日本千叶大学教授岩间厚志率领的研究小组在最新一期美国《细胞－干细胞》杂志上发表论文说，他们发现，缺失基因“Bmi1”会影响造血干细胞生成血液细胞。
研究人员对实验鼠进行基因操作，使其失去基因“Bmi1”。结果实验鼠本来应该生成红细胞或白细胞的造血干细胞，只生成了特定的淋巴细胞。
研究人员认为，没有“Bmi1”基因，造血干细胞中平时不发生作用的其他基因开始发挥作用，导致造血干细胞失去多功能性，只生成了淋巴细胞。他们由此判断，“Bmi1”对于造血干细胞分化成各种血液细胞是必不可少的。（生物谷Bioon.com）
2010年干细胞技术与应用讲座即将于上海召开，详情查看：http://www.stemcellasia.net/
生物谷推荐原始出处：
Cell Stem Cell, Volume 6, Issue 3, 279-286, 5 March 2010 10.1016/j.stem.2010.01.005
Poised Lineage Specification in Multipotential Hematopoietic Stem and Progenitor Cells by the Polycomb Protein Bmi1
Hideyuki Oguro, Jin Yuan, Hitoshi Ichikawa, Tomokatsu Ikawa, Satoshi Yamazaki, Hiroshi Kawamoto, Hiromitsu Nakauchi, Atsushi Iwama
Department of Cellular and Molecular Medicine, Graduate School of Medicine, Chiba University, Chiba 260-8670, Japan JST, CREST, Sanbancho, Chiyoda-ku, Tokyo 102-0075, Japan JST, ERATO, Sanbancho, Chiyoda-ku, Tokyo 102-0075, Japan Genetics Division, National Cancer Center Research Institute, Tokyo, 104-0045, Japan Laboratory for Lymphocyte Development, RIKEN Research Center for Allergy and Immunology, Yokohama 230-0045, Japan Laboratory of Stem Cell Therapy, Center for Experimental Medicine, Institute of Medical Sciences, University of Tokyo, Tokyo 108-8679, Japan Corresponding author
Polycomb group (PcG) proteins are essential regulators of stem cells. PcG and trithorax group proteins mark developmental regulator gene promoters with bivalent domains consisting of overlapping repressive and activating histone modifications to keep them poised for activation in embryonic stem cells. Bmi1, a component of PcG complexes, maintains the self-renewal capacity of adult stem cells, but its role in multipotency remains obscure. Here we show that Bmi1 is critical for multipotency of hematopoietic stem cells (HSCs) and multipotent progenitors (MPPs). B cell lineage developmental regulator genes, Ebf1 and Pax5, appeared to be transcriptionally repressed by bivalent domains before lineage commitment. Loss of Bmi1 resulted in a resolution of bivalent domains at the Ebf1 and Pax5 loci, leading to their premature expression in HSC/MPPs accompanied by accelerated lymphoid specification and a marked reduction in HSC/MPPs. Thus, Bmi1 is required to reinforce bivalent domains at key developmental regulator gene loci to maintain lineage specification poised for activation in adult stem cells.
