Mitochondrial homeostasis, closely associated with mitophagy and antioxidant mechanisms, is essential for proper meiotic spindle assembly and chromosome segregation during oocyte maturation. SIRT5, known to modulate mitochondrial function under various conditions, has been shown to impact oocyte quality when inhibited, however, the precise mechanisms linking SIRT5 to mitochondrial homeostasis during meiotic progression remain unclear. In this study, we demonstrate that SIRT5 localizes predominantly at the periphery of the meiotic spindle and is enriched on chromosomes during oocyte maturation. Inhibition of SIRT5 led to significant meiotic defects, including disrupted spindle organization and chromosome misalignment. These defects were associated with increased histone acetylation, which impaired kinetochore-microtubule attachments. Moreover, SIRT5 inhibition resulted in mitochondrial dysfunction, subsequently elevating ROS levels and triggering oxidative stress, which further exacerbated meiotic abnormalities. Mechanistically, SIRT5 inhibition disrupted the balance of Parkin-dependent mitophagy by inducing ULK phosphorylation. Additionally, it activated the PI3K/Akt signaling pathway, which increased NADPH consumption and reduced GSH levels. Collectively, these findings reveal that SIRT5 plays dual roles in maintaining mitochondrial homeostasis during oocyte maturation: (1) by regulating Parkin-dependent mitophagy to prevent excessive mitochondrial clearance, and (2) by preserving the NADPH/GSH antioxidant system to ensure redox balance. These insights provide potential targets for improving oocyte quality and addressing mitochondrial dysfunction-related reproductive disorders in females.

Silent information regulator 5 (SIRT5) is the fifth member of the sirtuin family, which is mainly expressed in mitochondrial matrix. SIRT5 plays a key role in metabolism and antioxidant responses, and is an important regulator for maintaining intracellular homeostasis. Given its involvement in multiple cellular processes, dysregulation of SIRT5 activity is associated with a variety of diseases. This review explores the structural characteristics of SIRT5 that influence its substrate specificity, highlights recent research advances, and summarizes its four key enzymatic activities along with their corresponding substrates in disease contexts. We also discuss the natural products that modulate SIRT5 activity and identify potential targets of SIRT5 through virtual docking, which may provide new therapeutic avenues. Although the mechanism of SIRT5 in diseases needs to be further elucidated and deglutathionylation activities are still at an early stage, targeting SIRT5 and its substrates holds significant promise for the development of novel therapeutics.

Succinate dehydrogenase (SDH), considered as the linkage between tricarboxylic acid cycle (TCA cycle) and electron transport chain, plays a vital role in adenosine triphosphate (ATP) production and cell physiology. SDH deficiency is a notable characteristic in many cancers. Recent studies have pinpointed the dysregulation of SDH can directly result its decreased catalytic activity and the accumulation of oncometabolite succinate, promoting tumor progression in different perspectives. This article expounds the various types of SDH deficiency in tumors and the corresponding pathological features. In addition, we discuss the mechanisms through which defective SDH fosters carcinogenesis, pioneering a categorization of these mechanisms as being either succinate-dependent or independent. Since SDH-deficient and cumulative succinate are regarded as the typical features of some cancers, like gastrointestinal stromal tumors, pheochromocytomas and paragangliomas, we summarize the presented medical management of SDH-deficient tumor patients in clinical and preclinical, identifying the potential strategies for future cancer therapeutics.

Metabolic reprogramming is a key contributor to cancer therapeutic resistance. Peroxisomes are highly metabolic organelles essential for lipid metabolism and reactive oxygen species (ROS) turnover. Recent studies pointed out that targeting peroxisomal genes could be a promising strategy for treating therapy-resistant cells. However, the role of peroxisomes in CRC chemoresistance remains largely unexplored. This study aimed to investigate the function of peroxisomes in CRC chemoresistance and uncover the underlying mechanisms. Our results showed that the protein level of peroxisome marker PMP70 was strongly correlated with oxaliplatin (LOHP)-treated tumor recurrence in CRC. LOHP was confirmed to induce pexophagy in CRC cells, whereas LOHP-resistant cells maintained stable peroxisome levels and resisted this selective autophagy. Moreover, depletion of PMP70 significantly reduced the viability of resistant CRC cells in response to LOHP, both in vitro and in vivo. Mechanistically, PMP70 acted as a potential protector against excessive lipid peroxidation (LPO) in PMP70High and LOHP-resistant CRC cells. Additionally, PMP70-depleted cells exhibited an altered metabolic profile, characterized by reduced neutral lipids, fewer lipid droplets (LDs), and cell cycle arrest, indicating that PMP70 downregulation resulted in metabolic impairment. In conclusion, our study unveiled the pivotal role of PMP70-mediated peroxisomal functions in conferring chemoresistance, particularly in the context of LOHP resistance in CRC.

Glioma is a highly aggressive brain tumor with limited treatment success due to its resistance to conventional therapies. Sirtuin 5 (SIRT5) has emerged as a promising target for cancer therapy, though it exhibits dual roles in different cancer types. In this study, we investigate the role of SIRT5 in glioma and its corresponding mechanisms. Our findings demonstrate that SIRT5 expression is elevated in glioma cells both in vitro and in vivo. SIRT5 knockdown significantly reduced glioma cell proliferation and enhanced sensitivity to ferroptosis. Proteomic and metabolomic analyses identifies branched-chain amino acid (BCAA) metabolism as a key downstream pathway regulated by SIRT5 through branched-chain aminotransferase 1 (BCAT1). Specifically, SIRT5-mediated desuccinylation of BCAT1 at K39 inhibits its interaction with the E3 ligase CHIP, thereby preventing BCAT1 degradation via the ubiquitin-proteasome system. Moreover, BCAT1 overexpression reverses the proliferation inhibition and ferroptosis sensitivity observed in SIRT5-knockdown cells. Clinically, we reveal a positive correlation between SIRT5 and BCAT1 levels in glioma samples, with higher expression levels predicting more advanced glioma grades and poorer clinical outcomes. Collectively, this study highlights the critical role of SIRT5 in promoting glioma progression via metabolic regulation and ferroptosis insensitivity, offering a potential therapeutic target for glioma treatment.

