title: Activin A induction of cell-cycle arrest involves modulation of cyclin D2 and p21CIP1/WAF1 in plasmacytic cells.
abstract: Activins, members of the transforming growth factor-beta family, have been implicated in the regulation of growth and differentiation of various types of cells. We have recently found that activin A induces apoptotic cell death of plasmacytic cells including B cell hybridoma cells and myeloma cells. In the present study, we demonstrated that activin A caused cell-cycle arrest in the G1 phase before appearance of apoptotic cells in mouse B cell hybridoma cells. Phosphorylation of retinoblastoma protein (Rb) and in vitro Rb kinase activity of cyclin-dependent kinase (CDK)4 was inhibited in activin A-treated cells. Analysis of expression of genes regulating Rb phosphorylation revealed that activin A suppressed cyclin D2, the sole D-type cyclin gene expressed in the hybridoma cells, and activated p21CIP1/WAF1 but had no effect on expression of cyclin-dependent kinases (CDK2, CDK4, CDK6) and other CDK inhibitors (p27KIP1, p16INK4a, p15INK4b). Modulation of cyclin D2 and p21CIP1/WAF1 expression resulted in a decrease in level of cyclin D2-CDK4 complex and an increase in level of CDK4 complexed with p21CIP1/WAF1. Moreover, overexpression of cyclin D2 partially abrogated inhibition of Rb phosphorylation and G1 arrest in the hybridoma cells.
authors.affiliation: Department of Oral Science, The National Institute of Infectious Diseases, Tokyo, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Yamato
authors.forename: T
authors.initials: T
authors.lastname: Koseki
authors.forename: M
authors.initials: M
authors.lastname: Ohguchi
authors.forename: M
authors.initials: M
authors.lastname: Kizaki
authors.forename: Y
authors.initials: Y
authors.lastname: Ikeda
authors.forename: T
authors.initials: T
authors.lastname: Nishihara
mesh_terms: D028341:Activins; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D042846:CDC2-CDC28 Kinases; D002352:Carrier Proteins / Q000187:drug effects / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects*; D018797:Cell Cycle Proteins; D002455:Cell Division / Q000187:drug effects; D056742:Cyclin D2; D051357:Cyclin-Dependent Kinase 2; D051358:Cyclin-Dependent Kinase 4; D050762:Cyclin-Dependent Kinase Inhibitor p15; D019941:Cyclin-Dependent Kinase Inhibitor p16; D050759:Cyclin-Dependent Kinase Inhibitor p21; D018844:Cyclin-Dependent Kinases / Q000187:drug effects / Q000378:metabolism; D016213:Cyclins / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D016193:G1 Phase; D006825:Hybridomas / Q000187:drug effects; D007265:Inhibins / Q000494:pharmacology*; D051379:Mice; D010766:Phosphorylation; D010950:Plasma Cells / Q000187:drug effects* / Q000473:pathology; D017346:Protein Serine-Threonine Kinases / Q000187:drug effects / Q000378:metabolism; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D016160:Retinoblastoma Protein / Q000187:drug effects / Q000378:metabolism; D025521:Tumor Suppressor Proteins
chemical_list: D002352:Carrier Proteins; C486196:Ccnd2 protein, mouse; C493957:Cdkn1a protein, mouse; C493968:Cdkn2b protein, mouse; D018797:Cell Cycle Proteins; D056742:Cyclin D2; D050762:Cyclin-Dependent Kinase Inhibitor p15; D019941:Cyclin-Dependent Kinase Inhibitor p16; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D016160:Retinoblastoma Protein; D025521:Tumor Suppressor Proteins; D028341:Activins; D007265:Inhibins; D017346:Protein Serine-Threonine Kinases; D042846:CDC2-CDC28 Kinases; C495893:Cdk2 protein, mouse; C495902:Cdk4 protein, mouse; D051357:Cyclin-Dependent Kinase 2; D051358:Cyclin-Dependent Kinase 4; D018844:Cyclin-Dependent Kinases