidence implicates Rho GTPases as regulators of processes of crucial importance for maintaining metabolic homeostasis. Thus, the time is now ripe for reviewing Rho GTPases in the context of metabolic health. Rho GTPase-mediated key processes include the release of insulin from pancreatic β-cells, glucose uptake into skeletal muscle and adipose tissue, and muscle mass regulation. Through the current review, we cast light on the important role of Rho GTPases in skeletal muscle, adipose tissue, and the pancreas and mechanisms by which Rho GTPases act to regulate glucose metabolism in health and disease. We also describe challenges and goals for future research.
REVIEW | doi:10.20944/preprints201711.0096.v1
Subject: Biology, Other Keywords: Hedgehog signaling; skin; epidermis; hair follicle; development; homeostasis; basal cell carcinoma; signaling crosstalk
Online: 15 November 2017 (07:11:15 CET)
The epidermis is the outermost layer of skin and provides a protective barrier against environmental insults. It is a rapidly renewing tissue undergoing constant regeneration, maintained by several types of stem cells. Hedgehog (HH) ligands activate one of the fundamental signaling pathways that contribute to epidermal development, homeostasis and repair. The HH pathway interacts with other signal transduction pathways such as those activated by Wnt and bone morphogenetic protein. Furthermore, aberrant activation of HH signaling is associated with various tumors, including basal cell carcinoma. Therefore, an understanding of the regulatory mechanisms of the HH signaling pathway is important to elucidate fundamental mechanisms underlying both organogenesis and carcinogenesis. In this review, we discuss the role of the HH signaling pathway in skin development, homeostasis and basal cell carcinoma formation, providing an update of current knowledge in this field.
ARTICLE | doi:10.20944/preprints202204.0312.v1
Subject: Engineering, Biomedical & Chemical Engineering Keywords: Tensional homeostasis; Traction microscopy; Gastric cancer cells; E-cadherin mutations; Extra-cellular matrix proteins
Online: 30 April 2022 (05:18:13 CEST)
In epithelia, breakdown of tensional homeostasis is closely associated with E-cadherin dysfunction and disruption of tissue function and integrity. In this study, we investigated the effect of E-cadherin mutations affecting distinct protein domains on tensional homeostasis of gastric cancer cells. We used micropattern traction microscopy to measure temporal fluctuations of cellular traction forces in AGS cells transfected with the wild-type E-cadherin or with variants affecting the extracellular, the juxtamembrane, and the intracellular domains of the protein. We focused on the dynamic aspect of tensional homeostasis, namely the ability of cells to maintain a consistent level of tension, with low temporal variability around a set point. Cells were cultured on hydrogels micropatterned with different extracellular matrix (ECM) proteins to test whether the ECM adhesion impacts cell behavior. A combination of Fibronectin and Vitronectin was used as a substrate that promotes the adhesive ability of E-cadherin dysfunctional cells, whereas Collagen VI was used to test an unfavorable ECM condition. Our results showed that mutations affecting distinct E-cadherin domains influenced differently cell tensional homeostasis, and pinpointed the juxtamembrane and intracellular regions of E-cadherin as the key players in this process. Furthermore, Fibronectin and Vitronectin might modulate cancer cell behavior towards tensional homeostasis.
Subject: Medicine & Pharmacology, Clinical Neurology Keywords: blood-brain barrier; copper/iron homeostasis; neurodegenerative (Alzheimers, Parkinsons, Prion) disease; North Ronaldsay sheep
Online: 27 May 2019 (12:27:10 CEST)
The neurodegenerative diseases (Alzheimers, Parkinsons, amyotrophic lateral sclerosis, Huntingdons) and the prion disorders, have in common a dysregulation of metalloprotein chemistry involving redox metals (Cu,Fe,Mn). The consequent oxidative stress gives rise to protein plaques and neuronal cell death. An equilibrium exists between the functional requirement of the brain for Cu and Fe and their destructive potential with the production of reactive oxygen species. The importance of the brain barrier is highlighted in regulating the import of these metals. Upregulation of key transporters occurs in foetal and neonatal life when brain metal requirement is high and is down-regulated in adult life when need is minimal. By contrast a neonatal mode of CTR1 upregulation persists in feral N.Ronaldsay sheep. This has led to the premise that metal regulation may return to the default setting in ageing with implications for neurodegenerative disease.
