title: Polyubiquitin up-regulation in corpora lutea of prostaglandin-treated ewes.
abstract: Genes that encode mRNAs for ubiquitin are activated by cells in metabolic distress. Cytosolic proteins that consequently become conjugated to ubiquitin are targeted for degradation. We hypothesized that ubiquitin mediates the endocrine demise of the corpus luteum induced by prostaglandin (PG) F2 alpha. Indeed, polyubiquitin gene expression increased abruptly (within 2 h) in luteal tissues of ewes treated with PGF2 alpha-before the precipitous decline in glandular progesterone accumulation indicative of functional luteolysis. A corresponding elevation in ubiquitin immunostaining was localized to large (PG-sensitive) luteal cells. It is suggested that luteal progesterone biosynthesis is disrupted by ubiquitination of steroidogenic regulatory proteins-perhaps those involved in the mechanics of mitochondrial delivery and side-chain cleavage of cholesterol.
authors.affiliation: Department of Animal Science, University of Wyoming, Laramie 82071, USA.
authors.forename: W J
authors.initials: WJ
authors.lastname: Murdoch
authors.forename: K A
authors.initials: KA
authors.lastname: Austin
authors.forename: T R
authors.initials: TR
authors.lastname: Hansen
mesh_terms: D000818:Animals; D001704:Biopolymers / Q000235:genetics / Q000378:metabolism*; D015152:Blotting, Northern; D003338:Corpus Luteum / Q000378:metabolism*; D015237:Dinoprost / Q000494:pharmacology*; D005260:Female; D007536:Isomerism; D025821:Polyubiquitin; D012333:RNA, Messenger / Q000378:metabolism; D012756:Sheep; D014452:Ubiquitins / Q000235:genetics / Q000378:metabolism*
chemical_list: D001704:Biopolymers; D012333:RNA, Messenger; D014452:Ubiquitins; D025821:Polyubiquitin; D015237:Dinoprost