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A Stat3-interacting protein (StIP1) regulates cytokine signal transduction.

ABSTRACT: Genetic and biochemical studies have led to the identification of the Stat3-Interacting Protein StIP1. The preferential association of StIP1 with inactive (i.e., unphosphorylated) Stat3 suggests that it may contribute to the regulation of Stat3 activation. Consistent with this possibility, StIP1 also exhibits an affinity for members of the Janus kinase family. Overexpression of the Stat3-binding domain of StIP1 blocks Stat3 activation, nuclear translocation, and Stat3-dependent induction of a reporter gene. These studies indicate that StIP1 regulates the ligand-dependent activation of Stat3, potentially by serving as a scaffold protein that promotes the interaction between Janus kinases and their Stat3 substrate. The ability of StIP1 to associate with several additional members of the signal transducer and activator of transcription family suggests that StIP1 may serve a broader role in cytokine-signaling events.

SUBMITTER: Collum RG

PROVIDER: S-EPMC27739 | biostudies-literature | 2000 Aug

REPOSITORIES: biostudies-literature

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A Stat3-interacting protein (StIP1) regulates cytokine signal transduction.

Collum R G RG Brutsaert S S Lee G G Schindler C C

Proceedings of the National Academy of Sciences of the United States of America 20000801 18

Genetic and biochemical studies have led to the identification of the Stat3-Interacting Protein StIP1. The preferential association of StIP1 with inactive (i.e., unphosphorylated) Stat3 suggests that it may contribute to the regulation of Stat3 activation. Consistent with this possibility, StIP1 also exhibits an affinity for members of the Janus kinase family. Overexpression of the Stat3-binding domain of StIP1 blocks Stat3 activation, nuclear translocation, and Stat3-dependent induction of a re ...[more]

PMID: 10954736

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Project description:Interleukin (IL)-22 is a member of the IL-10 family. Its main targets are epithelial cells, not immune cells. We examined IL-22 signal transduction in oral squamous cell carcinoma (OSCC) cells. Immunohistochemical staining revealed that IL-22R was expressed more highly in OSCC compared to normal regions. An IL-22R signal was also observed in metastatic OSCC cells in the lymph node. RT-PCR showed that the human OSCC cell lines MISK81-5, HSC-3, HSC-4, SAS and SQUU-B expressed IL-22 receptor chains. Immunoblotting showed that IL-22 induced a transient tyrosine phosphorylation of STAT3 (pY705-STAT3) in MISK81-5 cells. The change in the serine phosphorylation of STAT3 was subtle during the examination periods. Simultaneously, pY705-STAT3 activation in HSC-3 cells was undetectable after IL-22 stimulation. Immunocytochemistry demonstrated that IL-22 induced the translocation of phosphorylated STAT3 into the nucleus of MISK81-5 cells. IL-22 temporarily upregulated the expression of anti-apoptotic and mitogenic genes such as Bcl-x, survivin and c-Myc, as well as SOCS3. IL-22 transiently activated ERK1/2 and induced a delayed phosphorylation of p38 MAP kinase, but negligibly involved the activation of NF-?B in MISK81-5 cells. MISK81-5 and SQUU-B cells treated with IL-22 showed mild cellular proliferation. MISK81-5, HSC-4 and SAS cells treated with IL-22 downregulated the keratinocyte differentiation-related genes compared with unstimulated cells. Conversely, STAT3 suppression by STAT3 siRNA strongly disrupted the downregulation of these genes by IL-22, but it did not significantly affect the activation of ERK1/2 by IL-22. The OSCC cells used in this study upregulated the expression of SERPINB3/4 (SCCA1/2), well-known SCC markers, following treatment with IL-22. These results indicate that IL-22 differentially activates the STAT3 signaling system depending on the type of OSCC. IL-22 may therefore play a role in tumor growth, cell differentiation and progression through STAT3-dependent and -independent pathways.

Dataset Information

A Stat3-interacting protein (StIP1) regulates cytokine signal transduction.

Publications

A Stat3-interacting protein (StIP1) regulates cytokine signal transduction.

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