REVIEW | doi:10.20944/preprints202108.0411.v1
Subject: Life Sciences, Biotechnology Keywords: abiotic stresses; gene-expression; genomics; ion homeostasis; plant growth and development; plasma membrane; sugar translocation
Online: 20 August 2021 (11:43:31 CEST)
Membrane transporters (MTs) are mainly localized at the plasma membrane (PM), tonoplast and vacuolar membrane (VM) of cells in all plant organs. Their work is to maintain the cellular homeostasis by controlling ionic movements across PM channels from roots to upper plant parts, xylem loading and remobilization of sugar molecules from photosynthesis tissues in the leaf (source) to roots, stem and seeds (sink) via phloem loading. The plant’s whole source-to-sink relationship is regulated by multiple transporting proteins in a highly sophisticated manner and driven based on different stages of plant growth and development (PG&D), and environmental changes. The MTs play a pivotal role in PG&D in terms of increased plant height, branches/tiller numbers, enhanced numbers, length and filled panicles per plant, seed yield and grain quality. Dynamic climatic changes disturbed the ionic balance (salt, drought and heavy metals) and sugar supply (cold and heat stress). Due to poor selectivity, some of the MTs also uptake toxic elements in the roots that negatively impact on PG&D, later on also exported to upper parts and then deteriorate the grain quality. As an adaptive strategy, in response to salt and HMs plants activated PM and VM localized MTs that export toxic elements into vacuole, and also translocate in the root’s tips and shoot. However, in case of drought, cold and heat stresses, MTs increased the water and sugar supply to all organs. In this review, we mainly reviewed recent literature from Arabidopsis, halophytes, and major field crops such as rice, wheat, maize and oilseed rape to argue on the global role of MTs in PG&D and abiotic stress tolerance. We also discussed the gene expression level changes and genomic variations within a species as well as within a family in response to developmental and environmental cues.
HYPOTHESIS | doi:10.20944/preprints202108.0115.v1
Subject: Medicine & Pharmacology, Allergology Keywords: beta-amyloid toxicity, proteolytic digestion, membrane channel, intracellular ion disturbances, calcium homeostasis, intracellular pH, lysosome
Online: 4 August 2021 (13:19:50 CEST)
In this manuscript, we reassess the data on beta-amyloid-induced changes of intracellular ions concentrations published previously by Abramov et al. (2003, 2004). Their observations made using high-resolution confocal microscopy with fast temporal resolution of images formed by fluorescent ion-sensitive fluorescent probes in living cells represent an unequivocal support for the amyloid channel theory. However, closer look reveals multiple facts which cannot be explained by channel formation in plasma membrane. Recently proposed amyloid degradation toxicity hypothesis provides the interpretation to these facts by considering that channels are formed in the lysosomal membranes.
ARTICLE | doi:10.20944/preprints201910.0252.v1
Subject: Life Sciences, Molecular Biology Keywords: ferric ammonium citrate; deferoxamine; 2,2′-bipyridine; iron homeostasis; ISC; mitochondrial clearance; longevity; starvation; Parkinson’s disease
Online: 22 October 2019 (05:01:43 CEST)
Lifespan extension was recently achieved in Caenorhabditis elegans nematodes by mitochondrial stress and mitophagy, triggered via iron depletion. Conversely in man, deficient mitophagy due to Pink1/Parkin mutations triggers iron accumulation in patient brain and limits survival. We now aimed to identify murine fibroblast factors, which adapt their mRNA expression to acute iron manipulation, relate to mitochondrial dysfunction and may influence survival. After iron depletion, expression of the plasma membrane receptor Tfrc with its activator Ireb2, the mitochondrial membrane transporter Abcb10, the heme-release factor Pgrmc1, the heme-degradation enzyme Hmox1, the heme-binding cholesterol metabolizer Cyp46a1, as well as the mitophagy regulators Pink1 and Parkin showed a negative correlation to iron levels. After iron overload, these factors did not change expression. Conversely, a positive correlation of mRNA levels with both conditions of iron availability was observed for the endosomal factors Slc11a2 and Steap2, as well as for the iron-sulfur-cluster (ISC)-containing factors Ppat, Bdh2 and Nthl1. Positive correlation only after iron depletion was observed for the iron export factor Slc40a1, mitochondrial iron transporters Slc25a28, Abcb7 and Abcb8, mitochondrial ISC-containing factors Glrx5, Nfu1, Bola1 and Abce1, cytosolic Aco1 and Tyw5, as well as nuclear Dna2, Elp3, Pold1 and Prim2. The latter are regulators of nucleotide synthesis and DNA quality control, which have known importance for growth and lifespan. The only Pink1-/- triggered transcript modulation was the reduced expression of the ISC-containing ribosomal factor Abce1. These mammalian findings support previous fly data that Pink1 influences co-translational quality control via Abce1, as well as mitophagy. Our findings provide the first systematic survey how iron dosage triggers homeostatic transcriptional regulations and elucidate how iron deprivation results in mitophagy.
