ARTICLE | doi:10.20944/preprints201903.0089.v1
Subject: Biology, Other Keywords: Signalling, rhizosphere microbiome, plant hormones
Online: 7 March 2019 (11:58:15 CET)
Signalling is a strongly influenced area trending to be applied in almost every focus of biological sciences. The part of signalling or communication from cellular level to a whole organism including plant as well as animal drags a vast diversity of wealthy structural compounds. There is immense demand for new bioactive compounds for the pharmaceutical, agro and food industries. Plant-associated microbes present an attractive and promising source. The concept of the microbiome and the significance it has to host health, diseases state, and the role of immune have been the hub of research that has led to advances in our understanding of the massive power of the small unseen majority of the microbes (Peterson Andrew H., 2013). Before we say about microbiome—plant relation, it is important to first understand the working concept of the microbiome. Every organism on earth counts on their neighbours to sustain life. Microbiome can be considered a community of microorgasims who can prove to be loveable and hateful. The analysis of microbiome structure and function was protagonise in studies of human hosts and has been extensively documented as essential to genetic and functional capacity attributed to the host, comprehending aspects of metabolism and physiology. Plants are crowded with microbial organisms, counting those that colonize internal tissues, also those that adhere to external surfaces. The wide diversity of microorganisms in the soil rhizosphere is collectively plant–soil-associated microbes cover the plant microbiome. The intricate involvement of microbiome serves to plant health and as a tank of additional genes that plants can access when needed.
REVIEW | doi:10.20944/preprints201810.0707.v1
Online: 30 October 2018 (06:45:05 CET)
The immune system plays a major role in the surveillance and control of malignant cells, with the presence of tumor infiltrating lymphocytes (TILs) correlating with better patient prognosis in multiple tumor types. The development of ‘checkpoint blockade’ and adoptive cellular therapy has revolutionized the landscape of cancer treatment and highlights the potential of utilizing the patient’s own immune system to eradicate cancer. One mechanism of tumor-mediated immunosuppression that has gained attention as a potential therapeutic target is the purinergic signaling axis, whereby the production of the purine nucleoside adenosine in the tumor microenvironment can potently suppress T and NK cell function. The production of extracellular adenosine is mediated by the cell surface ectoenzymes CD73, CD39 and CD38 and therapeutic agents have been developed to target these as well as the downstream adenosine receptors (A1R, A2AR, A2BR, A3R) to enhance anti-tumor immune responses. This review will discuss the role of adenosine and adenosine receptor signaling in tumor and immune cells with a focus on their cell-specific function and their potential as targets in cancer immunotherapy.
REVIEW | doi:10.20944/preprints202104.0186.v1
Subject: Life Sciences, Biochemistry Keywords: Priming, endophytic bacteria; ISR; pathogens; signalling
Online: 7 April 2021 (10:30:06 CEST)
Bacterial endophytes interact closely with plant tissues and constitute an essential part of the plant microbiome. These interactions can promote plant growth and elicit specific defense responses against abiotic stresses and pathogen attacks. In this paper, we review the role of endophytic bacteria in modulating defenses of the host rendering the entire plant more resistant to pathogens and pests. The endophyte-induced resistance will probably introduce a new factor when consid-ering plant-pathogen interactions. The impact of the bacterial endosymbionts on the host leading to the priming state is also discussed since it confers a specific adaptation of the plant to the biotic threat.
Subject: Life Sciences, Biochemistry Keywords: Cyanobacteria; Gene expression; Regulation; Signalling; Stress
Online: 23 October 2020 (12:26:14 CEST)
Cyanobacteria are highly diverse, widely distributed photosynthetic bacteria inhabiting various environments ranging from deserts to the cryosphere. Throughout this range of niches, they have to cope with various stresses and kinds of deprivation which threaten their growth and viability. In order to adapt to these stresses and survive, they have developed several global adaptive responses which modulate the patterns of gene expression and the cellular functions at work. Sigma factors, two-component systems, transcriptional regulators and small regulatory RNAs acting either separately or collectively, for example, induce appropriate cyanobacterial stress responses. The aim of this review is to summarize our current knowledge about the diversity of the sensors and regulators involved in the perception and transduction of light, oxidative and thermal stresses and nutrient starvation responses. The studies discussed here point to the fact that various stresses affecting the photosynthetic capacity are transduced by common mechanisms.