Lysine succinyltransferase KAT3B plays a critical role in the progression of various cancers by modulating key metabolic pathways, including glycolysis. However, the function and underlying mechanism of KAT3B in glycolysis and lung cancer (LC) progression remain to be further studied. We determined mRNA expression levels of lysine succinyl-modifying enzymes through qRT-PCR. Protein expression and succinylation status of glycolysis-related proteins PKM2, LDHA, and ENO1 were analyzed via Western blot. Co-immunoprecipitation and immunofluorescence microscopy were employed to verify the interaction between KAT3B and PKM2. Bioinformatics analysis predicted succinylation sites on PKM2, which were subsequently validated through site-directed mutagenesis. The effects of KAT3B and PKM2 on LC cell malignancy and glycolysis were evaluated using CCK-8, transwell migration, glucose uptake, lactate production, ECAR, and OCR assays. A xenograft tumor model was utilized to assess the impact of KAT3B on LC tumor growth. We confirmed the augmentation of KAT3B in LC, which also was correlated with advanced TNM stages and elevated T stages of LC patients. Conversely, KAT3B knockdown suppressed the growth, metastasis, and glycolytic activity of LC cells in vitro, while also inhibiting tumor growth in vivo. KAT3B mediated succinylation at PKM2 K298, and the suppression of LC cell malignancy and glycolysis upon KAT3B downregulation was largely reversed by upregulation of PKM2. The KAT3B/PKM2 axis may be a novel target for LC therapy.

The osteogenic differentiation potential of bone marrow mesenchymal stem cells (BM-MSCs) is critical for bone regeneration and repair. In recent years, the role of protein succinylation modification in regulating cellular metabolism has garnered increasing attention. However, its mechanism in osteogenic differentiation remains unclear.

Oxygen consumption rate (OCR) and mitochondrial ROS (mtROS) were detected to assess mitochondrial function in BM-MSCs with successive passages. Alizarin red staining and western blot experiments were used to evaluate osteogenic differentiation capacity. Succinylation modification omics and Co-IP detection were conducted to determine SIRT5-mediated desuccinylation of UQCRC2.

Bioinformatics analysis revealed that sirtuin 5 (SIRT5) expression is upregulated with multiple rounds of BM-MSCs' passages, and is associated with biological pathways such as oxidative phosphorylation (OXPHOS), cellular senescence, and inhibition of osteogenic differentiation. Experiments in vitro confirmed the up-regulation of SIRT5 and the suppression of osteogenic differentiation with the increased times of BM-MSCs' passages. Overexpression of SIRT5 enhanced OXPHOS and elevated mtROS levels, but reduced the expression of Runx2 and osteocalcin, and decreased calcified nodules, thereby inhibiting the osteogenic differentiation of BM-MSCs. SIRT5-mediated desuccinylation of ubiquinol-cytochrome C reductase core protein 2 (UQCRC2) at the site of K250 promoted UQCRC2 translocation from cytoplasm to mitochondria, which enhanced the activity of mitochondrial respiratory complex III. It further increased mtROS, accelerated cellular senescence and inhibited the osteogenic differentiation of BM-MSCs.

SIRT5 reduces succinylation modification of UQCRC2, promotes mitochondrial respiration and mtROS, and thus reduces the osteogenic differentiation ability of BM-MSCs cells. SIRT5 might be a potential target to prevent the suppression of osteogenic differentiation of of BM-MSCs after multiple rounds passages.

Ferroptosis is recently discovered as an important player in the initiation, proliferation, and progression of human tumors. Insulin-like growth factor 2 mRNA-binding protein 3 (IGF2BP3) has been reported as an oncogene in multiple types of cancers, including lung adenocarcinoma (LUAD). However, little research has been designed to investigate the regulation of IGF2BP3 on ferroptosis in LUAD. qRT-PCR and western blot were used to measure the mRNA and protein expression of IGF2BP3 and transcription factor AP-2 alpha (TFAP2A). CCK-8 assay was performed to determine cell viability. DCFH-DA and C11-BODIPY staining were used to detect the levels of intracellular reactive oxygen species (ROS) and lipid ROS. The corresponding assay kits were used to analyze the levels of malondialdehyde (MDA) and glutathione (GSH). SRAMP website and m6A RNA immunoprecipitation (Me-RIP) were used to predict and confirm the m6A modification of TFAP2A. RIP experiments were conducted to confirm the binding of IGF2BP3 and TFAP2A. RNA stability assay was performed using actinomycin D. Chromatin immunoprecipitation (ChIP) and dual-luciferase reporter experiments were performed to confirm the interaction between TFAP2A and cystine/glutamate antiporter solute carrier family 7 member 11 (SLC7A11) or glutathione peroxidase 4 (GPX4). Mice xenotransplant model was also constructed to explore the effect of IGF2BP3 on LUAD tumor growth and ferroptosis. IGF2BP3 and TFAP2A were both highly expressed in LUAD. IGF2BP3 or TFAP2A knockdown induced ferroptosis by aggravating erastin-induced cell viability suppression, increasing the production of intracellular ROS, lipid ROS, and MDA, and decreasing GSH synthesis, GSH/GSSG ratio, and cystine uptake. Mechanistically, IGF2BP3 stabilized TFAP2A expression via m6A modification. Moreover, sh-IGF2BP3-mediated ferroptosis was significantly abated by TFAP2A overexpression. Furthermore, TFAP2A binds to the promoters of SLC7A11 and GPX4 to promote their transcription. Also, IGF2BP3 depletion suppressed LUAD tumor growth by inducing ferroptosis in mice. IGF2BP3 suppresses ferroptosis in LUAD by m6A-dependent regulation of TFAP2A to promote the transcription of SLC7A11 and GPX4. Our findings suggest that targeting IGF2BP3/TFAP2A/SLC7A11/GPX4 axis might be a potential therapeutic choice to increase ferroptosis sensitivity in LUAD.

Nonalcoholic fatty liver disease (NAFLD) manifests as chronic hepatic steatosis, occurring variably across people due to racial and genetic diversity. It represents a stage in the development of chronic liver disease, marked by fat accumulation, inflammatory responses, oxidative stress in the endoplasmic reticulum, and fibrosis as primary concerns. Understanding its underlying mechanisms remains a challenging and pivotal area of study. In the past, acute liver injury-related diseases were commonly treated with methods such as liver transplantation. However, the emergence of artificial liver has shifted focus to stem cell therapies. Unlike conventional drugs, stem cell therapies are continuously evolving. Despite being classified as drugs, stem cells demonstrated significant efficacy after multiple injections. Mesenchymal stem cells, unlike other types of stem cells, do not have the risk of tumor formation and low immunogenicity, reducing the hypersensitivity reactions associated with liver transplantation. Increasingly, studies suggest that mesenchymal stem cells hold promise in the treatment of chronic liver injury diseases. This review focuses on investigating the role of mesenchymal stem cells in chronic metabolic liver diseases, such as non-alcoholic fatty liver disease, and delves into their specific functions.

