Molecular mechanisms involved in the spatiotemporal signaling response of the CRH system.

INDA, CAROLINA; PIAZZA, VERÓNICA G.; DOS SANTOS CLARO, PAULA A.; BONFIGLIO, JUAN J.; SILBERSTEIN, SUSANA; ARMANDO, NATALIA G.

Congreso; LXIII Reunión Anual de la Sociedad Argentina de Investigación Clínica; 2018

The main goal of our work is the identification and characterization of cellular mechanisms and molecular components involved in signaling responses of the corticotropin-releasing hormone (CRH) system that includes the G protein-coupled receptors CRHR1 and CRHR2, and CRH and CRH-related peptides urocortins 1-3. CRH system dysregulation is causally linked to stress-related disorders: psychiatric conditions (depression, anxiety, addictions), neuroendocrinological alterations, and to the onset of neurodegenerative diseases. We investigate the spatiotemporal features of signaling responses of the CRH system by means of molecular and cell biology approaches including optical methods, in functionally relevant contexts. We demonstrated that ERK1/2 activation downstream CRHR1 in a hippocampal neuronal context involves a first acute phase dependent on B-Raf and and protein kinase A, and a second sustained phase dependent on CRHR1 internalization. Thus, CRHR1 activates G protein-dependent and internalization-dependent signaling mechanisms.The cyclic AMP (cAMP) response downstream CRHR1 includes the atypical soluble adenylyl cyclase (sAC) besides classic transmembrane adenylyl cyclases in neuronal and endocrine cells. Only sAC activity is essential for internalization-dependent cAMP generation and sustained ERK1/2 activation responses, revealing a functional association between sAC-generated cAMP and endosome-based GPCR signaling. Similar sustained cAMP responses downstream CRHR1 are detected in established hippocampal neuronal cell lines and in ex vivo primary neuronal cultures from wild-type and conditional mice mutants. We are currently exploring other activated effectors (Akt, CREB) of the CRH system response, and extended recently our analyses to the CRHR2. A precise definition of CRH signaling mechanisms with spatial and temporal resolution will enable identification of novel targets for pharmacological intervention in neuroendocrine tissues and specific brain areas involved in CRH-related disorders. Funded by ANPCyT, CONICET and FOCEM (COF 03/11).