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Muhammad AB, Xing B, Liu C, Naji A, Ma X, Simmons RA, Hua X. Menin and PRMT5 suppress GLP1 receptor transcript and PKA-mediated phosphorylation of FOXO1 and CREB. Am J Physiol Endocrinol Metab 2017; 313:E148-E166. [PMID: 28270438 PMCID: PMC5582886 DOI: 10.1152/ajpendo.00241.2016] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 01/11/2017] [Accepted: 02/20/2017] [Indexed: 12/23/2022]
Abstract
Menin is a scaffold protein that interacts with several epigenetic mediators to regulate gene transcription, and suppresses pancreatic β-cell proliferation. Tamoxifen-inducible deletion of multiple endocrine neoplasia type 1 (MEN1) gene, which encodes the protein menin, increases β-cell mass in multiple murine models of diabetes and ameliorates diabetes. Glucagon-like-peptide-1 (GLP1) is another key physiological modulator of β-cell mass and glucose homeostasis. However, it is not clearly understood whether menin crosstalks with GLP1 signaling. Here, we show that menin and protein arginine methyltransferase 5 (PRMT5) suppress GLP1 receptor (GLP1R) transcript levels. Notably, a GLP1R agonist induces phosphorylation of forkhead box protein O1 (FOXO1) at S253, and the phosphorylation is mediated by PKA. Interestingly, menin suppresses GLP1-induced and PKA-mediated phosphorylation of both FOXO1 and cAMP response element binding protein (CREB), likely through a protein arginine methyltransferase. Menin-mediated suppression of FOXO1 and CREB phosphorylation increases FOXO1 levels and suppresses CREB target genes, respectively. A small-molecule menin inhibitor reverses menin-mediated suppression of both FOXO1 and CREB phosphorylation. In addition, ex vivo treatment of both mouse and human pancreatic islets with a menin inhibitor increases levels of proliferation marker Ki67. In conclusion, our results suggest that menin and PRMT5 suppress GLP1R transcript levels and PKA-mediated phosphorylation of FOXO1 and CREB, and a menin inhibitor may reverse this suppression to induce β-cell proliferation.
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Affiliation(s)
- Abdul Bari Muhammad
- Abramson Family Cancer Research Institute, Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
- Institute for Diabetes, Obesity, and Metabolism Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Bowen Xing
- Shenzen University School of Medicine, Institute of Diabetes Research, Shenzhen, Guangdong, China
| | - Chengyang Liu
- Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Ali Naji
- Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
- Institute for Diabetes, Obesity, and Metabolism Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Xiaosong Ma
- Shenzen University School of Medicine, Institute of Diabetes Research, Shenzhen, Guangdong, China
| | - Rebecca A Simmons
- Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; and
- Division of Neonatology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Xianxin Hua
- Abramson Family Cancer Research Institute, Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania;
- Institute for Diabetes, Obesity, and Metabolism Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
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