title: Heat shock protein 90beta: a novel mediator of vitamin D action.
abstract: We investigated the role of Heat shock protein 90 (Hsp90) in vitamin D action in Caco-2 cells using geldanamycin (GA) to block Hsp90 function and RNA interference to reduce Hsp90beta expression. When cells were exposed to GA, vitamin D-mediated gene expression and transcriptional activity were inhibited by 69% and 54%, respectively. Gel shift analysis indicated that GA reduced vitamin D-mediated DNA binding activity of the vitamin D receptor (VDR). We tested the specific role of Hsp90beta by knocking down its expression with stably expressed short hairpin RNA. Vitamin D-induced gene expression and transcriptional activity were reduced by 90% and 80%, respectively, in Hsp90beta-deficient cells. Nuclear protein for VDR and RXRalpha, its heterodimer partner, were not reduced in Hsp90beta-deficient cells. These findings indicate that Hsp90beta is needed for optimal vitamin D responsiveness in the enterocyte and demonstrate a specific role for Hsp90beta in VDR signaling.
authors.affiliation: Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Mineral Bioavailability Laboratory, 711 Washington Street, Boston, MA 02111, USA.
authors.forename: Giana
authors.initials: G
authors.lastname: Angelo
authors.forename: Stefania
authors.initials: S
authors.lastname: Lamon-Fava
authors.forename: Larry A
authors.initials: LA
authors.lastname: Sonna
authors.forename: Meghan L
authors.initials: ML
authors.lastname: Lindauer
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Wood
mesh_terms: D016227:Benzoquinones / Q000494:pharmacology; D018938:Caco-2 Cells; D002117:Calcitriol / Q000494:pharmacology*; D004247:DNA / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D020895:Enterocytes / Q000187:drug effects* / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D018841:HSP90 Heat-Shock Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D006801:Humans; D047029:Lactams, Macrocyclic / Q000494:pharmacology; D016133:Polymerase Chain Reaction; D011485:Protein Binding / Q000187:drug effects; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D018167:Receptors, Calcitriol / Q000378:metabolism; D047490:Retinoid X Receptor alpha / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013250:Steroid Hydroxylases / Q000235:genetics; D065668:Vitamin D3 24-Hydroxylase
chemical_list: D016227:Benzoquinones; D004791:Enzyme Inhibitors; D018841:HSP90 Heat-Shock Proteins; C493165:HSP90AB1 protein, human; D047029:Lactams, Macrocyclic; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D018167:Receptors, Calcitriol; D047490:Retinoid X Receptor alpha; D004247:DNA; D013250:Steroid Hydroxylases; D065668:Vitamin D3 24-Hydroxylase; D002117:Calcitriol; C001277:geldanamycin