Fatty acid metabolism is closely associated with hepatocellular carcinoma (HCC). Elucidating the molecules that influence fatty acid metabolism in HCC is important for developing precision therapies. However, uncovering the precise molecular mechanisms underlying changes in fatty acid metabolism in tumour cells is challenging. In this study, we aimed to determine the characteristics of fatty acid metabolism in HCC.

We employed organoid models, single-cell RNA sequencing, and spatial transcriptomics to identify key genes involved in tumour fatty acid metabolism. Metabolomics, proteomics, metabolic flux analysis, and transmission electron microscopy were utilized to evaluate this metabolic process. Tumour malignancy was characterized using multi-species models. Changes in the immune microenvironment were analysed by time-of-flight mass cytometry and multiplexed immunohistochemistry. Gene knockdown targeting the liver was achieved using lipid nanoparticles.

Eukaryotic translation initiation factor 3 subunit f (eIF3f) is upregulated in HCC tissues and is associated with poor prognosis. eIF3f directly interacted with and stabilised long chain acyl CoA synthetase 4 (ACSL4) through K48-linked deubiquitination, promoting fatty acid biosynthesis and malignancy. The increased fatty acid levels in the tumour microenvironment indirectly reduced CD8+ T-cell infiltration. In addition, phosphorylated eIF3f enhanced the interaction between eIF3f and ACSL4.

Targeting the eIF3f-ACSL4-fatty acid biosynthesis axis could decelerate the progression of HCC and enhance anti-programmed cell death-1 efficacy, implicating eIF3f as a potential target for precision therapy in HCC.

Fatty acid metabolism is closely associated with hepatocellular carcinoma (HCC), yet the underlying mechanisms involved remain unclear. Here, we found that eIF3f is upregulated in HCC and is associated with poor prognosis. eIF3f interacts with and stabilizes ACSL4, thereby promoting fatty acid biosynthesis. Additionally, increased fatty acid levels reduce CD8+ T-cell infiltration and activation. These findings are of significant importance for clinicians and researchers in the field of HCC treatment, as eIF3f inhibition combined with anti-PD-1 therapy significantly improved anti-tumour efficacy in a mouse model and could offer therapeutic benefits for patients. These findings have practical implications, as eIF3f could serve as a novel therapeutic target in HCC. However, further clinical studies are needed to confirm the efficacy of eIF3f targeting in human patients.

The adverse effects of weightlessness on the human cardiovascular system greatly hinder the process of long-term and long-distance space exploration. Succinylation is an important type of protein post-translational modification. However, whether succinylation modification is able to play a role in altered vascular endothelial cell function under microgravity or simulated microgravity has not been reported. This study aims to investigate the quantitative global proteome and the changes in lysine succinylation in related proteins, seeking to facilitate a better understanding of the protein post-translational modification in cardiovascular deconditioning under microgravity. LC-MS/MS combined with bioinformatics analysis were used to quantitatively detect the perspectives at the global protein level. Immunoprecipitation and Western blot analysis were conducted to further verify the alterations of related proteins and lysine succinylation. A total of 132 differentially expressed proteins and 164 differentially expressed lysine succinylation sites were identified in human umbilical vein endothelial cells (HUVECs). Bioinformatics analysis indicates that lysine succinylation may play a potential role in energy metabolism. In addition, desuccinylase SIRT5 was downregulated and regulated succinylation modification levels of HUVECs under simulated microgravity. Notably, the overexpression of SIRT5 effectively protected HUVECs from apoptosis induced by simulated microgravity. And the succinylation of Lys396 in ERO1A was significantly increased in HUVECs under simulated microgravity. Mechanistically, the knockdown of SIRT5 was found to induce the apoptosis of HUVECs through the succinylation of Lys396 in ERO1A. These results can provide new ideas for elucidating the molecular mechanism of cardiovascular dysfunction in microgravity environments, and provide key molecular targets for scientific protective measures against microgravity in space.

Salt stress is considered to be one of the major abiotic stresses influencing rice growth and productivity. To improve rice crop productivity in saline soils, it is essential to choose a suitable variety for mitigating salt stress and gain a deep understanding of the underlying mechanisms. The current study explored the salt tolerance mechanism of wild rice 'HD96-1 (salt resistive)' and conventional rice 'IR29 (salt sensitive)' by evaluating morph-physiological, transcriptomic, and metabolomic approaches.

Physiological data indicated that HD96-1 had higher chlorophyll content, higher photosynthetic efficiency, more stable Na+/K+, less H₂O₂, and lower electrolyte leakage under salt stress compared with IR29. Transcriptomic and metabolomic data showed that the expression of NHXs in IR29 was significantly down-regulated under salt stress, leading to a large accumulation of Na⁺ in the cytoplasm, and that the expression of CHLH, PORA, and PORB was significantly down-regulated, inhibiting chlorophyll synthesis. HD96-1 maintained the balance of Na⁺ and K⁺ by increasing the expression of NHX4, and there was no significant change in the expression of genes related to chlorophyll synthesis, which made HD96-1 more resistant to salt stress than IR29. In addition, HD96-1 inhibited the excessive synthesis of hydrogen peroxide (H₂O₂) and alleviated oxidative damage by significantly down-regulating the expression of ACX4 under salt stress. HD96-1 promoted the accumulation of isoleucine by up-regulating genes of branched-chain amino acid aminotransferase 2 and branched-chain amino acid aminotransferase 4 and might promote the synthesis of raffinose and stachyose by up-regulating the expression of the gene for galactitol synthase 2, which, in turn, maintained a stable osmotic pressure and relieved osmotic stress. We also found that IR29 and HD96-1 alleviated the inhibition of photosynthesis by salt stress by down-regulating the expression of light-harvesting chromophore protein complex (LHCH II)-related genes and reducing the excessive accumulation of glucose metabolites, respectively. In addition, HD96-1 enhances salt tolerance by regulating C2H2 and bHLH153 transcription factors.

Under salt stress, HD96-1 maintained ionic balance and photosynthetic efficiency by up-regulating the expression of NHX4 gene and reducing the overaccumulation of glucose metabolites, respectively, and mitigated osmotic stress and oxidative stress by down-regulating the expression of ACX4 and promoting the accumulation of isoleucine, respectively, thereby enhancing the adaptability to salt stress. IR29 maintained photosynthetic efficiency under salt stress by down-regulating the expression of light-harvesting chromophore protein complex (LHCH II)-related genes, thereby enhancing adaptation to salt stress.

