Regulation of hematopoietic stem cells using protein transduction domain-fused Polycomb.
The Polycomb-group complex is a chromatin regulatory factor that is classified into two different complexes: Polycomb repressive complex 1 and 2. Components of Polycomb repressive complex 1 are involved in the self-renewal of hematopoietic stem cells. Bmi1, one of these components, maintains the immaturity of neural and cancer stem cells as well as that of hematopoietic stem cells. We constructed recombinant protein transduction domain (PTD)-Polycomb proteins and transduced them into murine bone marrow (BM) cells. We designed and fused the PTD-protein transduction domain to three proteins (i.e., green fluorescent protein, Bmi1, and Mel18). Murine BM cells were incubated for 48 h and each PTD-Polycomb protein was added. Then, we analyzed the function of hematopoiesis using the colony assay and transplantation. BM cells exposed to PTD-Bmi1 showed an increased number of colonies. In contrast, BM cells exposed to PTD-Mel18 or to both proteins showed a decreased number of colonies. Hematopoietic cells derived from PTD-Bmi1-transduced BM cells were significantly increased in the peripheral blood at 6 weeks after transplantation. Moreover, 80% of mice transplanted with PTD-Bmi1-transduced BM cells died at 8 to 24 weeks after transplantation. However, only a few early deaths were observed in the mice transplanted with BM cells exposed to both PTD-Bmi1 and PTD-Mel18. We expect that hematopoietic stem cells could proliferate after transduction with PTD-Bmi1, but this may generate undesirable effects, e.g., tumorigenesis. Thus, Bmi1 and Mel18 have opposing functions and are present in distinct complexes.
Department of Pediatrics, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan. kajiume@hiroshima-u.ac.jp
Teruyuki
T
Kajiume
Yasuhiko
Y
Sera
Yumi
Y
Kawahara
Masaya
M
Matsumoto
Takahiro
T
Fukazawa
Takeshi
T
Imura
Louis
L
Yuge
Masao
M
Kobayashi
D000818:Animals; D001665:Binding Sites / Q000235:genetics; D015153:Blotting, Western; D001854:Bone Marrow Cells / Q000378:metabolism; D016026:Bone Marrow Transplantation; D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D005434:Flow Cytometry; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006412:Hematopoietic Stem Cells / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D063150:Polycomb Repressive Complex 1 / Q000235:genetics / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors; D054322:tat Gene Products, Human Immunodeficiency Virus / Q000235:genetics
C489421:Bmi1 protein, mouse; C066476:Pcgf6 protein, mouse; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins; D054322:tat Gene Products, Human Immunodeficiency Virus; D049452:Green Fluorescent Proteins; D063150:Polycomb Repressive Complex 1