Proteomic Analysis of Rap1A GTPase Signaling-Deficient C57BL/6 Mouse Pancreas and Functional Studies Identify an Essential Role of Rap1A in Pancreas Physiology

ABSTRACT: The Ras-related Rap1A GTPase is implicated in pancreas β-cell insulin secretion, and is stimulated by the cAMP sensor Epac2, a guanine exchange factor and activator of Rap1 GTPase. In this study we examined the differential proteomic profiles by nanoLC-ESI-MS/MS of pancreata from C57BL/6 Rap1A-deficient (Null) and control wild-type (WT) mice, to assess targets of Rap1A potentially involved in insulin regulation. We identified 77 overlapping identifier proteins in both groups, 8 distinct identifier proteins in Null versus 56 distinct identifier proteins in WT mice pancreas. Functional enrichment analysis showed 4 of the 8 Null unique proteins, ERO1-like protein β (Ero1lβ), triosephosphate isomerase (TP1), 14-3-3 protein γ and kallikrein-1, were exclusively involved in insulin biogenesis, with role in insulin metabolism. Specifically, the mRNA expression of Ero1lβ and TP1 was significantly (p<0.05) increased in Null versus WT pancreas. Rap1A-deficiency significantly affected glucose tolerance during the first 15-30 min of glucose challenge, but showed no impact on insulin sensitivity. Ex vivo glucose-stimulated insulin secretion (GSIS) studies on isolated Null islets showed significantly impaired GSIS. Furthermore, in GSIS-impaired islets, the cAMP-Epac2-Rap1A pathway was significantly compromised as compared to WT. Altogether, these studies underscore an essential role of Rap1A GTPase in pancreas physiological function

INSTRUMENT(S): maXis

ORGANISM(S): Mus Musculus (mouse)

TISSUE(S): Pancreas

SUBMITTER: Durrey Shahwar  

LAB HEAD: Dr. Maqsood Ahmed Chotani

PROVIDER: PXD052896 | Pride | 2024-10-17

REPOSITORIES: Pride