Acute kidney injury (AKI) remains a critical condition with substantial morbidity and mortality in hospitalized patients. Emerging research has underscored the protective role of SIRT6 in kidney diseases through diverse signaling pathways. Our current report aimed to elucidate the mechanisms by which SIRT6 mitigated the progression of AKI. Immunohistochemical and Oil Red O staining techniques were employed to assess the expression of SIRT6 and lipid metabolism in both AKI patients and AKI mice treated with UBCS039, a specific SIRT6 activator (30 mg/kg, i.p.). Kidney tissues from AKI mice were analyzed using LC-MS/MS to uncover SIRT6-related signaling pathways involved in AKI. Additionally, human proximal renal tubule cells (HK-2) were exposed to UBCS039 or transfected pcDNA3.1-SIRT6 overexpression plasmid to investigate the underlying signaling mechanisms of SIRT6 on lipid metabolism using Western blotting analysis and Oil Red O staining. Gene expression levels of ACMSD was detected by qRT-PCR and Western blotting in HK-2 cells. Dual-luciferase reporter assay was used to verify the effect of SIRT6 on regulating ACMSD transcription. Our findings revealed a significant reduction in SIRT6 expression in both AKI patients and AKI mice. Treatment with UBCS039, however, significantly decreased lipid accumulation and apoptosis in AKI mice. Proteomic analysis and Dual-luciferase reporter assay identified ACMSD as a downstream target of SIRT6. In vitro studies further demonstrated that SIRT6 enhanced lipid metabolism and mitigated apoptosis through the inhibition of ACMSD expression. This study demonstrated that SIRT6 promoted lipid metabolism by inhibiting the ACMSD pathway, thereby reducing apoptosis in AKI. These findings suggested that targeting ACMSD could offer a novel therapeutic strategy for SIRT6-mediated intervention in AKI.

Cockayne Syndrome (CS) is a premature aging disorder caused by mutations in the CSA and CSB genes involved in DNA metabolism and other cellular processes. CS patients display many features including premature aging, neurodegeneration, and kidney abnormalities. Nicotinamide dinucleotide (NAD+) deprivation has been observed in CS patient-derived cells. NAD+ has essential roles in regulating cellular health, stress responses, and renal homeostasis. While kidney dysfunction is a common feature in CS patients, its molecular pathogenesis is not understood. Here, we report that severe kidney pathology is present in CS A and B mice. We find that the NAD+ biosynthetic pathways are impaired in kidneys from these mice. Using human renal tubular epithelial cells, we show that CSA/B downregulation causes persistent activation of the ATF3 transcription factor on the quinolinate phosphoribosyl transferase gene locus, a rate-limiting enzyme in de novo NAD+ biosynthesis in the kidney, causing impaired transcription and deficient NAD+ homeostasis.

Glucocorticoid resistance is a challenging problem in clinical practice. Increasing glucocorticoid sensitivity and reducing resistance are important in the management of certain diseases. In steroid-resistant airway inflammatory diseases, glucocorticoid receptor (GR) expression is reduced, and impaired GR nuclear translocation is closely related to glucocorticoid resistance. Histone deacetylase SIRT1 regulates steroid hormone receptor activity and interacts with the androgen receptor and GR. In some glucocorticoid-resistant diseases, SIRT1 expression is reduced. Here, we review recent advances in the role of SIRT1 in regulating glucocorticoid signaling. First, we describe the structure, tissue expression, and subcellular localization of SIRT1. We also discuss the molecular mechanisms by which SIRT1 regulates glucocorticoid activity and its association with GR, as well as the mechanisms and roles of SIRT1 in several common glucocorticoid-resistant diseases. SIRT1 may serve as a potential therapeutic target, providing an opportunity for the treatment of glucocorticoid-resistant diseases.

Recently published data indicate that elevated circulating concentrations of N1-methyl-2-pyridone-5-carboxamide (2PY, also described as Met2PY) and N1-methyl-4-pyridone-5-carboxamide (4PY, also described as Met4PY), terminal catabolites of nicotinamide adenine dinucleotide (NAD+), are associated with cardiovascular disease (CVD) risk in humans. Previously, we and the others have shown that patients with advanced stages of chronic kidney disease (CKD) exhibit several-fold higher circulating 2PY and 4PY concentrations compared to healthy subjects or patients in the early stages of the disease. It is also well documented that patients with advanced CKD stages exhibit markedly elevated CVD risk, which is the main cause of premature death (in these patients). Therefore, we hypothesize that high concentrations of circulating 2PY and 4PY are important factors that may contribute to cardiovascular events and, ultimately, premature death in CKD patients. However, further, accurately controlled clinical research is needed to provide definitive answers concerning the role of 2PY and 4PY in CVD risk in CKD patients. Moreover, we are dealing with some issues related to the use of NAD+ precursors (NAD+ boosters) as drugs (also in CKD patients) and/or supplements. Due to the increase in circulating 2PY and 4PY levels during treatment with NAD+ boosters, these precursors should be used with caution, especially in patients with increased CVD risk.

Recent pre-clinical evidence suggests that the tryptophan metabolite 3-hydroxyanthranilic acid (3-HAA) and the related enzyme activity along the kynurenine metabolic pathway (KP) are associated with lifespan extension. We aimed to translate these findings into humans and expose exercise training as a potential non-pharmacological intervention to modulate this metabolic hub.

