Acetate functions as an epigenetic metabolite to promote lipid synthesis under hypoxia

Gut microbiota and associated metabolites: key players in high-fat diet-induced chronic diseases

Excessive intake of dietary fats is strongly associated with an increased risk of various chronic diseases, such as obesity, diabetes, hepatic metabolic disorders, cardiovascular disease, chronic intestinal inflammation, and certain cancers. A significant portion of the adverse effects of high-fat diet on disease risk is mediated through modifications in the gut microbiota. Specifically, high-fat diets are linked to reduced microbial diversity, an overgrowth of gram-negative bacteria, an elevated Firmicutes-to-Bacteroidetes ratio, and alterations at various taxonomic levels. These microbial alterations influence the intestinal metabolism of small molecules, which subsequently increases intestinal permeability, exacerbates inflammatory responses, disrupts metabolic functions, and impairs signal transduction pathways in the host. Consequently, diet-induced changes in the gut microbiota play a crucial role in the initiation and progression of chronic diseases. This review explores the relationship between high-fat diets and gut microbiota, highlighting their roles and underlying mechanisms in the development of chronic metabolic diseases. Additionally, we propose probiotic interventions may serve as a promising adjunctive therapy to counteract the negative effects of high-fat diet-induced alterations in gut microbiota composition.

Dynamic metabolic regulation of histone modifications during the yeast metabolic cycle

Eukaryotes achieve a wide range of stable phenotypes by virtue of epigenetic modifications. However, what drives epigenetic diversification in the first place remains an open question. Here, we investigated the dynamic interplay between the production fluxes of epigenetic cosubstrates and histone post-translation modifications (PTMs) in Saccharomyces cerevisiae's Yeast Metabolic Cycle (YMC). We developed a novel approach integrating flux analysis with transcriptomic data to investigate the production fluxes of acetyl-CoA and SAM and their influence on histone marks H3K9Ac and H3K4me3. Our results show that acetyl-CoA and SAM flux dynamics are asynchronous during the YMC, suggesting distinct regulatory roles. Gene ontology analysis revealed that genes whose enrichment of H3K9Ac correlates with acetyl-CoA dynamics are associated with metabolic functions, while genes whose enrichment of H3K4me3 correlates with SAM dynamics are associated with translation processes. Finally, we found evidence that chromatin accessibility on genes promoter regions was a precondition for the metabolic fluxes influencing the enrichment of H3K4me3 and H3K9Ac. These findings support the concept that metabolism provides timely cosubstrates essential for histone PTMs.

SIRT2-mediated ACSS2 K271 deacetylation suppresses lipogenesis under nutrient stress

De novo lipogenesis is associated with the development of human diseases such as cancer, diabetes, and obesity. At the core of lipogenesis lies acetyl coenzyme A (CoA), a metabolite that plays a crucial role in fatty acid synthesis. One of the pathways contributing to the production of cytosolic acetyl-CoA is mediated by acetyl-CoA synthetase 2 (ACSS2). Here, we reveal that when cells encounter nutrient stress, particularly a deficiency in amino acids, Sirtuin 2 (SIRT2) catalyzes the deacetylation of ACSS2 at the lysine residue K271. This results in K271 ubiquitination and subsequently proteasomal degradation of ACSS2. Substitution of K271 leads to decreased ubiquitination of ACSS2, increased ACSS2 protein level, and thus increased lipogenesis. Our study uncovers a mechanism that cells employ to efficiently manage lipogenesis during periods of nutrient stress.

Fecal microbiota transplantation improves growth performance of chickens by increasing the intestinal Lactobacillus and glutamine

Chicken meat is an essential source of high-quality animal protein, mainly derived from slow-growth chicken (SC) and fast-growth chicken (FC) breeds. Skeletal muscle is a highly adaptable tissue that is influenced by breed differences and the gut microbiome. Investigation whether remodeling the gut microbiota by fecal microbiota transplantation (FMT) improves chicken growth is an interesting question. We compared the gut microbial composition of eight breeds of SC (Xinghua chicken, Yangshan chicken, Zhongshan Salan chicken, Qingyuan Partridge chicken, Huiyang Bearded chicken and Huaixiang chicken) and FC (Xiaobai chicken and White rock chicken). Fecal microbiota from donor FC (Xiaobai chickens) with superior growth performance were transferred to SC (Xinghua chickens). The effects of FMT on growth performance, metabolic profile and gut microbiome of recipient chickens were evaluated. We found significant differences in gut microbial composition, with a higher abundance of Bacteroidetes in SC and a higher abundance of Firmicutes in FC. Xiaobai chickens with better growth performance and abundant Lactobacillus, and FMT significantly enhanced growth performance, the expression of mRNA (MYOG, MYF5, MYF6 and IGF1) related to breast and leg muscle development and improved the villus/crypt ratio in the jejunum. FMT altered the microbiota in the duodenum, jejunum, and ileum, increased Lactobacillus abundance, decreased the relative mRNA expression of the intestinal inflammatory factors (IL-1β, IL-6 and TNF-α), increased glutamine levels in the host, including in muscle tissues and intestinal contents, and Spearman correlation analysis indicated that the relative abundance of Lactobacillus was positively correlated with glutamine levels. Additionally, antibiotic treatment reduces glutamine levels in the intestines, blood, and muscle tissues of chickens. Glutamine can increase the expression of cyclinD1, cyclinD2, cyclinB2, MYOG, MYF5, MYF6 and IGF1 mRNA to promote chicken myoblasts proliferation and differentiation. This study found that the SC and FC gut microbes were significantly different, and the FC chicken gut microbes were able to reshape the FC gut microbiota through FMT, i.e., higher Lactobacillus, promoted chicken myoblasts proliferation and differentiation and growth performance by increasing glutamine levels.

Mitochondrial fatty acid oxidation regulates adult muscle stem cell function through modulating metabolic flux and protein acetylation

During homeostasis and regeneration, satellite cells, the resident stem cells of skeletal muscle, have distinct metabolic requirements for fate transitions between quiescence, proliferation and differentiation. However, the contribution of distinct energy sources to satellite cell metabolism and function remains largely unexplored. Here, we uncover a role of mitochondrial fatty acid oxidation (FAO) in satellite cell integrity and function. Single-cell RNA sequencing revealed progressive enrichment of mitochondrial FAO and downstream pathways during activation, proliferation and myogenic commitment of satellite cells. Deletion of Carnitine palmitoyltransferase 2 (Cpt2), the rate-limiting enzyme in FAO, hampered muscle stem cell expansion and differentiation upon acute muscle injury, markedly delaying regeneration. Cpt2 deficiency reduces acetyl-CoA levels in satellite cells, impeding the metabolic flux and acetylation of selective proteins including Pax7, the central transcriptional regulator of satellite cells. Notably, acetate supplementation restored cellular metabolic flux and partially rescued the regenerative defects of Cpt2-null satellite cells. These findings highlight an essential role of fatty acid oxidation in controlling satellite cell function and suggest an integration of lipid metabolism and protein acetylation in adult stem cells.

Mitochondrial ACSS1-K635 acetylation knock-in mice exhibit altered liver lipid metabolism on a ketogenic diet

Acetyl-CoA Synthetase Short Chain Family Member-1 (ACSS1) catalyzes the ligation of acetate and coenzyme A to generate acetyl-CoA in the mitochondria to produce ATP through the tricarboxylic acid (TCA) cycle. We recently generated an ACSS1-acetylation (Ac) mimic knock-in mouse, where lysine 635 was mutated to glutamine (K635Q), which structurally and biochemically mimics an acetylated lysine. ACSS1 enzymatic activity is regulated, at least in part, through the acetylation of lysine 635 in mice (lysine 642 in humans), a Sirtuin 3 deacetylation target. We challenged our Acss1K635Q knock-in mice with a three-week ketogenic diet. While both wild-type and Acss1K635Q knock-in mice were in ketosis with similar blood glucose levels, the Acss1K635Q mice exhibited elevated blood acetate and liver acetyl-CoA. In addition, and importantly, compared to wild-type mice, the liver in the Acss1K635Q mice displayed a much more predominant liver steatosis morphology and accumulation of lipid drops, as measured by H&E and Oil Red O staining. RNAseq analysis identified that genes related to mitochondrial respiratory chain complexes and oxidative stress were significantly overexpressed in the Acss1K635Q mice on a KD. Finally, lipidomics analysis revealed very different lipid profiles for these groups, including a dramatic increase in triacylglycerides (TAGs), phosphatidylcholines (PCs), phosphatidylethanolamines (PEs), and cardiolipins in the Acss1K635Q liver.

