title: [Mechanism of hematopoietic stem/progenitor cell aging induced by radiation damage].
abstract: OBJECTIVE
  To explore the mechanism underlying the aging of hematopoietic stem/progenitor cells (HSC/HPC) induced by radiation stress.
  
  
  METHODS
  Male C57BL/6J mice were divided randomly into radiation group and control group. The radiation group were treated with total 6.5 Gy X-ray radiation for 24 h; the control group received the same treatment except radiation. Thereafter, Sca-1(+);HSC/HPC were isolated by magnetic-activated cell sorting (MACS) from bone marrow of all the mice. The distributions of cell cycle were tested by flow cytometry. The percentage of aging cells was detected by SA-β-Gal staining. The potentials of self-renewal and multi-differentiation were measured by CFU-Mix assay. DNA damages of Sca-1(+);HSC/HPC were analyzed by single cell gel electrophoresis technique (SCGE). The expressions of senescence-associated genes p16(INK4a);, p19(Arf);, p53, p21(Cip1/Waf1); mRNA were detected by RT-PCR. Western blotting was performed to analyze the expressions of p16(INK4a); and p21(Cip1/Waf1); proteins.
  
  
  RESULTS
  The purity of Sca-1(+);HSC/HPC reached 94% after MACS. Compared with control group cells, after radiation, the number of Sca-1(+);HSC/HPC per femur and CFU-Mix sharply decreased (P<0.05), Sca-1(+);HSC/HPC apparently showed G1 arrest and elevated percentage of SA-β-Gal positive cells (P<0.05), cell trailing had a prolonged time, and the expressions of senescence-associated genes (p16(INK4a);, p19(Arf);, p53, p21(Cip1/Waf1);) and relevant proteins (p16(INK4a);, p21(Cip1/Waf1);) were up-regulated significantly (P<0.05).
  
  
  CONCLUSIONS
  DNA damage and senescence-associated biological changes of Sca-1(+);HSC/HPC can be achieved by X-ray radiation, which may be involved in p16(INK4a);-Rb and p19(Arf);-p53-p21(Cip1/Waf1); signal pathways.
authors: Department of Histology and Embryology, Chongqing Medical University, Chongqing, China.
authors: Chen
authors: C
authors: Zhang
authors: Ke
authors: K
authors: Sun
authors: Shan
authors: S
authors: Geng
authors: Dianfeng
authors: D
authors: Liu
authors: Xianping
authors: X
authors: Zhang
authors: Jun
authors: J
authors: Liu
authors: Chunyan
authors: C
authors: Xu
authors: Jianwei
authors: J
authors: Wang
authors: Yaping
authors: Y
authors: Wang
mesh_terms: D000818:Animals; D000950:Antigens, Ly / Q000378:metabolism; D002452:Cell Count; D016922:Cellular Senescence / Q000528:radiation effects*; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000378:metabolism; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D004249:DNA Damage; D005786:Gene Expression Regulation / Q000528:radiation effects; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000201:enzymology / Q000378:metabolism / Q000528:radiation effects*; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D015398:Signal Transduction / Q000528:radiation effects; D013312:Stress, Physiological / Q000235:genetics / Q000528:radiation effects; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D000950:Antigens, Ly; C493957:Cdkn1a protein, mouse; C417743:Cdkn2a protein, mouse; D019941:Cyclin-Dependent Kinase Inhibitor p16; D050759:Cyclin-Dependent Kinase Inhibitor p21; C074650:Ly6a protein, mouse; D008565:Membrane Proteins; D016159:Tumor Suppressor Protein p53; D001616:beta-Galactosidase