REVIEW | doi:10.20944/preprints202209.0099.v1
Subject: Life Sciences, Virology Keywords: enterovirus; viral proteins; signalling pathways; host-pathogen interaction
Online: 7 September 2022 (04:41:56 CEST)
Enteroviruses are members of Pichornaviridae family consisting of human enterovirus group A, B, C, and D as well as nonhuman enteroviruses. Human enterovirus type 71 (EV71) has emerged as a major cause of viral encephalitis Hand, foot, and mouth disease (HFMD) in children worldwide especially in the Asia‐Pacific region. EV71 and coxsackievirus A16 are two viruses responsible for HFMD which are members of group A enterovirus. The identified EV71 receptors provide useful information for understanding viral replication and tissue tropism. Host factors interact with the internal ribosome entry site (IRES) of EV71 to regulate viral translation. However, the specific molecular features of the EV71 genome that determine virulence remain unclear. Although an EV71 vaccine has been currently approved, there is no effective therapy for treating EV71 infected patients. Therefore, understanding the host-pathogen interaction could provide the knowledge in viral pathogenesis and further benefit in the anti-viral therapy development. The aim of this study was to investigate the latest findings about the interaction of viral ligands to the host receptor as well as the activation of immune related signalling pathways for the activation of innate immunity and involvement of different cytokines and chemokines in the host pathogen interaction of EV71 along with interaction of viral proteins, mainly 2A and 3C protease, and Interferons production/signaling pathway and their inhibitory effects.
REVIEW | doi:10.20944/preprints201911.0170.v1
Subject: Biology, Other Keywords: PI3K signalling; cancer; stemness; pluripotent stem cells; development
Online: 15 November 2019 (03:59:00 CET)
The PI3K/AKT pathway is a key target in oncology where most efforts are focussed on phenotypes such as cell proliferation and survival. Comparatively little attention has been paid to PI3K in stemness regulation, despite the emerging link between acquisition of stem cell-like features and therapeutic failure in cancer. The aim of this review is to summarise current known and unknowns of PI3K-dependent stemness regulation, by integrating knowledge from the fields of developmental, signalling and cancer biology. Particular attention is given to the role of the PI3K pathway in pluripotent stem cells (PSCs) and the emerging parallels to dedifferentiated cancer cells with stem cell-like features. Compelling evidence suggests that PI3K/AKT signalling forms part of a ‘core molecular stemness programme’ in both mouse and human PSCs. In cancer, the oncogenic PIK3CAH1047R variant causes constitutive activation of the PI3K pathway and has recently been linked to increased stemness in a dose-dependent manner, similar to observations in mouse PSCs with heterozygous versus homozygous Pten loss. There is also evidence that the stemness phenotype may become ‘locked’ and thus independent of the original PI3K activation, posing limitations for the success of PI3K monotherapy in cancer.Ongoing therapeutic developments for PI3K-associated cancers may therefore benefit from a better understanding of the pathway’s two-layered and highly context-dependent regulation of cell growth versus stemness.
REVIEW | doi:10.20944/preprints201806.0168.v1
Subject: Medicine & Pharmacology, Ophthalmology Keywords: neovascular AMD; new therapies; anti-VEGFs; AMD signalling
Online: 12 June 2018 (06:26:56 CEST)
Neovascular age-related macular degeneration (nAMD) accounts for one of the leading causes of blindness among the aging population. The current treatment options for nAMD include intravitreal injections of anti-vascular endothelial growth factor (anti-VEGF). However, standardised frequent administration of anti-VEGF injections only improves the vision in approximately 30%-40% of nAMD patients. Current therapies targeting nAMD pose a significant risk of retinal fibrosis and geographic atrophy (GA) development in nAMD patients. A need exists to develop new therapies to treat nAMD with effective and long-term anti-angiogenic effects. Recent research on nAMD has discovered novel therapeutic targets and angiogenic signalling mechanisms involved in its pathogenesis. For example, tissue factor, human intravenous immune globulin, interferon-β signalling, cyclooxygenase-2 (COX-2) and cytochrome P450 monooxygenase lipid metabolites have been identified as key players in the development of angiogenesis in AMD disease models. Furthermore, novel therapies such as NLRP3 inflammasome inhibition, targeted intraceptor nanoparticle therapy, inhibitors of integrins and tissue factor are currently being tested at the level of clinical trials to treat nAMD. The aim of this review is to discuss the scope for alternative therapies proposed to anti-VEGFs for the treatment of nAMD.
