NADH Research Articles

Acute exercise boosts NAD+ metabolism of human peripheral blood mononuclear cells

Nicotinamide adenine dinucleotide (NAD+) coenzymes are the central electron carriers in biological energy metabolism. Low NAD+ levels are proposed as a hallmark of ageing and several diseases, which has given rise to therapeutic strategies that aim to tackle these conditions by boosting NAD+ levels. As a lifestyle factor with preventive and therapeutic effects, exercise increases NAD+ levels across various tissues, but so far human trials are mostly focused on skeletal muscle. Given that immune cells are mobilized and redistributed in response to acute exercise, we conducted two complementary trials to test the hypothesis that a single exercise session alters NAD+ metabolism of peripheral blood mononuclear cells (PBMCs). In a randomized crossover trial (DRKS00017686) with 24 young adults (12 female) we show that acute exercise increases gene expression and protein abundance of several key NAD+ metabolism enzymes with high conformity between high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT). In a longitudinal exercise trial (DRKS00029105) with 12 young adults (6 female) we confirm these results and reveal that – similar to skeletal muscle – NAD+ salvage is pivotal for PBMCs in response to exercise. Nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme of NAD+ salvage pathway, displayed a pronounced increase in gene expression during exercise, which was accompanied by elevated intracellular NAD+ levels and reduced serum levels of the NAD+ precursor nicotinamide. These results demonstrate that acute exercise triggers NAD+ biosynthesis of human PBMCs with potential implications for immunometabolism, immune effector function, and immunological exercise adaptions.

Pharmacophore-guided in-silico discovery of SIRT1 inhibitors for targeted cancer therapy

Epigenetic modifier, Sirtuin (SIRTs) is a family of seven isoforms (SIRT1-7) and nicotinamide adenine dinucleotide (NAD+) dependent class III histone deacetylase (HDACs) protein. SIRT1 in association with the p53 protein can regulate crucial cell processes such as glucose metabolism, lipid metabolism, mitochondrial biogenesis, DNA repair, oxidative stress, apoptosis, and inflammation through the process of deacetylation. When SIRT1 deacetylates p53, it loses its tumor suppression property. To promote apoptosis and decrease cell proliferation by inhibiting SIRT1 protein and ultimately raising the acetylation of p53 to regain its tumor suppressor function. Though we have many SIRT1 protein inhibitors, they exhibited off-target effects and inefficiency at the clinical trial stage. This study has been executed to identify more potentially effective and reliable SIRT1 inhibitors that can perform better than the existing options. To do so, pharmacophore-based screening of compound libraries followed by virtual screening, pharmacokinetic, drug-likeness, and toxicity studies were conducted which gave 42 compounds to evaluate further. Subsequently, exhaustive molecular docking and molecular dynamics simulation predicted four potential hits to inhibit the SIRT1 protein better than the reference compound. Further studies such as principal components analysis, free energy landscape, and estimation of binding free energy were done which concluded Hit4 (PubChem ID: 55753455) to be a novel and potent SIRT1 small molecule inhibitor among the others. The total binding free energy for Hit4 was found to be -44.68kcal/mol much better than the reference complex i.e., -29.38kcal/mol.

Deferiprone protects photoreceptors by inhibiting ferroptosis after experimental retinal detachment.

The detachment of the retinal neuroepithelium from the retinal pigment epithelium (RPE), often due to a retinal tear and subsequent subretinal fluid (SRF) accumulation, is a critical factor leading to photoreceptor cells (PR) death and permanent vision impairment in retinal detachment (RD) scenarios. Predicting postoperative visual recovery is challenging, even with surgical reattachment. Research has indicated that increased iron and transferrin (TF) saturation in the vitreous fluid (VF) correlates with poorer visual outcomes, suggesting a potential role for ferroptosis, a form of regulated cell death, in PR following RD. To explore this hypothesis, we analyzed the VF of RD patients for ferroptosis markers, revealing reduced levels of glutathione peroxidase 4 (GPX4), glutathione (GSH), and reduced nicotinamide adenine dinucleotide phosphate (NADPH), alongside elevated levels of Long-chain acyl-CoA synthetase 4(ACSL4), malondialdehyde (MDA), and ferrous iron. We then developed a mouse model to simulate RD and administered the iron chelator deferiprone (DFP) as a treatment. Our findings indicated that DFP mitigated ferroptosis in the retina, thereby preserving retinal architecture and function. Collectively, our study establishes the occurrence of ferroptosis in RD and demonstrates the therapeutic potential of DFP in protecting PR and treating RD.

