Adenosine-binding motif mimicry and cellular effects of a thieno[2,3-d]pyrimidine-based chemical inhibitor of atypical protein kinase C isozymes

The atypical protein kinase C (aPKC) isoforms iota (ι) and zeta (ζ) play crucial roles in the formation and maintenance of cell polarity and represent attractive anti-oncogenic drug targets in Ras-dependent tumours. To date, few isoform-specific chemical biology tools are available to inhibit aPKC catalytic activity. Here we describe the identification and functional characterization of potent and selective thieno[2,3-d]pyrimidine-based chemical inhibitors of aPKCs. A crystal structure of human PKCiota kinase domain bound to a representative compound, CRT0066854, reveals the basis for potent and selective chemical inhibition. Furthermore, CRT0066854 displaces a crucial Asn-Phe-Asp motif that is part of the adenosine-binding pocket and engages an acidic patch used by arginine-rich PKC substrates. We show that CRT0066854 inhibits the lethal giant larvae 2 (LLGL2) phosphorylation in cell lines and exhibits phenotypic effects in a range of cell-based assays. We conclude that this compound has utility as a chemical tool to modulate aPKC activity in vitro and in vivo and may guide the search for further aPKC-selective inhibitors.

Source: BJ Signal - February 18, 2013 Category: Biochemistry Authors: S Kjær, M Linch, A Purkiss, B Kostelecky, P P Knowles, C Rosse, P Riou, C Soudy, S Kaye, B Patel, E Soriano, J Murray-Rust, C Barton, C Dillon, J Roffey, P J Parker, N Q McDonald Tags: BJ ChemBio Source Type: research