Presentations

Abstract

Introduction:

Disruptions in glucagon receptor signaling leads to a state of hyperaminoacidemia which triggers compensatory proliferation of pancreatic ⍺ cells to normalize amino acid levels. We previously found that ErbB2/ErbB3 receptor tyrosine kinase is activated by hyperaminoacidemia independent of its ligand and this activation is required for a cell proliferation. How hyperaminoacidemia activates ErbB2/ErbB3 is unknown. We hypothesize that hyperaminoacidemia activates ErbB2/ErbB3 via transactivation by the amino acid sensitive calcium-sensing receptor (CaSR), which is also required for a cell proliferation.

Methods:

We cultured pancreatic ⍺TC1-6 cells (cell line clone derived from mouse glucagonoma) in low serum, high amino acid medium in the presence or absence of inhibitors of CaSR, Src kinase, or ADAM10/17 metalloproteinase for 15 minutes, 30 minutes, and 6 hours, and determined the level of activated ErbB3 (phospho-ErbB3) via western blot.

Results:

Based on the mechanism of transactivation, we expected decreases in relative phospho-ErbB3 expression in only the CaSR and Src kinase groups compared to the positive control group at all timepoints. However, we were unable to report any significant results from the western blot due to loss of biological replicates for all groups over the course of the experiment.

Conclusion:

Considering the nature of our results, we aim to improve cell culturing working conditions to maximize protein yield for future efforts. In doing so, we hope to generate broader conclusions in regard to how hyperaminoacidemia induces proliferation of pancreatic ⍺ cells. The results may shed light on how postprandial ⍺ cell proliferation can be controlled to limit adverse effects of glucagon receptor antagonism or provide more ⍺ cells for β cell transdifferentiation, for example.