Effects of compatibility of Clostridium butyricum and Bacillus subtilis on growth performance, lipid metabolism, antioxidant status and cecal microflora of broilers during the starter phase.

This study aimed to determine the effects of compatibility of Clostridium butyricum and Bacillus subtilis on growth performance, lipid metabolism, antioxidant status and cecal microflora of broilers during the starter phase. A total of 600 1-day-old Ross 308 broilers were randomly divided into two groups with six replicates in each group. Chickens in the control group were fed a basal diet, while chickens in the experimental group were fed a diet supplemented with 2×108 colony forming units (CFU)/kg of C. butyricum and 1×109 CFU/kg of B. subtilis. The experimental period was 21 days. Addition of C. butyricum and B. subtilis significantly increased (p<0.05) the body weight and liver nicotinamide adenine dinucleotide phosphate-malic enzyme (NADP-ME) activity of broilers, enhanced (p<0.05) the average daily gain and average daily feed intake of broilers. However, the addition of C. butyricum and B. subtilis did not significantly affect the concentrations of triglyceride and total cholesterol in the serum, the activities of fatty acid synthase and acetyl-CoA carboxylase in the liver, the total antioxidant capacity, glutathione peroxidase activity and malondialdehyde content in the serum and liver. Besides, microbial analysis revealed that supplementation of C. butyricum and B. subtilis increased (p<0.05) the abundance of Firmicutes such as CHKCI001 and Faecalibacterium, decreased (p<0.05) the abundance of Bacteroidota such as Bacteroides and Alistipes. Spearman correlation analysis confirmed that the above cecal microbiota were closely related to the growth performance of broilers (p<0.05). In addition, simultaneous supplementation of C. butyricum and B. subtilis significant affected (p<0.05) 33 different functional pathways such as lipid metabolism and carbohydrate metabolism. This explains the phenomenon of increased growth performance and liver NADP-ME activity in the probiotics group. The compatibility of C. butyricum and B. subtilis could improve the growth of broilers during the starter phase by changing the cecal microflora.

Waste Nitrogen Upcycling to Amino Acids during Anaerobic Fermentation on Biochar: An Active Strategy for Regulating Metabolic Reducing Power.

This study proposes a novel strategy that utilizes biochar (BC) during anaerobic fermentation (AF) to generate amino acids (AAs) toward nitrogen upcycling. The BC, pyrolyzed at 800 °C (BC800) to enhance graphite structures and electron-accepting sites, effectively addresses issues related to biosynthetic reducing power nicotinamide adenine dinucleotide phosphate insufficiency by altering cellular conditions and alleviates feedback inhibition through the immobilization of end products. This process establishes unique microbial signaling and energy networks, with Escherichia coli becoming dominant in the biofilm. The conversion rate of ammonia-N to AAs-N within the biofilm reached 67.4% in BC800-AF, which was significantly higher compared to the levels in other AF reactors with BC pyrolyzed at 600 and 400 °C (45.9 and 22.5%, respectively), as well as a control AF reactor (<5%). Furthermore, in BC800-AF, the aromatic AAs (Aro-AAs) were as high as 70.8% of the AAs within the biofilm. The activities of key enzymes for Aro-AAs biosynthesis uniquely positively correlated with the electron-accepting capacity on BC800 (R2 ≥ 0.95). These findings hold promise for transforming existing AF reactors into factories that produce BC-based AAs, providing a more sustainable fertilizing agent than chemical fertilizers.

Cycloastragenol reduces microglial NLRP3 inflammasome activation in Parkinson's disease models by promoting autophagy and reducing Scrib-driven ROS