REVIEW | doi:10.20944/preprints202106.0500.v1
Subject: Life Sciences, Biochemistry Keywords: anticancer; antimicrobial; antioxidants; cancer signalling; citral; Cymbopogon; essential oil
Online: 21 June 2021 (10:31:35 CEST)
The prominent cultivation of lemongrass relies on the pharmacological incentives of its essential oil. The lemongrass essential oil (LEO) has a significant amount of citral (mixture of geranial and neral), isoneral, isogeranial, geraniol, geranyl acetate, citronellal, citronellol, germacrene-D, and elemol in addition to numerous other bioactive compounds. These components confer various medicinal activities to LEO including antifungal, antibacterial, antiviral, anticancer, and antioxidant properties. These attributes are commercially exploited in pharmaceutical, cosmetics, and food preservations industries. Furthermore, the employment of LEO in the treatment of cancer opens a new vista in the field of therapeutics. Although different LEO components have shown promising anticancer activities in vitro, these effects have not been assessed yet in humans. Further studies on the anticancer mechanisms exerted by lemongrass components are required. The present review intends to provide a timely discussion on the relevance of lemongrass extracts in cancer and health treatment, and in food industry applications.
REVIEW | doi:10.20944/preprints202105.0367.v1
Subject: Life Sciences, Biochemistry Keywords: PI3K/mTOR signalling; feedback loop; crosstalk; nonlinear dynamics; cancer
Online: 17 May 2021 (07:54:13 CEST)
The PI3K/mTOR signalling pathway plays a central role in the governing of cell growth, survival and metabolism. As such, it must integrate and decode information from both external and internal sources to guide efficient decision-making by the cell. To facilitate this, the pathway have evolved an intricate web of complex regulatory mechanisms and elaborate crosstalk with neighbouring signalling pathways, making it a highly non-linear system. Here, we describe the mechanistic biological details that underpin these regulatory mechanisms, covering a multitude of negative and positive feedback loops, feed-forward loops, competing protein interactions, and crosstalk with major signalling pathways. Further, we highlight the non-linear and dynamic network behaviours that arise from these regulations, uncovered through both computational and experimental studies. Given the pivotal role of the PI3K/mTOR network in cellular homeostasis and its frequent dysregulation in pathologies including cancer and diabetes, a coherent and systems-level understanding of the complex regulation and consequential dynamic signalling behaviours within this network is imperative for advancing biology and development of new therapeutic approaches.
REVIEW | doi:10.20944/preprints201809.0392.v1
Subject: Life Sciences, Cell & Developmental Biology Keywords: H2O2, redox signalling, development, regeneration, adult stem cells, metazoan
Online: 19 September 2018 (21:42:44 CEST)
Reactive oxygen species (ROS), which were originally classified as exclusively deleterious compounds, have gained increasing interest in the recent years given their action as bona fide signalling molecules. The main target of ROS action is the reversible oxidation of cysteines, leading to the formation of disulfide bonds, which modulate protein conformation and activity. ROS endowed with signalling properties are mainly produced by NADPH oxidases at the plasma membrane, but their action also involves a complex machinery of multiple redox-sensitive protein families that differs in their subcellular localization and their activity. Given that the levels and distribution of ROS are highly dynamic in part due to their limited stability, the development of various fluorescent ROS sensors, some of which are quantitative (ratiometric), represents a clear breakthrough in the field and have been adapted to both ex vivo and in vivo applications. The physiological implication of ROS signalling will be presented mainly in the frame of morphogenetics processes, embryogenesis, regeneration, and stem cell differentiation. Gain and loss of function as well as pharmacological strategies have demonstrated the wide but specific requirement of ROS signalling at multiple stages of these processes and its intricate relationship with other well-known signalling pathways.
