GLP-1 signaling suppresses menins transcriptional block by phosphorylation in {beta} cells

Both menin and glucagon-like peptide 1 (GLP-1) pathways play central yet opposing role in regulating β cell function, with menin suppressing, and GLP-1 promoting, β cell function. However, little is known as to whether or how GLP-1 pathway represses menin function. Here, we show that GLP-1 signaling–activated protein kinase A (PKA) directly phosphorylates menin at the serine 487 residue, relieving menin-mediated suppression of insulin expression and cell proliferation. Mechanistically, Ser487-phosphorylated menin gains increased binding affinity to nuclear actin/myosin IIa proteins and gets sequestrated from the Ins1 promoter. This event leads to reduced binding of repressive epigenetic histone modifiers suppressor variegation 3–9 homologue protein 1 (SUV39H1) and histone deacetylases 1 (HDAC1) at the locus and subsequently increased Ins1 gene transcription. Ser487 phosphorylation of menin also increases expression of proproliferative cyclin D2 and β cell proliferation. Our results have uncovered a previously unappreciated physiological link in which GLP-1 signaling suppresses menin function through phosphorylation-triggered and actin/myosin cytoskeletal protein–mediated derepression of gene transcription.

Source: Journal of Cell Biology - March 3, 2019 Category: Cytology Authors: Xing, B., Ma, J., Jiang, Z., Feng, Z., Ling, S., Szigety, K., Su, W., Zhang, L., Jia, R., Sun, Y., Zhang, L., Kong, X., Ma, X., Hua, X. Tags: Disease, Cell Signaling, Biochemistry Articles Source Type: research