BackgroundIn Parkinson's disease (PD), microglial autophagy is crucial for the maintenance of cellular redox homeostasis. Meanwhile, cycloastragenol (CAG), a triterpenoid saponin and the principal active component of Astragalus, reduces the activation of NLRP3 inflammasomes. Nevertheless, the specific molecular mechanisms underlying the CAG-mitigated microglial neuroinflammation remains obscure in PD. PurposeThis study explored the role of CAG in the activation of microglial NLRP3 inflammasome and the mechanisms underlying its therapeutic potential for PD treatment. Study designThe effect of CAG was assessed in α-Syn-induced primary microglia and PD models. MethodsAAV1/2-hsyn-SNCA (A53T) was stereo-injected into the striatum of mice to induce PD models and CAG was orally administered. The mice underwent quantitative 4D proteomics analysis and behavioral assessments. The primary microglia and neuron cultures were analyzed by western blotting, immunofluorescence, transmission electron microscopy, etc. ResultsCAG reduced phagocytosis-induced reactive oxygen species (ROS) by suppressing the microglial Scribble (Scrib) and p22phox expression. Concurrently, CAG enhanced autophagy, promoted α-Syn clearance, and reduced mitochondrial damage. These synergistic effects downregulated NLRP3 inflammasome activation, in turn reducing gasdermin D cleavage, caspase-1 activation, and the release of interleukin-1β and interleukin-18. Further investigation revealed that CAG shielded neurons from α-Syn toxicity, thus attenuating behavioral impairments observed in the mouse PD model. ConclusionCAG mitigates neuroinflammation by inhibiting ROS-induced NLRP3 inflammasome activation in microglia via promoting microglial autophagy and reducing the activity of Scrib-associated nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, which signifies a promising alternative approach to PD management.

Nampt/SIRT2/LDHA pathway-mediated lactate production regulates follicular dysplasia in polycystic ovary syndrome

Decreased nicotinamide adenine dinucleotide (NAD+) content has been shown to contribute to metabolic dysfunction during aging, including polycystic ovary syndrome (PCOS). However, the effect of NAD+ on ovulatory dysfunction in PCOS by regulating glycolysis has not been reported. Based on the observations of granulosa cells (GCs) transcriptome data from the Gene Expression Omnibus (GEO) database, the signal pathways including glycolysis and nicotinate-nicotinamide metabolism were significantly enriched, and most genes of the above pathway like LDHA and SIRT2 were down-regulated in PCOS patients. Therefore, the PCOS rat model was established by combining letrozole with a high-fat diet (HFD), we demonstrate that in vivo supplementation of nicotinamide mononucleotide (NMN) significantly improves the ovulatory dysfunction by facilitating the follicular development, promoting luteal formation, as well the fertility in PCOS rats. Furthermore, target energy metabolomics and transcriptome results showed that NMN supplementation ameliorates the lactate production by activating glycolytic process in the ovary. In vitro, when NAD+ synthesis and SIRT2 expression were inhibited, lactate content in KGN cells was decreased and LDHA expression was significantly inhibited. We confirmed that FK866 can enhance the acetylation of LDHA on 293T cells by Co-immunoprecipitation (Co-IP) assay. We also observed that inhibition of NAD+ synthesis can reduce the activity and increase the apoptosis of KGN cells. Overall, these benefits of NMN were elucidated and the Nampt/SIRT2/LDHA pathway mediated lactate production in granulosa cells played an important role in the improvement of follicular development disorders in PCOS. This study will provide experimental evidence for the clinical application of NMN in the treatment of PCOS in the future.

Chromone Derivatives as a Novel NOX4 Inhibitor: Design, Synthesis, and Regulation of ROS in Renal Fibroblast.

Nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4) has emerged as a promising target for developing drugs to tackle renal fibrosis. In this study, a series of chromone derivatives were designed and synthesized. Additionally, we established a NOX4 overexpression model using the NRK-49F rat renal fibroblasts cell line and identified compound 14m as highly active through the assessment of intracellular reactive oxygen species (ROS) levels in this model. The drug affinity responsive target stability (DARTS) assay illuminated the robust binding stability of 14m with NOX4. Mechanistic studies further substantiated its efficacy in ameliorating fibrosis and inflammation. This investigation positions 14m as a noteworthy NOX4 inhibitor, shedding light on its regulatory role in renal fibroblasts. Importantly, it diversifies the structural landscape of NOX4 inhibitors, offering novel lead compounds for future development.

