Acetyl-CoA synthetase activity is enzymatically regulated by lysine acetylation using acetyl-CoA or acetyl-phosphate as donor molecule.

The AMP-forming acetyl-CoA synthetase is regulated by lysine acetylation both in bacteria and eukaryotes. However, the underlying mechanism is poorly understood. The Bacillus subtilis acetyltransferase AcuA and the AMP-forming acetyl-CoA synthetase AcsA form an AcuA•AcsA complex, dissociating upon lysine acetylation of AcsA by AcuA. Crystal structures of AcsA from Chloroflexota bacterium in the apo form and in complex with acetyl-adenosine-5'-monophosphate (acetyl-AMP) support the flexible C-terminal domain adopting different conformations. AlphaFold2 predictions suggest binding of AcuA stabilizes AcsA in an undescribed conformation. We show the AcuA•AcsA complex dissociates upon acetyl-coenzyme A (acetyl-CoA) dependent acetylation of AcsA by AcuA. We discover an intrinsic phosphotransacetylase activity enabling AcuA•AcsA generating acetyl-CoA from acetyl-phosphate (AcP) and coenzyme A (CoA) used by AcuA to acetylate and inactivate AcsA. Here, we provide mechanistic insights into the regulation of AMP-forming acetyl-CoA synthetases by lysine acetylation and discover an intrinsic phosphotransacetylase allowing modulation of its activity based on AcP and CoA levels.

HIF-2α expression and metabolic signaling require ACSS2 in clear cell renal cell carcinoma.

Clear cell renal cell carcinoma (ccRCC) is an aggressive cancer driven by VHL loss and aberrant HIF-2α signaling. Identifying means to regulate HIF-2α thus has potential therapeutic benefit. Acetyl-CoA synthetase 2 (ACSS2) converts acetate to acetyl-CoA and is associated with poor patient prognosis in ccRCC. Here we tested the effects of ACSS2 on HIF-2α and cancer cell metabolism and growth in ccRCC models and clinical samples. ACSS2 inhibition reduced HIF-2α levels and suppressed ccRCC cell line growth in vitro, in vivo, and in cultures of primary ccRCC patient tumors. This treatment reduced glycolytic signaling, cholesterol metabolism, and mitochondrial integrity, all of which are consistent with loss of HIF-2α. Mechanistically, ACSS2 inhibition decreased chromatin accessibility and HIF-2α expression and stability. While HIF-2α protein levels are widely regulated through pVHL-dependent proteolytic degradation, we identify a potential pVHL-independent pathway of degradation via the E3 ligase MUL1. We show that MUL1 can directly interact with HIF-2α and that overexpression of MUL1 decreased HIF-2α levels in a manner partially dependent on ACSS2. These findings identify multiple mechanisms to regulate HIF-2α stability and ACSS2 inhibition as a strategy to complement HIF-2α-targeted therapies and deplete pathogenically stabilized HIF-2α.

ACSS2 controls PPARγ activity homeostasis to potentiate adipose-tissue plasticity.

The appropriate transcriptional activity of PPARγ is indispensable for controlling inflammation, tumor and obesity. Therefore, the identification of key switch that couples PPARγ activation with degradation to sustain its activity homeostasis is extremely important. Unexpectedly, we here show that acetyl-CoA synthetase short-chain family member 2 (ACSS2) critically controls PPARγ activity homeostasis via SIRT1 to enhance adipose plasticity via promoting white adipose tissues beiging and brown adipose tissues thermogenesis. Mechanistically, ACSS2 binds directly acetylated PPARγ in the presence of ligand and recruits SIRT1 and PRDM16 to activate UCP1 expression. In turn, SIRT1 triggers ACSS2 translocation from deacetylated PPARγ to P300 and thereafter induces PPARγ polyubiquitination and degradation. Interestingly, D-mannose rapidly activates ACSS2-PPARγ-UCP1 axis to resist high fat diet induced obesity in mice. We thus reveal a novel ACSS2 function in coupling PPARγ activation with degradation via SIRT1 and suggest D-mannose as a novel adipose plasticity regulator via ACSS2 to prevent obesity.

