The SOCS proteins and CIS protein comprise a household of intracellular proteins. You can find eight CIS/SOCS household proteins: histone deacetylase inhibitor CIS, SOCS1, SOCS2, SOCS3, SOCS4, SOCS5, SOCS6, and SOCS7, every single of which features a central SH2 domain, an amino terminal domain of variable length and sequence, as well as a carboxy terminal 40 amino acid module known as the SOCS box.
Mainly because the receptors to which SOCS3 binds primarily activate histone deacetylase inhibitor STAT3, SOCS3 is an inhibitor that is relatively specic to STAT3. SOCS3 also inhibits STAT4, which is activated by IL 12. However, because SOCS3 does not bind to the IL 10 receptor, SOCS3 cannot inhibit IL 10 signaling. Therefore, IL 10 induces a robust and prolonged STAT3 activation, whereas IL 6 mediated STAT3 activation is transient in macrophages. This is an important mechanism to distinguish the anti inammatory activity of IL 10 and inammatory activity of IL 6. SOCS1 and SOCS3 inhibit not only STATs but also other signaling pathways such as Ras/ERK and PI3K, which affect cell proliferation, survival, and differentiation. Interestingly, SOCS3 is tyrosine phosphorylated upon cytokine or growth factor stimulation, and phosphorylated Y221 of SOCS3 interacts with p120 RasGAP, resulting in a sustained activation of ERK.
These results indicate that CIS/SOCS family proteins, as well as other SOCS box containing molecules, function as E3 ubiquitin ligases and mediate the degradation of proteins that are associated with these family members through their N terminal regions. The central SH2 domain determines the target of each PARP SOCS and CIS protein. The SH2 domain of SOCS1 directly binds to the activation loop of JAKs. The SH2 domains of CIS, SOCS2, and SOCS3 bind to phosphorylated tyrosine residues on activated cytokine receptors. SOCS3 binds to gp130 related cytokine receptors, including the phosphorylated tyrosine 757 residue of gp130, the Tyr800 residue of IL 12 receptor B2, and Tyr985 of the leptin receptor. Thus, SOCS3 in the brain has been implicated in leptin resistance. SOCS molecules bind to several tyrosine phosphorylated proteins, including Mal and IRS1/2.
SOCS1 deletion in NKT cells also enhanced sensitivity to ConA induced hepatitis. However, the number of iNKT cells was drastically decreased but that of type II NKT cells was increased by SOCS1 deciency.
Monday, March 25, 2013
Atypical Yet Somehow Doable histone deacetylase inhibitor IEM 1754 Tactics
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