‘Inner mitochondrial membrane peptidase 2 like’ (IMMP2L) is a nuclear encoded mitochondrial peptidase that has been conserved through evolutionary history as has its target enzyme ‘mitochondrial glycerol phosphate dehydrogenase 2’ (GPD2). IMMP2L is known to cleave the mitochondrial transit peptide from GPD2 and another nuclear encoded mitochondrial respiratory related protein cytochrome C1 (CYC1). However, it is not known whether IMMP2L peptidase activates or alters the activity or respiratory related functions of GPD2 or CYC1. Previous investigations found compelling evidence of behavioural change in the Immp2lKD-/- KO mouse and in this study EchoMRI analysis found that many organs of the Immp2lKD-/- KO mouse were smaller and that the KO mouse had significantly less lean mass and overall body weight compared with wildtype littermates (p<0.05). Moreover, all of the organs analysed from the Immp2lKD-/- KO had lower relative levels of mitochondrial reactive oxygen species (mitoROS). The kidneys of the Immp2lKD-/- KO mouse displayed the greatest decrease in mitoROS levels that were over 50% less compared with wildtype litter mates. Mitochondrial respiration was also lower in the kidney of the Immp2lKD-/- KO mouse compared with other tissues when using succinate as the respiratory substrate, whereas respiration was similar to wildtype when glutamate was used as substrate. When glycerol-3-phosphate (G3P) was used as the substrate for Gpd2 we observed ~20% and ~7% respective decreases in respiration in female and male Immp2lKD-/- KO mice over time. Together these findings suggest that the respiratory related functions of mGpd2 and Cyc1 have been compromised to different degrees in different tissues in the Immp2lKD-/- KO mouse. Structural analyses using AlphaFold2-Multimer further predicted that the interaction between Cyc1 and mitochondrial encoded cytochrome b (Cyb) in Complex III had been altered as had the homodimeric structure of the mGpd2 enzyme within the inner mitochondrial membrane of the Immp2lKD-/- KO mouse. mGpd2 functions as an integral component of the glycerol phosphate shuttle (GPS) which positively regulates both mitochondrial respiration and glycolysis. Interestingly, we found that nonmitochondrial respiration (NMR) was also dramatically lowered in the Immp2lKD-/- KO mouse. Primary mouse embryonic fibroblast (MEF) cell lines derived from the Immp2lKD-/- KO mouse displayed a ~27% decrease in total respiration comprised of a ~50% decrease in NMR and a ~12% decrease in total mitochondrial respiration where the latter was consistent with the decreases in substrate specific mitochondrial respiration reported here. This study is the first to report the role of Immp2l in enhancing Gpd2 structure and function, mitochondrial respiration, nonmitochondrial respiration, organ size and homeostasis.

Pancreatic cancer (pancreatic ductal adenocarcinoma: PDAC) is one of the most aggressive neoplastic diseases. Metformin use was associated with reduced pancreatic cancer incidence or better survival in diabetics. Metformin has been shown to inhibit PDAC cells survival and growth in vitro and in vivo. However, clinical trials using metformin failed to decrease pancreatic cancer progression in patients, raising important questions about molecular mechanisms that protect tumor cells from the antineoplastic activities of metformin. We confirm that metformin acts through inhibition of mitochondrial complex I, decreasing the NAD+/NADH ratio and that NAD+/NADH homeostasis determines metformin sensitivity in several cancer cell lines. Metabolites that can restore the NAD+/NADH ratio turned PDAC cells resistant to metformin. In addition, metformin treatment of PDAC cell lines induced a compensatory NAMPT expression increasing the pool of cellular NAD+. The NAMPT inhibitor FK866 sensitized PDAC cells to the antiproliferative effects of metformin in vitro and decreased cellular NAD+ pool. Intriguingly, FK866 combined with metformin increased survival in mice bearing KP4 cells xenografts but not in mice with PANC1 xenografts. Transcriptome analysis revealed that the drug combination reactivated genes in the p53 pathway and oxidative stress providing new insights about the mechanisms leading to cancer cell death.

