A sauvagine/corticotropin-releasing factor receptor expressed in heart and skeletal muscle

Abstract

Corticotropin-releasing factor (CRF) mediates many critical aspects of the physiological response to stress. These effects are elicited by binding to specific highaffinity receptors, which are coupled to guanine nucleotide stimulatory factor (Gs)-response pathways. Recently, a gene encoding a receptor for CRF, expressed in pituitary and the central nervous system (PC-CRF receptor), was isolated and characterized. Here we report the identification and characterization of a second, distinct CRF receptor that is expressed primarily in heart and skeletal muscle and exhibits a specific ligand preference and antagonist sensitivity compared with the PC-CRF receptor. We refer to this second receptor as the heart/muscle (HM)-CRF receptor.Corticotropin-releasing factor (CRF) (1) is a member of a family of peptides from different species that act as agonists of the CRF receptor. These peptides include the frog skin peptide, sauvagine (2), and the teleost fish urophysis peptide, urotensin I (3). CRF is a 41-amino acid hypothalamic neuropeptide that plays a central role in coordinating the communications between endocrine, nervous, and immune systems to achieve homeostasis in response to environmental adversities (4, 5). The peptide was originally characterized in the hypothalamo-hypophyseal system but was later found to be widely distributed throughout the central nervous system (CNS), where it appeared to function as a neurotransmitter or neuromodulator (6). In the CNS, CRF initiates the hypothalamic-pituitary-adrenal axis by stimulating the release of adrenocorticotropin (ACTH) and ,B-endorphin from the anterior pituitary. ACTH stimulates adrenal cortex to secrete corticosteroids that, in turn, elicit a wide range of biological responses and exert negative feedback on the hypothalamus and pituitary (4, 5, 7). Both sauvagine and urotensin I have been shown to stimulate the hypothalamic-pituitary-adrenal axis after i.v. administration (8). Intracerebroventricular administration of CRF provokes stress-like responses including activation of the sympathetic nervous system, resulting in an elevation of plasma epinephrine, norepinephrine, and glucose, which results in increased heart rate and mean arterial blood pressure (9, 10). Outside the CNS, CRF immunoreactivity is detectable in multiple peripheral organs, including placenta, adrenal medulla, pancreas, lung, stomach, duodenum, and liver (4, 5). i.v. administration of CRF, sauvagine, and urotensin I has been shown to elicit peripheral systemic responses, including vasodilation (11).CRF functions by binding to a membrane-bound receptor that is coupled to the guanine nucleotide stimulatory factor (G,) signaling protein, resulting in increased intracellular cAMP levels (12,13 (23), and growth hormonereleasing factor ]. The PC-CRF receptor mRNA was found to be most highly expressed in the cerebellum and pituitary and found at lower levels in other brain areas, intestine, and testes. This receptor is undetectable in other tissues examined, including heart and skeletal mus...

Is It Really a Matter of Simple Dualism? Corticotropin-Releasing Factor Receptors in Body and Mental Health

“…CRF receptor 2 is a 397–437 amino acid protein in mammals and it is abundantly expressed in both the CNS and in the periphery (Kishimoto et al, 1995; Lovenberg et al, 1995b; Kostich et al, 1998; Palchaudhuri et al, 1999; Van Pett et al, 2000; Korosi et al, 2007; Justice et al, 2008; Kuhne et al, 2012). In the CNS, CRFR2 is expressed in the olfactory bulb, hippocampus, amygdala, septum, the dorsal and median raphe nuclei, cortex, pituitary, and spinal cord (Palchaudhuri et al, 1999; Bittencourt and Sawchenko, 2000; Van Pett et al, 2000; Korosi et al, 2006, 2007; Lukkes et al, 2011).…”