REVIEW | doi:10.20944/preprints202107.0614.v1
Subject: Keywords: Triple-negative breast cancer; cannabinoid; marijuana; cell signalling; medicinal plants
Online: 28 July 2021 (08:56:32 CEST)
Triple-negative breast cancer (TNBC) is a subtype of breast cancer characterized by the lack of estrogen receptors (ER), progesterone receptors, and HER-2 receptors. Thus, TNBC tumours do not benefit from the current therapies targeting ER or HER-2. Therefore, there is an urgent need to develop novel treatment for this subtype of breast cancer. Marijuana is a common name given to Cannabis plants, a group of plants in the Cannabis genus of the Cannabaceae family. Cannabis plants are among the oldest cultivated crops, traced back at least 12,000 years and are well known for their multi-purpose usage, including medicinal purposes. The main active compounds extracted from Cannabis plants are 21-carbon-containing terpenophenolics, which are referred to as phytocannabinoids. Of these, the tetrahydrocannabinol (THC) group contains highly potent cannabinoids, including delta-9-tetrahydrocannabinol (∆9-THC) and delta-8-tetrahydrocannabinol (∆8-THC), which are the most abundant THCs and are largely responsible for psychological and physiological effects of marijuana. The use of Cannabis plants for medicinal purposes was first recorded in 2337 BC in China, where Cannabis plants were used to treat pains, rheumatism, and gout. Recently, several cannabinoids have been approved for a number of treatments, one of which is the treatment of nausea and vomiting caused by chemotherapy in cancer patients. Furthermore, increasing evidence shows that cannabinoids not only attenuate side effects due to cancer treatment, but might also potentially possess direct antitumor effects in several cancer types, including breast cancer. However, anti-tumour activity of marijuana has been variable in different studies and even promoted tumour growth in some cases. In addition, the mechanisms of cannabinoid action in cancer remain unclear. This review summarizes evidence about the mixed actions of cannabinoids in cancer in general and triple-negative breast cancer in particular.
REVIEW | doi:10.20944/preprints201909.0120.v1
Subject: Life Sciences, Biochemistry Keywords: Lysophosphatidic acid; Autotaxin; inhibitor; allosteric; orthosteric; lipid chaperone; signalling, GPCR
Online: 11 September 2019 (13:18:21 CEST)
Autotaxin (ATX) is a secreted lysophospholipase D, catalysing the conversion of lysophosphatidylcholine (LPC) to bioactive lysophosphatidic acid (LPA). LPA acts through two families of G protein-coupled receptors (GPCRs) controlling key cellular responses, and is implicated in many physiological processes and pathologies. ATX has therefore been established as an important drug target in the pharmaceutical industry. Structural and biochemical studies of ATX have shown that it has a bimetallic nucleophilic catalytic site, a substrate-binding (orthosteric) hydrophobic pocket that accommodates the lipid alkyl chain, and an allosteric tunnel that can accommodate various steroids and LPA. Here we first review what is known about ATX-mediated catalysis, crucially in light of allosteric regulation. We then present the known ATX catalysis-independent functions, including binding to cell-surface integrins and proteoglycans. In light of these data we then discuss the four types of ATX inhibitors, as classified depending on their binding to the orthosteric and/or the allosteric site. Finally, we analyse the binding mode of known members of all four types and discuss how mechanistic differences might differentially modulate the activity of the ATX-LPA signalling axis, and clinical applications including cancer.
CONCEPT PAPER | doi:10.20944/preprints201806.0255.v1
Subject: Biology, Plant Sciences Keywords: morphogenesis, cell wall protein, Hechtian oscillator, calcium signalling, H+ ATPase
Online: 15 June 2018 (14:15:29 CEST)
Morphogenesis remains a riddle, wrapped in a mystery, inside an enigma. It remains a formidable problem viewed from many different perspectives of morphology, genetics, and computational modelling. We propose a biochemical reductionist approach that shows how both internal and external physical forces contribute to plant morphogenesis via mechanical stress-strain transduction from the primary cell wall tethered to the plasma membrane by a specific arabinogalactan protein (AGP). The resulting stress vector with direction defined by Hechtian adhesion sites, has a magnitude of a few picoNewtons amplified by a hypothetical Hechtian growth oscillator. This paradigm shift involves stress activated plasma membrane Ca2+channels and auxin-activated H+-ATPase. The proton pump dissociates periplasmic AGP-glycomodules that bind Ca2+. Thus, as the immediate source of cytosolic Ca2+ an AGP-Ca2+ capacitor directs vectorial exocytosis of cell wall precursors and auxin efflux (PIN) proteins. In toto these components comprise the Hechtian Oscillator and also the gravisensor. Thus interdependent auxin and Ca2+ morphogen gradients account for the predominance of AGPs. The size and location of a cell surface AGP-Ca2+ capacitor is essential to differentiation and explains AGP correlation with all stages of morphogenetic patterning from embryogenesis to root and shoot. Finally, evolutionary origins of the Hechtian Oscillator in the unicellular Chlorophycean algae reflect the ubiquitous role of chemiosmotic proton pumps that preceded DNA at the dawn of life.
