title: Survivin regulates hematopoietic progenitor cell proliferation through p21WAF1/Cip1-dependent and -independent pathways.
abstract: The cyclin-dependent kinase inhibitor p21WAF1/Cip1 and Survivin enhance granulocyte macrophage colony-forming unit (CFU-GM) cell cycle and proliferation and have been implicated as antiapoptotic proteins. We investigated the relationships between p21 and Survivin in primary CFU-GM and c-kit+, lineage-negative (Lin-) cells and demonstrate p21-dependent and -independent pathways whereby Survivin regulates progenitor cell proliferation. Ectopic Survivin enhanced p21+/+ CFU-GM formation and expansion of c-kit+, Lin- cells, whereas p21 gene loss abrogated these effects, indicating a p21 requirement. A dominant-negative form of Survivin and p21 gene deletion accelerated the loss of CFU-GM upon growth factor deprivation, and wild-type Survivin overexpression inhibited apoptosis of p21+/+ CFU-GM and c-kit+, Lin- cells but not p21-/- cells, suggesting that both Survivin and p21 block apoptosis of progenitors and that Survivin-mediated antiapoptosis requires p21. In contrast to the p21-dependent antiapoptotic effects, Survivin increased the proportion of CFU-GM in S-phase in both p21+/+ and p21-/- cells. Furthermore, modulating Survivin expression increased polyploidy in c-kit+, Lin- cells, which was accentuated by p21 deficiency. These results suggest that the Survivin-p21 axis plays an important role in the proliferation of normal hematopoietic cells and that Survivin regulates apoptosis through a p21 WAF1/Cip1-dependent pathway but may control S-phase entry independent of p21.
authors.affiliation: Department of Microbiology and Immunology, Walther Oncology Center, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
authors.forename: Seiji
authors.initials: S
authors.lastname: Fukuda
authors.forename: Charlie R
authors.initials: CR
authors.lastname: Mantel
authors.forename: Louis M
authors.initials: LM
authors.lastname: Pelus
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics / Q000502:physiology; D002455:Cell Division / Q000235:genetics / Q000502:physiology; D003114:Colony-Forming Units Assay; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D005260:Female; D015870:Gene Expression; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000502:physiology; D066298:In Vitro Techniques; D051034:Inhibitor of Apoptosis Proteins; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008869:Microtubule-Associated Proteins / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D009363:Neoplasm Proteins; D011123:Polyploidy; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics / Q000502:physiology; D016196:S Phase / Q000235:genetics / Q000502:physiology; D000077022:Survivin
chemical_list: C107489:BIRC5 protein, human; C493957:Cdkn1a protein, mouse; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D051034:Inhibitor of Apoptosis Proteins; D008869:Microtubule-Associated Proteins; D009363:Neoplasm Proteins; D000077022:Survivin; D019009:Proto-Oncogene Proteins c-kit