A store-operated Ca2+-entry in Trypanosoma equiperdum: Physiological evidences of its presence

Abstract

The Trypanosomatidae family encompasses many unicellular organisms responsible of several tropical diseases that affect humans and animals. Livestock tripanosomosis caused by Trypanosoma brucei brucei (T. brucei), Trypanosoma equiperdum (T. equiperdum) and Trypanosoma evansi (T. evansi), have a significant socio-economic impact and limit animal protein productivity throughout the intertropical zones of the world. Similarly, to all organisms, the maintenance of Ca²⁺ homeostasis is vital for these parasites, and the mechanism involved in the intracellular Ca²⁺ regulation have been widely described. However, the evidences related to the mechanisms responsible for the Ca²⁺ entry are scarce. Even more, to date the presence of a store-operated Ca²⁺ channel (SOC) has not been reported. Despite the apparent absence of Orai and STIM-like proteins in these parasites, in the present work we demonstrate the presence of a store-operated Ca²⁺-entry (SOCE) in T. equiperdum, using physiological techniques. This Ca²⁺-entry is induced by thapsigargin (TG) and 2,5-di-t-butyl-1,4-benzohydroquinone (BHQ), and inhibited by 2-aminoethoxydiphenyl borate (2APB). Additionally, the use of bioinformatics techniques allowed us to identify putative transient receptor potential (TRP) channels, present in members of the Trypanozoon family, which would be possible candidates responsible for the SOCE described in the present work in T. equiperdum.

Keywords: 2, 5-di-t-butyl-1, 4-benzohydroquinone (BHQ); 2-aminoethoxydiphenyl borate (2APB); Ca(2+)-channel; Store operated calcium entry (SOCE); Thapsigargin (TG); Trypanosoma equiperdum.