Background Type 2 diabetes mellitus (T2DM) is a commonly observed
complication associated with obesity. The effect of fibroblast growth factor 19
(FGF19), a promising therapeutic agent for metabolic disorders, on pancreatic β
cells in obesity-associated T2DM remains poorly understood.
Methods Human pancreatic β cells were cultured with high glucose (HG) and
palmitic acid (PA), followed by treatment with FGF19. The cell proliferation,
apoptosis, and insulin secretion were evaluated by CCK-8, qRT-PCR, ELISA, flow
cytometry, and western blotting. The expression of the insulin receptor
substrate (IRS)/glucose transporter (GLUT) pathway was evaluated. The
interaction between FGF19 and IRS1 was predicted using the STRING database and
verified by co-immunoprecipitation and immunofluorescence. The regulatory
effects of the IRS1/GLUT4 pathway on human pancreatic β cells were assessed by
overexpressing IRS1 and silencing IRS1 and GLUT4.
Results HG+PA treatment reduced the human pancreatic β cell proliferation
and insulin secretion and promoted cell apoptosis. However, FGF19 treatment
restored these alterations and significantly increased the expressions of IRS1,
GLUT1, and GLUT4 in the IRS/GLUT pathway. Furthermore, FGF19 and IRS1 were found
to interact. IRS1 overexpression partially promoted the proliferation of
pancreatic β cells and insulin secretion through GLUT4. Additionally, the
silencing of IRS1 or GLUT4 attenuated the therapeutic effects of FGF19.
Conclusion In conclusion, FGF19 partly promoted the proliferation and
insulin secretion of human pancreatic β cells and inhibited apoptosis by
upregulating the IRS1/GLUT4 pathway. These findings establish a theoretical
framework for the clinical utilization of FGF19 in the treatment of
obesity-associated T2DM.