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SIRT5-mediated deacetylation of LDHB promotes autophagy and tumorigenesis in colorectal cancer.

ABSTRACT: Lactate dehydrogenase B (LDHB) is a glycolytic enzyme that catalyses the conversion of lactate and NAD⁺ to pyruvate, NADH and H⁺ . Protons (H⁺ ) generated by LDHB promote lysosomal acidification and autophagy in cancer, but how this role is regulated has not been defined. In this study, we identified an important post-translational mechanism by which LDHB is regulated during autophagy in cancer cells. Mass spectrometry revealed that protein sirtuin 5 (SIRT5) is a binding partner of LDHB that deacetylated LDHB at lysine-329, thereby promoting its enzymatic activity. Deacetylated LDHB increased autophagy and accelerated the growth of colorectal cancer (CRC) cells. Notably, SIRT5 knockout or inhibition by GW5074 increased LDHB acetylation at K329 and inhibited LDHB activity, which downregulated autophagy and CRC cell growth in vitro and in vivo. Clinically, the LDHB-Ac-K329 staining score in CRC tissues was lower than that in corresponding peritumour tissues. Low LDHB-Ac-K329 status was associated with malignant progression of human CRC and served as a potential prognostic indicator for patients with CRC. Altogether, we conclude that SIRT5-induced deacetylation of LDHB triggers hyperactivation of autophagy, a key event in tumorigenesis. Thus, the SIRT5/LDHB pathway may represent a novel target for treating CRC.

SUBMITTER: Shi L

PROVIDER: S-EPMC6360364 | biostudies-literature | 2019 Feb

REPOSITORIES: biostudies-literature

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SIRT5-mediated deacetylation of LDHB promotes autophagy and tumorigenesis in colorectal cancer.

Shi Liang L Yan Hui H An Shuxian S Shen Mengqin M Jia Wenzhi W Zhang Ruixue R Zhao Li L Huang Gang G Liu Jianjun J

Molecular oncology 20181203 2

Lactate dehydrogenase B (LDHB) is a glycolytic enzyme that catalyses the conversion of lactate and NAD+ to pyruvate, NADH and H+ . Protons (H+ ) generated by LDHB promote lysosomal acidification and autophagy in cancer, but how this role is regulated has not been defined. In this study, we identified an important post-translational mechanism by which LDHB is regulated during autophagy in cancer cells. Mass spectrometry revealed that protein sirtuin 5 (SIRT5) is a ...[more]

PMID: 30443978

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Project description:BackgroundUbiquitination is a basic post-translational modification for cellular homeostasis, and members of the conjugating enzyme (E2) family are the key components of the ubiquitin-proteasome system. However, the role of E2 family in colorectal cancer (CRC) is largely unknown. Our study aimed to investigate the role of Ube2v1, one of the ubiquitin-conjugating E2 enzyme variant proteins (Ube2v) but without the conserved cysteine residue required for the catalytic activity of E2s, in CRC.MethodsImmunohistochemistry and real-time RT-PCR were used to study the expressions of Ube2v1 at protein and mRNA levels in CRC, respectively. Western blotting and immunofluorescence, transmission electron microscopy, and in vivo rescue experiments were used to study the functional effects of Ube2v1 on autophagy and EMT program. Quantitative mass spectrometry, immunoprecipitation, ubiquitination assay, western blotting, and real-time RT-PCR were used to analyze the effects of Ube2v1 on histone H4 lysine 16 acetylation, interaction with Sirt1, ubiquitination of Sirt1, and autophagy-related gene expression.ResultsUbe2v1 was elevated in CRC samples, and its increased expression was correlated with poorer survival of CRC patients. Ube2v1 promoted migration and invasion of CRC cells in vitro and tumor growth and metastasis of CRC cells in vivo. Interestingly, Ube2v1suppressed autophagy program and promoted epithelial mesenchymal transition (EMT) and metastasis of CRC cells in an autophagy-dependent pattern in vitro and in vivo. Moreover, both rapamycin and trehalose attenuated the enhanced Ube2v1-mediated lung metastasis by inducing the autophagy pathway in an orthotropic mouse xenograft model of lung metastasis. Mechanistically, Ube2v1 promoted Ubc13-mediated ubiquitination and degradation of Sirt1 and inhibited histone H4 lysine 16 acetylation, and finally epigenetically suppressed autophagy gene expression in CRC.ConclusionsOur study functionally links Ube2v1, an E2 member in the ubiquitin-proteasome system, to autophagy program, thereby shedding light on developing Ube2v1 targeted therapy for CRC patients.

Project description:Salmonella typhimurium (S. typhimurium) infection of macrophage induces NLRC4 inflammasome-mediated production of the pro-inflammatory cytokines IL-1β. Post-translational modifications on NLRC4 are critical for its activation. Sirtuin3 (SIRT3) is the most thoroughly studied mitochondrial nicotinamide adenine dinucleotide (NAD+) -dependent deacetylase. We wondered whether SIRT3 mediated-deacetylation could take part in NLRC4 inflammasome activation. Methods: We initially tested IL-1β production and pyroptosis after cytosolic transfection of flagellin or S. typhimurium infection in wild type and SIRT3-deficient primary peritoneal macrophages via immunoblotting and ELISA assay. These results were confirmed in SIRT3-deficient immortalized bone marrow derived macrophages (iBMDMs) which were generated by CRISPR-Cas9 technology. In addition, in vivo experiments were conducted to confirm the role of SIRT3 in S. typhimurium-induced cytokines production. Then NLRC4 assembly was analyzed by immune-fluorescence assay and ASC oligomerization assay. Immunoblotting, ELISA and flow cytometry were performed to clarify the role of SIRT3 in NLRP3 and AIM2 inflammasomes activation. To further investigate the mechanism of SIRT3 in NLRC4 activation, co-immunoprecipitation (Co-IP), we did immunoblot, cellular fractionation and in-vitro deacetylation assay. Finally, to clarify the acetylation sites of NLRC4, we performed liquid chromatography-mass spectrometry (LC-MS) and immunoblotting analysis. Results: SIRT3 deficiency led to significantly impaired NLRC4 inflammasome activation and pyroptosis both in vitro and in vivo. Furthermore, SIRT3 promotes NLRC4 inflammasome assembly by inducing more ASC speck formation and ASC oligomerization. However, SIRT3 is dispensable for NLRP3 and AIM2 inflammasome activation. Moreover, SIRT3 interacts with and deacetylates NLRC4 to promote its activation. Finally, we proved that deacetylation of NLRC4 at Lys71 or Lys272 could promote its activation. Conclusions: Our study reveals that SIRT3 mediated-deacetylation of NLRC4 is pivotal for NLRC4 activation and the acetylation switch of NLRC4 may aid the clearance of S. typhimurium infection.

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SIRT5-mediated deacetylation of LDHB promotes autophagy and tumorigenesis in colorectal cancer.

Publications

SIRT5-mediated deacetylation of LDHB promotes autophagy and tumorigenesis in colorectal cancer.

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