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The transcriptional mediator subunit MED1/TRAP220 in stromal cells is involved in hematopoietic stem/progenitor cell support through osteopontin expression.

ABSTRACT: MED1/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 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.

SUBMITTER: Sumitomo A

PROVIDER: S-EPMC2950551 | biostudies-literature | 2010 Oct

REPOSITORIES: biostudies-literature

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The transcriptional mediator subunit MED1/TRAP220 in stromal cells is involved in hematopoietic stem/progenitor cell support through osteopontin expression.

Sumitomo Akiko A Ishino Ruri R Urahama Norinaga N Inoue Kana K Yonezawa Kenji K Hasegawa Natsumi N Horie Osamu O Matsuoka Hiroshi H Kondo Toru T Roeder Robert G RG Ito Mitsuhiro M

Molecular and cellular biology 20100816 20

MED1/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 osteo ...[more]

PMID: 20713445

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Project description:Purpose: The study focused on the RNA content of supportive (AFT024) and non supportive (BFC012) stromal lines and their respective exosomes to analyze the molecular complexity of the Hematopoietic Stem and Progenitor Cell niche Methods: All the samples from small RNA (SR) and polyA-RNA libraries were sequenced using 1Ã50 bp single reads high-throughput sequencing (RNA-Seq) in single lane on Illumina HiSeq 2500. The sequence reads that passed quality filters were analyzed at the transcript isoform level with TopHat followed by Cufflinks and by Fisher's test for polyA-RNA, or with bowtie and parse tools for smallRNA (galaxy server https://lbcd41.snv.jussieu.fr/). Results: Using an optimized data analysis workflow, we mapped about 30 million sequence reads per sample to the mouse genome (build mm10). We focused on differentially expressed transcripts between i) exosomes from supportive and non supportive stromal cells and ii) exosomes and their respective cells.Using a subtractive strategy, we identified 324 mRNAs and 23 miRNAs specific to the exosomes of the supportive stromal line AFT024. We used gene ontology annotation to study the biological functions associated to these specific gene sets. Transcripts involved in negative regulation of apoptosis were found enriched in AFT exosomes. Conclusions: Our RNA seq analysis combined with biological assays reveal that exosomes serve as an important and novel mediator for the HSPC supporting capacity of stromal cells. This unprecedented effort to resolve the molecular complexity of the HSPC-targeted exosomes, provide new candidat genes of the HSPC support and may help designing innovative stromal-free culture conditions to deliver specific molecules to HSPCs. Fetal liver derived stromal lines and their corresponding secreted exosomes were sequenced using Illumina HiSeq2500 technology (Fasteris, CH). Due to low amount of exosomal RNAs, several RNA extraction were pooled and split to perform 2 technical sequencing replicates that were merged during bionformatic analyses.

Dataset Information

The transcriptional mediator subunit MED1/TRAP220 in stromal cells is involved in hematopoietic stem/progenitor cell support through osteopontin expression.

Publications

The transcriptional mediator subunit MED1/TRAP220 in stromal cells is involved in hematopoietic stem/progenitor cell support through osteopontin expression.

Similar Datasets

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