Modulatory potentials of nitric oxide in obesity-induced endothelial dysfunction

Obesity is caused by a significant increase in adipose tissue due to excessive caloric intake that exceeds energy expenditure. Obesity has emerged as a significant public health issue in both poor resource and economic developed nations, owing to its increased incidence and links to chronic diseases, such osteoarthritis, hypertension, non-alcoholic fatty liver disease (NAFLD), and cardiovascular diseases (CVDs). It is believed that uncoupled eNOS, nicotinamide adenine dinucleotide phosphate (NADPH) oxidases, xanthine oxidase, lipoxygenase, cyclooxygenase, microsomal P-450 enzymes, and pro-oxidant heme molecules are responsible for the drastic decrease in NO production and the relative increase in reactive oxygen species (ROS) secretion, which are considered as the molecular mechanisms associated with obesity-induced endothelial dysfunction. Vascular endothelium defines a monolayer of cells, which lies between the vascular smooth muscle cells (VSMCs) and the vessel lumen. It performs a number of protective actions facilitated by the release of nitric oxide (NO), a soluble gas that is generated in endothelial cells by the amino acid L-arginine through the action of endothelial nitric oxide synthase (eNOS). The maintenance of vascular homeostasis is facilitated by various biological actions of NO, such as modulation of vascular dilator tone, control of local cell growth, and protection of the endothelium from the harmful effects of cellular components in blood circulation, while maintaining normal endothelial functions. Decreased peripheral arterial endothelium-dependent dilation (EDD) in response to mechanical (intravascular shear) or chemical (acetylcholine) stimuli suggests that decreased NO bioavailability has been recognised as major molecular mechanisms associated with the progress and development of obesity-induced endothelial dysfunction. In this review, the modulatory effects of NO in obesity-induced endothelial dysfunction will be discussed.

Modulatory Effect of Nicotinamide Adenine Dinucleotide Phosphate (NADPH) on the 2-Oxoglutarate Mitochondrial Carrier.

The 2-oxoglutarate carrier (OGC), pivotal in cellular metabolism, facilitates the exchange of key metabolites between mitochondria and cytosol. This study explores the influence of NADPH on OGC transport activity using proteoliposomes. Experimental data revealed the ability of NADPH to modulate the OGC activity, with a significant increase of 60% at 0.010 mM. Kinetic analysis showed increased Vmax and a reduction in Km for 2-oxoglutarate, suggesting a direct regulatory role. Molecular docking pointed to a specific interaction between NADPH and cytosolic loops of OGC, involving key residues such as K206 and K122. This modulation was unique in mammalian OGC, as no similar effect was observed in a plant OGC structurally/functionally related mitochondrial carrier. These findings propose OGC as a responsive sensor for the mitochondrial redox state, coordinating with the malate/aspartate and isocitrate/oxoglutarate shuttles to maintain redox balance. The results underscore the potential role of OGC in redox homeostasis and its broader implications in cellular metabolism and oxidative stress responses.

On-Chip NADH Detection in Multicellular Models Using an AlGaN/GaN Photodetector Array with Enhanced Sensitivity.

Nicotinamide adenine dinucleotide (NAD) is a pivotal coenzyme, existing in its oxidized form (NAD+) and reduced form (NADH). Both are essential in cellular redox reactions and are implicated in energy production and cancer. Current NADH detection methods often involve complex optical measurements. We propose a miniaturized, on-chip photoelectric sensor array using AlGaN/GaN two-dimensional electron gas (2DEG) photodetectors for NADH quantification. The device exhibits an ultralow dark current and ultrahigh UV light responsivity, enabling sensitive NADH detection. By exploiting the absorbance disparity between NADH and NAD+, our sensor achieves rapid, sensitive detection, surpassing commercial assays. It effectively detects NADH levels in 3D multicellular models, promising cancer screening and monitoring. This sensor platform offers a significant advancement in NADH quantification, with the potential for high-throughput testing and point-of-care diagnostics. Our study presents an efficient approach for NADH sensing, addressing the need for rapid and sensitive detection methods in biomedical research and clinical practice.

Novel Approach to Skin Anti-Aging: Boosting Pharmacological Effects of Exogenous Nicotinamide Adenine Dinucleotide (NAD+) by Synergistic Inhibition of CD38 Expression.

Nicotinamide adenine dinucleotide (NAD+) is indispensable for the regulation of biological metabolism. Previous studies have revealed its role in aging and degenerative diseases, while crucially showing that supplementation with NAD+ or its precursors could ameliorate or reverse the progression of aging. Despite extensive evidence for the role and action of NAD+ in aging, its pharmacological activity on the skin, or even its mechanism, has not been elucidated. In this study, we established a novel approach to effectively utilize NAD+ for skin anti-aging by enhancing the pharmacological efficacy of exogenous NAD+ using a phytochemical complex consisting of quercetin, and enoxolone through inhibition of CD38. Through the comprehensive in vitro experiments based on human fibroblasts, we observed that exogenous NAD+ could exert protective effects against both extrinsic aging induced by ultraviolet light exposure and intrinsic aging. Additionally, we found that its effects were significantly boosted by quercetin and enoxolone. In this in-depth study, we demonstrated that these beneficial effects are mediated by improved sirtuin activation, autophagy, and mitochondrial functionality. Our approach is expected to verify the applicability of the topical application of NAD+ and offer more effective solutions for the unmet needs of patients and consumers who demand more effective anti-aging effects.