ACSS3 regulates the metabolic homeostasis of epithelial cells and alleviates pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal interstitial lung disease of unknown etiology. The emerging evidence demonstrates that metabolic homeostatic imbalance caused by repetitive injuries of the alveolar epithelium is the potential pathogenesis of IPF. Proteomic analysis identified that Acetyl-CoA synthetase short chain family member 3 (ACSS3) expression was decreased in IPF patients and mice with bleomycin-induced fibrosis. ACSS3 participated in lipid and carbohydrate metabolism. Increased expression of ACSS3 downregulated carnitine palmitoyltransferase 1A (CPT-1A) and resulted in the accumulation of lipid droplets, while enhanced glycolysis which led to an increase in extracellular lactic acid levels in A549 cells. ACSS3 increases the production of succinyl-CoA through propionic acid metabolism, and decreases the generation of acetyl-CoA and ATP in alveolar epithelial cells. Overexpression of Acss3 inhibited the excessive deposition of ECM and attenuated the ground-glass opacity which determined by micro-CT in vivo. In a nutshell, our findings demonstrate that ACSS3 decreased the fatty acid oxidation through CPT1A deficiency and enhanced anaerobic glycolysis, this metabolic reprogramming deactivate the alveolar epithelial cells by lessen mitochondrial fission and fusion, increase of ROS production, suppression of mitophagy, promotion of apoptosis, suggesting that ACSS3 might be potential therapeutic target in pulmonary fibrosis.

ACSS2-mediated NF-κB activation promotes alkaliptosis in human pancreatic cancer cells.

Alkaliptosis is a recently discovered type of pH-dependent cell death used for tumor therapy. However, its underlying molecular mechanisms and regulatory networks are largely unknown. Here, we report that the acetate-activating enzyme acetyl-CoA short-chain synthase family member 2 (ACSS2) is a positive regulator of alkaliptosis in human pancreatic ductal adenocarcinoma (PDAC) cells. Using qPCR and western blot analysis, we found that the mRNA and protein expression of ACSS2 was upregulated in human PDAC cell lines (PANC1 and MiaPaCa2) in response to the classic alkaliptosis activator JTC801. Consequently, the knockdown of ACSS2 by shRNAs inhibited JTC801-induced cell death in PDAC cells, and was accompanied by an increase in cell clone formation and a decrease in intracellular pH. Mechanically, ACSS2-mediated acetyl-coenzyme A production and subsequent histone acetylation contributed to NF-κB-dependent CA9 downregulation, and this effect was enhanced by the histone deacetylase inhibitor trichostatin A. These findings may provide new insights for understanding the metabolic basis of alkaliptosis and establish a potential strategy for PDAC treatment.

Acetyl-Coenzyme A Synthetase 2 Potentiates Macropinocytosis and Muscle Wasting Through Metabolic Reprogramming in Pancreatic Cancer.

BACKGROUND & AIMS: Rapid deconditioning, also called cachexia, and metabolic reprogramming are two hallmarks of pancreatic cancer. Acetyl-coenzyme A synthetase short-chain family member 2 (ACSS2) is an acetyl-enzyme A synthetase that contributes to lipid synthesis and epigenetic reprogramming. However, the role of ACSS2 on the nonselective macropinocytosis and cancer cachexia in pancreatic cancer remains elusive. In this study, we demonstrate that ACSS2 potentiates macropinocytosis and muscle wasting through metabolic reprogramming in pancreatic cancer. METHODS: Clinical significance of ACSS2 was analyzed using samples from patients with pancreatic cancer. ACSS2-knockout cells were established using the clustered regularly interspaced short palindromic repeats-associated protein 9 system. Single-cell RNA sequencing data from genetically engineered mouse models was analyzed. The macropinocytotic index was evaluated by dextran uptake assay. Chromatin immunoprecipitation assay was performed to validate transcriptional activation. ACSS2-mediated tumor progression and muscle wasting were examined in orthotopic xenograft models. RESULTS: Metabolic stress induced ACSS2 expression, which is associated with worse prognosis in pancreatic cancer. ACSS2 knockout significantly suppressed cell proliferation in 2-dimensional and 3-dimensional models. Macropinocytosis-associated genes are upregulated in tumor tissues and are correlated with worse prognosis. ACSS2 knockout inhibited macropinocytosis. We identified Zrt- and Irt-like protein 4 (ZIP4) as a downstream target of ACSS2, and knockdown of ZIP4 reversed ACSS2-induced macropinocytosis. ACSS2 upregulated ZIP4 through ETV4-mediated transcriptional activation. ZIP4 induces macropinocytosis through cyclic adenosine monophosphate response element-binding protein-activated syndecan 1 (SDC1) and dynamin 2 (DNM2). Meanwhile, ZIP4 drives muscle wasting and cachexia via glycogen synthase kinase-ß (GSK3ß)-mediated secretion of tumor necrosis factor superfamily member 10 (TRAIL or TNFSF10). ACSS2 knockout attenuated muscle wasting and extended survival in orthotopic mouse models. CONCLUSIONS: ACSS2-mediated metabolic reprogramming activates the ZIP4 pathway, and promotes macropinocytosis via SDC1/DNM2 and drives muscle wasting through the GSK3ß/TRAIL axis, which potentially provides additional nutrients for macropinocytosis in pancreatic cancer.