A Computational Approach for Designing a Peptide-Based Acetyl-CoA Synthetase 2 Inhibitor: A New Horizon for Anticancer Development

Acetyl-CoA Synthetase 2 (ACSS2) has emerged as a new target for anticancer development owing to its high expression in various tumours and its enhancement of malignancy. Stressing the growing interest in peptide-derived drugs featuring better selectivity and efficacy, a computational protocol was applied to design a peptide inhibitor for ACSS2. Herein, 3600 peptide sequences derived from ACSS2 nucleotide motif were generated by classifying the 20 amino acids into six physiochemical groups. De novo modeling maintained essential binding interactions, and a refined library of 16 peptides was derived using Support Vector Machine filters to ensure proper bioavailability, toxicity, and therapeutic relevance. Structural and folding predictions, along with molecular docking, identified the top candidate, Pep16, which demonstrated significantly higher binding affinity (91.1 ± 1.6 kcal/mol) compared to a known inhibitor (53.7 ± 0.7 kcal/mol). Further molecular dynamics simulations and binding free energy calculations revealed that Pep16 enhances ACSS2 conformational variability, occupies a larger binding interface, and achieved firm binding. MM/GBSA analysis highlighted key electrostatic interactions with specific ACSS2 residues, including ARG 373, ARG 526, ARG 628, ARG 631, and LYS 632. Overall, Pep16 appears to lock the ACSS2 nucleotide pocket into a compact, rigid conformation, potentially blocking ATP binding and catalytic activity, and may serve as a novel specific ACSS2 inhibitor. Though, we urge further research to confirm and compare its therapeutic potential to existing inhibitors. We also believe that this systematic methodology would represent an indispensable tool for prospective peptide-based drug discovery.

Mutant KRAS and CK2 Cooperatively Stimulate SLC16A3 Activity to Drive Intrahepatic Cholangiocarcinoma Progression

Intrahepatic cholangiocarcinoma (iCCA) is a lethal malignancy affecting the liver and biliary system. Enhanced understanding of the pathogenic mechanisms underlying iCCA tumorigenesis and the discovery of appropriate therapeutic targets are imperative to improve patient outcomes. In this study, we investigated the functions and regulations of solute carrier family 16 member 3 (SLC16A3), which has been reported to be a biomarker of poor prognosis in iCCA. High SLC16A3 expression was enriched in KRAS viral oncogene homolog-mutated iCCA tumors, and mutant KRAS elevated SLC16A3 expression via the PI3K-AKT-mTORC1-HIF1α pathway. SLC16A3 not only enhanced glycolysis but also induced epigenetic reprogramming to regulate iCCA progression. Phosphorylation of SLC16A3 at S436 was vital for its oncogenic function and was linked to iCCA progression. Casein kinase 2 (CK2) directly phosphorylated SLC16A3 at S436, and CK2 inhibition with CX-4945 (silmitasertib) reduced the growth of KRAS-mutated iCCA tumor xenografts and patient-derived organoids. Together, this study provides valuable insights into the diverse functions of SLC16A3 in iCCA and comprehensively elucidates the upstream regulatory mechanisms, providing potential therapeutic strategies for patients with iCCA with KRAS mutations. Significance: Characterization of the oncogenic function and regulators of SLC16A3 in intrahepatic cholangiocarcinogenesis revealed the potential of CK2 inhibitors as a promising treatment for KRAS-mutated tumors.

HSD17B4 deficiency causes dysregulation of primary cilia and is alleviated by acetyl-CoA

Primary cilia are dynamic sensory organelles orchestrating key signaling pathways, and disruption of primary ciliogenesis is implicated in a spectrum of genetic disorders. The peroxisomal bifunctional enzyme HSD17B4 is pivotal for peroxisomal β-oxidation and acetyl-CoA synthesis, and its deficiency profoundly impairs peroxisomal metabolism. While patients with HSD17B4 deficiency exhibit ciliopathy-like symptoms due to dysfunctional primary cilia, the molecular connection between HSD17B4 and ciliopathy remains poorly understood. Here, we demonstrate that HSD17B4 deficiency impairs primary ciliogenesis and alters cilia-mediated signaling, suggesting a potential link between peroxisomal metabolism and ciliary function. Notably, elevation of acetyl-CoA rescues ciliary defects via HDAC6-mediated ciliogenesis in HSD17B4-deficient cells. Strikingly, acetate administration restores motor function, enhances primary cilia formation, and preserves the Purkinje layer in Hsd17B4-knockout mice. These findings provide insights into the functional link between HSD17B4 and primary cilia, highlighting acetyl-CoA as a potential therapeutic target for HSD17B4 deficiency and ciliopathy.

ACSS3 promotes the tumorigenesis of non-small cell lung cancer via suppressing p53-mediated ferroptosis

Non-small cell lung cancer (NSCLC) is a subtype of the most frequently diagnosed cancer, causing a considerable number of deaths globally. Mitochondrial dysfunction was found to promote malignant progression. However, the underlying mechanism remains unclear. Acyl-CoA synthetase short chain family member 3 (ACSS3) is mainly located in mitochondria, which abnormal regulation is usually accompanied by the occurrence and development of tumors. In this study, we found that the expression level of ACSS3 was correlated with poor prognosis in patients with NSCLC. Moreover, we demonstrated that ACSS3 knockdown led to mitochondrial contraction, increased reactive oxygen species levels, decreased mitochondrial membrane potential, and subsequently inhibited tumor growth of NSCLC cells in vitro and in vivo, whereas its overexpression promoted these processes. Mechanistically, ACSS3 knockdown promoted ferroptosis through transcriptional control of SLC7A11 and GPX4. Further investigations indicated that ACSS3 loss inhibited the SLC7A11/GPX4 axis by enhancing p53 stability. Taken together, our data confirmed that ACSS3 promotes NSCLC tumorigenesis through inhibiting the p53-mediated ferroptosis. Hence, ACSS3 emerges as a promising therapeutic target for NSCLC treatment.

Food supply toxicants and additives alter the gut microbiota and risk of metabolic disease

Metabolic disease is rising along with both global industrialization and the use of new commercial, agricultural, and industrial chemicals and food additives. Exposure to these compounds may contribute to aspects of metabolic diseases such as obesity, diabetes, and fatty liver disease. Ingesting compounds in the food supply is a key route of human exposure, resulting in the interaction between toxicants or additives and the intestinal microbiota. Toxicants can influence the composition and function of the gut microbiota, and these microbes can metabolize and transform toxicants and food additives. Microbe-toxicant interactions in the intestine can alter host mucosal barrier function, immunity, and metabolism, which may contribute to the risk or severity of metabolic disease development. Targeting the connection between toxicants, food, and immunity in the gut using strategies such as fermentable fiber (i.e., inulin) may mitigate some of the effects of these compounds on host metabolism. Understanding causative factors in the microbe-host relationship that promote toxicant-induced dysmetabolism is an important goal. This review highlights the role of common toxicants (i.e., persistent organic pollutants, pesticides, and fungicides) and food additives (emulsifiers and artificial sweeteners) found in our food supply that alter the gut microbiota and promote metabolic disease development.

Phospholipid Biosynthesis: An Unforeseen Modulator of Nuclear Metabolism

Glycerophospholipid biosynthesis is crucial not only for providing structural components required for membrane biogenesis during cell proliferation but also for facilitating membrane remodeling under stress conditions. The biosynthetic pathways for glycerophospholipid tails, glycerol backbones, and diverse head group classes intersect with various other metabolic processes, sharing intermediary metabolites. Recent studies have revealed intricate connections between glycerophospholipid synthesis and nuclear metabolism, including metabolite-mediated crosstalk with the epigenome, signaling pathways that govern genome integrity, and CTP-involved regulation of nucleotide and antioxidant biosynthesis. This review highlights recent advances in understanding the functional roles of glycerophospholipid biosynthesis beyond their structural functions in budding yeast and mammalian cells. We propose that glycerophospholipid biosynthesis plays an integrative role in metabolic regulation, providing a new perspective on lipid biology.

