Abstract
Phosphatidylinositol (3,4,5) trisphosphate (PIP3)-dependent Rac exchanger 1 (P-Rex1) is a Rho guanine-nucleotide exchange factor that was originally discovered in neutrophils and is regulated by G protein βγ subunits and the lipid PIP3 in response to chemoattractants. P-Rex1 has also become increasingly recognized for its role in promoting metastasis of breast cancer, prostate cancer, and melanoma. Recent structural, biochemical, and biologic work has shown that binding of PIP3 to the pleckstrin homology (PH) domain of P-Rex1 is required for its activation in cells. Here, differential scanning fluorimetry was used in a medium-throughput screen to identify six small molecules that interact with the P-Rex1 PH domain and block binding of and activation by PIP3. Three of these compounds inhibit N-formylmethionyl-leucyl-phenylalanine induced spreading of human neutrophils as well as activation of the GTPase Rac2, both of which are downstream effects of P-Rex1 activity. Furthermore, one of these compounds reduces neutrophil velocity and inhibits neutrophil recruitment in response to inflammation in a zebrafish model. These results suggest that the PH domain of P-Rex1 is a tractable drug target and that these compounds might be useful for inhibiting P-Rex1 in other experimental contexts.
SIGNIFICANCE STATEMENT A set of small molecules identified in a thermal shift screen directed against the phosphatidylinositol (3,4,5) trisphosphate–dependent Rac exchanger 1 (P-Rex1) pleckstrin homology domain has effects consistent with P-Rex1 inhibition in neutrophils.
Footnotes
- Received June 11, 2019.
- Accepted December 19, 2019.
This work was supported by the National Institutes of Health (NIH) National Cancer Institute and National Heart, Lung, and Blood Institute [Grants R01CA221289, R01HL122416, R01HL071818], a University of Michigan Center for the Discovery of New Medicines FY15 Round 1 grant, and the Walther Cancer Foundation (J.J.G.T.), the NIH National Institue of General Medical Sciences [Grant R35GM127303] (A.V.S.), a Michigan Pharmacology Centennial Fund Predoctoral Fellowship and a Benedict and Diana Lucchesi Fellowship (N.R.C.), the NIH National Institue of General Medical Sciences [Grant R35GM119787] (Q.D.), and a Purdue Cagiantas fellowship (A.Y.H). This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under contract number DE-AC02-06CH11357. Use of the Life Sciences Collaborative Access Team Sector 21 was supported by the Michigan Economic Development Corporation and the Michigan Technology Tri-Corridor (Grant 085P1000817). The authors would also like to acknowledge the contribution of American Cancer Society – Michigan Cancer Research Fund Postdoctoral Fellowship PF-14-224-01-DMC (J.N.C).
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- Copyright © 2020 by The American Society for Pharmacology and Experimental Therapeutics
