title: JNK2: a negative regulator of cellular proliferation.
abstract: The three different c-Jun N-terminal kinases (JNKs) are activated in multiple cell types by both apoptotic and mitogenic signals, and in turn regulate the activity of transcription factors such as c-Jun. Being highly homologous and ubiquitously expressed, the JNK1 and JNK2 proteins have been thought to perform redundant functions in many physiological process. However, our data from Jnk1-/- or Jnk2-/- cells and mice suggest that both JNK isozymes perform distinct functions in regulating cellular proliferation via differential regulation of c-Jun, which is a critical regulator of cell-cycle progression. Absence of JNK1, the positive regulator of c-Jun, leads to decreased fibroblast proliferation. In contrast, JNK2 deficiency leads to reduced c-Jun degradation, thereby augmenting c-Jun levels and cellular proliferation. Various cell types including fibroblasts, erythroblasts and hepatocytes from Jnk2-/- mice exhibit increased proliferation rates compared to their wild-type counterparts. These data therefore suggests that JNK2, in contrast to JNK1, is a negative regulator of cellular proliferation in multiple cell types.
authors.affiliation: National Cancer Centre, Singapore, Singapore. cmrksb@nccs.com.sg
authors.forename: Kanaga
authors.initials: K
authors.lastname: Sabapathy
authors.forename: Erwin F
authors.initials: EF
authors.lastname: Wagner
mesh_terms: D000818:Animals; D049109:Cell Proliferation; D005786:Gene Expression Regulation; D022781:Hepatocytes / Q000473:pathology; D015603:Keratinocytes; D048056:Mitogen-Activated Protein Kinase 9 / Q000378:metabolism*; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism
chemical_list: D016755:Proto-Oncogene Proteins c-jun; D048056:Mitogen-Activated Protein Kinase 9