Glucose regulates insulin mitogenic effect by modulating SHP-2 activation and localization in JAr cells

Area of Science:

• Cell Biology
• Endocrinology
• Molecular Biology

Background:

• Glucose is a primary energy source influencing cellular processes.
• Insulin signaling pathways regulate cell growth and proliferation.
• The interplay between glucose concentration and insulin action in cancer cells is not fully understood.

Purpose of the Study:

• To investigate the effect of varying glucose concentrations on JAr human choriocarcinoma cell growth.
• To elucidate the role of glucose in modulating insulin-induced mitogenic signaling.
• To identify key molecular players involved in glucose-mediated changes in insulin signaling.

Main Methods:

• JAr cells were cultured under low (6 mm) and high (25 mm) glucose conditions.
• Cell proliferation and thymidine incorporation assays were performed.
• Western blotting and co-immunoprecipitation were used to assess protein phosphorylation and interactions.
• Tyrosine phosphatase activity, specifically SHP-2, was measured.
• Antisense inhibition of SHP-2 was employed to determine its role.

Main Results:

• High glucose (HG) enhanced insulin-stimulated proliferation and thymidine incorporation compared to low glucose (LG).
• HG culturing increased insulin receptor and insulin receptor substrate 1 (IRS1) tyrosine phosphorylation.
• Cellular tyrosine phosphatase activity, particularly SHP-2, was significantly elevated in HG conditions.
• HG promoted SHP-2 translocation to the membrane, increasing its interaction with IRS1.
• Antisense inhibition of SHP-2 reversed HG-induced effects on phosphorylation and proliferation.

Conclusions:

• Glucose concentration modulates insulin's mitogenic action in JAr cells.
• High glucose potentiates insulin signaling by increasing SHP-2 activity and promoting its interaction with IRS1.
• SHP-2 acts as a key mediator in the glucose-dependent regulation of insulin-stimulated cell growth.