Different cAMP sources are critically involved in G protein-coupled receptor CRHR1 signaling in neuronal hippocampal cells.

BONFIGLIO J.J.; TURCK, C. W.; DOS SANTOS CLARO, P. A.; MACCARRONE G.; INDA, C.; SENIN, S.; SILBERSTEIN, S.

Buenos Aires

Simposio; Fronteras en Biociencia 2; 2016

Corticotropin-releasing hormone (CRH) and its type 1 receptor (CRHR1) coordinate the neuroendocrine and behavioral adaptation to stress and are causally linked to affective disorders. CRHR1 activates G protein-dependent and internalization-dependent signaling mechanisms in neuronal hippocampal cells. Using FRET-based biosensors, specific pharmacological inhibitors and gene silencing, we demonstrate that the cyclic AMP (cAMP) response of CRHR1 engages separate cAMP sources, involving the atypical soluble adenylyl cyclase (sAC) besides transmembrane adenylyl cyclases (tmACs).cAMP produced by tmACs and sAC is required for the acute phase of ERK1/2 activation triggered by CRH-stimulated CRHR1, but only sAC activity is essential for the sustained internalization- dependent phase. Thus, differential cAMP sources are involved in different signaling mechanisms. Examination of the cAMP response in cells expressing a dominant-negative mutant of dynamin or treated with Dyngo-4a revealed that CRH-activated CRHR1 generates cAMP after endocytosis. Characterizing CRHR1 signaling in physiologically relevant scenarios uncovered a specific link between CRH-activated CRHR1, sAC, and endosome-based signaling. We provide evidence of sAC being involved in an endocytosis-dependent cAMP response, strengthening the emerging model of GPCR signaling in which the cAMP response does not exclusively occur at the plasma membrane, and introducing the notion of sAC as an alternative source of cAMP.