title: Negative regulation of cytokine signaling pathways.
abstract: The Janus family of protein tyrosine kinases (JAKs) and STAT transcription factors regulate cellular processes involved in cell growth, differentiation, and transformation through their association with cytokine receptors. The CIS family of proteins (also referred to as the SOCS or SSI family) has been implicated in the regulation of signal transduction by a variety of cytokines. Most of them appear to be induced after stimulation with several different cytokines, and at least three of them (CIS1, CIS3/SOCS3, and JAB/SOCS1) negatively regulate cytokine signal transduction by various means: CIS1 inhibits STAT5 activation by binding to cytokine receptors that recruit STAT5, whereas JAB/SOCS-1 and CIS3/SOCS-3 directly bind to the kinase domain of JAKs, thereby inhibiting tyrosine-kinase activity. Therefore, these CIS family members seem to function in a classical negative feedback loop of cytokine signaling. Biochemical characterization as well as gene disruption studies indicate that JAB/SOCS1/SSI-1 is an important negative regulator of interferon gamma signaling. The mechanisms by which these inhibitors of cytokine signal transduction exert their effects have been extensively studied and will provide useful information for regulating tyrosine-kinase activity.
authors.affiliation: Institute of Life Science, Kurume University, Aikawamachi 2432-3, Kurume 839-0861, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Yasukawa
authors.forename: A
authors.initials: A
authors.lastname: Sasaki
authors.forename: A
authors.initials: A
authors.lastname: Yoshimura
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000276:immunology*; D016207:Cytokines / Q000276:immunology*; D004268:DNA-Binding Proteins; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors*; D011506:Proteins / Q000276:immunology*; D012097:Repressor Proteins; D015398:Signal Transduction / Q000276:immunology*; D000071222:Suppressor of Cytokine Signaling 1 Protein; D000071223:Suppressor of Cytokine Signaling 3 Protein; D050826:Suppressor of Cytokine Signaling Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D018909:src Homology Domains
chemical_list: D002352:Carrier Proteins; D016207:Cytokines; D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D011506:Proteins; D012097:Repressor Proteins; C108944:SOCS1 protein, human; C106643:SOCS2 protein, human; C106644:SOCS3 protein, human; D000071222:Suppressor of Cytokine Signaling 1 Protein; D000071223:Suppressor of Cytokine Signaling 3 Protein; D050826:Suppressor of Cytokine Signaling Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D011505:Protein-Tyrosine Kinases