O-GlcNAc transferase regulates glioblastoma acetate metabolism via regulation of CDK5-dependent ACSS2 phosphorylation.

Glioblastomas (GBMs) preferentially generate acetyl-CoA from acetate as a fuel source to promote tumor growth. O-GlcNAcylation has been shown to be elevated by increasing O-GlcNAc transferase (OGT) in many cancers and reduced O-GlcNAcylation can block cancer growth. Here, we identify a novel mechanism whereby OGT regulates acetate-dependent acetyl-CoA and lipid production by regulating phosphorylation of acetyl-CoA synthetase 2 (ACSS2) by cyclin-dependent kinase 5 (CDK5). OGT is required and sufficient for GBM cell growth and regulates acetate conversion to acetyl-CoA and lipids. Elevating O-GlcNAcylation in GBM cells increases phosphorylation of ACSS2 on Ser-267 in a CDK5-dependent manner. Importantly, we show that ACSS2 Ser-267 phosphorylation regulates its stability by reducing polyubiquitination and degradation. ACSS2 Ser-267 is critical for OGT-mediated GBM growth as overexpression of ACSS2 Ser-267 phospho-mimetic rescues growth in vitro and in vivo. Importantly, we show that pharmacologically targeting OGT and CDK5 reduces GBM growth ex vivo. Thus, the OGT/CDK5/ACSS2 pathway may be a way to target altered metabolic dependencies in brain tumors.

Acetyl CoA synthase 2 potentiates ATG5-induced autophagy against neuronal apoptosis after subarachnoid hemorrhage.

ATG5-induced autophagy is triggered in the early stages after SAH, which plays a vital role in subarachnoid hemorrhage (SAH). Acyl-CoA synthetase short-chain family 2 (ACSS2) is not just involved in energy metabolism but also binds to TEFB to form a complex translocated to related autophagy genes to regulate the expression of autophagy-related genes. However, the contribution of ACSS2 to the activation of autophagy in early brain injury (EBI) after SAH has barely been discussed. The purpose of this study was to investigate the alterations of ACSS2 and its neuroprotective effects following SAH. We first evaluated the expression of ACSS2 at different time points (6, 12, 24, and 72 h after SAH) in vivo and primary cortical neurons stimulated by oxyhemoglobin (OxyHb). Subsequently, adeno-associated virus and lentivirus were used to regulate ACSS2 expression to investigate the effect of ACSS2 after SAH. The results showed that the ACSS2 level decreased significantly in the early stages of SAH and was minimized at 24 h post-SAH. After artificial intervention to overexpress ACSS2, ATG5-induced autophagy was further enhanced in EBI after SAH, and neuronal apoptosis was alleviated to protect brain injury. In addition, brain edema and neurological function scores were improved. These results suggest that ACSS2 plays an important role in the neuroprotection against EBI after SAH by increasing ATG5-induce autophagy and inhibiting apoptosis.

Structural Characterization of the Reaction and Substrate Specificity Mechanisms of Pathogenic Fungal Acetyl-CoA Synthetases.

