Inhibition of SHP2 and SHP1 Protein Tyrosine Phosphatase Activity by Chemically Induced Dimerization

Abstract

Protein tyrosine phosphatases (PTPs), the enzymes that catalyze the dephosphorylation of phosphotyrosine residues, are important regulators of mammalian cell signaling, whose activity is misregulated in numerous human diseases. PTPs are also notoriously difficult to selectively modulate with small molecules, and relatively few small-molecule tools for controlling their activities in the context of complex signaling pathways have been developed. Here, we show that a chemical inducer of dimerization (CID) can be used to selectively and potently inhibit constructs of Src-homology-2-containing PTP 2 (SHP2) that have been engineered to contain dimerization domains. Our strategy was inspired by the naturally occurring mechanism of SHP2 regulation, in which the PTP activity of SHP2’s catalytic domain is autoinhibited through an intramolecular interaction with the protein’s N-terminal SH2 (N-SH2) domain. We have re-engineered this inhibitory interaction to function intermolecularly by independently fusing the SHP2 catalytic and N-SH2 domains to protein domains that heterodimerize upon the introduction of the CID rapamycin. We show that rapamycin-induced protein dimerization leads to potent inhibition of SHP2’s catalytic activity, which is driven by increased proximity of the SHP2 catalytic and N-SH2 domains. We also demonstrate that CID-based inhibition of PTP activity can be applied to an oncogenic gain-of-function SHP2 mutant (E76K SHP2) and to the catalytic domain of the SHP2’s closest homologue, SHP1. In sum, CID-driven inhibition of PTP activity provides a broadly applicable tool for inhibiting dimerizable forms of the SHP PTPs and represents a novel paradigm for selective PTP inhibition through inducible protein–protein interactions.