ARTICLE | doi:10.20944/preprints202208.0343.v1
Subject: Life Sciences, Molecular Biology Keywords: 14-3-3; interactome; protein-protein interaction; mitochondria; metabolism; protein quality control; homeostasis; left ventricule; network
Online: 18 August 2022 (10:54:49 CEST)
Rationale: The 14-3-3 protein family is known to interact with many proteins in non-cardiac cell types to regulate multiple signaling pathways, particularly those relating to energy and protein homeostasis; and the 14-3-3 network is a therapeutic target of critical metabolic and proteostatic signaling in cancer and neurological diseases. Although the heart is critically sensitive to nutrient and energy alterations, and multiple signaling pathways coordinate to maintain the cardiac cell homeostasis, neither the structure of cardiac 14-3-3 protein interactome, nor potential functional roles of 14-3-3 protein-protein interactions (PPIs) in heart has been explored. Objective: To establish the comprehensive landscape and characterize the functional role of cardiac 14-3-3 PPIs. Methods and Results: We evaluated both RNA expression and protein abundance of 14-3-3 isoforms in mouse heart, followed by co-immunoprecipitation of 14-3-3 proteins and mass spectrometry in left ventricle. We identified 52 proteins comprising the cardiac 14-3-3 interactome. Multiple bioinformatic analyses indicated that more than half of the proteins bound to 14-3-3 are related to mitochondria; and the deduced functions of the mitochondrial 14-3-3 network are to regulate cardiac ATP production via interactions with mitochondrial inner membrane proteins, especially those in mitochondrial complex I. Binding to ribosomal proteins, 14-3-3 proteins likely coordinate protein synthesis and protein quality control. Localizations of 14-3-3 proteins to mitochondria and ribosome were validated via immunofluorescence assays. The deduced function of cardiac 14-3-3 PPIs is to regulate cardiac metabolic homeostasis and proteostasis. Conclusions: Thus, the cardiac 14-3-3 interactome may be a potential therapeutic target in cardiovascular metabolic and proteostatic disease states, as it already is in cancer therapy.
REVIEW | doi:10.20944/preprints202012.0583.v1
Subject: Life Sciences, Biochemistry Keywords: sideroflexin; mitochondria; mitochondrial transporters; iron homeostasis; iron-sulfur cluster; heme biosynthesis; one-carbon metabolism; ferroptosis; ferritinophagy.
Online: 23 December 2020 (10:40:15 CET)
Sideroflexins (SLC56 family) are highly conserved multi-spanning transmembrane proteins inserted in the inner mitochondrial membrane in eukaryotes. Few data are available on their molecular function but, since their first description, they were thought to be metabolite transporters probably required for iron utilization inside the mitochondrion. Such as numerous mitochondrial transporters, sideroflexins remain poorly characterized. The prototypic member SFXN1 has been recently identified as the previously unknown mitochondrial transporter of serine. Nevertheless, pending questions on the molecular function of sideroflexins remain unsolved, especially their link with iron metabolism. Here, we review the current knowledge on sideroflexins, their presumed mitochondrial functions and the sparse - but growing - evidence linking sideroflexins to iron homeostasis and iron-sulfur cluster biogenesis. Since an imbalance in iron homeostasis can be detrimental at the cellular and organismal levels, we also investigate the relationship between sideroflexins, iron and physiological disorders. Investigating Sideroflexins’ functions constitutes an emerging research field of great interest and will certainly lead to main discoveries on mitochondrial physiopathology.
HYPOTHESIS | doi:10.20944/preprints202005.0177.v1
Subject: Biology, Physiology Keywords: SARS-CoV-2; COVID-19; homeostasis; hypoxic pulmonary vasoconstriction; renin-angiotensin system; hydrostatic edema; permeability edema
Online: 10 May 2020 (17:22:59 CEST)
A growing number of studies suggest that SARS-CoV-2 could interfere with homeostatic mechanisms in the lung but the implications of this possible interference have not been fully explored in the literature. In this work, we examine the consequences that can be drawn from this hypothesis according to currently available knowledge. We suggest that one such consequence is the potential disruption of normal ventilation and perfusion of lung regions that may be distant from the infection sites. Loss of ventilation might result in local alveolar hypoxia and contribute to hypoxemia, which in turn could trigger homeostatic responses that enhance blood oxygenation by redistributing pulmonary blood circulation. Sudden changes in perfusion might then lead to the development of hydrostatic edema and eventually to vascular remodeling and inflammation. Therefore, the immune response might not be the only source of the substantial inflammation observed in lung tissues of patients with severe COVID-19, as is often assumed in the literature. The balance between the homeostatic and the immune reaction in each patient could account for the observed heterogeneity of the clinical manifestations of COVID-19.
