title: Molecular mechanism of transforming growth factor beta-mediated cell-cycle modulation in primary human CD34(+) progenitors.
abstract: The mechanisms by which transforming growth factor beta (TGF-beta) exerts a negative effect on cell-cycle entry in primary human hematopoietic stem/progenitor cells were examined at the molecular and cellular levels. After treatment of primary human CD34+ progenitors with TGF-beta there was a decrease in the levels of cyclin D2 protein and an increase in levels of the cyclin-dependent kinase inhibitor (CDKI) p15 as compared to the levels in untreated cells. The converse was true after addition of neutralizing anti-TGF-beta antibody. Administration of TGF-beta to CD34+ cells in the presence of cytokines prevented retinoblastoma protein (pRb) phosphorylation, which occurred in the same cells treated with cytokines alone or cytokines and anti-TGF-beta antibody. Neutralization of TGF-beta during 24 to 48 hours of culture with cytokines significantly increased the number of colony-forming progenitors, but did not modulate the human stem cell pool, as measured in 6- to 12-month xenotransplantation assays. Equivalent numbers of human B, T, and myeloid cells were obtained after transplantation of cells treated with or without neutralization of TGF-beta.
authors.affiliation: Division of Research Immunology/Bone Marrow Transplantation, Children's Hospital Los Angeles, and Department of Pediatrics, University of Southern California School of Medicine, Los Angeles, CA 90027, USA.
authors.forename: Mo A
authors.initials: MA
authors.lastname: Dao
authors.forename: Joseph
authors.initials: J
authors.lastname: Hwa
authors.forename: Jan A
authors.initials: JA
authors.lastname: Nolta
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D018952:Antigens, CD34 / Q000032:analysis; D016203:CDC2 Protein Kinase / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects; D019070:Cell Lineage; D002478:Cells, Cultured / Q000166:cytology / Q000187:drug effects; D003114:Colony-Forming Units Assay; D056742:Cyclin D2; D051358:Cyclin-Dependent Kinase 4; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D016213:Cyclins / Q000378:metabolism; D016207:Cytokines / Q000494:pharmacology; D004247:DNA / Q000235:genetics; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000187:drug effects*; D006801:Humans; D051379:Mice; D008817:Mice, Mutant Strains; D008819:Mice, Nude; D010766:Phosphorylation / Q000187:drug effects; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D011518:Proto-Oncogene Proteins; D011828:Radiation Chimera; D016192:Resting Phase, Cell Cycle / Q000187:drug effects; D016160:Retinoblastoma Protein / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000276:immunology / Q000494:pharmacology*; D014183:Transplantation, Heterologous
chemical_list: D000911:Antibodies, Monoclonal; D018952:Antigens, CD34; C080336:CCND2 protein, human; C486196:Ccnd2 protein, mouse; D056742:Cyclin D2; D016213:Cyclins; D016207:Cytokines; D011518:Proto-Oncogene Proteins; D016160:Retinoblastoma Protein; D016212:Transforming Growth Factor beta; D004247:DNA; D016203:CDC2 Protein Kinase; C495900:CDK4 protein, human; C495902:Cdk4 protein, mouse; D051358:Cyclin-Dependent Kinase 4; D018844:Cyclin-Dependent Kinases