title: Mad2 is required for optimal hematopoiesis: Mad2 associates with c-Kit in MO7e cells.
abstract: Mitotic arrest deficiency 2 (Mad2) is a component of mitotic spindle checkpoint proteins and is essential for accurate chromosome segregation. We investigated a role for Mad2 in hematopoiesis using Mad2-haploinsufficient (Mad2+/-) mice. Mad2+/- bone marrow (BM) and spleen manifested decreased absolute numbers and cycling status of immature, but not mature, hematopoietic progenitor cells. Mad2+/- BM granulocyte-macrophage colony-forming units (CFU-GMs) did not manifest synergistic proliferation in response to stem cell factor (SCF) plus GM-CSF. The percentage of annexin V+ cells was higher in Mad2+/- than Mad2+/+c-Kit+lin- BM after culture with SCF and GM-CSF. However, no significant difference in phosphorylation of extracellular signal-related kinase (Erk1/2) at Thr202/Tyr204 and Akt at Ser473 between Mad2+/- and Mad2+/+BM c-Kit+lin- cells was observed. Immunoprecipitation assays performed in human MO7e cells demonstrated physical association of c-Kit with Mad2. Moreover, stimulation with SCF plus GM-CSF led to dissociation of Mad2 from c-Kit. Confocal microscopy demonstrated that Mad2 colocalized with c-Kit in the cytoplasm of MO7e cells. These results suggest that Mad2 is involved in synergistic growth of immature hematopoietic progenitor cells in response to SCF plus GM-CSF, effects that may be mediated via physical association of Mad2 with c-Kit.
authors.affiliation: Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis 46202, USA.
authors.forename: Shigeki
authors.initials: S
authors.lastname: Ito
authors.forename: Charlie R
authors.initials: CR
authors.lastname: Mantel
authors.forename: Myung-Kwan
authors.initials: MK
authors.lastname: Han
authors.forename: Sunanda
authors.initials: S
authors.lastname: Basu
authors.forename: Seiji
authors.initials: S
authors.lastname: Fukuda
authors.forename: Scott
authors.initials: S
authors.lastname: Cooper
authors.forename: Hal E
authors.initials: HE
authors.lastname: Broxmeyer
mesh_terms: D000818:Animals; D017209:Apoptosis; D001854:Bone Marrow Cells / Q000166:cytology / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D016207:Cytokines / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006239:Haplotypes; D006410:Hematopoiesis; D006801:Humans; D064246:Mad2 Proteins; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D011485:Protein Binding; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism*; D013154:Spleen / Q000166:cytology / Q000378:metabolism; D019089:Stem Cell Factor / Q000494:pharmacology
chemical_list: D018797:Cell Cycle Proteins; D016207:Cytokines; D064246:Mad2 Proteins; C577698:Mad2l1 protein, mouse; D019089:Stem Cell Factor; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D019009:Proto-Oncogene Proteins c-kit; D051057:Proto-Oncogene Proteins c-akt; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3