Intracellular Gold Nanocluster/Organic Semiconductor Heterostructure for Enhancing Photosynthesis

AbstractPhotosynthetic microorganisms, which rely on light‐driven electron transfer, store solar energy in self‐energy carriers and convert it into bioenergy. Although these microorganisms can operate light‐induced charge separation with nearly 100 % quantum efficiency, their practical applications are inherently limited by the photosynthetic energy conversion efficiency. Artificial semiconductors can induce an electronic response to photoexcitation, providing additional excited electrons for natural photosynthesis to improve solar conversion efficiency. However, challenges remain in importing exogenous electrons across cell membranes. In this work, we have developed an engineered gold nanocluster/organic semiconductor heterostructure (AuNCs@OFTF) to couple the intracellular electron transport chain of living cyanobacteria. AuNCs@OFTF exhibits a prolonged excited state lifetime and effective charge separation. The internalized AuNCs@OFTF permits its photogenerated electrons to participate in the downstream of photosystem II and construct an oriented electronic highway, which enables a five‐fold increase in photocurrent in living cyanobacteria. Moreover, the binding events of AuNCs@OFTF established an abiotic‐biotic electronic interface at the thylakoid membrane to enhance electron flux and finally furnished nicotinamide adenine dinucleotide phosphate. Thus, AuNCs@OFTF can be exploited to spatiotemporally manipulate and enhance the solar conversion of living cyanobacteria in cells, providing an extended nanotechnology for re‐engineering photosynthetic pathways.

Honokiol and Nicotinamide Adenine Dinucleotide Improve Exercise Endurance in Pulmonary Hypertensive Rats Through Increasing SIRT3 Function in Skeletal Muscle.

Pulmonary hypertension (PH) significantly impairs exercise capacity and the quality of life in patients, which is influenced by dysfunctions in multiple organ systems, including the right ventricle, lungs, and skeletal muscles. Recent research has identified metabolic reprogramming and mitochondrial dysfunction as contributing factors to reduced exercise tolerance in PH patients. In this study, we investigated the therapeutic potential of enhancing mitochondrial function through the activation of the mitochondrial deacetylase SIRT3, using SIRT3 activator Honokiol combined with the SIRT3 co-factor nicotinamide adenine dinucleotide (NAD), in a Sugen/Hypoxia-induced PH rat model. Our results show that Sugen/Hypoxia-induced PH significantly impairs RV, lung, and skeletal muscle function, leading to reduced exercise capacity. Treatment with Honokiol and NAD notably improved exercise endurance, primarily by restoring SIRT3 levels in skeletal muscles, reducing proteolysis and atrophy in the gastrocnemius, and enhancing mitochondrial complex I levels in the soleus. These effects were independent of changes in cardiopulmonary hemodynamics. We concluded that targeting skeletal muscle dysfunction may be a promising approach to improving exercise capacity and overall quality of life in PH patients.