Papillary thyroid cancer (PTC) is one of the malignant tumors with rapidly increasing morbidity and mortality. Sirtuin 7 (SIRT7) is a desuccinylase that is involved in tumorigenesis. The activation of large tumor suppressor 1 (LATS1) can effectively suppress tumorigenesis in multiple tumors and can be affected by SIRT7. This study aimed to explore the role and mechanism of SIRT7 in PTC progression.

The RNA and protein levels were detected by quantitative real-time PCR (qPCR) and western blot, respectively. Cell proliferation was measured by cell counting kit-8 and colony formation. The apoptosis of PTC cells was analyzed by flow cytometry and Live/dead cell staining. The interaction between proteins was detected by co-immunoprecipitation.

The results showed that SIRT7 was highly expressed in PTC tissues and cells. Functional studies showed that knockdown of SIRT7 inhibited the proliferation and induced apoptosis of PTC cells. Mechanistically, SIRT7 could directly interact with LATS1 and reduce the stability of the LATS1 protein. Later, rescue experiments suggested that LATS1 silencing reversed the effect of SIRT7 knockdown on PTC cell growth and apoptosis. In addition, SIRT7 promoted tumor growth in vivo.

Taken together, silencing of SIRT7 promotes the succinylation of LATS1 to enhance LATS1 stability, thus inhibiting the progression of PTC. Therefore, SIRT7 and LATS1 may become novel and potential therapeutic targets for PTC.

Superovulation and embryo transfer are key technologies to improve the reproductive ability of female animals and enhance the efficiency of livestock production. However, poor-quality oocytes or abnormal fluctuations of hormone levels caused by superovulation affect the embryonic development environment, which may lead to a significant decline in the number and quality of transferable embryos, thus reducing the efficiency of superovulation. In this study, nicotinamide adenine dinucleotide (NAD+) was injected into Huaxi cows during the superovulation period to observe the proliferation and apoptosis of transplanted embryos. We examined the proliferation, apoptosis, reactive oxygen species (ROS) and mitochondrial membrane potential of cumulus cells and oocytes directly treated with NAD+ and investigated the potential mechanism of NAD+ to improve the superovulation efficiency by serum metabolomics and single-cell RNA sequencing. The results show that the addition of NAD+ significantly increased the quantity and quality of transferable embryos after superovulation. Differential metabolites during estrus synchronization and embryo flushing are enriched in glycerophospholipid metabolic pathways, suggesting that NAD+ can regulate lipid metabolic pathways. We found that NAD+ optimized the secretion levels of the steroid hormone estradiol (E2) and progesterone (P4) during superovulation by regulating the activity of cumulus cells. In oocytes, we found that NAD+ can inhibit apoptosis, scavenge ROS, and enhance mitochondrial function, thereby promoting oocyte maturation and enhancing embryo developmental potential. In conclusion, NAD+ significantly improved the superovulation ability of Huaxi cattle and provides an effective way for animal husbandry to improve the yield of high-quality embryos.

Multiple myeloma (MM) remains an incurable hematological malignancy that necessitates the identification of novel therapeutic strategies. Here, we report that intracellular levels of very long chain fatty acids (VLCFAs) control the cytotoxicity of MM chemotherapeutic agents. Inhibition of VLCFA biosynthesis reduced cell death in MM cells caused by the proteasome inhibitor, bortezomib. Conversely, inhibition of VLCFA degradation via suppression of peroxisomal acyl-CoA oxidase 1 (ACOX1) increased the cytotoxicity of bortezomib, its next-generation analog, carfilzomib, and the immunomodulatory agent lenalidomide. Furthermore, treatment with an orally available ACOX1 inhibitor cooperated with bortezomib in suppressing the growth of bortezomib-resistant MM xenografts in mice. Increased VLCFA levels caused by genetic or pharmacological inhibition of VLCFA degradation reduced the activity of two major kinases involved in MM pathogenesis, MET proto-oncogene (MET) and insulin-like growth factor 1 receptor (IGF1R). Mechanistically, inhibition of ACOX1 promoted the accumulation of VLCFA-containing cerebrosides, altered MET and IGF1R interaction with a cerebroside analog, and selectively inhibited the association of these kinases with the plasma membrane signaling platforms, importantly, without disrupting the platforms' integrity. Our study revealed a specific metabolic vulnerability of MM cells and identified a targetable axis linking VLCFA metabolism to the regulation of MET and IGF1R activity.

The sirtuin family comprises seven NAD+-dependent enzymes which catalyze protein lysine deacylation and mono ADP-ribosylation. Sirtuins act as central regulators of genomic stability and gene expression and control key processes, including energetic metabolism, cell cycle, differentiation, apoptosis, and aging. As a result, all sirtuins play critical roles in cellular homeostasis and organism wellness, and their dysregulation has been linked to metabolic, cardiovascular, and neurological diseases. Furthermore, sirtuins have shown dichotomous roles in cancer, acting as context-dependent tumor suppressors or promoters. Given their central role in different cellular processes, sirtuins have attracted increasing research interest aimed at developing both activators and inhibitors. Indeed, sirtuin modulation may have therapeutic effects in many age-related diseases, including diabetes, cardiovascular and neurodegenerative disorders, and cancer. Moreover, isoform selective modulators may increase our knowledge of sirtuin biology and aid to develop better therapies. Through this review, we provide critical insights into sirtuin pharmacology and illustrate their enzymatic activities and biological functions. Furthermore, we outline the most relevant sirtuin modulators in terms of their modes of action, structure-activity relationships, pharmacological effects, and clinical applications.

Ammonia can cause cells to produce a large amount of reactive oxygen species (ROS), leading to the oxidative stress of cells. As the main intracellular reductant, nicotinamide adenine dinucleotide phosphate (NADPH) plays a crucial role in maintaining reduced glutathione (GSH), helping to remove ROS and protect cells from oxidative damage. Our study demonstrated that SIRT5 desuccinylated isocitrate dehydrogenase 2 (IDH2) to enhance its activity, resulting in increased NADPH production. Furthermore, we observed that SIRT5 overexpression alleviated ammonia-induced high levels of ROS in bovine mammary epithelial cells. This effect was achieved by activating IDH2 through SIRT5, which increased NADPH production and GSH levels, thereby improving the antioxidant capacity to scavenge ROS and reduce the susceptibility of cell to ROS. In conclusion, our findings revealed a SIRT5-dependent mechanism that modulated intracellular NADPH homeostasis to attenuate ammonia-induced oxidative stress by enhancing IDH2 enzymatic activity.