Acetyl CoA synthetases (ACSs) are Acyl-CoA/NRPS/Luciferase (ANL) superfamily enzymes that couple acetate with CoA to generate acetyl CoA, a key component of central carbon metabolism in eukaryotes and prokaryotes. Normal mammalian cells are not dependent on ACSs, while tumor cells, fungi, and parasites rely on acetate as a precursor for acetyl CoA. Consequently, ACSs have emerged as a potential drug target. As part of a program to develop antifungal ACS inhibitors, we characterized fungal ACSs from five diverse human fungal pathogens using biochemical and structural studies. ACSs catalyze a two-step reaction involving adenylation of acetate followed by thioesterification with CoA. Our structural studies captured each step of these two half-reactions including the acetyl-adenylate intermediate of the first half-reaction in both the adenylation conformation and the thioesterification conformation and thus provide a detailed picture of the reaction mechanism. We also used a systematic series of increasingly larger alkyl adenosine esters as chemical probes to characterize the structural basis of the exquisite ACS specificity for acetate over larger carboxylic acid substrates. Consistent with previous biochemical and genetic data for other enzymes, structures of fungal ACSs with these probes bound show that a key tryptophan residue limits the size of the alkyl binding site and forces larger alkyl chains to adopt high energy conformers, disfavoring their efficient binding. Together, our analysis provides highly detailed structural models for both the reaction mechanism and substrate specificity that should be useful in designing selective inhibitors of eukaryotic ACSs as potential anticancer, antifungal, and antiparasitic drugs.

Targeting acetate metabolism: Achilles' nightmare.

Recent advances in our understanding of tumour heterogeneity alongside studies investigating altered metabolism within transformed tissue have identified metabolic pathways critical to cancer cell survival. Leveraging this information presents a promising new avenue for the generation of cancer-specific therapeutics and improved patient outcomes.

Acetyl-CoA synthases are essential for maintaining histone acetylation under metabolic stress during zygotic genome activation in pigs.

ACSS1/2 converts acetate into acetyl-coenzyme A, which contributes to histone acetylation in the mitochondria and cytoplasm. Zygotic genome activation (ZGA) is critical for embryo development involving drastic histone modification. An efficient crRNAs-Cas13a targeting strategy was employed to investigate the ACSS1/2 function during ZGA. The results showed that nuclear accumulation of ACSS1 and ACSS2 occurs during ZGA. Knockdown of ACSS1/2 did not affect blastocyst formation when using a normal medium. On culturing embryos in a medium with acetate and no pyruvate (-P + Ace), knockdown of ACSS1 did not affect histone acetylation levels but significantly reduced ATP levels, whereas knockdown of ACSS2 significantly reduced histone acetylation levels in porcine embryos. Inhibition of fatty acid beta-oxidation by etomoxir significantly reduced ATP levels, which could be restored by acetate. The histone acetylation levels in the ACSS1 and ACSS2 knockdown groups both decreased considerably after etomoxir treatment. Moreover, acetate showed dose-dependent effects on SIRT1 and SIRT3 levels when under metabolic stress. The C-terminus of ACSS1 regulated the nuclear translocation. In conclusion, ACSS1/2 helps to maintain ATP and histone acetylation levels in porcine early embryos under metabolic stress during ZGA.

Acetyl-CoA Synthetase 2: A Critical Linkage in Obesity-Induced Tumorigenesis in Myeloma.

Obesity is often linked to malignancies including multiple myeloma, and the underlying mechanisms remain elusive. Here we showed that acetyl-CoA synthetase 2 (ACSS2) may be an important linker in obesity-related myeloma. ACSS2 is overexpressed in myeloma cells derived from obese patients and contributes to myeloma progression. We identified adipocyte-secreted angiotensin II as a direct cause of adiposity in increased ACSS2 expression. ACSS2 interacts with oncoprotein interferon regulatory factor 4 (IRF4), and enhances IRF4 stability and IRF4-mediated gene transcription through activation of acetylation. The importance of ACSS2 overexpression in myeloma is confirmed by the finding that an inhibitor of ACSS2 reduces myeloma growth both in vitro and in a diet-induced obese mouse model. Our findings demonstrate a key impact for obesity-induced ACSS2 on the progression of myeloma. Given the central role of ACSS2 in many tumors, this mechanism could be important to other obesity-related malignancies.

