Overexpression of G sα in NG108-15, neuroblastoma X glioma cells: effects on receptor regulation of the stimulatory adenylyl cyclase cascade

Abstract

Neuroblastoma X glioma hybrid, NG108-15 cells were stably transfected with an epitope tagged variant of G sα(HAG sα). The introduced HA-G sα was able to interact with the IP prostanoid receptor and was able to stimulate adenylyl cyclase activity as measured by an enhanced capacity of membrane extracts to reconstitute NaF-dependent adenylyl cyclase activity to membranes of S49 lymphoma cyc − cells. Despite this, neither the maximal stimulation nor the potency of agonist ligands at the IP prostanoid, A 2 adenosine or secretin receptors was altered substantially compared to the parental cells although the basal adenylyl cyclase activity was increased. These data indicate that cellular levels of G sα do not limit signal transduction capacity in NG108-15 cells, whereas enhanced expression of adenylyl cyclase allows greater maximal cAMP generation following receptor activation (MacEwan, D.J., Kim, G.D. and Milligan, G. (1996) Biochem. J. 318, 1033–1039).