2006 Fiscal Year Final Research Report Summary
Study on Mechanisms of Gene Silencing during Adult Stem Cell Differentiation
| Project/Area Number |
16390554
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
補綴理工系歯学
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| Research Institution | Osaka University |
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Principal Investigator |
YATANI Hirofumi Osaka University, Graduate School of Dentistry, Professor, 大学院歯学研究科, 教授 (80174530)
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| Co-Investigator(Kenkyū-buntansha) |
EGUSA Hiroshi Osaka University, Graduate School of Dentistry, Assistant Professor, 大学院歯学研究科, 助手 (30379078)
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| Project Period (FY) |
2004 – 2006
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| Keywords | bone marrow-derived stromal cells / differentiation mechanism / DNA methylation / epigenetics |
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| Research Abstract |
We carried out this research project in collaboration with Professor Ichiro Nishimura in UCLA School of Dentistry. We reported that mouse bone marrow stromal stem cells (BMSCs) in vitro expresses a broad range of gene clusters characteristic of the advanced phenotypes of the diverse potential endpoints, and guided differentiation employ a unique conversion from broad to specific phenotype expression through silencing of discordant gene clusters (J Biol Chem 2005.).
In addition, we used a custom-made extracellular matrix-related gene-focused microarray to characterize the gene expression signatures of uninduced and osteogenically-induced human BMSCs and adipose-tissue-derived stromal cells (ASCs). We found that BMSCs and ASCs both downregulate discrete ECMG sets during osteogenic differentiation, suggesting that osteogenically differentiating BMSCs and ASCs transition away from a diverse gene expression pattern reflecting their multipotency toward a configuration specifically meeting the
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requirements of the target lineage. This change may serve to normalize gene expression in mixed populations of stem cells derived from different tissues (Tissue Engineering, revision).
We hypothesized that this transcriptional downregulation during adult stem cell differentiation may involve epigenetic events such as DNA methylation. To test this hypothesis, we carried out restriction landmark genomic scanning (RLGS) method to detect changes in methylation status within CpG islands on genomic DNA from uninduced or osteogenically-induced BMSCs. As a result, approximately 1% of RLGS spots changed their presence, implying methylation status of some CpG sites changed during osteogenic differentiation. We further analyzed CpG methylation status in osteocalcin gene promoter region of uninduced or osteogenically-induced BMSCs by bisulfite PCR method. The sequence data showed that methylation status of some specific CpG sites was altered during osteogenic differentiation.
These results suggest that osteogenic differentiation of BMSCs downregulates sets of gene expressions, and DNA methylation and/or demethylation is involved in part in the gene silencing during the differentiation. Less
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