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Med14 phosphorylation shapes genomic response to GLP-1 agonists.
Sam Van de Velde1, Jungting Yu2, K Garrett Evensen2
1Peptide Biology Laboratories, The Salk Institute for Biological Studies, La Jolla, CA 92037.
Summary
Glucagon-like peptide-1 (GLP-1) receptor agonists promote pancreatic beta cell function. Phosphorylation of Med14, a transcription factor, is key to GLP-1
Area of Science:
- Endocrinology
- Molecular Biology
- Cell Biology
Background:
- Glucagon-like peptide-1 (GLP-1) receptor activation in pancreatic beta cells initiates signaling cascades, including cAMP pathway activation and CREB phosphorylation.
- Chronic GLP-1 analog exposure enhances beta cell gene expression, viability, and insulin secretion.
Purpose of the Study:
- To identify transcriptional coregulators mediating GLP-1's effects on beta cell gene expression.
- To investigate the role of Med14 phosphorylation in GLP-1 signaling.
Main Methods:
- Proteomic screening to identify transcriptional coregulators.
- Site-directed mutagenesis of Med14 (Ser983).
- Analysis of gene expression and cell ratios in primary mouse islets.
Main Results:
- Med14, a Mediator complex subunit, was identified as a GLP-1-responsive transcriptional coregulator.
- GLP-1 receptor agonists induced sustained Med14 phosphorylation at Ser983.
- Med14 Ser983 phosphorylation is crucial for Exendin-4-mediated gene expression and beta cell function.
Conclusions:
- Med14 phosphorylation at Ser983 is a critical mechanism linking GLP-1 receptor activation to beta cell-specific gene regulation.
- This phosphorylation event is essential for the salutary effects of GLP-1 analogs on beta cell function and survival.
- Dysregulation of Med14 phosphorylation impacts islet cell composition and response to GLP-1 analogs.
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