To explore whether recent pre-clinical findings might also be of relevance for humans, we analyzed the evolutionary conservation of KYNU and HAAO, the two core KP enzymes associated with 3-HAA. In a cross-sectional analysis of young-to-middle-aged adults (N = 84), we examined potential associations of serum 3-HAA and its precursor anthranilic acid with age. We then investigated whether 26 weeks of endurance exercise (increasing intensity (INC) during the intervention period (n = 17) vs. conventional moderate continuous training (CON) matched for energy expenditure (n = 17)) impacted 3-HAA levels, related metabolic ratios, and other KP metabolites.

We demonstrate that the core KP enzymes associated with 3-HAA are evolutionarily conserved in humans. Serum 3-HAA and its precursor anthranilic acid were consistently associated with age in young-to-middle-aged adults. Both exercise modes tested induced an increase in 3-HAA levels of 134% (p < 0.001) and 85% (p < 0.001) compared with baseline, respectively, without a significant time*group interaction effect.

We translate the association between systemic 3-HAA levels and age from animal models into humans and highlight longer-term exercise training as an efficient strategy to boost systemic 3-HAA levels in middle-aged adults. Our findings open promising research avenues concerning the mediating role of 3-HAA in training adaptations, health, and longevity.

Nicotinamide adenine dinucleotide (NAD) is a ubiquitous electron carrier essential for energy metabolism and post-translational modification of numerous regulatory proteins. Dysregulations of NAD metabolism are widely regarded as detrimental to health, with NAD depletion commonly implicated in aging. However, the extent to which cellular NAD concentration can decline without adverse consequences remains unclear. To investigate this, we generated a mouse model in which nicotinamide phosphoribosyltransferase (NAMPT)-mediated NAD+ biosynthesis was disrupted in adult skeletal muscle. The intervention resulted in an 85% reduction in muscle NAD+ abundance while maintaining tissue integrity and functionality, as demonstrated by preserved muscle morphology, contractility, and exercise tolerance. This absence of functional impairments was further supported by intact mitochondrial respiratory capacity and unaltered muscle transcriptomic and proteomic profiles. Furthermore, lifelong NAD depletion did not accelerate muscle aging or impair whole-body metabolism. Collectively, these findings suggest that NAD depletion does not contribute to age-related decline in skeletal muscle function.

As a critical molecule in biological systems, nicotinamide adenine dinucleotide (NAD+) influences the aging of mammals. Therefore, regulation of NAD+ synthesis and degradation may slow aging and mitigate related diseases.

This study investigated how mammalian tissues rely on different NAD+ synthesis pathways and prefer specific NAD+ precursors. Overexpressing the bacterial nicotinamidase PncA in mice increased NAD+ levels in the liver and kidneys but decreased levels in the heart and hippocampus. In aged mice (25 months old), this overexpression delayed aging indicators by boosting NAD+ levels in the liver and kidneys, indicating potential for PncA to improve age-related decline in these tissues. However, in younger mice (4 months old), PncA overexpression accelerates the senescence of cardiac cells, resulting in a reduction of NAD + levels, increased aging markers, and cognitive decline. These disparate results underscore the necessity of a nuanced, tissue-specific perspective when contemplating the use of NAD+ precursor supplementation as a means of addressing aging.

Our study highlights the complexity of NAD+ metabolism and its effects on aging in various tissues. It suggests personalized interventions for aging and age-related diseases by showing how different tissues respond to NAD+ precursor manipulation, emphasizing the importance of targeted strategies for optimal therapeutic results with minimal side effects.

Recent studies demonstrate that Parkinson's disease (PD) is associated with dysregulated metabolic flux through the kynurenine pathway (KP), in which tryptophan is converted to kynurenine (KYN), and KYN is subsequently metabolized to neuroactive compounds quinolinic acid (QA) and kynurenic acid (KA). Here, we used mass-spectrometry to compare blood and cerebral spinal fluid (CSF) KP metabolites between 158 unimpaired older adults and 177 participants with PD. We found increased neuroexcitatory QA/KA ratio in both plasma and CSF of PD participants associated with peripheral and cerebral inflammation and vitamin B6 deficiency. Furthermore, increased QA tracked with CSF tau, CSF soluble TREM2 (sTREM2) and severity of both motor and non-motor PD clinical symptoms. Finally, PD patient subgroups with distinct KP profiles displayed distinct PD clinical features. These data validate the KP as a site of brain and periphery crosstalk, integrating B-vitamin status, inflammation and metabolism to ultimately influence PD clinical manifestation.

The complex interplay between cancer progression and immune senescence is critically influenced by metabolic reprogramming in T cells. As T cells age, especially within the tumor microenvironment, they undergo significant metabolic shifts that may hinder their proliferation and functionality. This manuscript reviews how metabolic alterations contribute to T cell senescence in cancer and discusses potential therapeutic strategies aimed at reversing these metabolic changes. We explore interventions such as mitochondrial enhancement, glycolytic inhibition, and lipid metabolism adjustments that could rejuvenate senescent T cells, potentially restoring their efficacy in tumor suppression. This review also focuses on the significance of metabolic interventions in T cells with aging and further explores the future direction of the metabolism-based cancer immunotherapy in senescent T cells.

