title: The homeostasis but not the differentiation of T cells is regulated by p27(Kip1).
abstract: The cyclin-dependent kinase inhibitor p27(Kip1) is a critical regulator of T cell proliferation. To further examine the relationship of T cell proliferation and differentiation, we examined the ability of T cells deficient in p27(Kip1) to differentiate into Th subsets. We observed increased Th2 differentiation in p27(Kip1)-deficient cultures. In addition to increases in CD4(+) and CD8(+) T cells, there is a similar increase in gamma delta T cells in p27(Kip1)-deficient mice compared with wild-type mice. The increase in Th2 differentiation is correlated to an increase of IL-4 secretion by CD4(+)DX5(+)TCR alpha beta(+)CD62L(low) T cells but not to increased expansion of differentiating Th2 cells. While STAT4- and STAT6-deficient T cells have diminished proliferative responses to IL-12 and IL-4, respectively, proliferative responses are increased in T cells doubly deficient in p27(Kip1) and STAT4 or STAT6. In contrast, the increased proliferation and differentiative capacity of p27(Kip1)-deficient T cells has no effect on the ability of STAT4/p27(Kip1)- or STAT6/p27(Kip1)-deficient CD4(+) cells to differentiate into Th1 or Th2 cells, respectively. Thus, while p27(Kip1) regulates the expansion and homeostasis of several T cell subsets, it does not affect the differentiation of Th subsets.
authors.affiliation: Department of Microbiology and Immunology, Walther Oncology Center, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
authors.forename: Randy
authors.initials: R
authors.lastname: Shen
authors.forename: Mark H
authors.initials: MH
authors.lastname: Kaplan
mesh_terms: D000818:Animals; D015704:CD4 Antigens / Q000096:biosynthesis; D018797:Cell Cycle Proteins / Q000235:genetics / Q000502:physiology*; D002454:Cell Differentiation / Q000235:genetics / Q000276:immunology; D002455:Cell Division / Q000235:genetics / Q000276:immunology; D002478:Cells, Cultured; D050760:Cyclin-Dependent Kinase Inhibitor p27; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000172:deficiency / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006706:Homeostasis / Q000235:genetics / Q000276:immunology*; D016130:Immunophenotyping; D015847:Interleukin-4 / Q000096:biosynthesis / Q000378:metabolism; D008213:Lymphocyte Activation / Q000235:genetics; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000096:biosynthesis; D050797:STAT4 Transcription Factor; D050800:STAT6 Transcription Factor; D016176:T-Lymphocyte Subsets / Q000166:cytology* / Q000276:immunology / Q000378:metabolism / Q000502:physiology*; D018418:Th2 Cells / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D015534:Trans-Activators / Q000172:deficiency / Q000235:genetics; D025521:Tumor Suppressor Proteins / Q000172:deficiency / Q000235:genetics / Q000502:physiology*
chemical_list: D015704:CD4 Antigens; C493961:Cdkn1b protein, mouse; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D016692:Receptors, Antigen, T-Cell, gamma-delta; D050797:STAT4 Transcription Factor; D050800:STAT6 Transcription Factor; C494091:Stat4 protein, mouse; C494100:Stat6 protein, mouse; D015534:Trans-Activators; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D015847:Interleukin-4; D018844:Cyclin-Dependent Kinases