The emerging of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak is associated with high morbidity and mortality rates globally. One of the most prominent characteristics of coronavirus disease-19 (COVID-19) is lymphopenia which is in contrast to other viral infections. This controversy might be explained by the evaluation of impaired innate and adaptive immune responses during the SARS-CoV-2 infection. During the innate immune response, poly-ADP-ribose polymerase (PARP) hyperactivated due to virus entry and extensive DNA damage sequentially leading to NAD+ depletion, ATP depletion and finally cell death. In contrast to the immune response against viral infections, cytotoxic T lymphocytes decline sharply in SARS-CoV-2 infection which might be due to infiltration and trapping in the lower respiratory tract. In addition, there are more factors proposed to involve in lymphopenia in COVID-19 infection like the role of CD38 which functions as NADase and intensifies NAD depletion which in turn affects NAD+ dependent Sirtuin proteins, as the regulators of cell death and viability. Lung tissue sequestration following cytokine storm supposed to be another reason for lymphopenia in COVID-19 patients. Protein 7a as one of the virus-encoded proteins induces apoptosis in various organ-derived cell lines. These mechanisms proposed to induce lymphopenia, although there are still more studies needed to clarify the underlying mechanisms for lymphopenia in COVID-19 patients.

Nicotinamide riboside (NR) is an NAD+ precursor capable of regulating mammalian cellular metabolism. Phycocyanin oligopeptide (PC), a phytonutrient found in blue-green algae, has antioxidant and anti-inflammatory properties. This study explored the effects of NR, PC, and their combination on telomere length, inflammatory and antioxidant status in rats under chronic stressed conditions (CS). Forty-nine rats were allocated into seven groups: Control, chronic stress (CS), CS with NR (26.44 mg/kg), a low dose of 2.64 mg/kg of PC (PC-LD), or a high dose of 26.44 mg/kg PC (PC-HD), NR+PC-LD and NR+PC-HF. Rats were given daily corticosterone injections (40 mg/kg) to induce stressed conditions, or NR and PC were orally administered for 21 days. NR and PC supplementation, particularly NR plus PC, increased the serum antioxidant enzyme activities, hepatic nicotinamide adenine (NAD+) content, and telomere length (P<0.001 for all) compared with the CS group. The levels of serum malondialdehyde (MDA), liver interleukin-6 (IL-6), tumor necrosis factor α (TNF-α), IL-1β, and IL-8 were reduced under CS condition (P<0.001). In addition, CS decreased the levels of hepatic telomere-related proteins and sirtuin1 (SIRT1-3), while supplementation of NR and PC alone or in combination increased the levels of telomere-related proteins (e.g., POT1b, TRF1, and TRF2), and SIRT3, NAMPT P<0.05. In conclusion, NR and PC, especially their combination, can alleviate metabolic abnormalities by enhancing hepatic cytokines, SIRT3, NAMPT, and NAD+ levels in CS-exposed rats. More research is needed to elucidate further the potential health effects of the combination of NR and PC in humans.

Nicotinamide mononucleotide (NMN), a key NAD+ precursor, exhibits distinct metabolic characteristics and potential health benefits. Recent investigations underscore the pivotal role of gut bacteria and specialized uptake mechanisms in NMN metabolism. While human trials demonstrate NMN's safety and promising health outcomes, challenges persist. Variability in results is likely influenced by lifestyle, health conditions, and individual genetic and gut microbiota differences. Understanding how these factors affect NMN metabolism is crucial for personalized approaches and maximizing NMN's potential. Advances in delivery systems show promise for enhancing NMN bioavailability, but further understanding of optimal NAD+ levels and reliable measures of NMN's effects is necessary. This comprehensive approach is key to optimizing NMN's impact on human health and longevity.

In the context of the development of bioprocesses for the production of biofuels and bulk chemicals, microbial cells are rationally engineered to produce such molecules at high yield and titres in order to develop new biological methods that satisfy economic constraints. The redox and energetic balances of such strains play crucial roles in performance. Processes performed in strict anaerobes have a limited amount of energy available compared to that in aerobic organisms. This energy is obtained through fermentation and/or ion gradient-driven phosphorylation. Such anaerobic organisms have developed energy conservation mechanisms to increase ATP yields. This paper presents the properties of one of these mechanisms catalysed by the Rnf complex, an ion-translocating membrane complex with a ferredoxin NAD+ oxidoreductase activity. The Rnf complex performs the transfer of electrons from reduced ferredoxin to NAD+ coupled with an ion-motive transport. Ferredoxin is a common electron carrier for anaerobic bacteria and, with NAD+, is involved in several pathways of interest for the production of biofuels. This complex was first identified in Rhodobacter capsulatus and found to be involved in nitrogen fixation. It was then found to be involved in energy conservation in multiple anaerobic organisms, from acetobacteria such as Acetobacterium woodii to sulfate-reducing bacteria such as Desulfovibrio alaskensis and autotrophic bacteria such as Clostridium ljungdahlii and Clostridium aceticum. The Rnf complex triggers two types of ion transports: it can be either a sodium or a proton transporter. Both of these transports create a gradient of ions, generating a membrane potential that is then used by ATPase to produce ATP and thus serving as an energy conservation mechanism. In this review, the available information on the Rnf complex from genetic organization up to its in vivo and in vitro activities in several microorganisms is summarized, with a special focus on the proton-motive Rnf complex.