Targeting ACSS2 with a Transition-State Mimetic Inhibits Triple-Negative Breast Cancer Growth.

Acetyl-CoA is a vitally important and versatile metabolite used for many cellular processes including fatty acid synthesis, ATP production, and protein acetylation. Recent studies have shown that cancer cells upregulate acetyl-CoA synthetase 2 (ACSS2), an enzyme that converts acetate to acetyl-CoA, in response to stresses such as low nutrient availability and hypoxia. Stressed cancer cells use ACSS2 as a means to exploit acetate as an alternative nutrient source. Genetic depletion of ACSS2 in tumors inhibits the growth of a wide variety of cancers. However, there are no studies on the use of an ACSS2 inhibitor to block tumor growth. In this study, we synthesized a small-molecule inhibitor that acts as a transition-state mimetic to block ACSS2 activity in vitro and in vivo. Pharmacologic inhibition of ACSS2 as a single agent impaired breast tumor growth. Collectively, our findings suggest that targeting ACSS2 may be an effective therapeutic approach for the treatment of patients with breast cancer. SIGNIFICANCE: These findings suggest that targeting acetate metabolism through ACSS2 inhibitors has the potential to safely and effectively treat a wide range of patients with cancer.

miR-15a-5p inhibits metastasis and lipid metabolism by suppressing histone acetylation in lung cancer.

Metabolic reprogramme was a key characteristic of malignant tumors. Increased evidences indicated that besides Warburg effect (abnormal glucose metabolism), abnormal lipid metabolism played more and more important in progression and metastasis of malignant tumors. MiR-15a-5p could inhibit development of lung cancer, while its regulating mechanism, especially the role in lipid metabolism still remained unclear. In this study, we confirmed that miR-15a-5p inhibited proliferation, migration and invasion of lung cancer cells. The online analysis of Mirpath v.3 predicted that miR-15a-5p was closely associated with fatty acid synthesis and lipid metabolism. In vitro cell experiments revealed that miR-15a-5p significantly suppressed fatty acid synthesis of lung cancer cells by inhibiting acetate uptake. Extensive analysis indicated that miR-15a-5p could suppress acetyl-CoA activity and decrease histone H4 acetylation by inhibiting ACSS2 expression. In addition, we also observed that ACSS2 located in nucleus under hypoxic conditions, while miR-15a-5p could be transported into nucleus to inhibit the function of ACSS2. Our study unveiled a novel mechanism of miR-15a-5p in inhibiting metastasis of lung cancer cells by suppressing lipid metabolism via suppression of ACSS2 mediated acetyl-CoA activity and histone acetylation.

NRF2/ACSS2 axis mediates the metabolic effect of alcohol drinking on esophageal squamous cell carcinoma.

Alcohol drinking is a leading risk factor for the development of esophageal squamous cell carcinoma (ESCC). However, the molecular mechanisms of alcohol-associated ESCC remain poorly understood. One of the most commonly mutated genes in ESCC is nuclear factor erythroid 2 like 2 (NFE2L2 or NRF2), which is a critical transcription factor regulating oxidative stress response and drug detoxification. When NRF2 is hyperactive in cancer cells, however, it leads to metabolic reprogramming, cell proliferation, chemoradioresistance, and poor prognosis. In this study, hyperactive NRF2 was found to up-regulate acetyl-CoA synthetase short-chain family members 2 (ACSS2), an enzyme that converts acetate to acetyl-CoA, in ESCC cells and mouse esophagus. We also showed that knockdown of NRF2 or ACSS2 led to decreased ACSS2 expression, which in turn reduced the levels of acetyl-CoA and ATP with or without ethanol exposure. In addition, ethanol exposure enhanced lipid synthesis in ESCC cells. Moreover, we observed a change in the metabolic profile of ESCC cells exposed to ethanol as a result of their NRF2 or ACSS2 status. We further showed that ACSS2 contributed to the invasive capability of NRF2high ESCC cells exposed to ethanol. In conclusion, the NRF2/ACSS2 axis mediates the metabolic effect of alcohol drinking on ESCC.

