Description
B lymphoma Mo MLV insertion region 1, also known as RNF51, is a protein which in humans is encoded by the BMI1 gene. The gene is highly conserved in evolution as indicated by zoo blot hybridization with Bmi1 probes corresponding to the protein-encoding domain. By fluorescence in situ hybridization, the human gene is assigned to chromosome 10p13. It has a key role in regulating the proliferative activity of normal stem and progenitor cells. Most importantly, they provided evidence that the proliferative potential of leukemic stem and progenitor cells lacking BMI1 is compromised because they eventually undergo proliferation arrest and show signs of differentiation and apoptosis, leading to transplant failure of the leukemia. Complementation studies showed that the protein completely rescues these proliferative defects. Deletion analysis showed that the RING finger and helix-turn-helix domains of BMI1 were required for life span extension and repression of the tumor suppressor p16(INK4). BMI1 selectively extended the life span of these cultures. Confocal microscopy showed that the protein transiently colocalized with centromeres during interphase in HeLa cells