Molecular cloning of follicle-stimulating hormone receptor(FSHR) and expression analysis during the reproductive cycle in female yellow catfish(Pelteobagrus fulvidraco)

Abstract

Follicle-stimulating hormone(FSH)controls gonadal function in mammalian and many non-mammalian vertebrates through the interaction with their receptors(FSHR).Molecular cloning of the yellow catfish FSH receptor is reported together with changes in the gene expression throughout a reproductive cycle.This work describes the molecular cloning of the cDNA encoding the follicle-stimulating hormone receptor(FSHR)of yellow catfish(Pelteobagrus fulvidraco)by means of reverse transcriptase polymerase chain reaction(RT-PCR),degenerate primers PCR amplification and 5′ and 3′ rapid amplification of cDNA ends(RACE)analyses.We cloned the complete cDNA sequence of FSHR gene and the length is 2 340 bp,encoding a protein of 661 amino acids.This gene belongs to G protein-coupled receptor(GPCR)family,which contains the seven conserved transmembrane helix(TM helix)domains.We found that the amino acids sequence contains nine Leucine-rich repeats(LRRs),five potential N-linked glycosylation sites and that only one protein kinase C phosphorylation site is 403Y in ELⅠ(extracellular loop,ELⅠ)and three protein kinase C phosphorylation sites are 634S,643S,632T in C-terminal domain.The areas played the important role in the function of FSHR gene.The tissue distribution pattern showed high expression of FSHR gene in ovary and brain,and trace amount was detected weakly in other tissues.We also analyzed the mRNA expression level of FSHR gene in ovary at different stages of reproductive cycle.Result showed that the transcript level of FSHR gene was high from Ⅲ to Ⅳ phases then followed by a substantial decline.These changes in expression profiles may imply differences in the functionality of the enzyme gene between different stages,suggesting an important role of FSHR gene in yellow catfish development.We inferred that the gene of FSHR in ovary might also be involved in the processes which regulate ovulation maturation and ovulation,and preferentially promote vitellogenin accumulation.The result has provided an improtant theoretical basis for the function of FSHR gene and the breeding of yellow catfish.