POLYPHOSPHATE REGULATES HEXOKINASE ACTIVITY AND ROS GENERATION IN MITOCHONDRIA OF RHIPICEPHALUS MICROPLUS EMBRYOS
Autor(es): Amanda Fraga, Criscila de Souza, Naiane Chermauth, Jorge Moraes, José Roberto da Silva, Evenilton Costa, Jackson Menezes, Itabajara da Silva Vaz Jr, Carlos Logullo, Rodrigo Nunes da Fonseca, Eldo Campos
POLYPHOSPHATE REGULATES HEXOKINASE ACTIVITY AND ROS GENERATION IN MITOCHONDRIA OF RHIPICEPHALUS MICROPLUS EMBRYOS
» Área de pesquisa: ENTOMOLOGIA
» Instituição: Universidade Federal do Rio de Janeiro
» Agência de fomento e patrocinadores: Patrocínio: FAPERJ, CNPq and CAPES
The present study focused on the tick Rhipicephalus microplus, which is an important cattle ectoparasite in South and Central Americas, Asia, Africa and Oceania. Polyphosphate (poly P) metabolism in eukaryotic cells shows specific peculiarities for different cellular compartments and the physiological roles of polyphosphates recently found in arthropod mitochondria remains obscure. Here, the possible involvement of poly P with reactive oxygen species generation in mitochondria of Rhipicephalus microplus embryos was investigated. Mitochondria were isolated by differential centrifugation, mitochondrial hexokinase and scavenger antioxidant enzymes, such as superoxide dismutase, catalase, and glutathione reductase were assayed spectrophotometrically during embryogenesis of R. microplus. The influence of poly P3 and poly P15 were analyzed during the period of higher enzymatic activity during embryogenesis. Both poly Ps inhibited hexokinase activity by up to 90% and, interestingly, the mitochondrial membrane exopolyphosphatase activity was stimulated by the hexokinase reaction product, glucose-6-phosphate. Poly P increased hydrogen peroxide generation in mitochondria in a situation where mitochondrial hexokinase is also active. The superoxide dismutase, catalase and glutathione reductase activities were higher during embryo cellularization, at the end of embryogenesis and during embryo segmentation, respectively. All of the enzymes were stimulated by poly P3. However, superoxide dismutase was not affected by poly P15, catalase activity was stimulated only at high concentrations and glutathione reductase was the only enzyme that was stimulated in the same way by both poly Ps. Altogether, our results indicate that inorganic polyphosphate and mitochondrial membrane exopolyphosphatase regulation can be correlated with the generation of reactive oxygen species in the mitochondria of R. microplus embryos.
