Molecular evolution of CRH and CRHR subfamily before the evolutionary origin of vertebrate

Interdependence of Thyroid and Corticosteroid Signaling in Vertebrate Developmental Transitions

“…In 1955, a substance, present in extracts of mammalian hypothalamus and able to stimulate ACTH secretion in vitro, was named corticotropin-releasing factor (CRF) (Guillemin and Rosenberg, 1955;Saffran et al, 1955). CRF (or CRH) was first isolated from sheep hypothalamus (Vale et al, 1981) and identified in all vertebrates thereafter (Lovejoy et al, 2014;On et al, 2019). Together with urotensin I (UI) in teleosts, sauvagine (SVG) in amphibians, and urocortins (Ucn) in mammals, it forms a large family of peptides, the CRH/urocortin family.…”

“…As CRH, urotensin I, sauvagine and urocortins have roles in the regulation of ACTH and MSH, as well as energy metabolism and reproduction (Lovejoy and Balment, 1999). It was first suggested that two ancestral crh/ucn1 and ucn2/ucn3 genes likely arose by specific gene duplication before vertebrate WGD events (Hwang et al, 2013), as a single crh-like gene is identified in amphioxus and tunicates (On et al, 2019). Both ancestral genes were duplicated twice in ancestral vertebrates via 1R and 2R, followed by some paralog losses, leading to up to 5 genes (crh1, crh2, ucn1 coming from ancestral crh/ucn1; ucn2, ucn3 issued from ancestral ucn2/ucn3) in extant representative species of some vertebrate lineages such as chondrichthyans, holosteans and actinistians (Cardoso et al, 2016;On et al, 2019).…”

“…It was first suggested that two ancestral crh/ucn1 and ucn2/ucn3 genes likely arose by specific gene duplication before vertebrate WGD events (Hwang et al, 2013), as a single crh-like gene is identified in amphioxus and tunicates (On et al, 2019). Both ancestral genes were duplicated twice in ancestral vertebrates via 1R and 2R, followed by some paralog losses, leading to up to 5 genes (crh1, crh2, ucn1 coming from ancestral crh/ucn1; ucn2, ucn3 issued from ancestral ucn2/ucn3) in extant representative species of some vertebrate lineages such as chondrichthyans, holosteans and actinistians (Cardoso et al, 2016;On et al, 2019). Teleost specific 3R resulted in the duplication of crh1 into two paralogs crh1a and crh1b conserved in many species (Grone and Maruska, 2015;Cardoso et al, 2016).…”

Expression of Urocortin 3 mRNA in the Central Nervous System of the Sea Lamprey Petromyzon marinus

“…More recently, a family of CRH1-related peptides (i.e., CRH2, urotensin or urocortins) were identified in vertebrate and invertebrate species [3][4][5][6][7][8][9]. In invertebrate chordates such as amphioxus and ascidians, only one CRH-family gene was reported [10]. In vertebrates, however, the two rounds of whole-genome duplication led to multiple CRH/urocortin (Ucn) genes.…”

“…In vertebrates, however, the two rounds of whole-genome duplication led to multiple CRH/urocortin (Ucn) genes. It was proposed that a vertebrate ancestor originated two CRH-like genes that then led to two distinct gene lineages, one group coding for CRH1, CRH2 and Ucn/urotensin (Ucn1), and the other coding for urocortin 2 (Ucn2) and urocortin 3 (Ucn3 or stresscopin) [10,11]. Peptides of these two groups interact with two types of CRH receptors (CRHRs), those of the first group with type 1 (CRHR1), and those of the second group with type 2 (CRHR2) receptors [12].…”