Abstract
G protein–coupled receptor kinases (GRKs) phosphorylate activated receptors to promote arrestin binding, decoupling from heterotrimeric G proteins, and internalization. GRK2 and GRK5 are overexpressed in the failing heart and thus have become therapeutic targets. Previously, we discovered two classes of GRK2-selective inhibitors, one stemming from GSK180736A, a Rho-associated coiled-coil containing kinase 1 (ROCK1) inhibitor, the other from paroxetine, a selective serotonin-reuptake inhibitor. These two classes of compounds bind to the GRK2 active site in a similar configuration but contain different hinge-binding “warheads”: indazole and benzodioxole, respectively. We surmised from our prior studies that an indazole would be the stronger hinge binder and would impart increased potency when substituted for benzodioxole in paroxetine derivatives. To test this hypothesis, we synthesized a series of hybrid compounds that allowed us to compare the effects of inhibitors that differ only in the identity of the warhead. The indazole-paroxetine analogs were indeed more potent than their respective benzodioxole derivatives but lost selectivity. To investigate how these two warheads dictate selectivity, we determined the crystal structures of three of the indazole hybrid compounds (CCG224061, CCG257284, and CCG258748) in complex with GRK2–Gβγ. Comparison of these structures with those of analogous benzodioxole-containing complexes confirmed that the indazole-paroxetine hybrids form stronger interactions with the hinge of the kinase but also stabilize a distinct conformation of the kinase domain of GRK2 compared with previous complexes with paroxetine analogs. This conformation is analogous to one that can be assumed by GRK5, at least partially explaining the loss in selectivity.
Footnotes
- Received August 3, 2017.
- Accepted October 11, 2017.
↵1 R.B. and H.V.W. contributed equally to this work.
The work at University of Michigan was supported by the National Institutes of Health ((NIH) National Heart, Lung, and Blood Institute [Grants HL071818 and HL122416] to J.J.G.T.; the American Heart Association [Grant 15PRE22730028] to H.V.W.; and the University of Michigan Chemistry-Biology Interface (CBI) training program NIH [Grant 5T32GM008597] to M.C.C. The work at Temple University was supported by the NIH [Grants R37 HL061690, P01 HL075443, P01 HL108806, and P01 HL091799] to W.J.K. Use of the Advanced Photon Source was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract no. DE-AC02-06CH11357, and the use of LS-CAT sector 12 was supported by the Michigan Economic Development Corporation and Michigan Technology Tri-Corridor Grant [Grant 085P1000817].
↵This article has supplemental material available at molpharm.aspetjournals.org.
- Copyright © 2017 by The American Society for Pharmacology and Experimental Therapeutics
MolPharm articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|