ACSS2 drives senescence-associated secretory phenotype by limiting purine biosynthesis through PAICS acetylation

Senescence-associated secretory phenotype (SASP) mediates the biological effects of senescent cells on the tissue microenvironment and contributes to ageing-associated disease progression. ACSS2 produces acetyl-CoA from acetate and epigenetically controls gene expression through histone acetylation under various circumstances. However, whether and how ACSS2 regulates cellular senescence remains unclear. Here, we show that pharmacological inhibition and deletion of Acss2 in mice blunts SASP and abrogates the pro-tumorigenic and immune surveillance functions of senescent cells. Mechanistically, ACSS2 directly interacts with and promotes the acetylation of PAICS, a key enzyme for purine biosynthesis. The acetylation of PAICS promotes autophagy-mediated degradation of PAICS to limit purine metabolism and reduces dNTP pools for DNA repair, exacerbating cytoplasmic chromatin fragment accumulation and SASP. Altogether, our work links ACSS2-mediated local acetyl-CoA generation to purine metabolism through PAICS acetylation that dictates the functionality of SASP, and identifies ACSS2 as a potential senomorphic target to prevent senescence-associated diseases.

Gut Microbiome Regulation of Gut Hormone Secretion

The gut microbiome, comprising bacteria, viruses, fungi, and bacteriophages, is one of the largest microbial ecosystems in the human body and plays a crucial role in various physiological processes. This review explores the interaction between the gut microbiome and enteroendocrine cells (EECs), specialized hormone-secreting cells within the intestinal epithelium. EECs, which constitute less than 1% of intestinal epithelial cells, are key regulators of gut-brain communication, energy metabolism, gut motility, and satiety. Recent evidence shows that gut microbiota directly influence EEC function, maturation, and hormone secretion. For instance, commensal bacteria regulate the production of hormones like glucagon-like peptide 1 and peptide YY by modulating gene expression and vesicle cycling in EE cells. Additionally, metabolites such as short-chain fatty acids, derived from microbial fermentation, play a central role in regulating EEC signaling pathways that affect metabolism, gut motility, and immune responses. Furthermore, the interplay between gut microbiota, EECs, and metabolic diseases, such as obesity and diabetes, is examined, emphasizing the microbiome's dual role in promoting health and contributing to disease states. This intricate relationship between the gut microbiome and EECs offers new insights into potential therapeutic strategies for metabolic and gut disorders.

ACSS2 and metabolic diseases: from lipid metabolism to therapeutic target

Elevated incidence of metabolic disorders has been reported worldwide in the recent decade, highlighting the need for developing efficient therapies. These diseases result from a complex interplay of various factors that contribute to disease progression, complications, and resistance to current treatment options. Acetyl-CoA Synthetase Short Chain Family Member 2 (ACSS2) is a nucleo-cytosolic enzyme with both lipogenic and metabolic regulatory roles. Studies on ACSS2 have shown that it is involved in pathways commonly dysregulated in metabolic disorders, leading to fat deposition and disrupted cellular signaling. Although multiple studies have suggested a role of ACSS2 in the metabolic rewiring during tumorigenesis, few studies have examined its involvement in the pathophysiology of metabolic diseases. Recent evidence indicates that ACSS2 may contribute to the pathogenesis of various metabolic disorders making its examination of great interest and potentially aiding in the development of new therapeutic strategies. The objective of this review is to summarize the current understanding of ACSS2's role in metabolic disorders and its potential as a therapeutic target.

Hypoxia-induced histone methylation and NF-κB activation in pancreas cancer fibroblasts promote EMT-supportive growth factor secretion

The pancreatic ductal adenocarcinoma (PDAC) tumor microenvironment contains hypoxic tissue subdomains and cancer-associated fibroblasts (CAFs) of multiple subtypes that play tumor-promoting and -restraining roles. Here, we demonstrate that hypoxia promotes an inflammatory-like CAF phenotype and that hypoxic CAFs selectively promote epithelial-mesenchymal transition (EMT) in PDAC cancer cells through growth factor-mediated cell crosstalk. By analyzing patient tumor single-cell transcriptomics and conducting an inhibitor screen, we identified IGF-2 and HGF as specific EMT-inducing growth factors produced by hypoxic CAFs. We further found that reactive oxygen species-activated NF-κB cooperates with hypoxia-dependent histone methylation to promote IGF-2 and HGF expression in hypoxic CAFs. In lineage-traced autochthonous PDAC mouse tumors, hypoxic CAFs resided preferentially near hypoxic, mesenchymal cancer cells. However, in subcutaneous tumors engineered with hypoxia fate-mapped CAFs, once-hypoxic re-oxygenated CAFs lacked a spatial correlation with mesenchymal cancer cells. Thus, hypoxia promotes reversible CAF-malignant cell interactions that drive EMT through druggable signaling pathways.

One-sentence summary

We show that hypoxic fibroblasts in pancreas cancer leverage histone methylation and ROS-mediated NF-κB activation to produce growth factors that drive epithelial-mesenchymal transition in malignant cells, demonstrating how tumor stromal features cooperate to initiate a signaling process for disease progression.

ACOT12, a novel factor in the pathogenesis of kidney fibrosis, modulates ACBD5

Lipid metabolism, particularly fatty acid oxidation dysfunction, is a major driver of renal fibrosis. However, the detailed regulatory mechanisms underlying this process remain unclear. Here we demonstrated that acyl-CoA thioesterase 12 (Acot12), an enzyme involved in the hydrolysis of acyl-CoA thioesters into free fatty acids and CoA, is a key regulator of lipid metabolism in fibrotic kidneys. A significantly decreased level of ACOT12 was observed in kidney samples from human patients with chronic kidney disease as well as in samples from mice with kidney injuries. Acot12 deficiency induces lipid accumulation and fibrosis in mice subjected to unilateral ureteral obstruction (UUO). Fenofibrate administration does not reduce renal fibrosis in Acot12-/- mice with UUO. Moreover, the restoration of peroxisome proliferator-activated receptor α (PPARα) in Acot12-/-Pparα-/- kidneys with UUO exacerbated lipid accumulation and renal fibrosis, whereas the restoration of Acot12 in Acot12-/- Pparα-/- kidneys with UUO significantly reduced lipid accumulation and renal fibrosis, suggesting that, mechanistically, Acot12 deficiency exacerbates renal fibrosis independently of PPARα. In Acot12-/- kidneys with UUO, a reduction in the selective autophagic degradation of peroxisomes and pexophagy with a decreased level of ACBD5 was observed. In conclusion, our study demonstrates the functional role and mechanistic details of Acot12 in the progression of renal fibrosis, provides a preclinical rationale for regulating Acot12 expression and presents a novel means of preventing renal fibrosis.

Short-chain fatty acids and cancer

Short-chain fatty acids (SCFAs), derived from the diet and the microbiota, serve as crucial links between the diet, gut microbiota, metabolism, immunity, and cancer. They function as energy sources through β-oxidation and regulate macromolecular synthesis, G protein-coupled receptor (GPCR) and histone deacetylase (HDAC) activities, protein modifications, signaling pathways, and gene expression in cells within the tumor microenvironment, particularly in tumor and immune cells. The critical role of SCFAs in maintaining normal homeostasis and influencing tumor progression highlights the potential of targeting SCFA-mediated cellular processes for cancer prevention and treatment.

The role of acetylation and deacetylation in cancer metabolism

As a hallmark of cancer, metabolic reprogramming adjusts macromolecular synthesis, energy metabolism and redox homeostasis processes to adapt to and promote the complex biological processes of abnormal growth and proliferation. The complexity of metabolic reprogramming lies in its precise regulation by multiple levels and factors, including the interplay of multiple signalling pathways, precise regulation of transcription factors and dynamic adjustments in metabolic enzyme activity. In this complex regulatory network, acetylation and deacetylation, which are important post-translational modifications, regulate key molecules and processes related to metabolic reprogramming by affecting protein function and stability. Dysregulation of acetylation and deacetylation may alter cancer cell metabolic patterns by affecting signalling pathways, transcription factors and metabolic enzyme activity related to metabolic reprogramming, increasing the susceptibility to rapid proliferation and survival. In this review, we focus on discussing how acetylation and deacetylation regulate cancer metabolism, thereby highlighting the central role of these post-translational modifications in metabolic reprogramming, and hoping to provide strong support for the development of novel cancer treatment strategies. KEY POINTS: Protein acetylation and deacetylation are key regulators of metabolic reprogramming in tumour cells. These modifications influence signalling pathways critical for tumour metabolism. They modulate the activity of transcription factors that drive gene expression changes. Metabolic enzymes are also affected, altering cellular metabolism to support tumour growth.

