Prolactin augments progesterone-dependent uteroglobin gene expression by modulating promoter-binding proteins.
The sequence-specific binding of endometrial nuclear proteins to uteroglobin 200 (UG200) (-194/+9), the 203-base pair 5'-flanking region of the rabbit uteroglobin gene, and UG99 (-170/-85), a subfragment of UG200, was compared with gel shift assays. PRL + progesterone treatment of estrous rabbits produced a 6- to 7-fold increase in the primary shift compared to progesterone alone. PRL + progesterone treatment of long-term ovariectomized rabbits increased the primary shift 60% over progesterone alone, which increased the primary shift 30-fold over similarly treated estrous rabbits. The primary shift was eliminated when rabbits were treated with progesterone + estradiol benzoate (E2Bz). Changes in the steady state levels of UG mRNA paralleled changes in the intensity of the primary gel shift. Southwestern blotting revealed four proteins from progesterone-dominated endometrial nuclei that bind UG200. PRL pretreatment produced a 3- to 12-fold increase in each of the proteins. Protein binding was eliminated by E2Bz. A 100-kilodalton (kDa) protein from progesterone-dominated endometrial nuclei was UV cross-linked to UG200 and UG99. An additional protein was detected by each probe with long autoradiographic exposure. PRL pretreatment increased the 100-kDa protein, whereas covalent attachment of the 100-kDa protein to UG promoter DNA was eliminated by E2Bz. UV cross-linking in situ was used to identify the 100-kDa protein as responsible for the primary shift. Collectively, these experiments provide compelling evidence that PRL augments the progesterone-dependent transcription of the UG gene in the uterus by regulating at least one and as many as four proteins that bind to the UG promoter.
Kleis-SanFrancisco
S
S
Department of Cell Biology and Anatomy, Texas Tech University Health Sciences Center, Lubbock 79430.
Hewetson
A
A
Chilton
B S
BS
D000818:Animals; D004268:DNA-Binding Proteins / Q000378:metabolism; D004357:Drug Synergism; D004958:Estradiol / Q000494:pharmacology; D004971:Estrus; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects*; D011374:Progesterone / Q000502:physiology*; D011388:Prolactin / Q000494:pharmacology*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000096:biosynthesis; D011817:Rabbits; D014598:Uteroglobin / Q000096:biosynthesis* / Q000235:genetics
D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D011374:Progesterone; D004958:Estradiol; D011388:Prolactin; D014598:Uteroglobin