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 #
5R01AI089441-04
Application #
8485534
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
2013-07-01
Budget End
2014-06-30
Support Year
4
Fiscal Year
2013
Total Cost
$929,801
Indirect Cost
$248,027
Name
University of Washington
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
605799469
City
Seattle
State
WA
Country
United States
Zip Code
98195
Bansal, Abhisheka; Ojo, Kayode K; Mu, Jianbing et al. (2016) Reduced Activity of Mutant Calcium-Dependent Protein Kinase 1 Is Compensated in Plasmodium falciparum through the Action of Protein Kinase G. MBio 7:
Huang, Wenlin; Hulverson, Matthew A; Zhang, Zhongsheng et al. (2016) 5-Aminopyrazole-4-carboxamide analogues are selective inhibitors of Plasmodium falciparum microgametocyte exflagellation and potential malaria transmission blocking agents. Bioorg Med Chem Lett 26:5487-5491
Castellanos-Gonzalez, Alejandro; Sparks, Hayley; Nava, Samantha et al. (2016) A Novel Calcium-Dependent Kinase Inhibitor, Bumped Kinase Inhibitor 1517, Cures Cryptosporidiosis in Immunosuppressed Mice. J Infect Dis 214:1850-1855
Vidadala, Rama Subba Rao; Rivas, Kasey L; Ojo, Kayode K et al. (2016) Development of an Orally Available and Central Nervous System (CNS) Penetrant Toxoplasma gondii Calcium-Dependent Protein Kinase 1 (TgCDPK1) Inhibitor with Minimal Human Ether-a-go-go-Related Gene (hERG) Activity for the Treatment of Toxoplasmosis. J Med Chem 59:6531-46
Ojo, Kayode K; Dangoudoubiyam, Sriveny; Verma, Shiv K et al. (2016) Selective inhibition of Sarcocystis neurona calcium-dependent protein kinase 1 for equine protozoal myeloencephalitis therapy. Int J Parasitol 46:871-880
Pedroni, Monica J; Vidadala, Rama Subba Rao; Choi, Ryan et al. (2016) Bumped kinase inhibitor prohibits egression in Babesia bovis. Vet Parasitol 215:22-8
Hines, Siddra A; Ramsay, Joshua D; Kappmeyer, Lowell S et al. (2015) Theileria equi isolates vary in susceptibility to imidocarb dipropionate but demonstrate uniform in vitro susceptibility to a bumped kinase inhibitor. Parasit Vectors 8:33
Huang, Wenlin; Ojo, Kayode K; Zhang, Zhongsheng et al. (2015) SAR Studies of 5-Aminopyrazole-4-carboxamide Analogues as Potent and Selective Inhibitors of Toxoplasma gondii CDPK1. ACS Med Chem Lett 6:1184-1189
Sparks, Hayley; Nair, Gayatri; Castellanos-Gonzalez, Alejandro et al. (2015) Treatment of Cryptosporidium: What We Know, Gaps, and the Way Forward. Curr Trop Med Rep 2:181-187
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

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