New therapeutics are needed for infections caused by Cryptosporidium parvum and Toxoplasma gondii. Calcium dependent protein kinase 1 (CDPK1) of T. gondii is thought to be critical for the invasion process of T. gondii and thus is a drug target for toxoplasmosis. By inference, the homologous CDPK of C. parvum is likely to be critical for infection by cryptosporidium. We have solved the crystal structures of TgCDPK1 and CpCDPK1 and have shown the active sites are susceptible to "bumped" kinase inhibitors (BKI) that do not inhibit mammalian kinases. This differential sensitivity is due to the absence of a bulky gatekeeper side chain in the ATP binding site of both TgCDPK1 and CpCDPK1 that is present in mammalian protein kinases. Thus, these BKI offer tremendous selectivity for inhibition of TgCDPK1 &CpCDPK1 vs. human kinases. Furthermore, BKI compounds have shown minimal toxicity in mice when administered in the course of other work. Our preliminary results show that multiple BKI compounds based on a known scaffold can inhibit TgCDPK1 &CpCDPK1 and also inhibit T. gondii and C. parvum cell invasion at low-mid nanomolar concentrations. Expression of a mutant TgCDPK1 with a Met gatekeeper in T. gondii cells leads to resistance to the BKI effect, demonstrating the BKI inhibits cell entry via CDPK1. We will develop compounds that are orally bioavailable, sufficiently potent, lack toxicity, and cure animal models of T. gondii and/or C. parvum. By the end of this project we expect to identify and characterize 2 to 4 leads for evaluation as potential drugs for cryptosporidiosis and toxoplasmosis. This project will initiate development of new drugs to treat diseases caused by two parasitic protozoa, Cryptosporidium and Toxoplasma that are commonly transmitted by consumption of impure food or water. We have identified a class of chemical compounds that specifically inhibit a particular protein used by these parasites to invade human cells. We will design and characterize compounds of this class that are nontoxic to humans but effective in treating infection. Relevance: This project will initiate development of new drugs to treat diseases caused by two parasitic protozoa, Cryptosporidium and Toxoplasma, that are commonly transmitted by consumption of impure food or water. We have identified a class of chemical compounds that specifically inhibit a particular protein used by these parasites to invade human cells. We will design and characterize compounds of this class that are nontoxic to humans but effective in treating infection.

Public Health Relevance

This project will initiate development of new drugs to treat diseases caused by two parasitic protozoa, Cryptosporidium and Toxoplasma, that are commonly transmitted by consumption of impure food or water. We have identified a class of chemical compounds that specifically inhibit a particular protein used by these parasites to invade human cells. We will design and characterize compounds of this class that are nontoxic to humans but effective in treating infection.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI089441-03
Application #
8288293
Study Section
Special Emphasis Panel (ZAI1-GPJ-M (M1))
Program Officer
Rogers, Martin J
Project Start
2010-07-01
Project End
2015-06-30
Budget Start
2012-07-01
Budget End
2013-06-30
Support Year
3
Fiscal Year
2012
Total Cost
$992,830
Indirect Cost
$265,180
Name
University of Washington
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
605799469
City
Seattle
State
WA
Country
United States
Zip Code
98195
Doggett, J Stone; Ojo, Kayode K; Fan, Erkang et al. (2014) Bumped kinase inhibitor 1294 treats established Toxoplasma gondii infection. Antimicrob Agents Chemother 58:3547-9
Keyloun, Katelyn R; Reid, Molly C; Choi, Ryan et al. (2014) The gatekeeper residue and beyond: homologous calcium-dependent protein kinases as drug development targets for veterinarian Apicomplexa parasites. Parasitology 141:1499-509
Vidadala, Rama Subba Rao; Ojo, Kayode K; Johnson, Steven M et al. (2014) Development of potent and selective Plasmodium falciparum calcium-dependent protein kinase 4 (PfCDPK4) inhibitors that block the transmission of malaria to mosquitoes. Eur J Med Chem 74:562-73
Zhang, Zhongsheng; Ojo, Kayode K; Vidadala, Ramasubbarao et al. (2014) Potent and selective inhibitors of CDPK1 from T. gondii and C. parvum based on a 5-aminopyrazole-4-carboxamide scaffold. ACS Med Chem Lett 5:40-44
Crowther, Gregory J; Booker, Michael L; He, Min et al. (2014) Cofactor-independent phosphoglycerate mutase from nematodes has limited druggability, as revealed by two high-throughput screens. PLoS Negl Trop Dis 8:e2628
Ojo, Kayode K; Reid, Molly C; Kallur Siddaramaiah, Latha et al. (2014) Neospora caninum calcium-dependent protein kinase 1 is an effective drug target for neosporosis therapy. PLoS One 9:e92929
Ojo, Kayode K; Eastman, Richard T; Vidadala, Ramasubbarao et al. (2014) A specific inhibitor of PfCDPK4 blocks malaria transmission: chemical-genetic validation. J Infect Dis 209:275-84
Hari, Sanjay B; Merritt, Ethan A; Maly, Dustin J (2013) Sequence determinants of a specific inactive protein kinase conformation. Chem Biol 20:806-15
Krishnamurty, Ratika; Brigham, Jennifer L; Leonard, Stephen E et al. (2013) Active site profiling reveals coupling between domains in SRC-family kinases. Nat Chem Biol 9:43-50
Castellanos-Gonzalez, Alejandro; White Jr, A Clinton; Ojo, Kayode K et al. (2013) A novel calcium-dependent protein kinase inhibitor as a lead compound for treating cryptosporidiosis. J Infect Dis 208:1342-8

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