Acetate promotes SNAI1 expression by ACSS2-mediated histone acetylation under glucose limitation in renal cell carcinoma cell.

Metastasis is the main cause of cancer-associated deaths, yet this complex process is still not well understood. Many studies have shown that acetate is involved in cancer metastasis, but the molecular mechanisms remain to be elucidated. In the present study, we first measured the effect of acetate on zinc finger transcriptional repressor SNAI1 and acetyl-CoA synthetase 2 (ACSS2) under glucose limitation in renal cell carcinoma cell lines, 786-O and ACHN. Then, RNA interference and overexpression of ACSS2 were used to detect the role of acetate on SNAI1 expression and cell migration. Finally, chromatin immunoprecipitation assay (ChIP) was used to investigate the regulatory mechanism of acetate on SNAI1 expression. The results showed that acetate increased the expressions of SNAI1 and ACSS2 under glucose limitation. ACSS2 knockdown significantly decreased acetate-induced SNAI1 expression and cell migration, whereas overexpression of ACSS2 increased SNAI1 level and histone H3K27 acetylation (H3K27ac). ChIP results revealed that acetate increased H3K27ac levels in regulatory region of SNAI1, but did not increase ACSS2-binding ability. Our study identified a novel inducer, acetate, which can promote SNAI1 expression by ACSS2-mediated histone acetylation in partly. This finding has important implication in treatment of metastatic cancers.

mTORC2-AKT signaling to ATP-citrate lyase drives brown adipogenesis and de novo lipogenesis.

mTORC2 phosphorylates AKT in a hydrophobic motif site that is a biomarker of insulin sensitivity. In brown adipocytes, mTORC2 regulates glucose and lipid metabolism, however the mechanism has been unclear because downstream AKT signaling appears unaffected by mTORC2 loss. Here, by applying immunoblotting, targeted phosphoproteomics and metabolite profiling, we identify ATP-citrate lyase (ACLY) as a distinctly mTORC2-sensitive AKT substrate in brown preadipocytes. mTORC2 appears dispensable for most other AKT actions examined, indicating a previously unappreciated selectivity in mTORC2-AKT signaling. Rescue experiments suggest brown preadipocytes require the mTORC2/AKT/ACLY pathway to induce PPAR-gamma and establish the epigenetic landscape during differentiation. Evidence in mature brown adipocytes also suggests mTORC2 acts through ACLY to increase carbohydrate response element binding protein (ChREBP) activity, histone acetylation, and gluco-lipogenic gene expression. Substrate utilization studies additionally implicate mTORC2 in promoting acetyl-CoA synthesis from acetate through acetyl-CoA synthetase 2 (ACSS2). These data suggest that a principal mTORC2 action is controlling nuclear-cytoplasmic acetyl-CoA synthesis.

miR-30a-GNG2 and miR-15b-ACSS2 Interaction Pairs May Be Potentially Crucial for Development of Abdominal Aortic Aneurysm by Influencing Inflammation.

Abdominal aortic aneurysm (AAA) is a lethal vascular degenerative disease for the elderly, but current therapeutic options are limited. This study was to explore the molecular mechanisms of AAA to screen underlying treatment targets for AAA. The gene and microRNA (miRNA) expression profiles of human AAA were downloaded from Gene Expression Omnibus database under accession number GSE57691, GSE62179, and GSE63541. Differentially expressed genes (DEGs) and microRNAs (miRNAs; DEMs) were identified using the Linear Models for Microarray data method. Protein-protein interaction (PPI) network, module analysis, and miRNA-mRNA regulatory network analyses were performed to screen hub genes and miRNAs that regulated the hub genes. The Database for Annotation, Visualization and Integrated Discovery was used to predict the functions of genes. GEPIA and Tumor-miRNA-Pathway online software were used to validate the expressions of crucial DEMs and DEGs in other cancers, respectively. As a result, in the GSE57691 dataset, a total of 584 DEGs were found to be specific for AAA, 521 of which were used for constructing the PPI network. ACSS2 (acyl-CoA synthetase short-chain family member 2), GNG2 (G protein subunit gamma 2), and CXCL1 (C-X-C motif chemokine ligand 1) and CCR7 (C-C motif chemokine receptor 7) were believed to be hub genes by calculating their topological features in the PPI network. Upregulated GNG2 could interact with CXCL1 and CCR7 to involve in chemokine signaling pathway, while downregulated ACSS2 was associated with lipid biosynthetic process. In the miRNA-mRNA regulatory network, ACSS2 was found to be regulated by hsa-miR-15b; hsa-miR-30a could modulate the expression of GNG2. In line with our analysis in AAA, GNG2, ACSS2, hsa-miR-30a, and hsa-miR-15b were also confirmed to be significantly upregulated or downregulated in several cancer types. In conclusion, hsa-miR-30a-GNG2 and hsa-miR-15b-ACSS2 interaction pairs may represent novel mechanisms for explaining the pathogenesis of AAA. Targeted regulation of them may be potential strategies for treatment of AAA.

