Kinase mediated tyrosine phosphorylation is a crucial component of cellular signaling cascades. Precise regulatory control over kinase activity must be maintained during signaling as evidenced by numerous human diseases that arise upon dysregulation of protein kinases. Given the crucial role of kinases in cell signaling, these enzymes are key targets in treating numerous diseases. Traditional approaches for therapeutic targeting of kinases have involved small molecules that exert their effect directly on the kinase active site. Given the increasing instances of resistance to such drugs there is a need for devising new ways to target kinase activity. In our work on the Tec family tyrosine kinases (immunological kinases involved in signaling downstream of antigen receptors), we have characterized a number of specific allosteric sites and interactions that modulate the chemistry of the active site. These allosteric pockets are sometimes 30 angstrom removed from the active site or involve domains far from the kinase domain in primary sequence. The current application lays out specific aims to identify and characterize allosteric small molecule modulators of the Tec family kinases, Itk and Btk. In addition, we continue to move our understanding of Tec structure forward by solving the crystal structure of full length Btk. This will be the first strucure of any full length Tec kinase and the insight gained will facilitate further development of allosteric regulators for this family. We have established strong collaborations with immunologists that have extensive T- and B-cell signaling expertise (in particular as related to Itk and Btk). These colleagues are eager to test our small molecule reagents in their cellular and animal systems. Thus, this project spans basic structural biology and enzymology to small molecule discovery to physiological assays that will ultimately reveal the utility of the reagents we are developing to treat human disease.

Public Health Relevance

This proposal aims to exploit specific allosteric mechanisms that control the Tec family of tyrosine kinases within the immune response. The public health relevance of the project relates to developing new ways to either limit or enhance the immune response in the face of autoimmunity, immunosuppression or immunological diseases.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
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Study Section
Cellular and Molecular Immunology - A Study Section (CMIA)
Program Officer
Leitner, Wolfgang W
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Iowa State University
Schools of Arts and Sciences
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Wang, Xinxin; Boyken, Scott E; Hu, Jiancheng et al. (2014) Calmodulin and PI(3,4,5)P? cooperatively bind to the Itk pleckstrin homology domain to promote efficient calcium signaling and IL-17A production. Sci Signal 7:ra74
Boyken, Scott E; Chopra, Nikita; Xie, Qian et al. (2014) A conserved isoleucine maintains the inactive state of Bruton's tyrosine kinase. J Mol Biol 426:3656-69
Joseph, Raji E; Kleino, Iivari; Wales, Thomas E et al. (2013) Activation loop dynamics determine the different catalytic efficiencies of B cell- and T cell-specific tec kinases. Sci Signal 6:ra76
Xie, Qian; Joseph, Raji E; Fulton, D Bruce et al. (2013) Substrate recognition of PLC?1 via a specific docking surface on Itk. J Mol Biol 425:683-96
Joseph, Raji E; Ginder, Nathaniel D; Hoy, Julie A et al. (2012) Structure of the interleukin-2 tyrosine kinase Src homology 2 domain; comparison between X-ray and NMR-derived structures. Acta Crystallogr Sect F Struct Biol Cryst Commun 68:145-53
Joseph, Raji E; Ginder, Nathaniel D; Hoy, Julie A et al. (2011) Purification, crystallization and preliminary crystallographic analysis of the SH2 domain of IL-2-inducible T-cell kinase. Acta Crystallogr Sect F Struct Biol Cryst Commun 67:269-73
Min, Lie; Wu, Wenfang; Joseph, Raji E et al. (2010) Disrupting the intermolecular self-association of Itk enhances T cell signaling. J Immunol 184:4228-35
Joseph, Raji E; Xie, Qian; Andreotti, Amy H (2010) Identification of an allosteric signaling network within Tec family kinases. J Mol Biol 403:231-42
Andreotti, Amy H; Schwartzberg, Pamela L; Joseph, Raji E et al. (2010) T-cell signaling regulated by the Tec family kinase, Itk. Cold Spring Harb Perspect Biol 2:a002287
Joseph, Raji E; Severin, Andrew; Min, Lie et al. (2009) SH2-dependent autophosphorylation within the Tec family kinase Itk. J Mol Biol 391:164-77

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