To secure an adequate nicotinamide adenine dinucleotide (NAD+) supply for survival, organisms typically rely on two complementary mechanisms: the de novo synthesis pathway and the salvage pathway. Notably, the classic quinolinic acid phosphoribosyltransferase (QPRTase) for de novo NAD+ synthesis is absent in Caenorhabditis elegans (C. elegans), despite the reported alternative mechanism involving uridine monophosphate phosphoribosyltransferase (UMPS). However, the effectiveness of this proposed mechanism for NAD+ production of C. elegans remains unclear. Here, using a chemically defined medium, we observed that removing NAD+ salvage precursors from the medium results in a significant decrease in NAD+ levels, causing severe developmental delay and fecundity loss in C. elegans. Strikingly, these defects cannot be restored by any metabolites from the de novo synthesis pathway, including the direct QPRTase substrate quinolinic acid (QA). Furthermore, the deficiency of umps-1 does not cause any significant changes in the NAD+ levels of C. elegans. Moreover, the growth defects of the umps-1 mutant could be rescued by uridine, but not the salvage NAD+ supply. Additionally, we discovered that commercially available QA products contain substantial amounts of nicotinic acid, potentially producing misleading information. Collectively, our results demonstrate that C. elegans lacks the necessary mechanisms for de novo synthesis of NAD+.

Genome-wide association studies (GWAS) have identified loci associated with kidney diseases, but the causal variants, genes, and pathways involved remain elusive. Here, we identified a kidney disease gene called pancreatic progenitor cell differentiation and proliferation factor (PPDPF) through integrating GWAS on kidney function and multiomic analysis. PPDPF was predominantly expressed in healthy proximal tubules of human and mouse kidneys via single-cell analysis. Further investigations revealed that PPDPF functioned as a thiol-disulfide oxidoreductase to maintain cellular NAD+ levels. Deficiency in PPDPF disrupted NAD+ and mitochondrial homeostasis by impairing the activities of nicotinamide mononucleotide adenylyl transferases (NMNATs), thereby compromising the function of proximal tubules during injuries. Consequently, knockout of PPDPF notably accelerated the progression of chronic kidney disease (CKD) in mouse models induced by aging, chemical exposure, and obstruction. These findings strongly support targeting PPDPF as a potential therapy for kidney fibrosis, offering possibilities for future CKD interventions.

Elevated levels of the NAD+-generating enzyme nicotinamide phosphoribosyltransferase (NAMPT) are a common feature across numerous cancer types. Accordingly, we previously reported pervasive NAD+ dysregulation in multiple myeloma (MM) cells in association with upregulated NAMPT expression. Unfortunately, albeit being effective in preclinical models of cancer, NAMPT inhibition has proven ineffective in clinical trials because of the existence of alternative NAD+ production routes using NAD+ precursors other than nicotinamide. Here, by leveraging mathematical modeling approaches integrated with transcriptome data, we defined the specific NAD+ landscape of MM cells and established that the Preiss-Handler pathway for NAD+ biosynthesis, which uses nicotinic acid as a precursor, supports NAD+ synthesis in MM cells via its key enzyme nicotinate phosphoribosyltransferase (NAPRT). Accordingly, we found that NAPRT confers resistance to NAD+-depleting agents. Transcriptomic, metabolic, and bioenergetic profiling of NAPRT-knockout (KO) MM cells showed these to have weakened endogenous antioxidant defenses, increased propensity to oxidative stress, and enhanced genomic instability. Concomitant NAMPT inhibition further compounded the effects of NAPRT-KO, effectively sensitizing MM cells to the chemotherapeutic drug, melphalan; NAPRT added-back fully rescues these phenotypes. Overall, our results propose comprehensive NAD+ biosynthesis inhibition, through simultaneously targeting NAMPT and NAPRT, as a promising strategy to be tested in randomized clinical trials involving transplant-eligible patients with MM, especially those with more aggressive disease.

Chronic kidney disease (CKD) is associated with renal metabolic disturbances, including impaired fatty acid oxidation (FAO). Nicotinamide adenine dinucleotide (NAD+) is a small molecule that participates in hundreds of metabolism-related reactions. NAD+ levels are decreased in CKD, and NAD+ supplementation is protective. However, both the mechanism of how NAD+ supplementation protects from CKD, as well as the cell types involved, are poorly understood. Using a mouse model of Alport syndrome, we show that nicotinamide riboside (NR), an NAD+ precursor, stimulated renal PPARα signaling and restored FAO in the proximal tubules, thereby protecting from CKD in both sexes. Bulk RNA-sequencing showed that renal metabolic pathways were impaired in Alport mice and activated by NR in both sexes. These transcriptional changes were confirmed by orthogonal imaging techniques and biochemical assays. Single-nuclei RNA sequencing and spatial transcriptomics, both the first of their kind to our knowledge from Alport mice, showed that NAD+ supplementation restored FAO in proximal tubule cells. Finally, we also report, for the first time to our knowledge, sex differences at the transcriptional level in this Alport model. In summary, the data herein identify a nephroprotective mechanism of NAD+ supplementation in CKD, and they demonstrate that this benefit localizes to the proximal tubule cells.