Inhibition of ACSS2 triggers glycolysis inhibition and nuclear translocation to activate SIRT1/ATG5/ATG2B deacetylation axis, promoting autophagy and reducing malignancy and chemoresistance in ovarian cancer

BACKGROUND

Metabolic reprogramming is a hallmark of cancer, characterized by a high dependence on glycolysis and an enhanced utilization of acetate as an alternative carbon source. ACSS2 is a critical regulator of acetate metabolism, playing a significant role in the development and progression of various malignancies. ACSS2 facilitates the conversion of acetate to acetyl-CoA, which participates in multiple metabolic pathways and functions as an epigenetic regulator of protein acetylation, thereby modulating key cellular processes such as autophagy. However, the roles and intrinsic connections of ACSS2, glycolysis, protein acetylation, and autophagy in ovarian cancer (OC) remain to be elucidated.

BASIC PROCEDURES

Utilizing clinical specimens and online databases, we analysed the expression of ACSS2 in OC and its relationship with clinical prognosis. By knocking down ACSS2, we evaluated its effects on the malignant phenotype, acetate metabolism, glycolysis, and autophagy. The metabolic alterations in OC cells were comprehensively analysed using Seahorse assays, transmission electron microscopy, membrane potential measurements, and stable-isotope labeling techniques. CUT&TAG and co-immunoprecipitation techniques were employed to explore the deacetylation of autophagy-related proteins mediated by ACSS2 via SIRT1. Additionally, through molecular docking, transcriptome sequencing, and metabolomics analyses, we validated the pharmacological effects of paeonol on ACSS2 and the glycolytic process in OC cells. Finally, both in vitro and in vivo experiments were performed to investigate the impact of paeonol on autophagy and its anti-OC effects mediated through the ACSS2/SIRT1 deacetylation axis.

MAIN FINDINGS

ACSS2 is significantly upregulated in OC and is associated with poor prognosis. Knockdown of ACSS2 inhibits OC cells proliferation, migration, invasion, angiogenesis, and platinum resistance, while reducing tumour burden in vivo. Mechanistically, inhibiting ACSS2 reduces acetate metabolism and suppresses glycolysis by targeting HXK2. This glycolytic reduction promotes the translocation of ACSS2 from the cytoplasm to the nucleus, leading to increased expression of the deacetylase SIRT1. SIRT1 mediates the deacetylation of autophagy-related proteins, such as ATG5 and ATG2B, thereby significantly activating autophagy in OC cells and exerting antitumor effects. Paeonol inhibits acetate metabolism and glycolysis in OC cells by targeting ACSS2. Paeonol activates autophagy through the ACSS2/SIRT1/ATG5/ATG2B deacetylation axis, demonstrating inhibition of OC in vitro and in vivo.

PRINCIPAL CONCLUSIONS

Pae can serve as an effective, low-toxicity, multi-targeted drug targeting ACSS2 and glycolysis. It activates autophagy through the ACSS2/SIRT1/ATG5/ATG2B deacetylation signalling cascade, thereby exerting anti-OC effects. Our study provides new insights into the malignant mechanisms of OC and offers a novel strategy for its treatment.

Exogenous acetate attenuates inflammatory responses through HIF-1α-dependent glycolysis regulation in macrophage

Cytokine storm is a hallmark for acute systemic inflammatory disease like sepsis. Intrinsic microbiome-derived short-chain fatty acid (SCFAs) like acetate modulates immune cell function and metabolism has been well studied. However, it remains poorly investigated about the effects and the underlying mechanism of exogenous acetate in acute inflammation like sepsis. Here, we observed that serum acetate accumulates in patients undergoing abdominal gastrointestinal surgery and in septic mice. Short exposure to high-dose exogenous acetate protects mice from sepsis by inhibiting glycolysis in macrophages, both in vivo and in vitro. Hypoxia-inducible factor 1 subunit alpha (HIF-1α) stabilization or overexpression reverses the decreased glycolysis and pro-inflammatory cytokine production in macrophages and abrogates acetate's protective effect in septic mice. Meanwhile, we also found acetyl-CoA synthetase-2, but not GPR41 or GPR43, plays a key role in acetate's immunosuppressive effect. Acetate transiently increases acetyl-coenzyme A production, promoting histone acetylation and decreasing acetyl-transfer to NF-κB p65. These findings suggest that short exposure to mM-level acetate inhibits macrophage immune response linked to HIF-1α-dependent glycolysis. Taken together, we demonstrate short-term exposure of exogenous acetate could regulate inflammatory responses through attenuating HIF-1α-dependent glycolysis.

ACSS1-dependent acetate utilization rewires mitochondrial metabolism to support AML and melanoma tumor growth and metastasis

Cancer cells often use alternative nutrient sources to support their metabolism and proliferation. One important alternative nutrient source for many cancers is acetate. Acetate is metabolized into acetyl-coenzyme A (CoA) by acetyl-CoA synthetases 1 and 2 (ACSS1 and ACSS2), which are found in the mitochondria and cytosol, respectively. We show that ACSS1 and ACSS2 are differentially expressed in cancer. Melanoma, breast cancer, and acute myeloid leukemia cells expressing ACSS1 readily use acetate for acetyl-CoA biosynthesis and to fuel mitochondrial metabolism. ACSS1-dependent acetate metabolism decreases the relative contributions of glucose and glutamine to the tricarboxylic acid (TCA) cycle and alters the pentose phosphate pathway and redox state of cancer cells. ACSS1 knockdown decreases acute myeloid leukemia burden in vivo and inhibits melanoma tumor and metastatic growth. Our study highlights a key role for ACSS1-dependent acetate metabolism for cancer growth, raising the potential for ACSS1-targeting therapies in cancer.

ACSL4-mediated H3K9 and H3K27 hyperacetylation upregulates SNAIL to drive TNBC metastasis

Triple-negative breast cancer (TNBC) has profound unmet medical need globally for its devastating clinical outcome associated with rapid metastasis and lack of targeted therapies. Recently, lipid metabolic reprogramming especially fatty acid oxidation (FAO) has emerged as a major driver of breast cancer metastasis. Analyzing the expression of major FAO regulatory genes in breast cancer, we found selective overexpression of acyl-CoA synthetase 4 (ACSL4) in TNBC, which is primarily attributed to the absence of progesterone receptor. Loss of ACSL4 function, by genetic ablation or pharmacological inhibition significantly reduces metastatic potential of TNBC. Global transcriptome analysis reveals that ACSL4 activity positively influences the gene expression related to TNBC migration and invasion. Mechanistically, ACSL4 modulates FAO and intracellular acetyl-CoA levels, leading to hyperacetylation of particularly H3K9ac and H3K27ac marks resulting in overexpression of SNAIL during the course of TNBC metastatic spread to lymph node and lung. Further, human TNBC metastasis exhibits positive correlation among ACSL4, H3K9ac, H3K27ac, and SNAIL expression. Altogether, our findings provide molecular insights regarding the intricate interplay between metabolic alterations and epigenetic modifications, intertwined to orchestrate TNBC metastasis, and posit a rational understanding for the development of ACSL4 inhibitors as a targeted therapy against TNBC.

Advances in seed hypoxia research

Seeds represent essential stages of the plant life cycle: embryogenesis, the intermittent quiescence phase, and germination. Each stage has its own physiological requirements, genetic program, and environmental challenges. Consequently, the effects of developmental and environmental hypoxia can vary from detrimental to beneficial. Past and recent evidence shows how low-oxygen signaling and metabolic adaptations to hypoxia affect seed development and germination. Here, we review the recent literature on seed biology in relation to hypoxia research and present our perspective on key challenges and opportunities for future investigations.

Role of ATP citrate lyase and its complementary partner on fatty acid synthesis in gastric cancer

ATP citrate lyase (ACLY) and acyl-CoA short-chain synthetases 2 (ACSS2) are key enzymes in lipid metabolism. We explored the role of ACLY in gastric cancer (GC) and the effect of ACLY and ACSS2 compensation on GC growth. We used immunohistochemistry to verify the expression level of ACLY in GC, shRNA to stably knock down the expression level of ACLY in GC cells. The expression levels of lipid metabolizing enzymes were verified by qPCR and WB, and targeted lipidomics and quantification of lipid metabolism-related indicators helped us to understand the changes in lipid metabolism. Finally, subcutaneous graft tumors validate our findings from in vitro experiments. ACLY is upregulated in GC tissues, downregulation of ACLY reduced lipid accumulation and inhibited GC proliferation, migration, and invasion in vitro. ACSS2 maintains cell growth by compensatory elevation to maintain fatty acid synthesis activity in ACLY-depleted GC cells. Inhibition of ACSS2 enhanced the inhibitory effect of downregulation of ACLY on the growth of transplanted tumors in nude mice. Downregulation of ACLY inhibited GC cell growth in vitro and in vivo. ACSS2 was compensated to increase to maintain cell growth in ACLY-depleted GC cells.

