Photoactivable enchancement of insulin secretion by pancreatic beta-cells
MetadataShow full item record
Type 2 diabetes is associated with a severe loss of insulin secretory function due to peripheral tissue resistance to the hormone. Current pharmacological drugs (e.g. sulfonylureas) to boost the amount of insulin released by β-cells in diabetes patients act on mediators of insulin secretion. However, these drugs are frequently associated with side effects including weight gain and imprecise regulation of the blood glucose-insulin balance leading to hyperglycemia. One such mediator is cyclic AMP (cAMP) which increases upon exposure of β-cells to high glucose concentrations and enhance the glucose-stimulated release of insulin. In this work, we utilized a photoactivatable form of adenylyl cyclase (PAC) which is expressed in the unicellular flagellate E. gracilis to increase the amount of cAMP in β-cells. This heterotetramer protein consists of two subunits of PACα and PACβ, each containing a domain for photoactivation and an adenylyl cyclase moiety and can be activated by blue light resulting in the production of cAMP. A 3X-FLAG and 6X-His epitope was added to PACα and PACβ gene respectively and were expressed in the HEK293 cells and β-cells using a recombinant adenovirus system. Production of the recombinant adenoviruses was confirmed by PCR, immunocytochemistry and western blot. The cytotoxicity conferred by two viruses was measured and compared. Beta cells expressing forms of PAC were irradiated with blue light and cAMP was measured. Also, glucose-induced insulin secretion was assessed by determining the amount of insulin in the medium. This system of regulating insulin secretion in β-cells may provide an attractive alternative to current pharmacological interventions for improving glucose homeostasis in diabetes patients.