REVIEW | doi:10.20944/preprints202102.0300.v1
Subject: Biology, Anatomy & Morphology Keywords: Evolution of multicellularity; Amoebozoa; Dictyostelia; cAMP signalling; encystation; cell type evolution
Online: 12 February 2021 (11:15:40 CET)
Multicellularity evolved repeatedly in the history of life, but how it unfolded varies greatly between different lineages. Dictyostelid social amoebas offer a good system to study the evolution of multicellular complexity, with a well-resolved phylogeny and molecular genetic tools being available. We compare the life cycles of the Dictyostelids with closely related amoebozoans to show that complex life cycles were already present in the unicellular common ancestor of Dictyostelids. We propose frost resistance as an early driver of multicellular evolution in Dictyostelids and show that the cell signalling pathways for differentiating spore and stalk cells evolved from that for encystation. The stalk cell differentiation program was further modified, possibly through gene duplication, to evolve a new cell type, cup cells, in Group 4 Dictyostelids. Studies in various multicellular organisms including Dictyostelids, volvocine algae, and metazoans suggest as a common principle in the evolution of multicellular complexity that unicellular regulatory programs for adapting to environmental change serve as “proto-cell types” for subsequent evolution of multicellular organisms. Later, new cell types could further evolve by duplicating and diversifying the “proto-cell type” gene regulatory networks.
REVIEW | doi:10.20944/preprints202008.0359.v1
Subject: Biology, Plant Sciences Keywords: Abiotic stress; Melatonin; Water stress; Drought; Waterlogging; Antioxidants; Stress signalling, phytohormones
Online: 17 August 2020 (10:19:52 CEST)
Water stress (drought and waterlogging) is drastic abiotic stress to plant growth and development. Melatonin, bioactive plant hormone, has been widely tested in drought situations in diverse plant species, while a few studies on the role of melatonin in waterlogging stress conditions have been published. In the current review, we analyze the bio-stimulatory functions of melatonin on plants under both drought and waterlogging stress. Melatonin controls the levels of reactive oxygen and nitrogen species and positively changes the molecular defense to improve plant tolerance against drought and waterlogging stress. Moreover, the crosstalk of melatonin and other phytohormones is a key element on plant survival under drought stress, while this relationship needs further investigation under waterlogging stress. In this review, we draw the complete story of water stress on both sides: drought and waterlogging through discussing the previous critical studies under both conditions. Moreover, we suggest several research directions, especially for waterlogging, which remains a big vague piece of melatonin and water stress puzzle.
REVIEW | doi:10.20944/preprints201802.0029.v1
Subject: Biology, Plant Sciences Keywords: protease; plant; pathogen; defence; substrate; immunity; hypersensitive response; recognition; signalling; priming
Online: 5 February 2018 (04:11:42 CET)
Proteases are integral enzymes of the plant immune system. Multiple aspects of defence are regulated by proteases, including the hypersensitive response, pathogen recognition, priming and peptide hormone release. These processes are regulated by unrelated proteases residing at different subcellular locations. In this review we discuss ten prominent plant proteases contributing to the plant immune system, highlighting the diversity of roles they perform in plant defence.
ARTICLE | doi:10.20944/preprints201912.0238.v2
Subject: Life Sciences, Immunology Keywords: CCR6-CCL20 Axis; Colitis; Winnie; Multi-system pathophysiology; Molecular signalling; Immune mechanisms
Online: 13 January 2020 (11:07:04 CET)
The immunomodulatory behaviour of the CCR6/CCL20 axis in multi -system pathophysiology and molecular signalling was investigated at two clinically significant time points, using a Ccr6 - deficient mouse model of spontaneous colitis. Four groups of mice, (C57BL/6J, Ccr6-/- of C57BL/6J, Winnie x Ccr6 -/- and Winnie) were utilized and (I) colonic clinical parameters (2) histology of colon, spleen, kidney and liver (3) T and B lymphocyte distribution in the spleen and MLN by flowcytometry (5) colonic CCL20, phosphorylated PI3K and phosphorylated Akt expression by immunohistochemistry and (6) colonic cytokine expression by RT-PCR were evaluated. CCR6 deficiency was shown to attenuate inflammation in the spleen, liver and gut while renal histology remained unaffected. Marked focal lobular inflammation with reactive nuclear features were observed in hepatocytes and a significant neutrophil infiltration in red pulp with extra medullary hemopoiesis in the spleen existed in Winnie. These changes were considerably reduced in Winnie x Ccr6-/- with elevated goblet cell numbers and mucus production in the colonic epithelium. Results indicate that Ccr6- deficiency in the colitis model contributes towards resolution of disease. Our findings demonstrate an intricate networking role for CCR6 in immune activation, which is downregulated by Ccr6 deficiency, and could provide newer clinical therapies in colitis.