Alcohol-associated liver cancer

Heavy alcohol intake induces a wide spectrum of liver diseases ranging from steatosis, steatohepatitis, cirrhosis, and HCC. Although alcohol consumption is a well-known risk factor for the development, morbidity, and mortality of HCC globally, alcohol-associated hepatocellular carcinoma (A-HCC) is poorly characterized compared to viral hepatitis-associated HCC. Most A-HCCs develop after alcohol-associated cirrhosis (AC), but the direct carcinogenesis from ethanol and its metabolites to A-HCC remains obscure. The differences between A-HCC and HCCs caused by other etiologies have not been well investigated in terms of clinical prognosis, genetic or epigenetic landscape, molecular mechanisms, and heterogeneity. Moreover, there is a huge gap between basic research and clinical practice due to the lack of preclinical models of A-HCC. In the current review, we discuss the pathogenesis, heterogeneity, preclinical approaches, epigenetic, and genetic profiles of A-HCC, and discuss the current insights into and the prospects for future research on A-HCC. The potential effect of alcohol on cholangiocarcinoma and liver metastasis is also discussed.

The interplay of metabolic and epigenetic players in disease development

Epigenetic modifications and their alterations can cause variation in gene expression patterns which can ultimately affect a healthy individual. Until a few years ago, it was thought that the epigenome affects the transcriptome which can regulate the proteome and the metabolome. Recent studies have shown that the metabolome independently also plays a major role in regulating the epigenome bypassing the need for transcriptomic control. Alternatively, an imbalanced metabolome, stemming from transcriptome abnormalities, can further impact the transcriptome, creating a self-perpetuating cycle of interconnected occurrences. As a result, external factors such as nutrient intake and diet can have a direct impact on the metabolic pools and its reprogramming can change the levels and activity of epigenetic modifiers. Thus, the epigenetic landscape steers toward a diseased condition. In this review, we have discussed how different metabolites and dietary patterns can bring about changes in different arms of the epigenetic machinery such as methylation, acetylation as well as RNA mediated epigenetic mechanisms. We checked for limiting metabolites such as αKG, acetyl-CoA, ATP, NAD+, and FAD, whose abundance levels can lead to common diseases such as cancer, neurodegeneration etc. This gives a clearer picture of how an integrated approach including both epigenetics and metabolomics can be used for therapeutic purposes.

Contribution of glucose and glutamine to hypoxia-induced lipid synthesis decreases, while contribution of acetate increases, during 3T3-L1 differentiation

The molecular mechanisms linking obstructive sleep apnea syndrome (OSA) to obesity and the development of metabolic diseases are still poorly understood. The role of hypoxia (a characteristic feature of OSA) in excessive fat accumulation has been proposed. The present study investigated the possible effects of hypoxia (4% oxygen) on de novo lipogenesis by tracking the major carbon sources in differentiating 3T3-L1 adipocytes. Gas-permeable cultuware was employed to cultivate 3T3-L1 adipocytes in hypoxia (4%) for 7 or 14 days of differentiation. We investigated the contribution of glutamine, glucose or acetate using 13C or 14C labelled carbons to the newly synthesized lipid pool, changes in intracellular lipid content after inhibiting citrate- or acetate-dependent pathways and gene expression of involved key enzymes. The results demonstrate that, in differentiating adipocytes, hypoxia decreased the synthesis of lipids from glucose (44.1 ± 8.8 to 27.5 ± 3.0 pmol/mg of protein, p < 0.01) and partially decreased the contribution of glutamine metabolized through the reverse tricarboxylic acid cycle (4.6% ± 0.2-4.2% ± 0.1%, p < 0.01). Conversely, the contribution of acetate, a citrate- and mitochondria-independent source of carbons, increased upon hypoxia (356.5 ± 71.4 to 649.8 ± 117.5 pmol/mg of protein, p < 0.01). Further, inhibiting the citrate- or acetate-dependent pathways decreased the intracellular lipid content by 58% and 73%, respectively (p < 0.01) showing the importance of de novo lipogenesis in hypoxia-exposed adipocytes. Altogether, hypoxia modified the utilization of carbon sources, leading to alterations in de novo lipogenesis in differentiating adipocytes and increased intracellular lipid content.

Disentangling the molecular mystery of tumour-microbiota interactions: Microbial metabolites

The profound impact of the microbiota on the initiation and progression of cancer has been a focus of attention. In recent years, many studies have shown that microbial metabolites serve as key hubs that connect the microbiome and cancer progression, but the underlying molecular mechanisms have not been fully elucidated. Multiple mechanisms that influence tumour development and therapy resistance, including disrupting cellular signalling pathways, triggering oxidative stress, inducing metabolic reprogramming and reshaping tumour immune microenvironment, are reviewed. Focusing on recent advancements in this field, this review also summarises the methodological framework of studies regarding microbial metabolites. In this review, we outline the current state of research on tumour-associated microbial metabolites and describe the challenges in future scientific research and clinical applications. KEY POINTS: Metabolites derived from both gut and intratumoural microbiota play important roles in cancer initiation and progression. The dual roles of microbial metabolites pose an obstacle for clinical translations. Absolute quantification and tracing techniques of microbial metabolites are essential for addressing the gaps in studies on microbial metabolites. Integrating microbial metabolomics with multi-omics transcends current research paradigms.

The Role of Fatty Acid Metabolism, the Related Potential Biomarkers, and Targeted Therapeutic Strategies in Gastrointestinal Cancers

Gastrointestinal cancer has emerged as a significant global health concern due to its high incidence and mortality, limited effectiveness of early detection, suboptimal treatment outcomes, and poor prognosis. Metabolic reprogramming is a prominent feature of cancer, and fatty acid metabolism assumes a pivotal role in bridging glucose metabolism and lipid metabolism. Fatty acids play important roles in cellular structural composition, energy supply, signal transduction, and other lipid-related processes. Changes in the levels of fatty acid metabolite may indicate the malignant transformation of gastrointestinal cells, which have an impact on the prognosis of patients and can be used as a marker to monitor the efficacy of anticancer therapy. Therefore, targeting key enzymes involved in fatty acid metabolism, either as monotherapy or in combination with other agents, is a promising strategy for anticancer treatment. This article reviews the potential mechanisms of fatty acid metabolism disorders in the occurrence and development of gastrointestinal tumors, and summarizes the related potential biomarkers and anticancer strategies.

Acetate utilization promotes hormone therapy resistance in prostate cancer through neuroendocrine differentiation

AIMS

Tumor fatty acid (FA) metabolic plasticity plays a pivotal role in resistance to therapy and poses limitations to anticancer strategies. In this study, our aim is to uncover the role of acetate metabolism in neurodifferentiation (NED)-mediated castration-resistant prostate cancer (CRPC).

METHODS

We conducted analyses using LC-MS/MS on clinical prostate cancer tissue before and after hormone therapy. We established tumor xenograft mouse models, primary tumor cells, and human-derived organoids to detect the novel mechanism of NED and to identify potential therapies.

RESULTS

The hormone therapy-induced upregulation of acetate metabolism was mediated by acyl-CoA synthetase short-chain family member 2 (ACSS2), which increased c-MYC expression for NED induction. Notably, combined treatment with an ACSS2 inhibitor and enzalutamide significantly reduced the xenograft tumor volume.

CONCLUSION

Our findings uncovered the critical role of acetate metabolism in NED-mediated CRPC and suggest that ACSS2 inhibitors may represent a novel, low-toxicity strategy when combined with hormone therapy for treating patients with NED-mediated CRPC.

Acetate drives ovarian cancer quiescence via ACSS2-mediated acetyl-CoA production

Quiescence is a reversible cell cycle exit traditionally thought to be associated with a metabolically inactive state. Recent work in muscle cells indicates that metabolic reprogramming is associated with quiescence. Whether metabolic changes occur in cancer to drive quiescence is unclear. Using a multi-omics approach, we found that the metabolic enzyme ACSS2, which converts acetate into acetyl-CoA, is both highly upregulated in quiescent ovarian cancer cells and required for their survival. Indeed, quiescent ovarian cancer cells have increased levels of acetate-derived acetyl-CoA, confirming increased ACSS2 activity in these cells. Furthermore, either inducing ACSS2 expression or supplementing cells with acetate was sufficient to induce a reversible quiescent cell cycle exit. RNA-Seq of acetate treated cells confirmed negative enrichment in multiple cell cycle pathways as well as enrichment of genes in a published G0 gene signature. Finally, analysis of patient data showed that ACSS2 expression is upregulated in tumor cells from ascites, which are thought to be more quiescent, compared to matched primary tumors. Additionally, high ACSS2 expression is associated with platinum resistance and worse outcomes. Together, this study points to a previously unrecognized ACSS2-mediated metabolic reprogramming that drives quiescence in ovarian cancer. As chemotherapies to treat ovarian cancer, such as platinum, have increased efficacy in highly proliferative cells, our data give rise to the intriguing question that metabolically-driven quiescence may affect therapeutic response.

