ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Endocrine Abstracts (2019) 65 P206 | DOI: 10.1530/endoabs.65.P206

Role of palmitoylation on GLP-1 receptor responses in pancreatic beta cells

Zekun Lyu, Carolina Piedade, Stavroula Bitsi, Ben Jones & Alejandra Tomas

Imperial College London, London, UK

We have previously described how signaling responses for the glucagon-like peptide-1 receptor (GLP-1R), a class B GPCR that plays key roles in metabolic regulation and is a prime type 2 diabetes (T2D) target, are modulated by intracellular membrane trafficking. We have also recently shown that binding to the therapeutic GLP-1R agonist exendin-4 (Exenatide) triggers increased clustering and segregation of biologically active GLP-1Rs into cholesterol-rich plasma membrane nanodomains that enable compartmentalization of acute receptor signaling and clathrin-mediated endocytosis. Both disruption of plasma membrane microarchitecture via cholesterol depletion and mutation of cysteine 438 GLP-1R single palmitoylation site have a substantial impact on acute GLP-1R signaling and endocytosis. Downstream effects on insulin secretion from pancreatic beta cells indicate that these processes are relevant to GLP-1R physiological actions and might be therapeutically targetable. Here we present data on the role of three plasma membrane-localized palmitoyltransferases expressed in pancreatic beta cells in the regulation of GLP-1R responses downstream of exendin-4 stimulation. To examine this, we have engineered murine MIN6B1 beta cell lines using CRISPR/Cas9 to delete the expression of the plasma membrane palmitoyltransferases ZDHHC5, 20 and 21. We observe a reduction in exendin-4-induced cAMP production and incretin-stimulated insulin secretion in ZDHHC20 and 21 knockout compared to control cells, while ZDHHC5 deletion leads to increased cAMP and insulin responses downstream of GLP-1R activation. Experiments are underway to analyze the possible effects of knocking out these three palmitoyltransferases on the palmitoylation of the GLP-1R or related downstream effectors such as beta arrestins or G proteins, as well as on the dynamic behavior of the receptor in the lipid bilayer, in order to explain their identified impact on beta cell function.

Article tools

My recent searches

No recent searches.