Sirtuin 5 (SIRT5) in mitochondria possesses a strong capacity for lysine desuccinylation, involving in various biological processes. Our previous research demonstrated that NH3 regulated autophagy dependent on SIRT5 in bovine mammary epithelial cells (bMECs). Interestingly, we discovered that SIRT5 reduced the content of NH3 and glutamate by inhibiting GLS activity in bMECs, the ratio of ADP/ATP also declined. In this study, we identified that SIRT5 interacted with endogenous GLS and GDH through Co-IP assay, but had no effect on endogenous GLS and GDH expression. SIRT5 made the succinylation levels of GLS and GDH significantly declined and resulted in the reduction of GLS and GDH activity. Next, the content of ammonia and glutamate, as well as the related autophagy markers were measured, we found that SIRT5 affected the glutamine metabolism, which attenuated ammonia release in MAC-T cells, accompanying with cellular autophagy decline, reducing the formation of autophagosome. Deletion of SIRT5 gene in MAC-T cells by means of CRISPR-cas9, we found the content of NH3 and glutamate increased, as well as autophagy promoted, which could be alleviated by SIRT5 overexpression. SIRT5 KO also resulted in increase of succinylation of GLS and GDH, as well as autophagy response in bMECs. Furthermore, SIRT5 promoted the maintenance of mitochondria homeostasis. Mechanistically, SIRT5 reduced ammonia release by modulating the succinylation levels and enzymatic activities of GLS and GDH in mitochondria and promoted the maintenance of mitochondria homeostasis, as well as further attenuated ammonia-stimulated autophagy in bovine mammary epithelial cells.

Succinylation represents an emerging class of post-translational modifications (PTMs), characterized by the enzymatic or non-enzymatic transfer of a negatively charged four-carbon succinyl group to the ϵ-amino group of lysine residues, mediated by succinyl-coenzyme A. Recent studies have highlighted the involvement of succinylation in various diseases, particularly cancer progression. Sirtuin 5 (SIRT5), a member of the sirtuin family, has been extensively studied for its robust desuccinylase activity, alongside its deacetylase function. To date, only a limited number of SIRT5 substrates have been identified. These substrates mediate diverse physiological processes such as glucose oxidation, fatty acid oxidation, ammonia detoxification, reactive oxygen species scavenging, anti-apoptosis, and inflammatory responses. The regulation of these activities can occur through either the same enzymatic activity acting on different substrates or distinct enzymatic activities targeting the same substrate. Aberrant expression of SIRT5 has been closely linked to tumorigenesis and disease progression; however, its role remains controversial. SIRT5 exhibits dual functionalities: it can promote tumor proliferation, metastasis, drug resistance, and metabolic reprogramming, thereby acting as an oncogene; conversely, it can also inhibit tumor cell growth and induce apoptosis, functioning as a tumor suppressor gene. This review aims to provide a comprehensive overview of the current research status of SIRT5. We discuss its structural characteristics and regulatory mechanisms, compare its functions with other sirtuin family members, and elucidate the mechanisms regulating SIRT5 activity. Specifically, we focus on the role of succinylation modification mediated by SIRT5 in tumor progression, highlighting how desuccinylation by SIRT5 modulates tumor development and delineating the underlying mechanisms involved.

Non-alcoholic steatohepatitis (NASH) is the most common cause of chronic liver diseases with its pathophysiological mechanism poorly understood. In this work, serological, histological, molecular biological, biochemical, and immunological methods were applied to explore the pathological significance and action of zinc finger protein 281 (ZFP281 in mouse, ZNF281 in human) and targeted strategies. We reported that ZFP281/ZNF281 abundance in hepatocytes was positively correlated with the progression of NASH. Hepatocyte-specific knockdown of Zfp281 prevented mice from NASH diet-induced liver injury, steatosis, inflammation, and fibrosis. Consistently, the metabolic syndromes in NASH mice, characterized by obesity, hyperglycemia, insulin resistance, and hyperlipidemia, were also relieved by hepatocyte-specific Zfp281 deficiency. Mechanistically, incremental ZNF281 led to the upregulation of proinflammatory signaling, receptor-interacting protein kinase 1 (RIPK1)/RIPK3/mixed lineage kinase domain like pseudokinase (MLKL) axis in hepatocytes bearing free fatty acid stress. Activated MLKL translocated to the mitochondrial membrane, disrupting mitochondrial fatty acid β-oxidation and facilitating lipid accumulation in hepatocytes exposed to free fatty acid stimulation; also, MLKL in activated form orientated to the plasma membrane, triggering the lytic death mode in hepatocytes and launching hepatocellular proinflammatory responses. Moreover, we screened a ZFP281 inhibitor, pterostilbene, and demonstrated that pterostilbene, by inhibiting ZFP281 elevation in NASH livers, reduced hepatocyte injury, steatosis, inflammatory responses and fibrogenesis. In conclusion, this work proposes that induction of ZFP281/ZNF281-RIPK1/RIPK3/MLKL signaling disrupts fatty acid metabolism, promoting lipid accumulation, and triggers proinflammatory cell death, accelerating hepatic necroinflammation. Our work identifies ZFP281/ZNF281 as a promising target as well as pterostilbene as a potential strategy for NASH managing.

Acyl-CoA oxidase 1 (ACOX1), a member of the acyl-coenzyme A oxidase family, is considered a crucial regulator whose dysregulation is implicated in the occurrence and progression of various cancers. This study aims to elucidate the impact of ACOX1 in CRC, shedding light on its potential as a therapeutic target. Through analysis of the GEO dataset, it was found that ACOX1 is significantly downregulated in colorectal cancer (CRC), and this lower expression level is associated with a worse prognosis. Additionally, in vitro as well as in vivo, ACOX1 overexpression dramatically reduced the proliferation and metastasis of CRC cells. Mass spectrometry revealed the crucial role of ACOX1 in fatty acid β-oxidation, as its overexpression led to a substantial increase in reactive oxygen species (ROS) derived from fatty acid β-oxidation. Further experiments demonstrated that ACOX1 overexpression, through modulation of fatty acid metabolism, increased ROS levels, reduced the phosphorylation activation of the key autophagy regulator mTOR, enhanced autophagy, and ultimately suppressed the growth and metastasis of CRC. In conclusions, ACOX1 expression is decreased in CRC. ACOX1 may regulate autophagy by reprogramming lipid metabolism to modulate the ROS/mTOR signaling pathway, consequently inhibiting the proliferation and migration of CRC.

Sepsis-induced lung injury represents a clinical syndrome encompassing various forms of acute respiratory failure. Understanding the mechanisms underlying its development is critical for identifying promising therapeutic targets.