Acetate supplementation improves neurological outcomes by preventing hyperglycemia and suppressing Serpina3n expression in CA1 region after cardiac arrest and cardiopulmonary resuscitation

BACKGROUND

Hyperglycemia is common after cardiac arrest and cardiopulmonary resuscitation (CA/CPR). More importantly, it is associated with a worse neurological outcome after CA/CPR. Acetate has been proven to be of great value to reprogram glucose metabolism in the whole body. Nevertheless, the impact of acetate on hyperglycemia and neurological outcomes after CA/CPR remains largely unexplored.

METHODS

Glucose metabolism-related parameters were examined to assess the changes of glucose metabolism in our CA/CPR model. Survival and neurological function were measured after return of spontaneous circulation. Acetate supplementation was achieved by gavage to assess the impact of acetate on CA/CPR-induced hyperglycemia. Proteomics investigation of the changes in proteins of the CA1 region were performed to explore the differences of protein expression. The correlation between acetate supplementation and improvement of neurological outcomes after CA/CPR was elucidated by Serpina3n over-expression and knockdown in CA1 region.

RESULTS

CA/CPR induces hyperglycemia, hyperinsulinemia, glucose intolerance, and insulin resistance with upregulation of Serpina3n in CA1 region. Acetate supplementation could attenuate hyperglycemia, reduce protein levels of Serpina3n in CA1 region, and improves neurological outcomes after CA/CPR. Mechanistically, the acetate-dependent improvement of neurological outcomes after CA/CPR and attenuation of CA/CPR-induced hyperglycemia were correlated with the down-regulation of Serpina3n in CA1 region.

CONCLUSIONS

Our findings suggest that acetate supplementation improves neurological outcomes of CA/CPR mice by maintaining glucose homeostasis in the whole body and suppression of Serpina3n expression in CA1 region.

Using Genetics to Assess the Role of Acetate in Ischemic Heart Disease, Diabetes, and Sex-Hormone-Related Cancers: A Mendelian Randomization Study

BACKGROUND

Acetate, a short-chain fatty acid, has gained attention for its contrasting roles, with evidence suggesting it may offer cardiovascular protection but also promote cancer, particularly those involving sex hormones. However, these influences have been scarcely assessed in epidemiological research.

OBJECTIVE

To investigate the relationship between acetate and ischemic heart disease (IHD), diabetes, and cancers related to sex hormones.

METHODS

Mendelian randomization (MR) was used to assess potential causal effects, selecting genetic variants without linkage disequilibrium (r2 < 0.001) and with genome-wide significance for acetate (p < 5 × 10-8). These variants were applied to large genome-wide association studies (GWAS) for ischemic heart disease (IHD; up to 154,373 cases), diabetes (109,731 cases), and five sex-hormone-related cancers (breast, colorectal, prostate, ovarian, and endometrial cancers, ranging from 8679 to 122,977 cases). We employed various methods for analysis, including penalized inverse variance weighting (pIVW), inverse variance weighting, weighted mode, and weighted median.

RESULTS

This study indicates that acetate may be associated with a lower risk of ischemic heart disease (IHD), with an odds ratio (OR) of 0.62 per standard deviation (SD) increase in acetate and a 95% confidence interval (CI) of 0.39 to 0.98. Additionally, acetate was linked to a higher breast cancer risk, with an OR of 1.26 and a 95% CI ranging from 1.08 to 1.46. This association remained robust across multiple sensitivity analyses.

CONCLUSIONS

Acetate, along with factors that influence its activity, may serve as possible targets for breast cancer treatment and possibly IHD, offering opportunities for new drug development.

Acetylation of Histone H3 in Cancer Progression and Prognosis

Cancer is a multifactorial disease resulting from both genetic factors and epigenetic changes. Histone acetylation, a post-translational modification, which alters chromatin architecture and regulates gene expression is associated with cancer initiation, development and progression. Aberrations in global histone acetylation levels are observed in various cancer cells and are also associated with patients' tumor aggressiveness. Therefore, histone acetylation may have prognostic utility and serve as a potential biomarker of cancer progression and patients' prognosis. The reversible modification of histones by an acetyl group is versatile. One particular histone can be acetylated on different lysine residues, subsequently resulting in different biological outcomes. Here, we discuss recent findings on the acetylation of the highly conserved histone protein H3 in the context of cancer biology. Specifically, we review the acetylation of particular H3 residues in various cancer types. We further highlight the significance of H3 acetylation levels as a potential cancer biomarker with prognostic implications.

Amelioration of nonalcoholic fatty liver disease by inhibiting the deubiquitylating enzyme RPN11

Nonalcoholic fatty liver disease (NAFLD), including its more severe manifestation nonalcoholic steatohepatitis (NASH), is a global public health challenge. Here, we explore the role of deubiquitinating enzyme RPN11 in NAFLD and NASH. Hepatocyte-specific RPN11 knockout mice are protected from diet-induced liver steatosis, insulin resistance, and steatohepatitis. Mechanistically, RPN11 deubiquitinates and stabilizes METTL3 to enhance the m6A modification and expression of acyl-coenzyme A (CoA) synthetase short-chain family member 3 (ACSS3), which generates propionyl-CoA to upregulate lipid metabolism genes via histone propionylation. The RPN11-METTL3-ACSS3-histone propionylation pathway is activated in the livers of patients with NAFLD. Pharmacological inhibition of RPN11 by Capzimin ameliorated NAFLD, NASH, and related metabolic disorders in mice and reduced lipid contents in human hepatocytes cultured in 2D and 3D. These results demonstrate that RPN11 is a novel regulator of NAFLD/NASH and that suppressing RPN11 has therapeutic potential for the treatment.

Ionizing Radiation Dose Differentially Affects the Host-Microbe Relationship over Time

Microorganisms that colonize in or on a host play significant roles in regulating the host's immunological fitness and bioenergy production, thus controlling the host's stress responses. Radiation elicits a pro-inflammatory and bioenergy-expensive state, which could influence the gut microbial compositions and, therefore, the host-microbe bidirectional relationship. To test this hypothesis, young adult mice were exposed to total body irradiation (TBI) at doses of 9.5 Gy and 11 Gy, respectively. The irradiated mice were euthanized on days 1, 3, and 9 post TBI, and their descending colon contents (DCCs) were collected. The 16S ribosomal RNAs from the DCCs were screened to find the differentially enriched bacterial taxa due to TBI. Subsequently, these data were analyzed to identify the metagenome-specific biofunctions. The bacterial community of the DCCs showed increased levels of diversity as time progressed following TBI. The abundance profile was the most divergent at day 9 post 11 Gy TBI. For instance, an anti-inflammatory and energy-harvesting bacterium, namely, Firmicutes, became highly abundant and co-expressed in the DCC with pro-inflammatory Deferribacteres at day 9 post 11 Gy TBI. A systems evaluation found a diverging trend in the regulation profiles of the functional networks that were linked to the bacteria and metabolites of the DCCs, respectively. Additionally, the network clusters associated with lipid metabolism and bioenergy synthesis were found to be activated in the DCC bacteria but inhibited in the metabolite space at day 9 post 11 Gy. Taking these results together, the present analysis indicated a disrupted mouse-bacteria symbiotic relationship as time progressed after lethal irradiation. This information can help develop precise interventions to ameliorate the symptoms triggered by TBI.