The intricate relationship between cancer, circadian rhythms, and aging is increasingly recognized as a critical factor in understanding the mechanisms underlying tumorigenesis and cancer progression. Aging is a well-established primary risk factor for cancer, while disruptions in circadian rhythms are intricately associated with the tumorigenesis and progression of various tumors. Moreover, aging itself disrupts circadian rhythms, leading to physiological changes that may accelerate cancer development. Despite these connections, the specific interplay between these processes and their collective impact on cancer remains inadequately explored in the literature. In this review, we systematically explore the physiological mechanisms of circadian rhythms and their influence on cancer development. We discuss how core circadian genes impact tumor risk and prognosis, highlighting the shared hallmarks of cancer and aging such as genomic instability, cellular senescence, and chronic inflammation. Furthermore, we examine the interplay between circadian rhythms and aging, focusing on how this crosstalk contributes to tumorigenesis, tumor proliferation, and apoptosis, as well as the impact on cellular metabolism and genomic stability. By elucidating the common pathways linking aging, circadian rhythms, and cancer, this review provides new insights into the pathophysiology of cancer and identifies potential therapeutic strategies. We propose that targeting the circadian regulation of cancer hallmarks could pave the way for novel treatments, including chronotherapy and antiaging interventions, which may offer important benefits in the clinical management of cancer.

Mitochondria are multifaceted organelles with crucial roles in energy generation, cellular signalling and a range of synthesis pathways. The study of mitochondrial biology is complicated by its own small genome, which is matrilineally inherited and not subject to recombination, and present in multiple, possibly different, copies. Recent methodological developments have enabled the analysis of mitochondrial DNA (mtDNA) in large-scale cohorts and highlight the far-reaching impact of mitochondrial genetic variation. Genome-editing techniques have been adapted to target mtDNA, further propelling the functional analysis of mitochondrial genes. Mitochondria are finely tuned signalling hubs, a concept that has been expanded by advances in methodologies for studying the function of mitochondrial proteins and protein complexes. Mitochondrial respiratory complexes are of dual genetic origin, requiring close coordination between mitochondrial and nuclear gene-expression systems (transcription and translation) for proper assembly and function, and recent findings highlight the importance of the mitochondria in this bidirectional signalling.

Recent studies have shown that disruptions in the nicotinamide adenine dinucleotide (NAD+) de novo synthesis pathway accelerate ovarian aging, yet its role in spermatogenesis remains largely unknown. In this study, we investigated the impact of the NAD+ de novo synthesis pathway on spermatogenesis by generating Qprt-deficient mice using CRISPR-Cas9 to target quinolinate phosphoribosyl transferase (Qprt), a key enzyme predominantly expressed in spermatocytes. Our results revealed that the deletion of Qprt did not affect NAD+ levels or spermatogenesis in the testes of 3-month-old mice. However, from 6 months of age onward, Qprt-deficient mice exhibited significantly reduced NAD+ levels in the testes compared to wild-type (WT) controls, along with a notable decrease in germ cell numbers and increased apoptosis. Additionally, these mice demonstrated mitochondrial dysfunction in spermatocytes, impaired progression through prophase I of meiosis, defective double-strand break (DSB) repair, and abnormal meiotic sex chromosome inactivation. Importantly, supplementation with the NAD+ precursor nicotinamide riboside (NR) in Qprt-deficient mice restored NAD+ levels and rescued the spermatogenic defects. These findings underscore the critical role of NAD+ de novo synthesis in maintaining NAD+ homeostasis and highlight its importance in meiotic recombination and meiotic sex chromosome inactivation in spermatogenesis.

Recent findings reveal the importance of tryptophan-initiated de novo nicotinamide adenine dinucleotide (NAD+) synthesis in the liver, a process previously considered secondary to biosynthesis from nicotinamide. The enzyme α-amino-β-carboxymuconate-ε-semialdehyde decarboxylase (ACMSD), primarily expressed in the liver and kidney, acts as a modulator of de novo NAD+ synthesis. Boosting NAD+ levels has previously demonstrated remarkable metabolic benefits in mouse models. In this study, we aimed to investigate the therapeutic implications of ACMSD inhibition in the treatment of metabolic dysfunction-associated steatotic liver disease/steatohepatitis (MASLD/MASH).

In vitro experiments were conducted in primary rodent hepatocytes, Huh7 human liver carcinoma cells and induced pluripotent stem cell-derived human liver organoids (HLOs). C57BL/6J male mice were fed a western-style diet and housed at thermoneutrality to recapitulate key aspects of MASLD/MASH. Pharmacological ACMSD inhibition was given therapeutically, following disease onset. HLO models of steatohepatitis were used to assess the DNA damage responses to ACMSD inhibition in human contexts.

Inhibiting ACMSD with a novel specific pharmacological inhibitor promotes de novo NAD+ synthesis and reduces DNA damage ex vivo, in vivo, and in HLO models. In mouse models of MASLD/MASH, de novo NAD+ biosynthesis is suppressed, and transcriptomic DNA damage signatures correlate with disease severity; in humans, Mendelian randomization-based genetic analysis suggests a notable impact of genomic stress on liver disease susceptibility. Therapeutic inhibition of ACMSD in mice increases liver NAD+ and reverses MASLD/MASH, mitigating fibrosis, inflammation, and DNA damage, as observed in HLO models of steatohepatitis.

