bims-meprid 2023-10-08 papers

Issue of 2023‒10‒08
five papers selected by
Alessandro Carrer, Veneto Institute of Molecular Medicine

Cell Mol Life Sci. 2023 Oct 06. 80(11): 315

BCAT2 promotes melanoma progression by activating lipogenesis via the epigenetic regulation of FASN and ACLY expressions.

Yangzi Tian, Jingjing Ma, Hao Wang, Xiuli Yi, Huina Wang, Hengxiang Zhang, Sen Guo, Yuqi Yang, Baolu Zhang, Juan Du, Qiong Shi, Tianwen Gao, Weinan Guo, Chunying Li.

Melanoma is the most lethal skin cancer originating from the malignant transformation of epidermal melanocyte. The dysregulation of cellular metabolism is a hallmark of cancer, including in melanoma. Aberrant branched-chain amino acids (BCAA) metabolism and related enzymes has been greatly implicated in the progression of multiple types of cancer, whereas remains far from understood in melanoma. Herein, we reported that the critical BCAA metabolism enzyme branched-chain amino acid transaminase 2 (BCAT2) is an oncogenic factor in melanoma by activating lipogenesis via the epigenetic regulation of fatty acid synthase (FASN) and ATP-citrate lyase (ACLY) expressions. Firstly, we found that BCAT2 expression was prominently increased in melanoma, and highly associated with clinical stage. Then, it was proved that the deficiency of BCAT2 led to impaired tumor cell proliferation, invasion and migration in vitro, and tumor growth and metastasis in vivo. Further, RNA sequencing technology and a panel of biochemical assays demonstrated that BCAT2 regulated de novo lipogenesis via the regulation of the expressions of both FASN and ACLY. Mechanistically, the inhibition of BCAT2 suppressed the generation of intracellular acetyl-CoA, mitigating P300-dependent histone acetylation at the promoter of FASN and ACLY, and thereby their transcription. Ultimately, zinc finger E-box binding homeobox 1 (ZEB1) was identified as the upstream transcriptional factor responsible for BCAT2 up-regulation in melanoma. Our results demonstrate that BCAT2 promotes melanoma progression by epigenetically regulating FASN and ACLY expressions via P300-dependent histone acetylation. Targeting BCAT2 could be exploited as a promising strategy to restrain tumor progression in melanoma.

Keywords: ACLY; BCAT2; Epigenetic; FASN; Lipogenesis; Melanoma

DOI: https://doi.org/10.1007/s00018-023-04965-8

Exp Mol Med. 2023 Oct 02.

Lactate as a major epigenetic carbon source for histone acetylation via nuclear LDH metabolism.

Yong Jin An, Sihyang Jo, Jin-Mo Kim, Han Sun Kim, Hyun Young Kim, Sang-Min Jeon, Dawool Han, Jong In Yook, Keon Wook Kang, Sunghyouk Park.

Histone acetylation involves the transfer of two-carbon units to the nucleus that are embedded in low-concentration metabolites. We found that lactate, a high-concentration metabolic byproduct, can be a major carbon source for histone acetylation through oxidation-dependent metabolism. Both in cells and in purified nuclei, 13C3-lactate carbons are incorporated into histone H4 (maximum incorporation: ~60%). In the purified nucleus, this process depends on nucleus-localized lactate dehydrogenase (LDHA), knockout (KO) of which abrogates incorporation. Heterologous expression of nucleus-localized LDHA reverses the KO effect. Lactate itself increases histone acetylation, whereas inhibition of LDHA reduces acetylation. In vitro and in vivo settings exhibit different lactate incorporation patterns, suggesting an influence on the microenvironment. Higher nuclear LDHA localization is observed in pancreatic cancer than in normal tissues, showing disease relevance. Overall, lactate and nuclear LDHA can be major structural and regulatory players in the metabolism-epigenetics axis controlled by the cell's own status or the environmental status.

DOI: https://doi.org/10.1038/s12276-023-01095-w

Nat Commun. 2023 Oct 05. 14(1): 6208

Acetylation-dependent coupling between G6PD activity and apoptotic signaling.

Fang Wu, Natali H Muskat, Inbar Dvilansky, Omri Koren, Anat Shahar, Roi Gazit, Natalie Elia, Eyal Arbely.

