title: Sequence of the bovine HDL-receptor (SR-BI) cDNA and changes in receptor mRNA expression during granulosa cell luteinization in vivo and in vitro.
abstract: Steroidogenic activity in the mature corpus luteum of most mammals depends upon provision of cholesterol from the circulating lipoproteins. In cattle, as in many species, high-density lipoprotein (HDL) is the major lipoprotein involved. The recent identification of the scavenger receptor SR-BI as an HDL-receptor allows control of this process to be investigated more closely. In this study, we have sequenced the bovine SR-BI HDL-receptor and examined changes in expression of the receptor mRNA during corpus luteum development in vivo and granulosa cell luteinization in vitro. Sequencing of the bovine HDL-receptor showed that it codes for a protein of 509 amino acids with close identity to hamster, mouse, rat and human sequences. Examination of the tissue distribution of the HDL-receptor mRNA showed high levels in adrenal cortex and corpus luteum and lower levels in spleen and liver. Using a semi-quantitative, reverse transcription-polymerase chain reaction technique levels of HDL-receptor mRNA were measured in corpora lutea from cattle at known stages of the oestrus cycle and in bovine granulosa cells luteinized in culture. Levels of HDL-receptor mRNA were low in isolated bovine granulosa cells, but increased 7-fold during corpus luteum development in vivo and 5-fold during granulosa cell luteinization in culture. Results show that luteinization of granulosa cells is associated with an increase in HDL-receptor RNA levels which, along with changes in steroidogenic enzyme activity, is likely to explain the marked increase in steroidogenic capacity which occurs during corpus luteum formation.
authors.affiliation: Department of Veterinary Pre-clinical Studies, University of Glasgow Veterinary School, UK.
authors.forename: W R
authors.initials: WR
authors.lastname: Rajapaksha
authors.forename: M
authors.initials: M
authors.lastname: McBride
authors.forename: L
authors.initials: L
authors.lastname: Robertson
authors.forename: P J
authors.initials: PJ
authors.lastname: O'Shaughnessy
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D018955:CD36 Antigens / Q000235:genetics*; D002417:Cattle; D002478:Cells, Cultured; D003338:Corpus Luteum / Q000737:chemistry / Q000254:growth & development; D018076:DNA, Complementary / Q000235:genetics; D004971:Estrus / Q000235:genetics; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D006107:Granulosa Cells / Q000737:chemistry / Q000502:physiology*; D008075:Lipoproteins, HDL; D008184:Luteal Cells / Q000502:physiology; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D009928:Organ Specificity; D012333:RNA, Messenger / Q000032:analysis; D011971:Receptors, Immunologic; D018110:Receptors, Lipoprotein / Q000235:genetics*; D051116:Receptors, Scavenger; D051122:Scavenger Receptors, Class B; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
chemical_list: D018955:CD36 Antigens; D018076:DNA, Complementary; D008075:Lipoproteins, HDL; D008565:Membrane Proteins; D012333:RNA, Messenger; D011971:Receptors, Immunologic; D018110:Receptors, Lipoprotein; D051116:Receptors, Scavenger; C454739:Scarb1 protein, mouse; D051122:Scavenger Receptors, Class B