EXPLORING CRHR2alpha SIGNALING AND TRAFFICKING IN A HIPPOCAMPAL CELLULAR CONTEXT

NATALIA ARMANDO; CAROLINA INDA; SERGIO SENIN; SUSANA SILBERSTEIN

Buenos Aires

Congreso; Reunión Conjunta de Sociedades de Biociencias; 2017

SAIC

The corticotropin-releasing hormone (CRH) system orchestratesthe response and adaptation to stress, acting on the hypothalamic-pituitary-adrenal axis and in different brain regions. A largebody of evidence points to dysregulation of CRH system signalingas causally linked to anxiety and depressive disorders. There aretwo different G-protein-coupled receptors (GPCRs), CRHR1 andCRHR2, encoded by different genes which display different localizationand ligand preferences. We are particularly interested in thealpha splicing isoform (CRHR2α) given that it is the most importantin the brain. CRHR2α has a pseudo signal peptide which gives thisreceptor specific trafficking and signaling characteristics. We are exploringthe signaling pathways activated by CRHRs in order to identifymechanisms involved in CRH and its related peptides action inthe brain. Given that previous results showed specific CRH actionsin vivo in particular limbic structures such as hippocampus, we performour studies in HT22 cells, a mouse hippocampal neuronal cellline widely used as a neuronal model. We generated stable clonesexpressing CRHR1 and CRHR2α in HT22 cells to explore the mechanismsinvolved in the signaling cascade and trafficking of each receptor. We used CRH and UCNs as ligands for each receptor to assesswhether different signaling pathways are activated dependingon the ligand. The stimulation of both CRHR1 and CRHR2α led toan increase of intracellular cAMP measured with FRET biosensors.We compared similarities and differences of the activation of CREB,ERK1/2 and AKT by western blot. We have previously reported thatCRH-dependent ERK1/2 activation downstream of CRHR1 is biphasic,being dependent on G protein and receptor endocytosis mechanisms.Remarkably, the same pattern was observed when UCN1was used as a CRHR1 ligand. However, the kinetics of ERK1/2 activationdownstream of CRHR2α were different, either when CRH orUCNs were used for stimulation.