Neurotensin receptor-2 and -3 are crucial for the anti-apoptotic effect of neurotensin on pancreatic β-TC3 cells

The neuropeptide neurotensin (NT) has been recently shown to protect pancreatic beta cells from toxic agents-induced apoptosis through interaction with the NT receptor-2 (NTSR2) and activation of the phosphatidyl inositol-3 kinase pathway. However, expression of the NT receptor-3/sortilin (NTSR3) in the mouse pancreatic beta cell line β-TC3 led us to investigate its possible functional role in these cells. By using siRNA, immunoprecipitation, co-localization and caspase-3 assays, we provide evidence for a functional endogenous interaction between NTSR2 and NTSR3. Expression of both receptors is necessary for the protective action of NT on staurosporine-induced caspase-3 activity in β-TC3 cells. Moreover, NTSR2 and NTSR3 co-immunoprecipitate and are co-localized at the plasma membrane. Thus, the NT response in beta cells is controlled by the formation of a functional complex between NTSR2 and NTSR3.