Sarcosine, Trigonelline and Phenylalanine as Urinary Metabolites Related to Visceral Fat in Overweight and Obesity

The objective of the present study is to analyze the urinary metabolome profile of patients with obesity and overweight and relate it to different obesity profiles. This is a prospective, cross-sectional study in which patients with a body mass index (BMI) ≥25 kg/m were selected. Anthropometric data were assessed by physical examination and body composition was obtained by bioimpedance (basal metabolic rate, body fat percentile, skeletal muscle mass, gross fat mass and visceral fat). Urine was collected for metabolomic analysis. Patients were classified according to abdominal circumference measurements between 81 and 93, 94 and 104, and >104 cm; visceral fat up to 16 kilos and less than; and fat percentiles of <36%, 36-46% and >46%. Spectral alignment of urinary metabolite signals and bioinformatic analysis were carried out to select the metabolites that stood out. NMR spectrometry was used to detect and quantify the main urinary metabolites and to compare the groups. Seventy-five patients were included, with a mean age of 38.3 years, and 72% females. The urinary metabolomic profile showed no differences in BMI, abdominal circumference and percentage of body fat. Higher concentrations of trigonelline (p = 0.0488), sarcosine (p = 0.0350) and phenylalanine (p = 0.0488) were associated with patients with visceral fat over 16 kg. The cutoff points obtained by the ROC curves were able to accurately differentiate between patients according to the amount of visceral fat: sarcosine 0.043 mg/mL; trigonelline 0.068 mg/mL and phenylalanine 0.204 mg/mL. In conclusion, higher visceral fat was associated with urinary levels of metabolites such as sarcosine, related to insulin resistance; trigonelline, related to muscle mass and strength; and phenylalanine, related to glucose metabolism and abdominal fat. Trigonelline, sarcosine and phenylalanine play significant roles in regulating energy balance and metabolic pathways essential for controlling obesity. Our findings could represent an interesting option for the non-invasive estimation of visceral fat through biomarkers related to alterations in metabolic pathways involved in the pathophysiology of obesity.

Probiotics for pancreatic β-cell function: from possible mechanism of action to assessment of effectiveness

Type 2 diabetes (T2D) is a metabolic disease characterized by chronic hyperglycemia because of insulin resistance (IR) and\or pancreatic β-cell dysfunction. Last century research showed that gut microbiota has a direct effect on metabolism and metabolic diseases. New studies into the human microbiome and its connection with the host is making it possible to develop new therapies for a wide variety of diseases. Inflammation is a well-known precursor to metabolic syndrome, which increases the risk of hypertension, visceral obesity, and dyslipidemia, which can lead to T2D through the damage of pancreatic β-cell and reduce insulin secretion. Current understanding for beneficial effects of probiotics in T2D strictly rely on both animal and clinical data, which mostly focused on their impact on IR, anthropometric parameters, glycemic control and markers of chronic systemic inflammation. From the other hand, there is a lack of evidence-based probiotic efficacy on pancreatic β-cell function in terms of T2D and related metabolic disorders. Therefore, current review will focus on the efficacy of probiotics for the protection of β-cells damage and it`s mechanism in patients with T2D.

Metabolic ripple effects - deciphering how lipid metabolism in cancer interfaces with the tumor microenvironment

Cancer cells require a constant supply of lipids. Lipids are a diverse class of hydrophobic molecules that are essential for cellular homeostasis, growth and survival, and energy production. How tumors acquire lipids is under intensive investigation, as these mechanisms could provide attractive therapeutic targets for cancer. Cellular lipid metabolism is tightly regulated and responsive to environmental stimuli. Thus, lipid metabolism in cancer is heavily influenced by the tumor microenvironment. In this Review, we outline the mechanisms by which the tumor microenvironment determines the metabolic pathways used by tumors to acquire lipids. We also discuss emerging literature that reveals that lipid availability in the tumor microenvironment influences many metabolic pathways in cancers, including those not traditionally associated with lipid biology. Thus, metabolic changes instigated by the tumor microenvironment have 'ripple' effects throughout the densely interconnected metabolic network of cancer cells. Given the interconnectedness of tumor metabolism, we also discuss new tools and approaches to identify the lipid metabolic requirements of cancer cells in the tumor microenvironment and characterize how these requirements influence other aspects of tumor metabolism.

Inhibiting mitochondrial citrate shuttling induces hepatic triglyceride deposition in Nile tilapia (Oreochromis niloticus) through lipid anabolic remodeling

The solute carrier family 25 member 1 (Slc25a1)-dependent mitochondrial citrate shuttle is responsible for exporting citrate from the mitochondria to the cytoplasm for supporting lipid biosynthesis and protein acetylation. Previous studies on Slc25a1 concentrated on pathological models. However, the importance of Slc25a1 in maintaining metabolic homeostasis under normal nutritional conditions remains poorly understood. Here, we investigated the mechanism of mitochondrial citrate shuttle in maintaining lipid metabolism homeostasis in male Nile tilapia (Oreochromis niloticus). To achieve the objective, we blocked the mitochondrial citrate shuttle by inhibiting Slc25a1 under normal nutritional conditions. Slc25a1 inhibition was established by feeding Nile tilapia with 250 mg/kg 1,2,3-benzenetricarboxylic acid hydrate for 6 weeks or intraperitoneal injecting them with dsRNA to knockdown slc25a1b for 7 days. The Nile tilapia with Slc25a1 inhibition exhibited an obesity-like phenotype accompanied by fat deposition, liver damage and hyperglycemia. Moreover, Slc25a1 inhibition decreased hepatic citrate-derived acetyl-CoA, but increased hepatic triglyceride levels. Furthermore, Slc25a1 inhibition replenished cytoplasmic acetyl-CoA through enhanced acetate pathway, which led to hepatic triglycerides accumulation. However, acetate-derived acetyl-CoA caused by hepatic Slc25a1 inhibition did not activate de novo lipogenesis, but rather modified protein acetylation. In addition, hepatic Slc25a1 inhibition enhanced fatty acids esterification through acetate-derived acetyl-CoA, which increased Lipin1 acetylation and its protein stability. Collectively, our results illustrate that inhibiting mitochondrial citrate shuttle triggers lipid anabolic remodeling and results in lipid accumulation, indicating the importance of mitochondrial citrate shuttle in maintaining lipid metabolism homeostasis.

The proto-oncogene tyrosine kinase c-SRC facilitates glioblastoma progression by remodeling fatty acid synthesis

Increased fatty acid synthesis benefits glioblastoma malignancy. However, the coordinated regulation of cytosolic acetyl-CoA production, the exclusive substrate for fatty acid synthesis, remains unclear. Here, we show that proto-oncogene tyrosine kinase c-SRC is activated in glioblastoma and remodels cytosolic acetyl-CoA production for fatty acid synthesis. Firstly, acetate is an important substrate for fatty acid synthesis in glioblastoma. c-SRC phosphorylates acetyl-CoA synthetase ACSS2 at Tyr530 and Tyr562 to stimulate the conversion of acetate to acetyl-CoA in cytosol. Secondly, c-SRC inhibits citrate-derived acetyl-CoA synthesis by phosphorylating ATP-citrate lyase ACLY at Tyr682. ACLY phosphorylation shunts citrate to IDH1-catalyzed NADPH production to provide reducing equivalent for fatty acid synthesis. The c-SRC-unresponsive double-mutation of ACSS2 and ACLY significantly reduces fatty acid synthesis and hampers glioblastoma progression. In conclusion, this remodeling fulfills the dual needs of glioblastoma cells for both acetyl-CoA and NADPH in fatty acid synthesis and provides evidence for glioma treatment by c-SRC inhibition.

Correlated Responses to Selection for Intramuscular Fat on the Gut Microbiome in Rabbits

Intramuscular fat (IMF) content is important for meat production and human health, where the host genetics and its microbiome greatly contribute to its variation. The aim of this study is to describe the consequences of the genetic modification of IMF by selecting the taxonomic composition of the microbiome, using rabbits from the 10th generation of a divergent selection experiment for IMF (high (H) and low (L) lines differ by 3.8 standard deviations). The selection altered the composition of the gut microbiota. Correlated responses were better distinguished at the genus level (51 genera) than at the phylum level (10 phyla). The H-line was enriched in Hungateiclostridium, Limosilactobacillus, Legionella, Lysinibacillus, Phorphyromonas, Methanosphaera, Desulfovibrio, and Akkermansia, while the L-line was enriched in Escherichia, Methanobrevibacter, Fonticella, Candidatus Amulumruptor, Methanobrevibacter, Exiguobacterium, Flintibacter, and Coprococcus, among other genera with smaller line differences. A microbial biomarker generated from the abundance of four of these genera classified the lines with 78% accuracy in a logit regression. Our results demonstrate different gut microbiome compositions in hosts with divergent IMF genotypes. Furthermore, we provide a microbial biomarker to be used as an indicator of hosts genetically predisposed to accumulate muscle lipids, which opens up the opportunity for research to develop probiotics or microbiome-based breeding strategies targeting IMF.

