Identification by differential display PCR of the selenoprotein thioredoxin reductase as a 1\alpha,25(OH)_2‐vitamin D_3‐responsive gene in human osteoblasts – regulation by selenite
Affiliations: Klinische Forschergruppe, Medizinische Poliklinik, Universität Würzburg, Germany
Note: [] To whom correspondence should be addressed: Dr. Franz Jakob, Klinische Forschergruppe, Medizinische Poliklinik, Klinikstrasse 6–8, 97070 Würzburg, Germany. Tel.: 0931 201 7067; Fax: 0931 56537.
Abstract: 1\alpha,25(OH)_{2} vitamin D_{3} (1,25(OH)_{2}D_{3}) is a potent hormone, stimulating bone cell growth and differentiation. In order to detect novel targets for 1,25(OH)_{2}D_{3} action, we applied differential display PCR (ddPCR) to human fetal osteoblasts (FOB cells). By ddPCR analysis, we identified the selenoprotein thioredoxin reductase (TRR) as a 1,25(OH)_{2}D_{3}‐responsive gene. In FOB cells, the response of TRR mRNA steady state levels to 1,25(OH)_{2}D_{3} was fast and transient. Maximal stimulation was observed after one hour of 1,25(OH)_{2}D_{3} treatment, thereafter TRR steady state mRNA levels declined to control levels. This transient response of TRR mRNA was not reflected at the TRR enzyme activity level upon treatment with 1,25(OH)_{2}D_{3} for up to 48 h. Sodium selenite added to differentiated FOB cells increased TRR enzyme activity 2.6‐fold, whereas no selenite effect on TRR mRNA steady state levels was measurable. Our data might provide a link between the induction of a differentiation program by 1,25(OH)_{2}D_{3} and the expression of the selenium responsive TRR system in human osteoblasts.
