ArrayExpress Uploader0mouseMed1+/+ p53-/-Med1+/+ p53-/-Med1-/- p53-/-Med1-/- p53-/-8487arrayexpress_sid8MED1/TRAP220, a subunit of the transcriptional Mediator/TRAP complex, is crucial for various biological events through its interaction...E-GEOD-22471/profile/8773/arrayexpressuploader14bonebone marrowDec.12, 2014Falsetranscriptional-mediator-subunit-med1trap220-in-stE-GEOD-22471_A-AFFY-36Transcriptional Mediator Subunit MED1/TRAP220 in Stromal Cells Is Involved in Hematopoietic Stem/Progenitor Cell Support through Osteopontin ExpressionNov.24, 2014MED1/TRAP220, a subunit of the transcriptional Mediator/TRAP complex, is crucial for various biological events through its interaction with distinct activators such as nuclear receptors and GATA family activators. In hematopoiesis, MED1 plays a pivotal role in optimal nuclear receptor-mediated myelomonopoiesis and GATA-1-induced erythropoiesis. In this study, we present evidence that MED1 in stromal cells is involved in supporting hematopoietic stem and/or progenitor cells (HSPCs) through osteopontin (OPN) expression. We found that the proliferation of bone marrow (BM) cells cocultured with MED1 knockout (Med1-/-) mouse embryonic fibroblasts (MEFs) was significantly suppressed when compared to the control. Furthermore, the number of long-term culture-initiating cells (LTC-ICs) was attenuated for BM cells cocultured with Med1-/- MEFs. The vitamin D receptor (VDR)- and Runx2-mediated expression of OPN, as well as Mediator recruitment to the Opn promoter, was specifically attenuated in the Med1-/- MEFs. Addition of OPN to these MEFs restored the growth of cocultured BM cells and the number of LTC-ICs, both of which were attenuated by the addition of the anti-OPN antibody to Med1+/+ MEFs and to BM stromal cells. Consequently, MED1 in niche appears to play an important role in supporting HSPCs, by upregulating VDR- and Runx2-mediated transcription on the Opn promoter. Total RNAs of mouse embryonic fibroblasts (MEFs) derived from Med1-/-/p53-/- and Med1+/+/p53-/- E10.0 embryos were compared. Duplicate samples for each MEF type were analyzed.http://www.ebi.ac.uk/arrayexpress/experiments/E-GEOD-22471http://www.ebi.ac.uk/arrayexpress/experiments/E-GEOD-22471/samples/