Acetate drives ovarian cancer quiescence via ACSS2-mediated acetyl-CoA production

Quiescence is a reversible cell cycle exit traditionally thought to be associated with a metabolically inactive state. Recent work in muscle cells indicates that metabolic reprogramming is associated with quiescence. Whether metabolic changes occur in cancer to drive quiescence is unclear. Using a multi-omics approach, we found that the metabolic enzyme ACSS2, which converts acetate into acetyl-CoA, is both highly upregulated in quiescent ovarian cancer cells and required for their survival. Indeed, quiescent ovarian cancer cells have increased levels of acetate-derived acetyl-CoA, confirming increased ACSS2 activity in these cells. Furthermore, either inducing ACSS2 expression or supplementing cells with acetate was sufficient to induce a reversible quiescent cell cycle exit. RNA-Seq of acetate treated cells confirmed negative enrichment in multiple cell cycle pathways as well as enrichment of genes in a published G0 gene signature. Finally, analysis of patient data showed that ACSS2 expression is upregulated in tumor cells from ascites, which are thought to be more quiescent, compared to matched primary tumors. Additionally, high ACSS2 expression is associated with platinum resistance and worse outcomes. Together, this study points to a previously unrecognized ACSS2-mediated metabolic reprogramming that drives quiescence in ovarian cancer. As chemotherapies to treat ovarian cancer, such as platinum, have increased efficacy in highly proliferative cells, our data give rise to the intriguing question that metabolically-driven quiescence may affect therapeutic response.

Mitochondrial inhibitors: a new horizon in breast cancer therapy

Breast cancer, due to resistance to standard therapies such as endocrine therapy, anti-HER2 therapy and chemotherapy, continues to pose a major health challenge. A growing body of research emphasizes the heterogeneity and plasticity of metabolism in breast cancer. Because differences in subtypes exhibit a bias toward metabolic pathways, targeting mitochondrial inhibitors shows great potential as stand-alone or adjuvant cancer therapies. Multiple therapeutic candidates are currently in various stages of preclinical studies and clinical openings. However, specific inhibitors have been shown to face multiple challenges (e.g., single metabolic therapies, mitochondrial structure and enzymes, etc.), and combining with standard therapies or targeting multiple metabolic pathways may be necessary. In this paper, we review the critical role of mitochondrial metabolic functions, including oxidative phosphorylation (OXPHOS), the tricarboxylic acid cycle, and fatty acid and amino acid metabolism, in metabolic reprogramming of breast cancer cells. In addition, we outline the impact of mitochondrial dysfunction on metabolic pathways in different subtypes of breast cancer and mitochondrial inhibitors targeting different metabolic pathways, aiming to provide additional ideas for the development of mitochondrial inhibitors and to improve the efficacy of existing therapies for breast cancer.

The Gut Microbial Regulation of Epigenetic Modification from a Metabolic Perspective

Obesity is a global health challenge that has received increasing attention in contemporary research. The gut microbiota has been implicated in the development of obesity, primarily through its involvement in regulating various host metabolic processes. Recent research suggests that epigenetic modifications may serve as crucial pathways through which the gut microbiota and its metabolites contribute to the pathogenesis of obesity and other metabolic disorders. Hence, understanding the interplay between gut microbiota and epigenetic mechanisms is crucial for elucidating the impact of obesity on the host. This review primarily focuses on the understanding of the relationship between the gut microbiota and its metabolites with epigenetic mechanisms in several obesity-related pathogenic mechanisms, including energy dysregulation, metabolic inflammation, and maternal inheritance. These findings could serve as novel therapeutic targets for probiotics, prebiotics, and fecal microbiota transplantation tools in treating metabolic disruptions. It may also aid in developing therapeutic strategies that modulate the gut microbiota, thereby regulating the metabolic characteristics of obesity.

Acetyl-CoA metabolic accumulation promotes hepatocellular carcinoma metastasis via enhancing CXCL1-dependent infiltration of tumor-associated neutrophils

High levels of acetyl-CoA are considered a key metabolic feature of metastatic cancers. However, the impacts of acetyl-CoA metabolic accumulation on cancer microenvironment remodeling are poorly understood. In this study, using human hepatocellular carcinoma (HCC) tissues and orthotopic xenograft models, we found a close association between high acetyl-CoA levels in HCCs, increased infiltration of tumor-associated neutrophils (TANs) in the cancer microenvironment and HCC metastasis. Cytokine microarray and enzyme-linked immunosorbent assays (ELISA) revealed the crucial role of the chemokine (C-X-C motif) ligand 1(CXCL1). Mechanistically, acetyl-CoA accumulation induces H3 acetylation-dependent upregulation of CXCL1 gene expression. CXCL1 recruits TANs, leads to neutrophil extracellular traps (NETs) formation and promotes HCC metastasis. Collectively, our work linked the accumulation of acetyl-CoA in HCC cells and TANs infiltration, and revealed that the CXCL1-CXC receptor 2 (CXCR2)-TANs-NETs axis is a potential target for HCCs with high acetyl-CoA levels.

Unraveling the intricate relationship between lipid metabolism and oncogenic signaling pathways

Lipids, the primary constituents of the cell membrane, play essential roles in nearly all cellular functions, such as cell-cell recognition, signaling transduction, and energy provision. Lipid metabolism is necessary for the maintenance of life since it regulates the balance between the processes of synthesis and breakdown. Increasing evidence suggests that cancer cells exhibit abnormal lipid metabolism, significantly affecting their malignant characteristics, including self-renewal, differentiation, invasion, metastasis, and drug sensitivity and resistance. Prominent oncogenic signaling pathways that modulate metabolic gene expression and elevate metabolic enzyme activity include phosphoinositide 3-kinase (PI3K)/AKT, MAPK, NF-kB, Wnt, Notch, and Hippo pathway. Conversely, when metabolic processes are not regulated, they can lead to malfunctions in cellular signal transduction pathways. This, in turn, enables uncontrolled cancer cell growth by providing the necessary energy, building blocks, and redox potentials. Therefore, targeting lipid metabolism-associated oncogenic signaling pathways could be an effective therapeutic approach to decrease cancer incidence and promote survival. This review sheds light on the interactions between lipid reprogramming and signaling pathways in cancer. Exploring lipid metabolism as a target could provide a promising approach for creating anticancer treatments by identifying metabolic inhibitors. Additionally, we have also provided an overview of the drugs targeting lipid metabolism in cancer in this review.

Specific regulation of epigenome landscape by metabolic enzymes and metabolites

Metabolism includes anabolism and catabolism, which play an essential role in many biological processes. Chromatin modifications are post-translational modifications of histones and nucleic acids that play important roles in regulating chromatin-associated processes such as gene transcription. There is a tight connection between metabolism and chromatin modifications. Many metabolic enzymes and metabolites coordinate cellular activities with alterations in nutrient availability by regulating gene expression through epigenetic mechanisms such as DNA methylation and histone modifications. The dysregulation of gene expression by metabolism and epigenetic modifications may lead to diseases such as diabetes and cancer. Recent studies reveal that metabolic enzymes and metabolites specifically regulate chromatin modifications, including modification types, modification residues and chromatin regions. This specific regulation has been implicated in the development of human diseases, yet the underlying mechanisms are only beginning to be uncovered. In this review, we summarise recent studies of the molecular mechanisms underlying the metabolic regulation of histone and DNA modifications and discuss how they contribute to pathogenesis. We also describe recent developments in technologies used to address the key questions in this field. We hope this will inspire further in-depth investigations of the specific regulatory mechanisms involved, and most importantly will shed lights on the development of more effective disease therapies.

Short-chain fatty acids: Important components of the gut-brain axis against AD

Alzheimer's disease (AD) comprises a group of neurodegenerative disorders with some changes in the brain, which could lead to the deposition of certain proteins and result in the degeneration and death of brain cells. Patients with AD manifest primarily as cognitive decline, psychiatric symptoms, and behavioural disorders. Short-chain fatty acids (SCFAs) are a class of saturated fatty acids (SFAs) produced by gut microorganisms through the fermentation of dietary fibre ingested. SCFAs, as a significant mediator of signalling, can have diverse physiological and pathological roles in the brain through the gut-brain axis, and play a positive effect on AD via multiple pathways. Firstly, differences in SCFAs and microbial changes have been stated in AD cases of humans and mice in this paper. And then, mechanisms of three main SCFAs in treating with AD have been summarized, as well as differences of gut bacteria. Finally, functions of SCFAs played in regulating intestinal flora homeostasis, modulating the immune system, and the metabolic system, which were considered to be beneficial for the treatment of AD, have been elucidated, and the key roles of gut bacteria and SCFAs were pointed out. All in all, this paper provides an overview of SCFAs and gut bacteria in AD, and can help people to understand the importance of gut-brain axis in AD.