Our findings highlight the benefits of ACMSD inhibition in enhancing hepatic NAD+ levels and enabling genomic protection, underscoring its therapeutic potential in MASLD/MASH.

Enhancing NAD+ levels has been shown to induce remarkable health benefits in mouse models of metabolic dysfunction-associated steatotic liver disease/steatohepatitis (MASLD/MASH), yet liver-specific NAD+ boosting strategies remain underexplored. Here, we present a novel pharmacological approach to enhance de novo synthesis of NAD+ in the liver by inhibiting α-amino-β-carboxymuconate-ε-semialdehyde decarboxylase (ACMSD), an enzyme highly expressed in the liver. Inhibiting ACMSD increases NAD+ levels, enhances mitochondrial respiration, and maintains genomic stability in hepatocytes ex vivo and in vivo. These molecular benefits prevent disease progression in both mouse and human liver organoid models of steatohepatitis. Our preclinical study identifies ACMSD as a promising target for MASLD/MASH management and lays the groundwork for developing ACMSD inhibitors as a clinical treatment.

Nicotinamide adenine dinucleotide (NAD+) is an essential coenzyme for redox reactions and regulates cellular catabolic pathways. An intertwined relationship exists between NAD+ and mitochondria, with consequences for mitochondrial function. Dysregulation in NAD+ homeostasis can lead to impaired energetics and increased oxidative stress, contributing to the pathogenesis of cardiometabolic diseases. In this review, we explore how disruptions in NAD+ homeostasis impact mitochondrial function in various cardiometabolic diseases. We discuss emerging studies demonstrating that enhancing NAD+ synthesis or inhibiting its consumption can ameliorate complications of this family of pathological conditions. Additionally, we highlight the potential role and therapeutic promise of mitochondrial NAD+ transporters in regulating cellular and mitochondrial NAD+ homeostasis.

This study aimed to investigate the effects of nicotinamide (NAM) applied to diets with different crude protein levels on immune function, antioxidant capacity, and intestinal flora in growing-finishing pigs. Forty barrows (37.0±1.0 kg) were randomly allocated to one of four dietary treatments (n=10 per group). The diets in the two phases consisted of a basal diet with 30 mg/kg NAM, a basal diet with 360 mg/kg NAM, a low-protein diet with 30 mg/kg NAM, and a low-protein diet with 360 mg/kg NAM. The results showed that dietary addition of 360 mg/kg NAM decreased IL-12, malondialdehyde, IgG and IgM contents in the plasma and increased total superoxide dismutase activity and total antioxidant capacity in the colonic mucosa (P < .05). Supplementing the diet with 360 mg/kg NAM increased mRNA expression of the nucleotide-binding oligomerization domain containing 2 and nuclear factor erythroid 2-related factor 2 and protein expression of nuclear factor kappa-B and toll-like receptor 4 in the colonic mucosa (P < .05). The concentrations of acetic acid and butyric acid in the colonic contents and the abundance of Actinobacteriota in the colon at the phylum level were significantly decreased by feeding low-protein diets (P < .05). Additionally, the addition of 360 mg/kg NAM to diets increased (P < .05) the Sobs, Ace, and Chao indices of colonic microorganisms in pigs. Overall, the rational use of NAM can improve inflammatory status, enhance antioxidant capacity and intestinal barrier function, and increase colonic microbial diversity in growing-finishing pigs.

Alcohol-associated liver disease (ALD) is a significant global health concern and a leading cause of liver disease-related deaths. However, the treatment options are limited due to the lack of animal models that accurately replicate ALD pathogenesis. An ideal ALD animal model should have pathological characteristics similar to those of human ALD, with a clear pathological process and ease of drug intervention. Over the years, researchers have focused on developing ideal ALD preclinical animal models by testing various methods, such as ad libitum drinking water with ethanol, acute, single large doses of ethanol gavage, multiple alcohol gavages in a short period, the Lieber-DeCarli liquid diet feeding model, the intragastric infusion model, and the Gao-binge model. With the increasing occurrence of obesity and metabolic dysfunction-associated steatotic liver disease, a new category of metabolic and alcohol-associated liver disease (MetALD) is also emerging. Studies have investigated the combined effects of a high-fat diet combined with binge alcohol or drinking water containing ethanol to mimic MetALD. In addition to mice, other species such as rats, guinea pigs, zebrafish, and non-human primates have also been tested to establish ALD preclinical models. This review aims to summarize current animal ALD models, particularly the emerging MetALD models, with the hope of providing a valuable reference for establishing more effective animal models in ALD studies in the future.

Mitochondria is the cell's powerhouse. Mitochondrial disease refers to a group of clinically heterogeneous disorders caused by dysfunction in the mitochondrial respiratory chain, often due to mutations in mitochondrial DNA (mtDNA) or nuclear DNA (nDNA) that encodes mitochondrial proteins. This dysfunction can lead to a variety of clinical phenotypes, particularly affecting organs with high energy demands, such as the brain and muscles. Epilepsy is a prevalent neurological disorder in children and is also a frequent manifestation of mitochondrial disease. The exact mechanisms underlying epilepsy in mitochondrial disease remain unclear and are thought to involve multiple contributing factors. This review explores common mitochondrial diseases associated with epilepsy, focusing on their prevalence, seizure types, EEG features, therapeutic strategies, and outcomes. It also summarizes the relationship between the molecular genetics of mitochondrial respiratory chain components and the development of epilepsy.

