Regulator of G protein signaling RGS3 is a GTPase-activating protein (GAP) that binds G-alpha subunits of heterotrimeric G proteins and accelerates their GTPase activity. We and others have shown that through this mechanism, RGS3 regulates the signaling of Gq- and Gi-coupled receptors to angiotensin II, endothelin-1, carbachol, gonadotropin-releasing hormone and sphingosine-1 phosphate. Our new data suggest that a) RGS3 interacts with the transducers of TGF-2 signaling, Smad transcription factors that were previously thought to be unrelated to G protein / RGS axis;b) RGS3 inhibits Smad-mediated gene transcription;and c) RGS3 is abundant in T-lymphocytes and its expression in T cells is further induced by TGF-2 treatment. In T cells, G protein signaling is associated with migration towards various chemokines, whereas TGF-2 signaling controls proliferation and differentiation of T cells at multiple levels. The function of endogenous RGS3 has not been investigated in T cells. Based on our preliminary data, we hypothesize that (i) RGS3 is a multifunctional protein that, in addition to regulating G protein signaling, also modulates the signaling of TGF-2, and (ii) endogenous RGS3 controls T cell migration, proliferation and differentiation through the regulation of both G protein- and TGF-2 signaling. To test these hypotheses, we propose three specific aims: (i) investigate the molecular nature and functional consequences of RGS3 / Smad interaction by overexpression of RGS3 and its mutants, (ii) investigate the regulation of G protein- and TGF-2 signaling by endogenous RGS3 in EL4 T thymoma cell line;and (iii) examine how RGS3 controls T cell migration, proliferation and differentiation in response to TGF-2 and chemokines, using T cells from RGS3-knockout mouse. The fundamental significance of this study relates to a potential discovery of a novel, non-canonical function of RGS3 as a regulator of TGF-2 signaling. The practical importance of this study relates to understanding the diseases associated with abnormal immune responses of T cell.

Public Health Relevance

Appropriate function of T lymphocytes is critical for the adaptive immunity, whereas abnormal function of T cells leads to autoimmune and inflammatory diseases such as asthma, multiple sclerosis, rheumatoid arthritis, type I diabetes and others. Therefore, defining the molecular mechanisms of T cell activation and differentiation may lead to a better understanding the pathogenesis of these diseases.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM085058-04
Application #
8251220
Study Section
Molecular and Integrative Signal Transduction Study Section (MIST)
Program Officer
Dunsmore, Sarah
Project Start
2009-05-01
Project End
2013-04-30
Budget Start
2012-05-01
Budget End
2013-04-30
Support Year
4
Fiscal Year
2012
Total Cost
$305,791
Indirect Cost
$109,771
Name
University of Chicago
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
005421136
City
Chicago
State
IL
Country
United States
Zip Code
60637
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Kach, Jacob; Sandbo, Nathan; Sethakorn, Nan et al. (2013) Regulation of myofibroblast differentiation and bleomycin-induced pulmonary fibrosis by adrenomedullin. Am J Physiol Lung Cell Mol Physiol 304:L757-64
Williams, Jesse W; Yau, Douglas; Sethakorn, Nan et al. (2013) RGS3 controls T lymphocyte migration in a model of Th2-mediated airway inflammation. Am J Physiol Lung Cell Mol Physiol 305:L693-701
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Kach, Jacob; Sethakorn, Nan; Dulin, Nickolai O (2012) A finer tuning of G-protein signaling through regulated control of RGS proteins. Am J Physiol Heart Circ Physiol 303:H19-35
Sandbo, Nathan; Dulin, Nickolai (2011) Actin cytoskeleton in myofibroblast differentiation: ultrastructure defining form and driving function. Transl Res 158:181-96
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Sandbo, Nathan; Lau, Andrew; Kach, Jacob et al. (2011) Delayed stress fiber formation mediates pulmonary myofibroblast differentiation in response to TGF-?. Am J Physiol Lung Cell Mol Physiol 301:L656-66
O'Sullivan, Jeremy A; Zloza, Andrew; Kohlhapp, Frederick J et al. (2011) Priming with very low-affinity peptide ligands gives rise to CD8(+) T-cell effectors with enhanced function but with greater susceptibility to transforming growth factor (TGF)?-mediated suppression. Cancer Immunol Immunother 60:1543-51

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