Mitochondrial dysfunction has been linked to psoriasis, and may be an important underlying factor contributing to this disease. However, a precise methodology for assessing mitochondrial dysfunction has yet to be developed. One promising approach is to measure NADH autofluorescence from affected skin areas. In this study, we show that Flow Mediated Skin Fluorescence (FMSF) can be used for non-invasive assessment of mitochondrial dysfunction in psoriasis. The fluorescence level at baseline and the half-time of ischemic growth (t1/2) derived from the FMSF traces can be used for non-invasive assessment of NADH/NAD+ redox imbalance in psoriatic lesions compared to unaffected skin. These results are supported by analysis of the key FMSF parameters, Reactive Hyperemia Response (RHR) and Hypoxia Sensitivity (HS). This method not only contributes to understanding of the biochemical processes involved in the etiopathogenesis of psoriasis, but also provides a basis for identifying new drug targets and improving the treatment process.

Nicotinamide adenine dinucleotide (NAD+) is an essential molecule involved in various metabolic reactions, acting as an electron donor in the electron transport chain and as a co-factor for NAD+-dependent enzymes. In the early 2000s, reports that NAD+ declines with aging introduced the notion that NAD+ metabolism is globally and progressively impaired with time. Since then, NAD+ became an attractive target for potential pharmacological therapies aiming to boost NAD+ levels to promote vitality and protect against age-related diseases. This review summarizes and discusses a collection of studies that report the levels of NAD+ with aging in different species (i.e., yeast, C. elegans, rat, mouse, monkey, and human) to determine whether the notion that overall NAD+ levels decrease with aging stands true. We find that despite systematic claims of overall changes in NAD+ levels with aging, the evidence to support it is very limited and often restricted to a single tissue or cell type. This is particularly true in humans, where the development of NAD+ levels during aging is still poorly characterized. There is a need for much larger, preferably longitudinal, studies aimed to assess how NAD+ levels develop with aging in various tissues. This will strengthen our conclusions on NAD+ during aging and should provide a foundation for better pharmacological targeting of relevant tissues.

The study of the impact of polyQ expansion driven proteotoxicity on cell metabolism has evi-denced NAD molecule as a central player in regulating metabolic response and cell repair in neurodegeneration. The decline in NAD intracellular levels represents a hallmark of ageing aris-ing from a dysregulation between NAD-consuming and biosynthetic enzymatic reactions in which NMNAT plays a key role. By an integrated bioanalytical and proteomic experimental design, the derangement of NAD metabolism deriving from the accumulation of polyQ-Htt protein has been analysed in Saccha-romices cerevisiae harbouring a 103Q-Htt and compared with wild-type Htt, in absence and in presence of a phenolic extract from EVOO, as a source of antioxidant bioactive compounds. Quantification of NAD and its precursors and proteomic analysis of the differential protein ex-pression has been performed by LC-DAD-MS. Chronological lifespan and NAD homeostasis was strongly impaired by proteotoxic polyQ-Htt, eliciting a depletion of NAD levels and accumulation of NaMN. In parallel a downregulation of Sirt2 expression levels has been observed. Phenolic extract administration had no meaningful ef-fects on NAD replenishment to prevent proteotoxicity. NaMN can represent a biomarker of accel-erated aging, and/or a signaling molecule for cell repair.

A mathematical model of energy metabolism in erythrocyte-bioreactors loaded with alcohol dehydrogenase and acetaldehyde dehydrogenase was constructed and analyzed. Such erythrocytes can convert ethanol to acetate using intracellular NAD and, thus, can be used to treat an alcohol intoxication. Analysis of the model reveals that the rate of ethanol consumption by the erythrocyte-bioreactors increases proportionally to activity of incorporated ethanol-consuming enzymes until their activity reaches a specific threshold level. When the ethanol-consuming enzyme activity exceeds this threshold, the steady state in the model becomes unstable and the model switches to an oscillation mode caused by a competition of glyceraldehyde phosphate dehydrogenase and ethanol-consuming enzymes for NAD. An amplitude and period of metabolite oscillations first increase with the increase in the activity of e encapsulated enzymes. A further increase in these activities leads to a loss of the glycolysis steady state, and a permanent accumulation of glycolytic intermediates. The oscillation mode and the loss of the steady state can lead to osmotic destruction of erythrocyte-bioreactors due to an accumulation of intracellular metabolites. Our results demonstrate that the interaction of enzymes encapsulated into erythrocyte-bioreactors with erythrocyte metabolism should be taken into account in order to obtain an optimal efficacy of these bioreactors.

