Alpha-Thrombin and interleukin-6 (IL-6) play important roles in inflammation, tissue repair and wound healing. Their cellular responses are mediated via activation of signal transduction pathways. While alpha- thrombin mediates its effects through numerous signaling intermediates including mitogen-activated protein (MAP) kinases, IL-6 acts via stimulation of the JAK-STAT (Janus kinase-Signal Transducers and Activators of Transcription) pathway. In primary human lung fibroblast cultures and established cell lines, we recently demonstrated that alpha- thrombin, through a MAP kinase 1-dependent mechanism, inhibits IL-6 induced tyrosine phosphorylation of Stat3 protein. Stat3 is a member of STAT family of transcription factors, and its activation by tyrosine phosphorylation is a critical event in IL-6 induced signaling. Alpha- Thrombin's capacity to inhibit IL-6-induced signaling defines a new role for this multi-functional serine protease. Transforming growth factor-beta also inhibits IL-6 induced signaling in lung fibroblast indicating that crosstalk also involves other agonists implicated in the pathogenesis of lung injury and repair. Our working hypothesis is that alpha-thrombin interferes with IL-6- induced signaling at multiple steps, mediated by the actions kinases/phosphatases. In this study, utilizing biochemical and molecular approaches, we will elucidate the mechanism by which alpha-thrombin inhibits IL-6-induced JAK-STAT signaling in lung fibroblasts, and identify IL-6 induced genes inhibited by alpha-thrombin via this crosstalk. This proposal will enhance our understanding of signaling mechanisms by which alpha-thrombin and IL-6 are locally expressed in the alveolar space during lung injury, elucidation of this regulatory pathway could suggest novel strategies to prevent or attenuate pulmonary inflammation and/or fibrosis.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
1R01HL066000-01
Application #
6041474
Study Section
Lung Biology and Pathology Study Section (LBPA)
Project Start
2000-02-14
Project End
2003-11-30
Budget Start
2000-02-14
Budget End
2000-11-30
Support Year
1
Fiscal Year
2000
Total Cost
$146,821
Indirect Cost
Name
Icogenex Corporation
Department
Type
DUNS #
836856351
City
Seattle
State
WA
Country
United States
Zip Code
98103
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Bhat, G Jayarama; Samikkannu, Thangavel; Thomas, Jason J et al. (2004) alpha-thrombin rapidly induces tyrosine phosphorylation of a novel, 74-78-kDa stress response protein(s) in lung fibroblast cells. J Biol Chem 279:48915-22
Gunaje, J J; Bhat, G J (2001) Involvement of tyrosine phosphatase PTP1D in the inhibition of interleukin-6-induced Stat3 signaling by alpha-thrombin. Biochem Biophys Res Commun 288:252-7
Gunaje, J J; Bhat, G J (2000) Distinct mechanisms of inhibition of interleukin-6-induced Stat3 signaling by TGF-beta and alpha-thrombin in CCL39 cells. Mol Cell Biol Res Commun 4:151-7