The fission yeast, Schizosaccharomyces pombe, is an excellent eukaryote model organism for studying essential biological processes. Its genome contains ∼1,200 genes essential for cell viability, most of which are evolutionarily conserved. To study these essential genes, resources enabling conditional perturbation of target genes are required. Here, we constructed comprehensive arrayed libraries of plasmids and strains to knock down essential genes in S. pombe using dCas9-mediated CRISPRi. These libraries cover ∼98% of all essential genes in fission yeast. We estimate that in ∼60% of these strains, transcription of a target gene was repressed so efficiently that cell proliferation was significantly inhibited. To demonstrate the usefulness of these libraries, we performed metabolic analyses with knockdown strains and revealed flexible interaction among metabolic pathways. Libraries established in this study enable comprehensive functional analyses of essential genes in S. pombe and will facilitate the understanding of essential biological processes in eukaryotes.

Disturbances in kidney tubular cell metabolism are increasingly recognized as a feature of acute kidney injury (AKI). In AKI, tubular epithelial cells undergo abnormal metabolic shifts that notably disrupt NAD+ metabolism. Recent advancements have highlighted the critical role of NAD+ metabolism in AKI, revealing that acute disruptions may lead to lasting cellular changes, thereby promoting the transition to chronic kidney disease (CKD). This review explores the molecular mechanisms underlying metabolic dysfunction in AKI, with a focus on NAD+ metabolism, and proposes several cellular processes through which acute aberrations in NAD+ may contribute to long-term changes in the kidney.

This goal of this study was to optimize spectrally selective 1H-MRS methods for large-volume acquisition of low-concentration metabolites with downfield resonances at 7 T and 3 T, with particular attention paid to detection of nicotinamide adenine dinucleotide (NAD+) and tryptophan.

Spectrally selective excitation was used to avoid magnetization-transfer effects with water, and various sinc pulses were compared with a band-selective, uniform response, pure-phase (E-BURP) pulse. Localization using a single-slice selective pulse was compared with voxel-based localization that used three orthogonal refocusing pulses, and low bandwidth refocusing pulses were used to take advantage of the chemical shift displacement of water. A technique for water sideband removal was added, and a method of coil channel combination for large volumes was introduced.

Proposed methods were compared qualitatively with previously reported techniques at 7 T. Sinc pulses resulted in reduced water signal excitation and improved spectral quality, with a symmetric, low bandwidth-time product pulse performing best. Single-slice localization allowed shorter TEs with large volumes, enhancing signal, whereas low-bandwidth slice-selective localization greatly reduced the observed water signal. Gradient cycling helped remove water sidebands, and frequency aligning and pruning individual channels narrowed spectral linewidths. High-quality brain spectra of NAD+ and tryptophan are shown in 4 subjects at 3 T.

Improved spectral quality with higher downfield signal, shorter TE, lower nuisance signal, reduced artifacts, and narrower peaks was realized at 7 T. These methodological improvements allowed for previously unachievable detection of NAD+ and tryptophan in human brain at 3 T in under 5 min.

To investigate the functions of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) in the goose fatty liver, a total of 30 healthy 63-day-old male Landes geese were selected and randomly assigned to control group and overfeeding group. The overexpression or RNA interference assay of PGC-1α was performed in goose primary hepatocytes. Our data showed that the PGC-1α expression was increased in fatty liver. The abundance of mitochondrial biosynthesis-related and energy metabolism-related genes, including mitochondrial transcription factor A (TFAM), mitochondrial transcription factor B1 (TFB1M), mitochondrial transcription factor B2 (TFB2M), nuclear respiratory factor 1 (NRF1), DNA topoisomerase I mitochondrial (TOP1MT), peroxisome proliferator-activated receptor gamma coactivator 1-beta (PGC-1β), sirtuin 3 (SIRT3), mitochondrially encoded cytochrome B (CYTB), and AMP-activated protein kinase alpha (AMPKα) were significantly increased in fatty liver. The abundance of TFAM, TFB1M, TFB2M, NRF1, and TOP1MT transcript was induced by PGC-1α overexpression, but inhibited by PGC-1α interference in primary hepatocytes. The mRNA expression levels of PGC-1β, SIRT3, SIRT5, CYTB, and AMPKα were significantly enhanced after PGC-1α overexpression. However, the mRNA expression levels of PGC-1β, SIRT5 and AMPKα were decreased after PGC-1α interference. Furthermore, we observed a significant increase in the mitochondrial DNA (mtDNA) copy number, the activity of mitochondrial respiratory chain complex Ⅳ (MRCC Ⅳ), succinate dehydrogenase (SDH), malate dehydrogenase (MDH), and the NAD+/NADH ratio in fatty liver. But the activity of MRCC Ⅴ, as well as the levels of ADP and ATP in fatty liver were reduced. Additionally, the mtDNA copy number, the activity of MRCC Ⅰ, MRCC Ⅲ-Ⅴ, SDH, and MDH, and NAD+/NADH ratio were enhanced by PGC-1α overexpression; Whereas the mtDNA copy number, the activity of MRCC Ⅰ, SDH, and MDH, and the ratio of NAD+/NADH were inhibited by PGC-1α interference. In conclusion, these findings suggest that PGC-1α improves mitochondrial biosynthesis and energy metabolism in goose fatty liver, which may be an adaptive mechanism for goose fatty liver to cope with steatosis.