In this study, both in vitro and in vivo models of septic lung injury were established using a mouse model and the human lung microvascular endothelial cell line HULEC-5a. Quantitative real-time PCR and Western blotting were utilized to measure messenger RNA and protein expression levels. Flow cytometry was employed to assess pyroptosis, and coimmunoprecipitation was used to detect protein-protein interactions. Hematoxylin and eosin staining was performed to evaluate the pathological changes in lung tissues.

Our results demonstrated that Sirtuin 5 expression was significantly downregulated in the blood of patients with septic lung injury, as well as in mice and HULEC-5a cells treated with lipopolysaccharide. SIRT5 suppressed lipopolysaccharide-induced pyroptosis in HULEC-5a cells and septic lung injury in mice. Mechanistically, SIRT5 was shown to directly bind to Serine-Arginine Protein Kinase 1 (SRPK1) and desuccinylate it at lysine residues K588 and K598, thereby reducing its protein stability. Rescue experiments further confirmed that SIRT5 exerts its protective effects against septic lung injury through regulation of SRPK1.

Collectively, these findings suggested that the SIRT5/SRPK1 signaling pathway may serve as a potential therapeutic target for the treatment of septic lung injury.

Extranodal natural killer/T-cell lymphoma, nasal type (ENKTL) is a malignant tumor harboring a poor prognosis and unsatisfactory treatment outcomes. This study was performed to explore the pathogenesis and exact etiology of ENKTL. Methods Bioinformatic analysis was conducted to investigate the expression of SIRT5 and glucose-6-phosphate isomerase (GPI), as well their correlation with ENKTL overall survival. Cell proliferation ability and cell apoptosis were determined by CCK8, soft-agar colony formation and Tunel assays. Pyruvic acid and lactate production, GPI activity and F6P levels were detected to indicate glycolysis process. Succinylation modification in GPI protein was quantified by 4D label-free succinylation modification quantitative proteome. ENKTL mouse model was established by the injection of SNK6 cells.

SIRT5 suppressed the NKTL cell proliferation through the desuccinylation effect, while it was down-regulated in the ENKTL. SIRT5 catalyzed the desuccinylation of glycolytic enzyme GPI in ENKTL cells, which accelerated GPI protein degradation through the autophagy-lysosome system. SIRT5 inhibited glycolysis via mediating the desuccinylation of GPI, thereby suppressing ENKTL cell proliferation. The antitumor role of SIRT5 was also certified in ENKTL mouse model by targeting GPI.

SIRT5 inhibits glycolysis via catalyzed the desuccinylation of glycolytic enzyme GPI, thereby repressing ENKTL cells proliferation and tumor growth. As SIRT5 serves as a tumor suppressor in ENKTL, it may be a promising molecular target in therapy strategy.

Lysine succinylation is an emerging post-translational modification of proteins. It involves the addition of the succinyl group to lysine residues of target proteins through both enzymatic and non-enzymatic pathways. This modification can alter the structure of the target protein, which, in turn, impacts protein activity and function and is involved in a wide range of diseases. In the field of cancer biology, lysine succinylation has been shown to exert a substantial influence on metabolic reprogramming of tumor cells, regulation of gene expression, and activation of oncogenic signaling pathways. Furthermore, lysine succinylation modulates the activity of immune cells, thereby affecting the immune evasion of tumor cells. Notably, researchers are currently developing inhibitors and activators of lysine succinylation which can inhibit tumor cell proliferation, migration, and metastasis, with potential usefulness in future clinical practice. This article provides an overview of the biological functions of lysine succinylation in cancer and its potential applications in cancer treatment, offering a novel perspective for future cancer management.

Semen quality and persistence are critical for evaluating the usability of individual boars in AI, a standard practice in pig breeding. We conducted GWASs on various semen traits of Duroc boars, including MOT, DEN, ABN, MMP, AIR, and ROS levels. These traits were assessed using FCM and CASA. A total of 1183 Duroc boars were genotyped using the GeneSeek GGP Porcine 50 K SNP BeadChip. The GWAS was performed using three different models: GLM, MLM, and FarmCPU. Additionally, trait heritability was estimated using single- and multiple-trait PBLUP models, yielding 0.19, 0.29, 0.13, 0.18, 0.11, and 0.14 heritability for MOT, DEN, ABN, MMP, AIR, and ROS, respectively. All semen traits exhibited low heritability except ABN, which demonstrated medium heritability. Nine candidate genes (GPX5, AWN, PSP-II, CCDC62, TMEM65, SLC8B1, TRPV4, UBE3B, and SIRT5) were potentially associated with semen traits. These genes are associated with antioxidant and mitochondrial functions in porcine sperm. Our findings provide insight into the genetic architecture of semen traits in Duroc boars, and the identified SNPs and candidate genes may enhance economic outcomes in the pig breeding industry while improving sperm quality through targeted breeding strategies.

Lactation mastitis is a debilitating inflammatory mammary disease in postpartum animals. Myeloid differentiation primary response protein MyD88 is the key downstream adapter for innate pattern recognition receptor toll-like receptor 4 (TLR4), which plays an important role in inflammation. However, the specific role of MyD88 in mammary epithelial cells in the progression of mastitis has not been investigated. In this study, lipopolysaccharide (LPS)-induced mouse mastitis model was used and cytokines such as Tnf-α, Il-1β, Il-6, Cxcl1, Cxcl2 and Ccl2 were significantly increased in inflammatory mammary gland as shown by real time-qPCR. However, the mice with MyD88-deficienet in mammary epithelial cells (cKO) showed a reduction in the expression of Tnf-α, Il-1β, Il-6, Cxcl1 and Cxcl2 in mammary gland compared with control mice, when subjected to LPS induced mastitis. Immunohistochemical staining of cleaved caspase-3 showed that the cell apoptosis induced by inflammation were decreased in MyD88 cKO mice. Furthermore, there were significantly fewer infiltrating inflammatory cells in alveolar lumen of MyD88 cKO mice, including Ly6G-positive neutrophils and F4/80-positive macrophages. RNA-seq in LPS treated mammary glands showed that MyD88 cKO mice had significantly downregulated inflammation-related genes and upregulated genes related to anti-inflammation processes and lipid metabolism compared with control mice. Thus, these results demonstrate that MyD88 in mammary epithelial cells is essential for mastitis progression. And this study not only has important implications for understanding the innate immune response in mammary epithelial cells, but also potentially helps the development of new therapeutic drugs for treating mastitis.

