Promoter usage and estrogen regulation of prolactin receptor gene in the brain of the female rat.
Mechanisms underlying hormonal regulation of prolactin receptor (PRL-R) gene in the brain are unknown. The 5'-untranslated region of PRL-R mRNA in peripheral tissues contains at least three alternative first exons (1A, B, C) that are expressed as tissue-specific, suggesting the differential usage of PRL-R gene promoters. The present study aimed to investigate: (1). the possible regulation of PRL-R mRNA levels by estrogen in in vitro and in vivo tissues; (2). which exon (1A, or 1B, or 1C)-containing PRL-R mRNA transcript is expressed in the brain, and (3). how the specific exon 1-containing mRNA is affected by estrogen by using RT-PCR, Southern blot and 5'Race PCR techniques. The RT-PCR results showed that PRL-R mRNA was detected in the cerebral cortex and pons medulla in addition to the choroid plexus and hypothalamus in the female rat. The expression of PRL-R mRNA was up-regulated by estrogen treatment in the rat brain tissue and in the GT1-7 cell culture. Both exon 1A- and 1C-containing transcripts were expressed in all four regions, suggesting that promoters 1A and 1C for the PRL-R gene are utilized in the rat brain. Exon 1A-containing transcript was up-regulated by estrogen treatment in all four brain regions, whereas Exon 1C-containing transcript was up-regulated by estrogen treatment in 3 of the 4 brain regions, cerebral cortex being the exception. Exon 1B-containing transcript was neither detectable nor induced by estrogen treatment in any of the brain regions examined. The RT-PCR results were confirmed by partial isolation of 5'-untranslated regions of exon 1A- and 1C-containing PRL-R mRNA transcripts from brain tissue by using 5'Race PCR. The present result confirms the expression of PRL-R mRNA in the cerebral cortex and pons medulla in the female rat. The levels of PRL-R mRNA were up-regulated by estrogen in rat brain tissue and GT1-7 cell cultures. Detection of exon 1A- and 1C-containing transcripts implies that the promoter 1A and 1C are active in the female rat brain. Estrogen differentially regulates expression of the PRL-R mRNA in the different brain regions by increasing the utilization of PRL-R gene promoters 1A and 1C in the female rat.
Pi
Xiujun
X
Department of Molecular and Integrative Physiology, Kansas University Medical Center, Kansas City, Kansas 66160-7401, USA.
Zhang
Bo
B
Li
Jun
J
Voogt
James L
JL
D017398:Alternative Splicing; D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000166:cytology / Q000502:physiology*; D001923:Brain Chemistry; D002478:Cells, Cultured; D017931:DNA Primers; D004958:Estradiol / Q000502:physiology*; D005091:Exons / Q000235:genetics / Q000502:physiology; D005260:Female; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000502:physiology*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D011981:Receptors, Prolactin / Q000235:genetics*; D014018:Tissue Distribution; D015854:Up-Regulation
D017931:DNA Primers; D012333:RNA, Messenger; D011981:Receptors, Prolactin; D004958:Estradiol