Genetic mutations arising from various internal and external factors drive cells to become cancerous. Cancerous cells undergo numerous changes, including metabolic reprogramming and epigenetic modifications, to support their abnormal proliferation. This metabolic reprogramming leads to the altered expression of many metabolic enzymes and the accumulation of metabolites. Recent studies have shown that these enzymes and metabolites can serve as substrates or cofactors for chromatin-modifying enzymes, thereby participating in epigenetic modifications and promoting carcinogenesis. Additionally, epigenetic modifications play a role in the metabolic reprogramming and immune evasion of cancer cells, influencing cancer progression. This review focuses on the origins of cancer, particularly the metabolic reprogramming of cancer cells and changes in epigenetic modifications. We discuss how metabolites in cancer cells contribute to epigenetic remodeling, including lactylation, acetylation, succinylation, and crotonylation. Finally, we review the impact of epigenetic modifications on tumor immunity and the latest advancements in cancer therapies targeting these modifications.

NAD+ plays a pivotal role in energy metabolism and adaptation to external stimuli and stressful conditions. A significant reduction in intracellular NAD+ levels is associated with aging and contributes to the development of chronic cardiovascular, neurodegenerative, and metabolic diseases. It is of particular importance to maintain optimal levels of NAD+ in cells with high energy consumption, particularly in the brain. Maintaining the tissue level of NAD+ with pharmacological tools has the potential to slow down the aging process, to prevent the development of age-related diseases. This review covers key aspects of NAD+ metabolism in terms of brain metabolic plasticity, including NAD+ biosynthesis and degradation in different types of brain cells, as well as its contribution to the development of neurodegeneration and aging, and highlights up-to-date approaches to modulate NAD+ levels in brain cells.

Sarcopenia is a progressive muscle wasting disorder that severely impacts the quality of life of elderly individuals. Although the natural aging process primarily causes sarcopenia, it can develop in response to other conditions. Because muscle function is influenced by numerous changes that occur with age, the etiology of sarcopenia remains unclear. However, recent characterizations of the aging muscle transcriptional landscape, signaling pathway disruptions, fiber and extracellular matrix compositions, systemic metabolomic and inflammatory responses, mitochondrial function, and neurological inputs offer insights and hope for future treatments. This review will discuss age-related changes in healthy muscle and our current understanding of how this can deteriorate into sarcopenia. As our elderly population continues to grow, we must understand sarcopenia and find treatments that allow individuals to maintain independence and dignity throughout an extended lifespan.

Mitochondria are essential for cellular energy production and are implicated in numerous diseases, including diabetic kidney disease (DKD). Current evidence indicates that mitochondrial dysfunction results in alterations in several metabolic pathways within kidney cells, thereby contributing to the progression of DKD. Furthermore, mitochondrial dysfunction can engender an inflammatory milieu, leading to the activation and recruitment of immune cells to the kidney tissue, potentially perturbing intrarenal metabolism. In addition, this inflammatory microenvironment has the potential to modify immune cell metabolism, which may further accentuate the immune-mediated kidney injury. This understanding has led to the emerging field of immunometabolism, which views DKD as not just a metabolic disorder caused by hyperglycemia but also one with significant immune contributions. Targeting mitochondrial function and immunometabolism may offer protective effects for the kidneys, complementing current therapies and potentially mitigating the risk of DKD progression. This comprehensive review examines the impact of mitochondrial dysfunction and the potential role of immunometabolism in DKD. We also discuss tools for investigating these mechanisms and propose avenues for integrating this research with existing therapies. These insights underscore the modulation of mitochondrial function and immunometabolism as a critical strategy for decelerating DKD progression.

Neurodegenerative diseases, as common diseases in the elderly, tend to become younger due to environmental changes, social development and other factors. They are mainly characterized by progressive loss or dysfunction of neurons in the central or peripheral nervous system, and common diseases include Parkinson's disease, Alzheimer's disease, Huntington's disease and so on. Mitochondria are important organelles for adenosine triphosphate (ATP) production in the brain. In recent years, a large amount of evidence has shown that mitochondrial dysfunction plays a direct role in neurodegenerative diseases, which is expected to provide new ideas for the treatment of related diseases. This review will summarize the main mechanisms of mitochondrial dysfunction in neurodegenerative diseases, as well as collating recent advances in the study of mitochondrial disorders and new therapies.

Chronic kidney disease (CKD) is associated with renal metabolic disturbances, including impaired fatty acid oxidation (FAO). Nicotinamide adenine dinucleotide (NAD + ) is a small molecule that participates in hundreds of metabolism-related reactions. NAD + levels are decreased in CKD, and NAD + supplementation is protective. However, both the mechanism of how NAD + supplementation protects from CKD, as well as the cell types involved, are poorly understood. Using a mouse model of Alport syndrome, we show that nicotinamide riboside (NR), an NAD + precursor, stimulates renal peroxisome proliferator-activated receptor alpha signaling and restores FAO in the proximal tubules, thereby protecting from CKD in both sexes. Bulk RNA-sequencing shows that renal metabolic pathways are impaired in Alport mice and activated by NR in both sexes. These transcriptional changes are confirmed by orthogonal imaging techniques and biochemical assays. Single nuclei RNA-sequencing and spatial transcriptomics, both the first of their kind from Alport mice, show that NAD + supplementation restores FAO in proximal tubule cells. Finally, we also report, for the first time, sex differences at the transcriptional level in this Alport model. In summary, we identify a nephroprotective mechanism of NAD + supplementation in CKD, and we demonstrate that the proximal tubule cells substantially contribute to this benefit.