Cancer is a disease characterized by the acquisition of a multitude of unique traits. It has long been understood that cancer cells divert significantly from normal cell metabolism. The most obvious of metabolic changes is that cancer cells strongly rely on glucose conversion by aerobic glycolysis. In addition, they also regularly develop mechanisms to use lipids and fatty acids for their energy needs. Peroxisomes lie central to these adaptive changes of lipid metabolism. Peroxisomes are metabolic organelles that take part in over 50 enzymatic reactions crucial for cellular functioning. Thus, they are essential for an effective and comprehensive use of lipids' energy supplied to cells. Cancer cells display a substantial increase in the biogenesis of peroxisomes and an increased expression of proteins necessary for the enzymatic functions provided by peroxisomes. Moreover, the enzymatic conversion of FAs in peroxisomes is a significant source of reactive oxygen and nitrogen species (ROS/RNS) that strongly impact cancer malignancy. Important regulators in peroxisomal FA oxidation and ROS/RNS generation are the transcription factors of the peroxisome proliferator-activated receptor (PPAR) family. This review describes the metabolic changes in tumorigenesis and cancer progression influenced by peroxisomes. We will highlight the ambivalent role that peroxisomes and PPARs play in the different stages of tumor development and summarize our current understanding of how to capitalize on the comprehension of peroxisomal biology for cancer treatment.

The greatest challenges that organisms face today are effective responses or detection of life-threatening environmental changes due to an obvious semblance of stress and metabolic fluctuations. These are associated with different pathological conditions among which cancer is most important. Sirtuins (SIRTs; NAD+-dependent enzymes) are versatile enzymes with diverse substrate preferences, cellular locations, crucial for cellular processes and pathological conditions. This article describes in detail the distinct roles of SIRT isoforms, unveiling their potential as either cancer promoters or suppressors and also explores how both natural and synthetic compounds influence the SIRT function, indicating promise for therapeutic applications. We also discussed the inhibitors/activators tailored to specific SIRTs, holding potential for diseases lacking effective treatments. It may uncover the lesser-studied SIRT isoforms (e.g., SIRT6, SIRT7) and their unique functions. This article also offers a comprehensive overview of SIRTs, linking them to a spectrum of diseases and highlighting their potential for targeted therapies, combination approaches, disease management, and personalized medicine. We aim to contribute to a transformative era in healthcare and innovative treatments by unraveling the intricate functions of SIRTs.

Lysine succinylation, and its reversal by sirtuin-5 (SIRT5), is known to modulate mitochondrial fatty acid β-oxidation (FAO). We recently showed that feeding mice dodecanedioic acid, a 12-carbon dicarboxylic acid (DC12) that can be chain-shortened four rounds to succinyl-CoA, drives high-level protein hypersuccinylation in the peroxisome, particularly on peroxisomal FAO enzymes. However, the ability of SIRT5 to reverse DC12-induced peroxisomal succinylation, or to regulate peroxisomal FAO in this context, remained unexplored. Here, we showed that feeding DC12 strongly recruits SIRT5 into hepatic peroxisomes. Knocking out SIRT5 impaired peroxisomal FAO as evidenced by reduced 14C-DC12 flux in liver homogenates and elevated levels of partially shortened DC12 catabolites in urine. Further, mass spectrometry revealed a trend toward less peroxisomal protein succinylation in SIRT5 knockout liver. This is consistent with a reduced flux of DC12 through the peroxisomal FAO pathway, thereby reducing the production of the succinyl-CoA that chemically reacts with lysine residues to produce protein succinylation. Mass spectrometry comparisons of site-level succinylation in wildtype and SIRT5 knockout liver did not reveal any clear pattern of SIRT5 target sites in the peroxisome after DC12 feeding. However, SIRT5 co-immunoprecipitated with 15 peroxisomal proteins, including the key peroxisomal FAO enzymes acyl-CoA oxidase-1 and enoyl-CoA/3-hydroxyacyl-CoA dehydrogenase (EHHADH). In vitro, recombinant SIRT5 partially desuccinylated chemically modified recombinants ACOX1a, ACOX1b, and EHHADH. Desuccinylation by SIRT5 had no effect on enzyme activity for ACOX1a and EHHADH. For ACOX1b, SIRT5-mediated desuccinylation decreased activity by ~15%. Possible interpretations of these data are discussed.

Nonalcoholic steatohepatitis (NASH), a chronic liver disease characterized by the accumulation of fat in the liver, is highly prevalent on a global scale. In this study, we investigated the effects of total glucosides of Picrorhizae Rhizome (TGPR), the primary active ingredients in traditional Chinese herbal medicine derived from Picrorhiza scrophulariiflora Pennell. TGPR is known for its efficiency in attenuating NASH, in mouse models induced by methionine-choline deficient (MCD) diet or high-fat diet (HFD). Our findings indicated that TGPR exhibited efficacy in reducing hepatic steatosis and lowering serum lipid levels, specifically triglyceride and total cholesterol in the NASH model. Meanwhile, TGPR exhibited a suppressive effect on the production of pro-inflammatory cytokines. Mechanistically, we identified acyl-CoA oxidase 1 (Acox1) as a crucial cellular target of TGPR, influencing lipid metabolism and ATP production to treat NASH. Additionally, we found that the major components of TGPR, including Picroside I, Picroside II, and Picroside IV, exhibit significant binding abilities to the target Acox1 at its catalytic C-terminal α-domain, stabilizing its protein expression. TGPR binding to Acox1 facilitated the degradation of fatty acids via the Acox1-mediated MAPK signaling pathways, and consequently plays a role in regulating energy metabolism and reducing liver inflammation. In summary, our study demonstrates that TGPR effectively counteracts NASH by specifically targeting Acox1, thereby providing a significant clinical solution for the treatment of NASH.

This study aimed to explore novel targets for hepatocellular carcinoma (HCC) treatment by investigating the role of fatty acid metabolism.

RNA-seq and clinical data of HCC were obtained from the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) databases. Bioinformatic analyses were employed to identify differentially expressed genes (DEGs) related to prognosis. A signature was then constructed using the Least Absolute Shrinkage and Selection Operator (LASSO) Cox regression to classify HCC patients from the TCGA database into low-risk and high-risk groups. The predictive performance of the signature was evaluated through principal components analysis (PCA), Kaplan Meier (KM) survival analysis, receiver operating characteristics (ROC) curves, nomogram, genetic mutations, drug sensitivity analysis, immunological correlation analysis, and enrichment analysis. Single-cell maps were constructed to illustrate the distribution of core genes. Immunohistochemistry (IHC), quantitative real-time PCR (qRT-PCR), and western blot were employed to verify the expression of core genes. The function of one core gene was validated through a series of in vitro assays, including cell viability, colony formation, wound healing, trans-well migration, and invasion assays. The results were analyzed in the context of relevant signaling pathways.

