1999 Fiscal Year Final Research Report Summary
Molecular mechanism of negative regulation of JAK/STAT pathway by the CIS/JAB family members
| Project/Area Number |
10670128
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
General medical chemistry
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| Research Institution | Kurume University |
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Principal Investigator |
YASUKAWA Hideo Institute of Life Science, Assistant Professor, 分子生命科学研究所, 助手 (60289361)
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| Co-Investigator(Kenkyū-buntansha) |
OHTSUBO Motoaki Institute of Life Science, Assistant Professor, 分子生命科学研究所, 助手 (10211799)
YOSHIMURA Akihiko Institute of Life Science, Professor, 分子生命科学研究所, 教授 (90182815)
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| Project Period (FY) |
1998 – 1999
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| Keywords | tyrosine kinase / JAK / STAT / CIS / cytokine / knockout mice / tyrosine phosphorylation / kinase inhibitor |
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| Research Abstract |
The Janus family of protein tyrosine kinases (JAKs) regulate cellular processes involved in cell growth, differentiation and transformation through their association with cytokine receptors. However, compared with other kinases, little is known about cellular regulators of the JAKs. We have recently identified a JAK-binding protein (JAB) that inhibits JAK signaling in cells. We demonstrate that JAB specifically binds to the tyrosine residue (Y1007) in the activation loop of JAK2 whose phosphorylation is required for activation of kinase activity. Binding to the phosphorylated activation loop requires the JAB SH2 domain and an additional N-terminal 12 amino acids (extended SH2 subdomain) containing two residues (Ile68 and Leu75) that are conserved in JAB related proteins. An additional N-terminal 12 amino acid region (kinase inhibitory region) of JAB also. Contributes to tight binding to the JAK2 tyrosine kinase domain and is required for inhibition of JAK2 signaling and kinase activity
… More
. Our studies define a novel type of regulation of tyrosine kinases and might provide a basis for the design of specific tyrosine kinase inhibitors. Similar mechanism was found for another JAK-binding protein, CIS3.
We have shown that JAB is strongly induced by interferon-γ. JAB deficient mice die perinatally with altered lymphoid development including the generation of activated T cells in vivo. The lethality is eliminated on a Rag2 or interferon-Y deficient background. Based on the results, we propose that JAB plays an essential role in negative feedback regulation of interferon-γ.
During embryonic development CIS3 is highly expressed in some but not all erythroid lineage cells of the fecal liver. Deletion of CIS3 gene results in an embryonic lethality at 12-l6 days that is associated with a marked erythrocytosis. Moreover, the individual in vitro proliferative capacity of fetal liver. Progenitors is greatly increased. The results suggest a specific negative regulatory effect of CIS3 on EPO signaling. Less
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Research Products
(8 results)