Tryptophan is an essential amino acid involved in critical cellular processes in vertebrates, serving as a precursor for serotonin and kynurenine, which are key neuromodulators to influence neural and immune functions. Systematic and quantitative measurement of tryptophan is vital to understanding these processes.

Here, we utilized a robust and highly responsive green ratiometric indicator for tryptophan (GRIT) to quantitatively measure tryptophan dynamics in bacteria, mitochondria of mammalian cell cultures, human serum, and intact zebrafish. At the cellular scale, these quantitative analyses uncovered differences in tryptophan dynamics across cell types and organelles. At the whole-organism scale, we revealed that inflammation-induced tryptophan concentration increases in zebrafish brain led to elevated serotonin and kynurenine levels, prolonged sleep duration, suggesting a novel metabolic connection between immune response and behavior. Moreover, GRIT's application in detecting reduced serum tryptophan levels in patients with inflammation symptoms suggests its potential as a high-throughput diagnostic tool.

In summary, this study introduces GRIT as a powerful method for studying tryptophan metabolism and its broader physiological implications, paving the way for new insights into the metabolic regulation of health and disease across multiple biological scales.

Immunosenescence, the aging of the immune system, leads to functional deficiencies, particularly in T cells, which undergo significant changes. While numerous studies have investigated age-related T-cell phenotypes in healthy aging, senescent T cells have also been observed in younger populations during pathological conditions like cancer. This review summarizes the recent advancements in age-associated alterations and markers of T cells, mechanisms, and the relationship between senescent T cells and the tumor microenvironment. We also discuss potential strategies for targeting senescent T cells to prevent age-related diseases and enhance tumor immunotherapy efficacy.

Nicotinamide phosphoribosyltransferase (NAMPT) is the key enzyme in the salvaging synthesize pathway of nicotinamide adenine dinucleotide (NAD). The neuroprotective roles of NAMPT on neurodegeneration have been explored in aging brain and Alzheimer's Disease. However, its roles in Parkinson's Disease (PD) remain to be elucidated. We found that the dopaminergic neurons in substantia nigra expressed higher levels of NAMPT than the other types of neurons. Using conditional knockout of the Nampt gene in dopaminergic neurons and utilizing a NAMPT inhibitor in the substantia nigra of mice, we found that the NAMPT deficiency triggered the time-dependent loss of dopaminergic neurons, the impairment of the dopamine nigrostriatal pathway, and the development of PD-like motor dysfunction. In the rotenone-induced PD mouse model, nicotinamide ribose (NR), a precursor of NAD, rescued the loss of dopaminergic neurons, the impairment of dopamine nigrostriatal pathway, and mitigated PD-like motor dysfunction. In SH-SY5Y cells, NAD suppression induced the accumulation of reactive oxygen species (ROS), mitochondrial impairment, and cell death, which was reversed by N-acetyl cysteine, an antioxidant and ROS scavenger. Rotenone decreased NAD level, induced the accumulation of ROS and the impairment of mitochondria, which was reversed by NR. In summary, our findings show that the ablation of NAMPT in dopaminergic neurons leads to neurodegeneration and contributes to the development of PD. The NAD precursors have the potential to protect the degeneration of dopaminergic neurons, and offering a therapeutic approach for the treatment of PD.

The prevalence of age-related disorders, particularly in neurological and cardiovascular systems, is an increasing global health concern. Mesenchymal stem cell (MSC) therapy, particularly using human umbilical cord-derived MSCs (HUCMSCs), has shown promise in mitigating these disorders. This study investigates the effects of HUCMSCs on aging-related conditions in a senescence-accelerated mouse model (SAMP8), with a focus on DNA damage, gut microbiota alterations, and metabolic changes.

SAMP8 mice were treated with clinical-grade HUCMSCs via intraperitoneal injections. Behavioral and physical assessments were conducted to evaluate cognitive and motor functions. The Single-Strand Break Mapping at Nucleotide Genome Level (SSiNGLe) method was employed to assess DNA single-strand breaks (SSBs) across the genome, with particular attention to exonic regions and transcription start sites. Gut microbiota composition was analyzed using 16S rRNA sequencing, and carboxyl metabolomic profiling was performed to identify changes in circulating metabolites.

HUCMSC treatment significantly improved motor coordination and reduced anxiety in SAMP8 mice. SSiNGLe analysis revealed a notable reduction in DNA SSBs in MSC-treated mice, especially in critical genomic regions, suggesting that HUCMSCs may mitigate age-related DNA damage. The functional annotation of the DNA breaktome indicated a potential link between reduced DNA damage and altered metabolic pathways. Additionally, beneficial alterations in gut microbiota were observed, including an increase in short-chain fatty acid (SCFA)-producing bacteria, which correlated with improved metabolic profiles.