V1b and CRHR1 Receptor Heterodimerization Mediates Synergistic Biological Actions of Vasopressin and CRH

Abstract

Vasopressin (AVP) and CRH synergistically regulate adrenocorticotropin and insulin release at the level of the pituitary and pancreas, respectively. Here, we first extended these AVP and CRH coregulation processes to the adrenal medulla. We demonstrate that costimulation of chromaffin cells by AVP and CRH simultaneously induces a catecholamine secretion exceeding the one induced by each hormone alone, thus demonstrating a net potentiation. To further elucidate the molecular mechanisms underlying this synergism, we coexpressed human V1b and CRH receptor (CRHR)1 receptor in HEK293 cells. In this heterologous system, AVP also potentiated CRH-stimulated cAMP accumulation in a dose-dependent and saturable manner. This effect was only partially mimicked by phorbol ester or inhibited by a phospholipase C inhibitor respectively. This finding suggests the existence of an new molecular mechanism, independent from second messenger cross talk. Similarly, CRH potentiated the AVP-induced inositol phosphates production. Using bioluminescence resonance energy transfer, coimmunoprecipitation, and receptor rescue experiments, we demonstrate that V1b and CRHR1 receptors assemble as heterodimers. Moreover, new pharmacological properties emerged upon receptors cotransfection. Taken together, these data strongly suggest that direct molecular interactions between V1b and CRHR1 receptors play an important role in mediating the synergistic interactions between these two receptors.

Oligomerization of GPCRs involved in endocrine regulation

“…This interaction modifies ERK1/2-activation allosterically in dependency of ligand treatment (agonists or antagonists) (Wrzal et al 2012a,b). Interestingly, direct interactions between V1b and the corticotropin-releasing hormone receptor 1 were recently described (Murat et al 2012). Via costimulation, this heterodimer mediates a synergistic catecholamine secretion compared with single ligand stimulation.…”

“…Moreover, vasopressin potentiated CRH-induced cAMP accumulation and CRH potentiated AVD-induced inositol phosphate production. Vasopressin and CRH are both involved in the regulation of adrenocorticotropin and insulin release (Murat et al 2012).…”

Vasopressin V1a and V1b Receptors: From Molecules to Physiological Systems

“…When these receptors were tagged at COOH termini either with a Renilla luciferase (Rluc), or yellow fluorescent protein (YFP), and differently tagged receptor fusion proteins were coexpressed in HEK cells, bioluminescence resonance energy transfer (BRET) was detected between the Rluc-and YFP-fusion constructs. Concerning heterodimers formed between the AVP receptor and other receptor family members, the V1b receptor was reported to form a heterodimer with the CRHR1 receptor (358,545). On the other hand, none of the V1a, V2, or OT receptors formed efficient heteromers with the GABA (B2) receptor subunit (493).…”

Family-Based Study of AVPR1B Association and Interaction with Stressful Life Events on Depression and Anxiety in Suicide Attempts

“…Variants of AVPR1B and CRHR1 were previously shown to have combined genetic effects in association with panic disorder, suggesting the potential for observing gene-gene interaction effects (G Â Gs) in adequately powered studies (Keck et al, 2008). Moreover, AVPR1B and CRHR1 are capable of physically interacting (Young et al, 2007), and heterodimerization affects their pharmacological properties in vitro (Murat et al, 2012). However, heterodimerization in vivo or G Â Gs on stress-related outcomes have not been shown.…”