title: Induction of cell cycle regulatory proteins in anti-immunoglobulin-stimulated mature B lymphocytes.
abstract: Progression through the cell cycle is a tightly controlled process that integrates signals generated at the plasma membrane with the proteins that form the cell cycle machinery. The current study chronicles the induction of cyclins, cyclin-dependent kinases (cdk), and cdk inhibitors in low density primary mouse B lymphocytes after anti-immunoglobulin plus interleukin 4 (IgM + IL-4) stimulation. In this system, > 85% of cells remain in the G0/G1 phase of cell cycle for an initial 24-h period, followed by entry of up to 50% of the cells into S phase, commencing around 30 h and peaking at 48 h. Extensive time course analyses of these anti-IgM + IL-4-stimulated B cells revealed that the G1-associated D-type cyclins D2 and D3 were induced by 3 h after stimulation, and that cyclins E, A, and B were subsequently induced sequentially, beginning at mid-G1, G1/S transition, and S phase, respectively. The G1-associated cyclin D1 was not expressed at any stage of the anti-Ig + IL-4-induced B cell cycle. cdk2, cdk4, and cdk6 were induced during G1, whereas cell division cycle-2 (cdc2) was induced concomitantly with S phase. Irrespective of their expression, the kinases cdk2 and cdc2 were only active from S phase onwards, suggesting that productive cyclin/kinase complex formation did not occur until that time. Cell cycle inhibitors p21 and p19 were induced by anti-Ig + IL-4, peaking in expression at mid-G1 and S phase, respectively. Stimulation of low density B cells with anti-Ig + IL-4 caused rapid down regulation of the p27 inhibitor, however this protein was reexpressed at 54-96 h after stimulation. In contrast, B cells stimulated with anti-CD40, a stimulus which induces long-term B cell proliferation, permanently down regulated p27. These findings are consistent with the concept that p27 reexpression contributes to the G1 arrest that follows antigen receptor crosslinking. Low density B cells cultured in the viability-enhancing cytokine IL-4 alone also showed induction of D2 and D3 cyclin expression. However, the D2 expression was transient, and the D3 expression was substantially lower than that observed in B cells induced to proliferate by anti-Ig + IL-4. This partial induction of D2 and D3 expression may explain IL-4's ability to promote B cell entry into G1 but not S phase of cell cycle, and furthermore, its ability to truncate G1 progression when B cells are subsequently stimulated with anti-Ig.
authors: Department of Immunology, DNAX Research Institute, Palo Alto, California 94304-1104, USA.
authors: N
authors: N
authors: Solvason
authors: W W
authors: WW
authors: Wu
authors: N
authors: N
authors: Kabra
authors: X
authors: X
authors: Wu
authors: E
authors: E
authors: Lees
authors: M C
authors: MC
authors: Howard
mesh_terms: D000818:Animals; D000888:Antibodies, Anti-Idiotypic; D001402:B-Lymphocytes / Q000166:cytology* / Q000378:metabolism; D016203:CDC2 Protein Kinase / Q000378:metabolism; D002453:Cell Cycle; D002469:Cell Separation; D019938:Cyclin D1; D056742:Cyclin D2; D056743:Cyclin D3; D051358:Cyclin-Dependent Kinase 4; D051361:Cyclin-Dependent Kinase 6; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D016213:Cyclins / Q000378:metabolism; D015847:Interleukin-4 / Q000494:pharmacology; D051379:Mice; D008807:Mice, Inbred BALB C; D015513:Oncogene Proteins / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins; D011947:Receptors, Antigen, B-Cell / Q000502:physiology; D016160:Retinoblastoma Protein / Q000378:metabolism; D015398:Signal Transduction; D013154:Spleen / Q000166:cytology; D013997:Time Factors
chemical_list: D000888:Antibodies, Anti-Idiotypic; C486196:Ccnd2 protein, mouse; C534697:Ccnd3 protein, mouse; D056742:Cyclin D2; D056743:Cyclin D3; D016213:Cyclins; D015513:Oncogene Proteins; D011518:Proto-Oncogene Proteins; D011947:Receptors, Antigen, B-Cell; D016160:Retinoblastoma Protein; D019938:Cyclin D1; D015847:Interleukin-4; D017346:Protein Serine-Threonine Kinases; D016203:CDC2 Protein Kinase; C495902:Cdk4 protein, mouse; C495912:Cdk6 protein, mouse; D051358:Cyclin-Dependent Kinase 4; D051361:Cyclin-Dependent Kinase 6; D018844:Cyclin-Dependent Kinases