Regulation of CD28 binding to SH2 domains of Grb2 and PI3K by trisubstituted carboranes for T-cell activation.

Bioorg Med Chem Lett

Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, 1-5 Shimogamo Hangi-cho, Sakyo-ku, Kyoto, Kyoto 606-8522, Japan. Electronic address:

Published: December 2022

Binding of adaptor molecules, such as growth factor receptor-bound protein 2 (Grb2) and phosphoinositide 3-kinase (PI3K), to the cytoplasmic region of CD28 is critical for T-cell activation. The Src homology 2 (SH2) domains of Grb2 and PI3K interact with the cytoplasmic region, including phosphorylated Tyr, of CD28. We found that trisubstituted carboranes efficiently increased the proliferation of T cells obtained from C57BL/6 mice. The carboranes specifically increased the binding of Grb2 Src homology 2 (SH2) to CD28-derived phosphopeptide but decreased the binding of PI3K C-terminal SH2 (cSH2). Based on the crystal structures of CD28-derived phosphopeptides complexed with Grb2 SH2 and PI3K cSH2, the bound structures of compound 4 (CRL266481) were modeled to determine the molecular mechanism of the regulation.

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http://dx.doi.org/10.1016/j.bmcl.2022.129049DOI Listing

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