Studies on Cellular Regulation of Hematopoietic Microembironment

骨髓通过复杂的细胞间相互作用为造血干/祖细胞的自我更新和分化提供微环境。为了研究造血微循环的细胞调控，我们从温度敏感型SV 40 Large T抗原转基因小鼠骨髓中建立了多种基质细胞系，并以这些基质细胞系为饲养细胞，建立了几种基质依赖性造血细胞系。一些基质细胞系被证明是间充质干细胞，因为它们可以在体外向肌肉、脂肪细胞、软骨细胞和平滑肌细胞分化，并且通过微阵列分析来检查这些基质细胞系的基因表达谱。我们发现造血细胞产生的Oncostatin M调节基质细胞的造血支持能力和分化表型，提示基质细胞和造血细胞之间的相互细胞间通讯对维持造血微环境是重要的。MyPDZ基因是一个新的基因，其表达水平与基质细胞的造血支持能力相关。在基质细胞中表达的MysPDZ在NH 2-末端含有富含KE和PDZ结构域，但鉴定了3种剪接异构体（造血细胞特异性、脑特异性、肌肉特异性），其在N-末端区域缺少PDZ结构域。我们的研究表明，一个新的作用，丰富的KE和PDZ结构域在指导亚细胞定位。

Bone marrow provides microenvironment for self-renewal and differentiation of hematopojetic stem/progenitor cells through complex cell-cell interaction. To study the cellular regulation of hematopoietic micorenvironment, we established variety of stromal cell lines from bone marrow of temperature sensitive SV40 Large T-antigen transgenic mice and using these stromal cell lines as feeder cells, we established several stroma-dependent hematopoietic cell lines. Some stromal cell lines were shown to be mesenchymal stem cells because they can differentiate toward muscles, adipocytes, chondrocytes and smooth muscle cells in vitro and gene expression profiles of these stromal cell lines were examined by microarray analysis. We demonstrated that Oncostatin M that was produced by the hematopoietic cells regulates hematopoeiteic supporting ability and differentiation phenotypes of the stromal cells, suggesting that reciprocal cell to cell communication between stromal cells and hematopoietic cells is important to maintain the hematopoietic microenvironment.MysPDZ gene was isolated as a new gene whose expression level was correlated with the hematopoietic supportive ability of the stromal cells. MysPDZ expressed in the stromal cells contains the KE-rich and PDZ domains in the NH2-terminal, but 3 spliced isoforms (hematopoietic cell-, brain-, muscle-specific) that lack PDZ-domain in the N-terminal region are identified. Our study suggests a novel role of the KE-rich and PDZ domains in directing subcellular localization.