Subject: Medicine & Pharmacology, Allergology Keywords: cardiac fibroblasts; WNT3a; WNT5a; beta-catenin; TGF-beta signalling; IL-11; cardiac fibrosis
Online: 29 July 2021 (13:15:00 CEST)
Cardiac fibrosis is a pathological process associated with development of heart failure. TGF-β and WNT signaling have been implicated in pathogenesis of cardiac fibrosis, however little is known about molecular cross-talk between these two pathways. The aim of this study was to examine the effect of exogenous canonical WNT3a and non-canonical WNT5a in TGF-β-activated human cardiac fibroblasts. We found that WNT3a and TGF-β induced -catenin-dependent response, whereas WNT5a prompted AP-1 activity. TGF-β triggered profibrotic signature in cardiac fibroblasts, and co-stimulation with WNT3a or co-activation of the β-catenin pathway with GSK3β inhibitor CHIR99021 enhanced collagen I and fibronectin production and development of active contractile stress fibers. In the absence of TGF-β, neither WNT3a nor CHIR99021 exerted profibrotic response. On a molecular level, in TGF-β-activated fibroblasts WNT3a enhanced phosphorylation of TAK1 and production and secretion of IL-11 but showed no effect on Smad pathway. Neutralization of IL-11 activity with the blocking anti-IL-11 antibody effectively reduced profibrotic response of cardiac fibroblasts activated with TGF-β and WNT3a. In contrast to canonical WNT3a, co-activation with non-canonical WNT5a suppressed TGF-β-induced production of collagen I. In conclusion, WNT/β-catenin signaling promotes TGF-β-mediated fibroblast-to-myofibroblast transition by enhancing IL-11 production. Thus, the uncovered mechanism broadens our knowledge on molecular basis of cardiac fibrogenesis and defines novel therapeutic targets for fibrotic heart diseases.
Subject: Life Sciences, Cell & Developmental Biology Keywords: Prostaglandin D2; BW245c; prostanoid signalling; EP4 receptor; endothelial barrier; barrier disruption; microvascular endothelium
Online: 12 June 2020 (05:05:37 CEST)
Life-threatening inflammatory conditions such as acute respiratory distress syndrome or sepsis often go hand in hand with severe vascular leakage. During inflammation, endothelial cell integrity and intact barrier function are crucial to limit leukocyte and plasma extravasation. Prostaglandin D2 (PGD2) is a potent inflammatory lipid mediator with vasoactive properties. It has been suggested that PGD2 is involved in the regulation of endothelial barrier function; however, it is unclear whether this is also true for primary human pulmonary microvascular endothelial cells. Furthermore, as PGD2 is a highly promiscuous ligand, we set out to determine which receptors are important in human pulmonary endothelial cells. In the current study, we found that PGD2 and the DP1 agonist BW245c potently strengthened pulmonary and dermal microvascular endothelial cell barrier function and protected against thrombin-induced barrier disruption. Yet surprisingly, these effects were mediated only to a negligible extent via DP1 receptor activation. In contrast, we observed that the EP4 receptor was most important and mediated the barrier enhancement by PGD2 and BW245c. These data demonstrate a novel mechanism by which PGD2 may modulate inflammation and emphasizes the role of EP4 receptors in human endothelial cell function.
REVIEW | doi:10.20944/preprints202009.0051.v1
Subject: Life Sciences, Biochemistry Keywords: PDE2; cAMP/cGMP crosstalk; natriuretic peptides; NO signalling; heart failure; arrhythmia; inflammation; cardiovascular disease
Online: 3 September 2020 (04:20:07 CEST)
Phosphodiesterases (PDEs) are the principal superfamily of enzymes responsible for degrading the secondary messengers 3’,5’-cyclic nucleotides cAMP and cGMP. Their refined subcellular localization and substrate specificity contribute to finely regulate cAMP/cGMP gradients in various cellular microdomains. Redistribution of multiple signal compartmentalization components is often perceived under pathological conditions. Thereby PDEs have long been pursued as therapeutic targets in diverse disease conditions including neurological, metabolic, cancer and autoimmune disorders in addition to numerous cardiovascular diseases. PDE2 is a unique member of the broad family of PDEs. In addition to its capability to hydrolyze both cAMP and cGMP, PDE2 is the sole isoform that may be allosterically activated by cGMP increasing its cAMP hydrolyzing activity. Within the cardiovascular system, PDE2 serves as an integral regulator for the crosstalk between cAMP/cGMP pathways and thereby may couple chronically adverse augmented cAMP signalling with cardioprotective cGMP signalling. This review provides a comprehensive overview of PDE2 regulatory functions in multiple cellular components within the cardiovascular system and also within various subcellular microdomains. Implications for PDE2 mediated crosstalk mechanisms in diverse cardiovascular pathologies are discussed highlighting the prospective use of PDE2 as a potential therapeutic target in cardiovascular disorders.
