title: Molecular cloning and partial characterization of an ovarian receptor with seven ligand binding repeats, an orthologue of low-density lipoprotein receptor, in the cutthroat trout (Oncorhynchus clarki).
abstract: Teleost fish eggs contain a substantial yolk mass consisting of lipids and proteins that provides essential nutrients for embryonic and larval development. The polar lipid and protein components of the yolk are delivered to oocytes by circulating vitellogenins, however the source(s) of the neutral lipid remains unknown. We cloned a cDNA encoding an orthologue of low-density-lipoprotein receptor (LDLR) from the ovary of cutthroat trout, Oncorhynchus clarki (ct-Ldlr). Predominant expression of ct-ldlr mRNA was observed in the ovary and moderate expression was detected in intestine, gill and brain. The relative abundance of ct-ldlr transcripts was highest in early pre-vitellogenic ovaries and significantly decreased during vitellogenesis, followed by a slight increase during final maturation and in post-ovulatory follicles. In situ hybridization revealed an intense and evenly distributed localization of ct-ldlr transcripts in the ooplasm of pre-vitellogenic oocytes and these signals disappeared in vitellogenic follicles. Collectively, these results suggest that the Ldlr is involved in deposition of yolk lipids in cutthroat trout oocytes. The ct-ldlr transcripts also were detected in theca and granulosa cells, suggesting that this receptor may be involved in cholesterol uptake for ovarian steroidogenesis. This is the first report on partial characterization of an ldlr orthologue in any fish species.
authors.affiliation: Division of Marine Life Sciences, Faculty of Fisheries Sciences, Hokkaido University, 3-1-1 Minato, Hakodate, Hokkaido 041-8611 Japan.
authors.forename: Wenshu
authors.initials: W
authors.lastname: Luo
authors.forename: Yuta
authors.initials: Y
authors.lastname: Ito
authors.forename: Hiroko
authors.initials: H
authors.lastname: Mizuta
authors.forename: Kiyohiro
authors.initials: K
authors.lastname: Massaki
authors.forename: Naoshi
authors.initials: N
authors.lastname: Hiramatsu
authors.forename: Takashi
authors.initials: T
authors.lastname: Todo
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Reading
authors.forename: Craig V
authors.initials: CV
authors.lastname: Sullivan
authors.forename: Akihiko
authors.initials: A
authors.lastname: Hara
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D005260:Female; D029941:Fish Proteins / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism; D009928:Organ Specificity; D006080:Ovarian Follicle / Q000166:cytology / Q000378:metabolism*; D010802:Phylogeny; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011973:Receptors, LDL / Q000235:genetics* / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014337:Trout / Q000235:genetics* / Q000378:metabolism
chemical_list: D029941:Fish Proteins; D012333:RNA, Messenger; D011973:Receptors, LDL
keywords: AA; EGF; IAS; LA; LDL; LDLR; LR7; LR8; LRP; LRP3; LpR; NRT; ORF; Oocyte lipidation; Ovarian growth; PB; PFA; RT-PCR; Salmonid; Teleost fish; UTR; VLDL; VLDLR/Vtgr; Vtg; Yolk; amino acid; class A ligand binding repeat; ef1alpha; elongation factor 1 alpha gene; epidermal growth factor; inter-assay standard; ldlr; lipophorin receptor protein; lipoprotein receptor with 7 ligand binding repeats; lipoprotein receptor with 8 ligand binding repeats; low-density lipoprotein; low-density lipoprotein receptor gene; low-density lipoprotein receptor protein; low-density lipoprotein receptor related protein; low-density lipoprotein receptor related protein 3; negative reverse transcribed controls; open reading frame; paraformaldehyde; phosphate buffer; real-time quantitative RT-PCR; reverse transcription polymerase chain reaction; rtqRT-PCR; untranslated region; very low-density lipoprotein; very low-density lipoprotein receptor gene; very low-density lipoprotein receptor protein; vitellogenin; vldlr