title: Enzymes Involved in Pyrophosphate and Calcium Metabolism as Targets for Anti-scuticociliate Chemotherapy.
abstract: Inorganic pyrophosphate (PPi) is a key metabolite in cellular bioenergetics under chronic stress conditions in prokaryotes, protists and plants. Inorganic pyrophosphatases (PPases) are essential enzymes controlling the cellular concentration of PPi and mediating intracellular pH and Ca(2+) homeostasis. We report the effects of the antimalarial drugs chloroquine (CQ) and artemisinin (ART) on the in vitro growth of Philasterides dicentrarchi, a scuticociliate parasite of turbot; we also evaluated the action of these drugs on soluble (sPPases) and vacuolar H+-PPases (H+-PPases). CQ and ART inhibited the in vitro growth of ciliates with IC50 values of respectively 74 ± 9 μM and 80 ± 8 μM. CQ inhibits the H+ translocation (with an IC50 of 13.4 ± 0.2 μM), while ART increased translocation of H+ and acidification. However, both drugs caused a decrease in gene expression of H+-PPases. CQ significantly inhibited the enzymatic activity of sPPases, decreasing the consumption of intracellular PPi. ART inhibited intracellular accumulation of Ca(2+) induced by ATP, indicating an effect on the Ca(2+) -ATPase. The results suggest that CQ and ART deregulate enzymes associated with PPi and Ca(2+) metabolism, altering the intracellular pH homeostasis vital for parasite survival and providing a target for the development of new drugs against scuticociliatosis.
authors.affiliation: Departamento de Microbiología y Parasitología, Instituto de Investigación y Análisis Alimentarios, Universidad de Santiago de Compostela, Santiago de Compostela, Spain.
authors.forename: Natalia
authors.initials: N
authors.lastname: Mallo
authors.affiliation: Departamento de Biología Celular y Ecología, Facultad de Biología, Instituto de Acuicultura, Universidad de Santiago de Compostela, Santiago de Compostela, Spain.
authors.forename: Jesús
authors.initials: J
authors.lastname: Lamas
authors.affiliation: Departamento de Microbiología y Parasitología, Instituto de Investigación y Análisis Alimentarios, Universidad de Santiago de Compostela, Santiago de Compostela, Spain.
authors.forename: Ana-Paula
authors.initials: AP
authors.lastname: DeFelipe
authors.affiliation: Departamento de Microbiología y Parasitología, Instituto de Investigación y Análisis Alimentarios, Universidad de Santiago de Compostela, Santiago de Compostela, Spain.|Departamento de Biología Celular y Ecología, Facultad de Biología, Instituto de Acuicultura, Universidad de Santiago de Compostela, Santiago de Compostela, Spain.
authors.forename: Rosa-Ana
authors.initials: RA
authors.lastname: Sueiro
authors.affiliation: Departamento de Biología Celular y Ecología, Facultad de Biología, Instituto de Acuicultura, Universidad de Santiago de Compostela, Santiago de Compostela, Spain.
authors.forename: Francisco
authors.initials: F
authors.lastname: Fontenla
authors.affiliation: Departamento de Microbiología y Parasitología, Instituto de Investigación y Análisis Alimentarios, Universidad de Santiago de Compostela, Santiago de Compostela, Spain.
authors.forename: José-Manuel
authors.initials: JM
authors.lastname: Leiro
mesh_terms: D000818:Animals; D037621:Artemisinins / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002738:Chloroquine / Q000494:pharmacology; D016798:Ciliophora / Q000187:drug effects* / Q000201:enzymology* / Q000254:growth & development; D016770:Ciliophora Infections / Q000469:parasitology / Q000662:veterinary; D011756:Diphosphates / Q000378:metabolism*; D005393:Fish Diseases / Q000469:parasitology; D005412:Flatfishes / Q000469:parasitology*; D006706:Homeostasis / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D020128:Inhibitory Concentration 50; D043564:Inorganic Pyrophosphatase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: D037621:Artemisinins; D011756:Diphosphates; D002738:Chloroquine; C031327:artemisinin; D043564:Inorganic Pyrophosphatase; D002118:Calcium
keywords: Artemisinin; Philasterides dicentrarchi; chloroquine; inorganic pyrophosphatases; intracellular pH