Lysine acetylation has been discovered in thousands of non-histone human proteins, including most metabolic enzymes. Deciphering the functions of acetylation is key to understanding how metabolic cues mediate metabolic enzyme regulation and cellular signaling. Glucose-6-phosphate dehydrogenase (G6PD), the rate-limiting enzyme in the pentose phosphate pathway, is acetylated on multiple lysine residues. Using site-specifically acetylated G6PD, we show that acetylation can activate (AcK89) and inhibit (AcK403) G6PD. Acetylation-dependent inactivation is explained by structural studies showing distortion of the dimeric structure and active site of G6PD. We provide evidence for acetylation-dependent K95/97 ubiquitylation of G6PD and Y503 phosphorylation, as well as interaction with p53 and induction of early apoptotic events. Notably, we found that the acetylation of a single lysine residue coordinates diverse acetylation-dependent processes. Our data provide an example of the complex roles of acetylation as a posttranslational modification that orchestrates the regulation of enzymatic activity, posttranslational modifications, and apoptotic signaling.

DOI: https://doi.org/10.1038/s41467-023-41895-2

Cell Metab. 2023 Sep 29. pii: S1550-4131(23)00340-6. [Epub ahead of print]

High dietary fructose promotes hepatocellular carcinoma progression by enhancing O-GlcNAcylation via microbiota-derived acetate.

Peng Zhou, Wen-Yi Chang, De-Ao Gong, Jie Xia, Wei Chen, Lu-Yi Huang, Rui Liu, Yi Liu, Chang Chen, Kai Wang, Ni Tang, Ai-Long Huang.

Emerging studies have addressed the tumor-promoting role of fructose in different cancers. The effects and pathological mechanisms of high dietary fructose on hepatocellular carcinoma (HCC) remain unclear. Here, we examined the effects of fructose supplementation on HCC progression in wild-type C57BL/6 mice using a spontaneous and chemically induced HCC mouse model. We show that elevated uridine diphospho-N-acetylglucosamine (UDP-GlcNAc) and O-GlcNAcylation levels induced by high dietary fructose contribute to HCC progression. Non-targeted metabolomics and stable isotope tracing revealed that under fructose treatment, microbiota-derived acetate upregulates glutamine and UDP-GlcNAc levels and enhances protein O-GlcNAcylation in HCC. Global profiling of O-GlcNAcylation revealed that hyper-O-GlcNAcylation of eukaryotic elongation factor 1A1 promotes cell proliferation and tumor growth. Targeting glutamate-ammonia ligase or O-linked N-acetylglucosamine transferase (OGT) remarkably impeded HCC progression in mice with high fructose intake. We propose that high dietary fructose promotes HCC progression through microbial acetate-induced hyper-O-GlcNAcylation.

Keywords: GLUL; O-GlcNAcylation; acetate; eEF1A1; fructose; hepatocellular carcinoma

DOI: https://doi.org/10.1016/j.cmet.2023.09.009

Nat Commun. 2023 Oct 04. 14(1): 6201

Cytoplasmic Endonuclease G promotes nonalcoholic fatty liver disease via mTORC2-AKT-ACLY and endoplasmic reticulum stress.

Wenjun Wang, Junyang Tan, Xiaomin Liu, Wenqi Guo, Mengmeng Li, Xinjie Liu, Yanyan Liu, Wenyu Dai, Liubing Hu, Yimin Wang, Qiuxia Lu, Wen Xing Lee, Hong-Wen Tang, Qinghua Zhou.

Endonuclease G (ENDOG), a nuclear-encoded mitochondrial intermembrane space protein, is well known to be translocated into the nucleus during apoptosis. Recent studies have shown that ENDOG might enter the mitochondrial matrix to regulate mitochondrial genome cleavage and replication. However, little is known about the role of ENDOG in the cytosol. Our previous work showed that cytoplasmic ENDOG competitively binds with 14-3-3γ, which released TSC2 to repress mTORC1 signaling and induce autophagy. Here, we demonstrate that cytoplasmic ENDOG could also release Rictor from 14-3-3γ to activate the mTORC2-AKT-ACLY axis, resulting in acetyl-CoA production. Importantly, we observe that ENDOG could translocate to the ER, bind with Bip, and release IRE1a/PERK to activate the endoplasmic reticulum stress response, promoting lipid synthesis. Taken together, we demonstrate that loss of ENDOG suppresses acetyl-CoA production and lipid synthesis, along with reducing endoplasmic reticulum stress, which eventually alleviates high-fat diet-induced nonalcoholic fatty liver disease in female mice.

DOI: https://doi.org/10.1038/s41467-023-41757-x