Dataset Information

HCBP6 upregulates human SREBP1c expression by binding to C/EBP?-binding site in the SREBP1c promoter.

ABSTRACT: Sterol regulatory element-binding protein-1c (SREBP1c) plays an important role in triglyceride (TG) homeostasis. Although our previous study showed that hepatitis C virus core-binding protein 6 (HCBP6) regulates SREBP1c expression to maintain intracellular TG homeostasis, the mechanism underlying this regulation is unclear. In the present study, we found that HCBP6 increased intracellular TG levels by upregulating SREBP1c expression. HCBP6 increased SREBP1c transcription by directly binding to the SREBP1c promoter (at the -139- to +359-bp region). Moreover, we observed that HCBP6 interacted with C/EBP?-binding site in the SREBP1c promoter both in vitro and in vivo. These results indicate that HCBP6 upregulates human SREBP1c expression by binding to the C/EBP?-binding site in the SREBP1c promoter. [BMB Reports 2018; 51(1): 33-38].

SUBMITTER: Yang X

PROVIDER: S-EPMC5796632 | biostudies-literature | 2018 Jan

REPOSITORIES: biostudies-literature

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HCBP6 upregulates human SREBP1c expression by binding to C/EBPβ-binding site in the SREBP1c promoter.

Yang Xueliang X Han Ming M Liu Shunai S Yuan Xiaoxue X Liu Xiaojing X Feng Shenghu S Zhou Li L Li Yaru Y Lu Hongping H Cheng Jun J Lin Shumei S

BMB reports 20180101 1

Sterol regulatory element-binding protein-1c (SREBP1c) plays an important role in triglyceride (TG) homeostasis. Although our previous study showed that hepatitis C virus core-binding protein 6 (HCBP6) regulates SREBP1c expression to maintain intracellular TG homeostasis, the mechanism underlying this regulation is unclear. In the present study, we found that HCBP6 increased intracellular TG levels by upregulating SREBP1c expression. HCBP6 increased SREBP1c transcription by directly binding to t ...[more]

PMID: 29187281

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Project description:UnlabelledBackgroundThe p38 mitogen-activated protein kinases (MAPK) family plays pivotal roles in skeletal muscle metabolism. Recent evidence revealed that p38? and p38? exert paradoxical effects on muscle protein homeostasis. However, it is unknown why p38?, but not p38?, is capable of mediating muscle catabolism via selective activation of the C/EBP? that upregulates atrogin1/MAFbx.MethodsTryptic phosphopeptide mapping was carried out to identify p38?- and p38?-mediated phosphorylation sites in C/EBP?. Chromosome immunoprecipitation (ChIP) assay was used to evaluate p38? and p38? effect on C/EBP? binding to the atrogin1/MAFbx promoter. Overexpression or siRNA-mediated gene knockdown of p38? and p38?, and site-directed mutagenesis or knockout of C/EBP?, were used to analyze the roles of these kinases in muscle catabolism in C2C12 myotubes and mice.ResultsCellular expression of constitutively active p38? or p38? resulted in phosphorylation of C/EBP? at multiple serine and threonine residues; however, only p38? phosphorylated Thr-188, which had been known to be critical to the DNA-binding activity of C/EBP?. Only p38?, but not p38?, activated C/EBP?-binding to the atrogin1/MAFbx promoter. A C/EBP? mutant in which Thr-188 was replaced by alanine acted as a dominant-negative inhibitor of atrogin1/MAFbx upregulation induced by either p38? or Lewis lung carcinoma (LLC) cell-conditioned medium (LCM). In addition, knockdown of p38? specifically inhibited C/EBP? activation and atrogin1/MAFbx upregulation induced by LCM. Finally, expression of active p38? in mouse tibialis anterior specifically induced C/EBP? phosphorylation at Thr-188, atrogin1/MAFbx upregulation and muscle mass loss, which were blocked in C/EBP?-null mice.ConclusionsThe ? and ? isoforms of p38 MAPK are capable of recognizing distinct phosphorylation sites in a substrate. The unique capacity of p38? in mediating muscle catabolism is due to its capability in phosphorylating Thr-188 of C/EBP?.

Dataset Information

HCBP6 upregulates human SREBP1c expression by binding to C/EBP?-binding site in the SREBP1c promoter.

Publications

HCBP6 upregulates human SREBP1c expression by binding to C/EBPβ-binding site in the SREBP1c promoter.

Similar Datasets

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