Disrupted biological function, manifesting through the hallmarks of aging, poses as one of the largest threats to healthspan and risk of disease development, such as metabolic disorders, cardiovascular ailments, and neurodegeneration. In recent years, numerous geroprotectors, senolytics, and other nutraceuticals have emerged as potential disruptors of aging and may be viable interventions in the immediate state of human longevity science. In this review, we focus on the decrease of nicotinamide adenine dinucleotide (NAD+) with age and the supplementation of NAD+ precursors, such as nicotinamide mononucleotide (NMN) or nicotinamide riboside (NR), in combination with other geroprotective compounds to restore youthful NAD+ levels. Furthermore, these geroprotectors may enhance the efficacy of NMN supplementation while concurrently providing their own numerous health benefits. By analyzing the prevention of NAD+ degradation through inhibition of CD38 or supporting protective downstream agents of SIRT1, we provide a potential framework of the CD38/NAD+/SIRT1 axis through which geroprotectors may enhance the efficacy of NMN supplementation and reduce the risk of age-related diseases, thereby potentiating healthspan in humans.

Arabidopsis contains eight different h-type thioredoxins (Trx) being distributed in different cell organelles. Although Trx h2 is deemed to be localized in mitochondria, its subcellular localization and function remains a matter of debate. Here, Trx h2 localization and function were investigated using cell fractionation studies and reverse genetics. Differential centrifugation and immunodetection showed the Trx h2 protein to be distributed to the microsomal fraction rather than to mitochondrial preparations. To analyze whether Trx h2 has different roles than mitochondrial Trxs, Arabidopsis mutants lacking Trx h2 were compared with mutants deficient in mitochondrial Trx o1 and double mutants with joint deficiencies in both Trxs. Under constant medium light, trxh2 grew as the wild type, while trxo1 and trxo1h2 mutants showed impaired growth. This was accompanied by differences in the metabolite profiles. The trxo1 and trxo1h2 mutants clustered differently from the wild type during the night, revealing a decrease in ascorbate and glutathione redox states. In fluctuating light intensities, genotypic differences in growth rates were attenuated. Compared to the wild type, the fluctuating-light induced decrease in the NADPH/NADP ratio was diminished in the mutants, with the trxo1h2 double mutant showing the strongest effect. This was accompanied by an increase in the photosynthetic efficiency of the trxo1h2 mutant, specifically in the high light phases of fluctuating light. Conclusively, these results support the view that Trxs o1 and h2 are localized in different subcellular compartments, and have different effects on ascorbate and glutathione redox states and growth in medium light, but cooperatively affect NADP(H) redox state and photosynthetic efficiency in fluctuating light.

Understanding molecular mechanisms of neurological disorders is required for development of personalized medicine. When the diagnosis considers not only the disease symptoms, but also their molecular basis, the treatments tailored for individual patients may be suggested. The vitamins-responsive neurological disorders are induced by deficiencies in the vitamin-dependent processes. The deficiencies may occur due to genetic impairments of proteins whose functions are involved with the vitamins. This review considers the enzymes encoded by DHTKD1, PDK3 and PDXK genes, whose mutations are observed in patients with Charcot-Marie-Tooth (CMT) disease. The enzymes bind or produce the coenzyme forms of vitamins B1 (thiamine diphosphate, ThDP) and B6 (pyridoxal-5’-phosphate, PLP). Alleviation of such disorders by administration of the lacking vitamin or its derivative calls upon a better introduction of the mechanistic knowledge to medical diagnostics and therapies. Recent data on lower levels of the vitamin B3 derivative, NAD+, in the blood of patients with CMT disease, compared to the control subjects, are also considered in view of the NAD-dependent mechanisms of pathological axonal degeneration, suggesting therapeutic potential of vitamin B3. Thus, improved diagnostics of the underlying causes of the CMT disease may allow the patients with the vitamin-responsive disease forms to benefit from the administration of the vitamins B1, B3, B6, their natural derivatives or pharmacological forms.

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.