Cloning and expression analysis of follicle-stimulating hormone and luteinizing hormone receptor during the reproductive cycle in Korean rockfish (Sebastes schlegeli)

Abstract

Full-length cDNA sequences encoding the receptors for follicle-stimulating hormone (FSHR) and luteinizing hormone (LHR) were isolated from ovary of Korean rockfish (Sebastes schlegeli) using reverse transcription-polymerase chain reaction (PCR) and rapid amplification of cDNA ends procedures. The cDNA of the KrFSHR encodes a predicted protein of 703 amino acids that showed the greatest homology with European seabass (Dicentrarchus labrax) (78 %) and gilthead seabream (Sparus aurata) (73 %). The cDNA of the KrLHR encodes a predicted protein of 703 amino acids and exhibited the highest homology with European seabass (Dicentrarchus labrax) (79 %) and gilthead seabream (Sparus aurata) (76 %). Besides the gonads, expressions of GTHRs mRNA were also obtained in extra gonadal tissues. Seasonal changes in the gonads expression profiles of KrGTHRs mRNA were examined by quantitative real-time PCR, and the present results suggest that levels for KrFSHR mRNA increase during gonadal growth, whereas KrLHR shows high levels during the late gamete generation period. Our study provides molecular characterization of the GTHRs and expressions profile during reproductive cycles, reinforcing previous knowledge of GTHRs important role in the reproductive endocrine regulation of Korean rockfish.

Demonstration of the Coexistence of Duplicated LH Receptors in Teleosts, and Their Origin in Ancestral Actinopterygians

“…Lhcgr2 transcript is expressed in the brain in various teleosts, including African catfish, Atlantic salmon and European sea bass [ 20 , 73 , 86 , 91 ]. Lhcgr1 is also expressed in the brain of the Korean rockfish, Sebastes schlegelii [ 92 ] and Atlantic halibut [ 85 ], while its expression is not detectable in the brain of the channel catfish [ 15 ].…”

“…Eel fshr , lhcgr1 and lhcgr2 showed a very low expression, at the limit of detection level, in the other tissues investigated, such as pituitary, liver, intestine, muscle and thyroid. Lhcgr1 transcript is also undetectable by PCR in various non-gonadal tissues, including liver, intestine, heart and spleen, in Korean rockfish [ 92 ] and medaka [ 72 ]. In contrast, lhcgr1 transcript has been demonstrated in muscle, liver, stomach and heart in channel catfish [ 16 ] and in spleen in goby [ 101 ].…”

In silico analysis, temporal expression and gonadotropic regulation of receptors for follicle‐stimulating hormone and luteinizing hormone in testis of spotted snakehead Channa punctata

“…In general, Fsh regulates the initial stages of spermatogenesis i.e ., proliferation and differentiation of somatic and germ cells, while Lh is indirectly involved, through sex steroids, in controlling later stages of spermatogenesis i.e ., spermiation and spawning (Schulz et al ., ). These spermatogenic stage‐specific roles of gonadotropins are further substantiated by expression pattern of their receptors in S. senegalensis (Chauvigné et al ., ) and Korean rockfish Sebastes schlegeli Hilgendorf 1880 (Mu et al ., ) in which fshra expression decreased with progression of spermatogenesis while lhcgr expression gradually increased and reached to its highest level at the time of spermiation. However, contradictory observations are also reported regarding the temporal expression of gonadotropin receptors along the testicular cycle in teleosts.…”

“…In the past decade, efforts have been made to understand the expression profile of gonadotropin receptors along the testicular cycle in seasonally breeding teleosts. However, these studies are largely confined to marine fishes (Chauvigné et al ., ; de Almeida et al ., ; Mu et al ., ; Rocha et al ., ; Sambroni et al ., ) and little attention has been paid to freshwater males. African catfish Clarias gariepinus (Burchell 1822) is the only freshwater teleost where differential expression of fshra and lhcgr along the testicular cycle has been investigated (García‐López et al ., ).…”

“…The existence of gonadotropin receptors in fishes was first demonstrated in salmonids following ligand binding studies (Breton et al, 1986;Salmon et al, 1984). The complementary DNAs (cDNAs) for two distinct gonadotropin receptors, fshr and lhcgr, were detected first in amago salmon Oncorhynchus rhodurus Jordan & McGregor 1925 (Oba et al, 1999a(Oba et al, , 1999b and thereafter in Anguilliformes (Kazeto et al, 2012), Carangiformes (Nyuji et al, 2016), Cypriniformes (Kwok et al, 2005), Cyprinodontiformes (Ohkubo et al, 2013), Gadiformes (Mittelholzer et al, 2009), Labriformes (Kitano et al, 2011), Perciformes (Mu et al, 2013;Rocha et al, 2007), Pleuronectiformes (Chauvigné et al, 2010), Salmoniformes (Oba et al, 1999a(Oba et al, , 1999bSambroni et al, 2007), Scombriformes (Nyuji et al, 2013) and Siluriformes (Bogerd et al, 2001;Vischer & Bogerd, 2003). Recently, dual forms of lhcgr (lhcgr1 and lhcgr2) have been identified by cloning and genome analysis in several fishes (Maugars & Dufour, 2015) while a single form of fshr is known in fishes to date.…”