REVIEW | doi:10.20944/preprints202108.0552.v1
Subject: Life Sciences, Cell & Developmental Biology Keywords: antagonistic pleiotropy; insulin/IGF-1 signalling; hyperfunction; quasi-programs; mTOR; theories of aging; programmatic aging
Online: 30 August 2021 (16:11:02 CEST)
The process of senescence (aging) is largely determined by the action of wild-type genes. For most organisms, this does not reflect any adaptive function of senescence, but rather evolutionary effects of declining selection against genes with deleterious effects later in life. To understand aging requires an account of how evolutionary mechanisms give rise to pathogenic gene action and late-life disease, that integrates evolutionary (ultimate) and mechanistic (proximate) causes into a single explanation. A well-supported evolutionary explanation by G.C. Williams argues that senescence can evolve due to pleiotropic effects of alleles with antagonistic effects on fitness and late-life health (antagonistic pleiotropy, AP). What has remained unclear is how gene action gives rise to late-life disease pathophysiology. One ultimate-proximate account is T.B.L. Kirkwood’s disposable soma theory. Based on the hypothesis that stochastic molecular damage causes senescence, this reasons that aging is coupled to reproductive fitness due to preferential investment of resources into reproduction, rather than somatic maintenance. An alternative and more recent ultimate-proximate theory argues that aging is largely caused by programmatic, developmental-type mechanisms. Here ideas about AP and programmatic aging are reviewed, particularly those of M.V. Blagosklonny (the hyperfunction theory) and J.P. de Magalhães (the developmental theory), and their capacity to make sense of diverse experimental findings is described.
Subject: Biology, Physiology Keywords: calmodulin; calmodulin binding proteins; calmodulin binding motifs; calcium signalling; EF hands; heart arrythmia; neurodegeneration; Dictyostelium discoideum
Online: 15 December 2019 (15:44:35 CET)
Dictyostelium discoideum is gaining increasing attention as a model organism for the study of calcium binding and calmodulin function in basic biological events as well as human diseases. After a short overview of calcium-binding proteins, the structure of Dictyostelium calmodulin and the conformational changes effected by calcium ion binding to its four EF hands is compared to its human counterpart, emphasizing the highly conserved nature of this central regulatory protein. The calcium-dependent and -independent motifs involved in calmodulin binding to target proteins are discussed with examples of the diversity of calmodulin binding proteins that have been studied in this amoebozoan. The methods used to identify and characterize calmodulin binding proteins is covered followed by the ways Dictyostelium is currently being used as a system to study several neurodegenerative diseases and how it could serve as a model for studying calmodulinopathies such as those associated with specific types of heart arrythmia. Because of its rapid developmental cycles, its genetic tractability, and a richly endowed stock center, Dictyostelium is in a position to become a leader in the field of calmodulin research.
REVIEW | doi:10.20944/preprints202012.0112.v1
Subject: Life Sciences, Biochemistry Keywords: Hypoxia; HIF-1α; HIF-2α; Posttranslational modifications; Phosphorylation; Acetylation; Ubiquitination; Sumoylation; S-Nitrosylation; Signalling; cystein phosphorylation; methylation
Online: 4 December 2020 (13:45:45 CET)
The hypoxia signalling pathway enables adaptation of cells to decreased oxygen availability. When oxygen becomes limiting, the central transcription factors of the pathway, hypoxia-inducible factors (HIFs), are stabilised and activated to induce the expression of hypoxia-regulated genes, thereby maintaining cellular homeostasis. Whilst hydroxylation has been thoroughly described as the major and canonical modification of the HIF-α subunits, regulating both HIF stability and activity, a range of other post-translational modifications decorating the entire protein play also a crucial role in altering HIF localisation, stability, and activity. These modifications, their conservation throughout evolution and their effects on HIF-dependent signalling are discussed in this review.