REVIEW | doi:10.20944/preprints201911.0389.v1
Subject: Life Sciences, Cell & Developmental Biology Keywords: GH and eNOS; IGF-I; oxidative stress and arterial inflammation; vascular homeostasis; Neovascularization; arteriogenesis; GHAS trial
Online: 30 November 2019 (10:14:06 CET)
Despite the important role that the GH/IGF-I axis plays in vascular homeostasis, these kind of growth factors barely appear in articles addressing the neovascularization process. Currently, the vascular endothelium has turned to be considered as an authentic gland of internal secretion due to the wide variety of released factors and functions with local effect, including the paracrine/autocrine production of GH or IGF-I, for which the endothelium has specific receptors. In this comprehensive review, it will be described the evidence involving these proangiogenic hormones in arteriogenesis dealing with the arterial occlusion and making of them a potential therapy. It will be analyzed all those elements triggering the local and systemic production of GH/IGF-I and their possible role both in physiological and pathological conditions. The whole evidence will be combined with important data from the GHAS trial, in which GH or placebo were administrated to patients suffering from critical limb ischemia with no option for revascularization. We postulate that GH, alone or in combination, should be considered as a promising therapeutic agent for helping in the approach of the ischemic disease.
ARTICLE | doi:10.20944/preprints202011.0709.v1
Subject: Life Sciences, Biochemistry Keywords: Sphingosine-1-phosphate receptor analogue; fingolimod phosphate; neuroprotection; mitochondrial damage; glycolytic pathway; pentose phosphate pathway; REDOX homeostasis.
Online: 30 November 2020 (08:31:50 CET)
Imbalance in the oxidative status in neurons, along with mitochondrial damage, are common characteristics in some neurodegenerative diseases. The maintenance in energy production is crucial to face and recover from the oxidative damage and the coexistence of different sources of energy production, such as mitochondrial and glycolytic ATP, allows faster adaptative mechanisms to situations of high energy demand and may help in the maintenance of neuronal function in stress situations. Fingolimod phosphate is a drug with neuroprotective and antioxidant actions, used in the treatment of Multiple Sclerosis. This work has been performed in a model of oxidative damage on neuronal cell cultures exposed to menadione, in presence or absence of fingolimod phosphate. We have studied the mitochondrial function and several pathways related with glucose metabolism, including oxidative, glycolytic and pentose phosphate in neuronal cells cultures. Our results showed a beneficial effect on neuronal survival probably based in the recovery of all, oxidative balance, glycolysis and pentose phosphate, promoted by fingolimod phosphate. These effects are mediated, at least in part by the interaction with its specific receptor. These actions would make this drug a potential tool to the treatment of neurodegenerative processes, either to slow progression or alleviate symptoms.
ARTICLE | doi:10.20944/preprints202105.0132.v1
Subject: Life Sciences, Biochemistry Keywords: aqueous fullerene dispersions; pristine fullerenes; metallofullerenes; ROS homeostasis; oxidative stress; NOX4; Nrf2; PRAR-γ; heme oxygenase 1; NAD(P)H quinone dehydrogenase 1; an-ti-inflammatory pathways
Online: 7 May 2021 (09:38:38 CEST)
Background: Fullerenes and metallofullerenes can be considered promising nanopharmaceuticals themselves and as a basis for chemical modification. As reactive oxygen species homeostasis plays a vital role in cells, the study of their effect on genes involved in oxidative stress and anti-inflammatory response is of particular importance. Methods: Human fetal lung fibroblasts were incubated with aqueous dispersions of C60, C70, and Gd@C82 in concentrations of 5 nM and 1.5 µM for 1, 3, 24, and 72 hours. Cell viability, intracellular ROS, NOX4, NFκB, PRAR-γ, NRF2, heme oxygenase 1, and NAD(P)H quinone dehydrogenase 1 expression have been studied. Results & conclusion: The aqueous dispersions of C60, C70, and Gd@C82 fullerenes are active participants in ROS homeostasis. Low and high concentrations of AFDs have similar effects. C70 was the most inert substance, C60 was the most active substance. All AFDs have both a “prooxidant” and “antioxidant” effect, but with a different balance. Gd@C82 was a substance with more pronounced antioxidant and anti-inflammatory properties, while C70 had more pronounced “prooxidant” properties.