Bioinformatic analyses identified 15 FAMGs that were related to prognosis. A 4-gene signature was constructed, and patients were divided into high- and low-risk groups according to the signature. The high-risk group exhibited a poorer prognosis compared to the low-risk group in both the training (P < 0.001) and validation (P = 0.020) sets. Furthermore, the risk score was identified as an independent predictor of OS (P < 0.001, HR = 8.005). The incorporation of the risk score and clinicopathologic features into a nomogram enabled the effective prediction of patient prognosis. The model was able to effectively predict the immune microenvironment, drug sensitivity to chemotherapy, and gene mutation for each group. Single-cell maps demonstrated that FAMGs in the model were distributed in tumor cells. Enrichment analyses revealed that the cell cycle, fatty acid β oxidation and PPAR signaling pathways were the most significant pathways. Among the four key prognostically related FAMGs, Spermine Synthase (SMS) was selected and validated as a potential oncogene affecting cell cycle, PPAR-γ signaling pathway and fatty acid β oxidation in HCC.

The risk characteristics based on FAMGs could serve as independent prognostic indicators for predicting HCC prognosis and could also serve as evaluation criteria for gene mutations, immunity, and chemotherapy drug therapy in HCC patients. Meanwhile, targeted fatty acid metabolism could be used to treat HCC through related signaling pathways.

T-2 toxin (T-2) is a highly toxic mycotoxin that threatens organism health, yet its hepatoxicity on ducks remains unknown. The present study aimed to assess the hepatoxicity and redox reactions induced by T-2 in ducks. Sixty 7-day-old ducklings were divided into 4 groups and exposed to 0, 200, 400 and 800 μg/kg bodyweight of T-2 through oral gavage for 2 weeks. The growth performance, liver histopathology, biochemical indicators, antioxidant capacity and hepatic damage-related genes of ducks were analyzed. The results revealed that 800 µg/kg T-2 inhibited the growth and feed intake of ducks, whereas liver index increased with the elevation of T-2 concentration. Histological examinations exhibited that T-2 caused hepatic cord disappeared and severe steatosis. Moreover, serum AST, ALT and TG were substantially higher in 400 μg/kg group, while γ-GT and ALB were reduced under 800 μg/kg T-2 exposure. In addition, significant increase of malondialdehyde (MDA) in liver, decrease of hepatic total antioxidant capacity (T-AOC) and serum glutathione peroxidase (GPx) were observed in all T-2 groups. Furthermore, T-2 disrupted lipid metabolism and oxidative stress-related genes expression in liver. The transcript level of fatty acid binding protein 1 (FABP1) was markedly raised in all T-2 groups, and hepatic acyl-CoA oxidase 1 (ACOX1) was significantly raised in 200 and 400 μg/kg T-2 groups. Under 800 μg/kg T-2, significant induction of hypoxia inducible factor-1 alpha (HIF-1α), and downregulated peroxisome proliferator-activated receptor (PPAR)-alpha, carnitine palmitoyl transferase 1A (CPT1A), peroxisome proliferator-activated receptor gamma coactivator 1alpha (PGC-1α), GPx1, catalase (CAT) mRNA levels were observed. Therefore, we conclude that T-2 caused liver injury through lipid metabolism disruption and oxidative stress in ducks, which reinforces understanding about the hepatoxicity mechanisms of T-2 and provides new targets for detoxication and prevention.

The fundamental role of cells in safeguarding the genome's integrity against DNA double-strand breaks (DSBs) is crucial for maintaining chromatin homeostasis and the overall genomic stability. Aberrant responses to DNA damage, known as DNA damage responses (DDRs), can result in genomic instability and contribute significantly to tumorigenesis. Unraveling the intricate mechanisms underlying DDRs following severe damage holds the key to identify therapeutic targets for cancer. Chromatin lysine acylation, encompassing diverse modifications such as acetylation, lactylation, crotonylation, succinylation, malonylation, glutarylation, propionylation, and butyrylation, has been extensively studied in the context of DDRs and chromatin homeostasis. Here, we delve into the modifying enzymes and the pivotal roles of lysine acylation and their crosstalk in maintaining chromatin homeostasis and genome integrity in response to DDRs. Moreover, we offer a comprehensive perspective and overview of the latest insights, driven primarily by chromatin acylation modification and associated regulators.

The circadian clock is an autonomous timekeeping system evolved by organisms to adapt to external changes, regulating a variety of important physiological and behavioral processes. Recent studies have shown that the sirtuin family of histone deacetylases is involved in regulating the expression of clock genes and plays an important role in maintaining the normal rhythm of clock gene expression and behavior. Moreover, sirtuins are regulated directly or indirectly by the circadian clock system. The mutual regulation between the circadian clock and sirtuins is likely involved in a variety of signal transduction and metabolism processes. In this review, we discuss the molecular mechanisms and research progress on the intertwined relationship between the circadian clock and sirtuins, mainly in mammals, highlighting sirtuins as molecular links between metabolic control and circadian rhythms and offering our perspectives on future developments in the field.

Per- and polyfluoroalkyl substances (PFAS) may interact with peroxisome proliferator activated receptors (PPARs) and alter lipid homeostasis. Using Xenopus laevis, we investigated the effect of PFAS on (a) lipid homeostasis and whether this correlated to changes in body and hepatic condition; (b) the expression of hepatic genes regulated by PPAR; and (c) the hepatic lipidome. We chronically exposed tadpoles to 0.5 µg/L of either PFOS, PFHxS, PFOA, PFHxA, a binary mixture of PFOS and PFHxS (0.5 µg/L of each), or a control, from NF stage 52 through metamorphic climax. Growth, development, and survival were not affected, but we detected a sex-specific decrease in body condition at NF 66 (6.8%) and in hepatic condition (16.6%) across metamorphic climax for male tadpoles exposed to PFOS. We observed weak evidence for the transient downregulation of apolipoprotein-V (apoa5) at NF 62 in tadpoles exposed to PFHxA. Acyl-CoA oxidase 1 (acox1) was downregulated only in males exposed to PFHxS (Ln(Fold Change) = -0.54). We detected PFAS-specific downregulation of structural glycerophospholipids, while semi-quantitative profiling detected the upregulation in numerous glycerophospholipids, sphingomyelins, and diglycerides. Overall, our findings indicate that PFAS can induce sex-specific effects that change across larval development and metamorphosis. We demonstrate that PFAS alter lipid metabolism at environmentally relevant concentrations through divergent mechanisms that may not be related to PPARs, with an absence of effects on body condition, demonstrating the need for more molecular studies to elucidate mechanisms of PFAS-induced lipid dysregulation in amphibians and in other taxa.