The effect of CD38 inhibition in age-associated vascular dysfunction

Abstract Introduction Aging is characterized by age-related vascular dysfunction, mainly caused by endothelial dysfunction and arterial stiffness. Levels of nicotinamide adenine dinucleotide (NAD) decrease with aging and accordingly, NAD is thought to be involved in the progression of age-related vascular dysfunction. Recent studies reported the involvement of CD38 in NAD regulation; indeed, its inhibition significantly prolongs the lifespan of progeroid and aged mice. However, whether CD38 is involved in the progression of age-related vascular dysfunction remains to be investigated. Methods CD38 expression was investigated in aortic homogenates of young (12-16 weeks) and aged (18-24 months) C57BL/6 wild-type mice, as well as in vitro in young (passage 5-7) and senescent (passage 14-15) primary human aortic endothelial cells (HAECs). Ex vivo tension myograph experiments were performed on thoracic aortas isolated from aged C57BL/6 mice (22-24 months old) pre-incubated for 1 hour with CD38-specific inhibitor, 78c, or DMSO as control. The effect of CD38 inhibition was also observed in vitro in senescent HAECs. Results A significant upregulation of CD38 expression was detected in the aortas of aged mice compared to the young ones as well as in senescent HAECs compared to young cells. Ex vivo tension myograph experiments showed a significant increase in endothelium-dependent relaxation responses to acetylcholine upon CD38 inhibition. The improvement of endothelial function was prevented by the addition of endothelial nitric oxide synthase (eNOS) inhibitor (L-NAME), but not by the COXs inhibitor, indomethacin, indicating that the observed effect achieved by CD38 inhibition is eNOS dependent. The involvement of the eNOS pathway was further supported by the in vitro finding in HAECs of increased eNOS activation upon CD38 inhibition. Conclusion The herein-reported data suggests an involvement of CD38 in the development of age-related endothelial dysfunction. Further studies are ongoing to investigate the underlying molecular mechanisms as well as the effect of long-term CD38 inhibitor supplementation on the progression of age-related vascular dysfunction.

Neutrophil-Mimetic Upconversion Photosynthetic Nanosystem Derived from Microalgae for Targeted Treatment of Thromboembolic Stroke.

Thromboembolic stroke constitutes the majority of brain strokes, resulting in elevated mortality and morbidity rates, as well as significant societal and economic burdens. Although intravenous thrombolysis serves as the standard clinical treatment, its narrow therapeutic window and the inflammatory response induced by tissue plasminogen activator (tPA) administration limit its efficacy. In the initial stages of stroke, the abrupt cessation of blood flow leads to an energy metabolism disorder, marked by a substantial decrease in adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide phosphate (NADPH) levels, causing irreversible damage to neural cells. In this study, we introduce a neutrophil-mimetic, microalgae-derived upconversion photosynthetic nanosystem designed for targeted treatment of thromboembolic stroke. This system features upconversion nanoparticles coated with a thylakoid membrane and wrapped in an activated neutrophil membrane, further decorated with ROS-responsive thrombolytic tPA on its surface. The neutrophil-mimetic design facilitates high targeting specificity and accumulation at the thrombus site after intravenous administration. Upon exposure to elevated levels of reactive oxygen species (ROS) at the thrombus location, the nanosystem promptly demonstrated potent thrombolytic efficacy through the surface-modified tPA. Furthermore, near-infrared II (NIR-II) laser irradiation activated the generation of ATP and NADPH, which inhibited inflammatory cell infiltration, platelet activation, oxidative stress, and neuronal injury. This constructed nanoplatform not only showcases exceptional targeting efficiency at the stroke site and controllable release of the thrombolytic agent but also facilitates ATP/NADPH-mediated thrombolytic, anti-inflammatory, antioxidative stress, and neuroprotective effects. Additionally, it offers valuable insights into the potential therapeutic applications of microalgae-based derivatives in managing thromboembolic stroke.

Unraveling the Molecular Mechanisms of SIRT7 in Angiogenesis: Insights from Substrate Clues.

Angiogenesis, a vital physiological or pathological process regulated by complex molecular networks, is widely implicated in organismal development and the pathogenesis of various diseases. SIRT7, a member of the Sirtuin family of nicotinamide adenine dinucleotide + (NAD+) dependent deacetylases, plays crucial roles in cellular processes such as transcriptional regulation, cell metabolism, cell proliferation, and genome stability maintenance. Characterized by its enzymatic activities, SIRT7 targets an array of substrates, several of which exert regulatory effects on angiogenesis. Experimental evidence from in vitro and in vivo studies consistently demonstrates the effects of SIRT7 in modulating angiogenesis, mediated through various molecular mechanisms. Consequently, understanding the regulatory role of SIRT7 in angiogenesis holds significant promise, offering novel avenues for therapeutic interventions targeting either SIRT7 or angiogenesis. This review delineates the putative molecular mechanisms by which SIRT7 regulates angiogenesis, taking its substrates as a clue, endeavoring to elucidate experimental observations by integrating knowledge of SIRT7 substrates and established angiogenenic mechanisms.

High glucose combined with lipopolysaccharide stimulation inhibits cell proliferation and migration of human HaCaT keratinocytes by impacting redox homeostasis and activating the polyol pathway.