ACSS2/AMPK/PCNA pathway­driven proliferation and chemoresistance of esophageal squamous carcinoma cells under nutrient stress.

Although platinum­based chemotherapy is the first­line choice for locally advanced or metastatic esophageal squamous cell carcinoma (ESCC) patients, accelerated recurrence and chemoresistance remain inevitable. New evidence suggests that metabolism reprogramming under stress involves independent processes that are executed with a variety of proteins. This study investigated the functions of nutrient stress (NS)­mediated acetyl­CoA synthetase short­chain family member 2 (ACSS2) in cell proliferation and cisplatin­resistance and examined its combined effects with proliferating cell nuclear antigen (PCNA), a key regulator of DNA replication and repair. Here, it was demonstrated that under NS, when the AMP­activated protein kinase (AMPK) pathway was activated, ESCC cells maintained proliferation and chemoresistance was distinctly upregulated as determined by CCK­8 assay. As determined using immunoblotting and RT­qPCR, compared with normal esophageal epithelial cells (Het­1A), ESCC cells were less sensitive to NS and showed increased intracellular levels of ACSS2. Moreover, it was shown that ACSS2 inhibition by siRNA not only greatly interfered with proliferation under NS but also participated in DNA repair after cisplatin treatment via PCNA suppression, and the acceleration of cell death was dependent on the activation of the AMPK pathway as revealed by the Annexin V/PI and TUNEL assay results. Our study identified crosstalk between nutrient supply and chemoresistance that could be exploited therapeutically to target AMPK signaling, and the results suggest ACSS2 as a potential biomarker for identifying higher­risk patients.

Enhanced Ganoderic Acids Accumulation and Transcriptional Responses of Biosynthetic Genes in Ganoderma lucidum Fruiting Bodies by Elicitation Supplementation.

Ganoderic acids (GAs) are a type of highly oxygenated lanostane-type triterpenoids that are responsible for the pharmacological activities of Ganoderma lucidum. They have been investigated for their biological activities, including antibacterial, antiviral, antitumor, anti-HIV-1, antioxidation, and cholesterol reduction functions. Inducer supplementation is viewed as a promising technology for the production of GAs. This study found that supplementation with sodium acetate (4 mM) significantly increased the GAs content of fruiting bodies by 28.63% compared to the control. In order to explore the mechanism of ganoderic acid accumulation, the transcriptional responses of key GAs biosynthetic genes, including the acetyl coenzyme A synthase gene, and the expression levels of genes involved in calcineurin signaling and acetyl-CoA content have been analyzed. The results showed that the expression of three key GAs biosynthetic genes (hmgs, fps, and sqs) were significantly up-regulated. Analysis indicated that the acetate ion increased the expression of genes related to acetic acid assimilation and increased GAs biosynthesis, thereby resulting in the accumulation of GAs. Further investigation of the expression levels of genes involved in calcineurin signaling revealed that Na+ supplementation and the consequent exchange of Na+/Ca2+ induced GAs biosynthesis. Overall, this study indicates a feasible new approach of utilizing sodium acetate elicitation for the enhanced production of valuable GAs content in G. lucidum, and also provided the primary mechanism of GAs accumulation.