ARTICLE | doi:10.20944/preprints201810.0456.v1
Subject: Life Sciences, Biochemistry Keywords: chlorophyll fluorescence; J8-1 plum line; mandelonitrile; Prunus domestica; redox signalling; salicylic acid; salt-stress; soluble nutrients
Online: 19 October 2018 (14:57:02 CEST)
Salinity is considered as one of the most important abiotic challenges that affect crop productivity. Plant hormones, including salicylic acid (SA), are key factors in the defence signalling output triggered during plant responses against environmental stresses. We have previously reported in peach a new SA biosynthetic pathway from mandelonitrile (MD), the molecule at the hub of the cyanogenic glucoside turnover in Prunus sp. In this work, we have studied whether this new SA biosynthetic pathway is also present in plum and the possible role this pathway plays in plant plasticity under salinity, focusing on the transgenic plum line J8-1, which displays stress tolerance via an enhanced antioxidant capacity. The SA biosynthesis from MD in non-transgenic and J8-1 micropropagated plum shoots was studied by metabolomics. Then the response of J8-1 to salt stress in presence of MD or Phe (MD precursor) was assayed by measuring: chlorophyll content and fluorescence parameters, stress related hormones, levels of non-enzymatic antioxidants, the expression of two genes coding redox-related proteins, and the content of soluble nutrients. The results from in vitro assays suggest that the SA synthesis from the MD pathway demonstrated in peach is not clearly present in plum, at least under in vitro conditions. Nevertheless, in J8-1 NaCl-stressed seedlings, an increase in SA was recorded as a result of the MD treatment, suggesting that MD could be involved in the SA biosynthesis under NaCl stress conditions in plum plants. We have also shown that the plum line J8-1 was tolerant to NaCl under greenhouse conditions, and this response was somewhat different in MD-treated plants. In that regards, the MD treatment produced an increase in SA, jasmonic acid (JA) and reduced ascorbate (ASC) contents as well as in the coefficient of non-photochemical quenching (qN) and the gene expression of Non-Expressor of Pathogenesis-Related 1 (NPR1) and thioredoxin H (TrxH) under salinity conditions, suggesting a crosstalk between different signalling pathways (NPR1/Trx and SA/JA) leading to salinity tolerance in the transgenic plum line J8-1.
REVIEW | doi:10.20944/preprints201807.0237.v1
Subject: Medicine & Pharmacology, General Medical Research Keywords: TRPM7, kinase, inflammation, lymphocytes, calcium signalling, SMAD, TH17, hypersensitivity, regulatory T cells, thrombosis, graft versus host disease, T cells, innate immunity
Online: 13 July 2018 (14:14:56 CEST)
The enzyme-coupled transient receptor potential channel subfamily M member 7, TRPM7, has been associated with immunity and immune cell signalling. Here, we review the role of this remarkable signalling protein in lymphocyte proliferation, differentiation, activation and survival. We also discuss its role in mast cell, neutrophil and macrophage function and highlight the potential of TRPM7 to regulate immune system homeostasis. Further, we shed light on how the cellular signalling cascades involving TRPM7 channel and/or kinase activity culminate in pathologies as diverse as allergic hypersensitivity, arterial thrombosis, and graft versus host disease (GVHD), stressing the need for TRPM7 specific pharmacological modulators.
ARTICLE | doi:10.20944/preprints202207.0058.v1
Subject: Life Sciences, Biophysics Keywords: human interferon gamma; human interferon gamma receptor; receptor binding; heparan sulfate; co-receptor; molecular dynamics simulations; sodium chlorate; kynurenine antiproliferative assays; hIFNγ signalling
Online: 5 July 2022 (04:43:05 CEST)
The extremely controversial conclusions about the function of human interferon-gamma (hIFNγ) C-terminus as well as the lack of a consistent model explaining its role in the receptor binding prompted us to scrutinize the interaction of hIFNγ with its extracellular receptor hIFNGR1 in different scenarios by means of molecular dynamics simulations. We find that the two molecules alone fail to form a stable complex but the presence of heparan-sulfate-like oligosaccharides largely facilitates the process by both demobilizing the highly flexible C-termini of the cytokine and assisting in the proper positioning of its globule between the receptor subunits. An antiproliferative-activity essay on cells depleted from surface sulfation confirms qualitatively the simulation-based multistage complex-formation model. Our results reveal the key role of HS and its proteoglycans in all processes involving hIFNγ signalling.