The role of pregnancy hormones in the regulation of Pdx-1 expression.
During pregnancy, pancreatic beta cells undergo changes that are probably due to an increase in the lactogenic hormones prolactin (PRL) and placental lactogen (PL). Since the transcription factor PDX-1 is involved in the regulation of the beta cell function and phenotype, we tested the possibility that the effect of PRL on beta cells was mediated by PDX-1. Exposure of islet cells to PRL in vitro resulted in increased levels of PDX-1 protein and mRNA and a stimulation of pdx-1 transcription. However, PDX-1 levels in islets exposed in vivo to high concentration of prolactin was similar to controls. In vitro studies suggested that the up-regulation of PDX-1 by PRL was opposed by glucocorticoids (GC) at concentrations similar to those present in pregnant and control female mice. We conclude that, although pdx-1 is a key regulator of beta cell specific genes, it does not appear to play a central role in the up-regulation of islet cell function during pregnancy.
Nasir
Irem
I
Department of Anatomy and Cell Biology, SUNY-Downstate, Room 2-94, 450 Clarkson Avenue, Brooklyn, NY 11203, USA.
Kedees
Mamdouh H
MH
Ehrlich
Michelle E
ME
Teitelman
Gladys
G
D000818:Animals; D003907:Dexamethasone / Q000494:pharmacology; D005260:Female; D005786:Gene Expression Regulation; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D011247:Pregnancy; D011374:Progesterone / Q000494:pharmacology / Q000502:physiology; D011388:Prolactin / Q000037:antagonists & inhibitors / Q000494:pharmacology / Q000502:physiology*; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D020218:Response Elements / Q000235:genetics; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects; D015854:Up-Regulation / Q000187:drug effects
D018398:Homeodomain Proteins; D012333:RNA, Messenger; D015534:Trans-Activators; C084010:pancreatic and duodenal homeobox 1 protein; D011374:Progesterone; D003907:Dexamethasone; D011388:Prolactin