High glucose level and chronic inflammation are characteristic features of diabetic cutaneous wounds. Keratinocytes make up the epidermis and play an important role in skin repair. However, metabolomic changes of keratinocytes in chronic diabetic ulcers have not been fully studied. This study used high levels of glucose combined with lipopolysaccharide to treat human HaCaT keratinocytes. Untargeted metabolomic combined with colorimetric assays were used to explore the changes of keratinocyte metabolites and related metabolic pathways caused by high glucose and lipopolysaccharide. Results demonstrated that high glucose combined with lipopolysaccharide treatment increased intracellular reactive oxygen species and impaired proliferation and migration of keratinocytes. Untargeted metabolomics analysis identified a total of 273 differential metabolites. Redox metabolism associated metabolites were largely altered. Reduced nicotinamide adenine dinucleotide, gamma-glutamylcysteine, superoxide dismutase activity and SOD2 gene expression were significantly upregulated while nicotinamide adenine dinucleotide, glutathione, glutathione peroxidase, several types of lysophosphatidylcholine, lysophosphatidylinositol, and GPR55 gene expression were downregulated. Alterations of glutathione and nicotinamide adenine dinucleotide were verified by colorimetric assays. For the first time, high glucose and LPS were observed to boost the levels of fructose, aldose reductase and sorbitol dehydrogenase of the polyol pathway in HaCaT cells. Further treatment of HaCaT with fructose leading to inhibition of cell proliferation and migration. Our data suggest high glucose combined with lipopolysaccharide significantly altered redox homeostasis associated metabolites and activate the polyol pathway in keratinocytes to impact cell proliferation and migration, providing new strategies for the treatment of chronic diabetic ulcers.

Regulatory roles of NAMPT and NAD+ metabolism in uterine leiomyoma progression: Implications for ECM accumulation, stemness, and microenvironment

Uterine leiomyoma (UL), commonly referred to as benign tumors, is characterized by excessive cell proliferation, extracellular matrix (ECM) accumulation, and the presence of stem cell-like properties. Nicotinamide adenine dinucleotide (NAD+) metabolism, regulated in part by nicotinamide phosphoribosyltransferase (NAMPT), plays a crucial role in these pathological processes and has emerged as a potential therapeutic target. Additionally, redox signaling pathways are integral to the pathogenesis of UL, influencing the dynamics of NAD+ metabolism. This study sought to elucidate the regulatory functions of NAMPT and NAD+ metabolism, in conjunction with redox signaling, in the progression of UL, and to explore potential therapeutic strategies targeting these pathways. Evaluation of NAMPT expression in human UL tissues revealed a positive correlation between elevated NAMPT levels and increased ECM deposition, as well as the expression of stemness markers. The use of FK866 and nicotinamide (NAM), to inhibit NAMPT significantly suppressed UL cell viability and attenuated stem cell-like characteristics. Redox signaling pathways, including those associated with DNA damage, lysosomal function homeostasis, and redox-sensitive phagophore formation, were implicated in the regulation of ECM dynamics, particularly through ECM-targeted inhibition. This study highlights the pivotal roles of NAMPT, NAD+ metabolism, and redox signaling in the pathophysiology of UL. Targeting NAMPT, particularly through the use of inhibitors FK866 and NAM, represents a promising therapeutic approach for mitigating UL progression by modulating redox and ECM dynamics. These findings offer novel insights into UL pathogenesis and establish NAMPT as a compelling target for future clinical investigation.

Cell‐Permeable Nicotinamide Adenine Dinucleotides for Exploration of Cellular Protein ADP‐Ribosylation

AbstractPosttranslational modifications (PTMs) greatly enhance the functional diversity of proteins, surpassing the number of gene‐encoded variations. One intriguing PTM is ADP‐ribosylation, which utilizes nicotinamide adenine dinucleotide (NAD+) as a substrate and is essential in cell signaling pathways regulating cellular responses. Here, we report the first cell‐permeable NAD+ analogs and demonstrate their utility for investigating cellular ADP‐ribosylation. Using a desthiobiotin‐labelled analog for affinity enrichment of proteins that are ADP‐ribosylated in living cells under oxidative stress, we identified protein targets associated with host‐virus interactions, DNA damage and repair, protein biosynthesis, and ribosome biogenesis. Most of these targets have been noted in various literature sources, highlighting the potential of our probes for cellular ADP‐ribosylome studies.