PEPCK and glucose metabolism homeostasis in arthropods.

The fat body is responsible for a variety of functions related to energy metabolism in arthropods, by controlling the processes of de novo glucose production (gluconeogenesis) and glycogen metabolism. The rate-limiting factor of gluconeogenesis is the enzyme phosphoenolpyruvate carboxykinase (PEPCK), generally considered to be the first committed step in this pathway. Although the study of PEPCK and gluconeogenesis has been for decades restricted to mammalian models, especially focusing on muscle and liver tissue, current research has demonstrated particularities about the regulation of this enzyme in arthropods, and described new functions. This review will focus on arthropod PEPCK, discuss different aspects to PEPCK regulation and function, its general role in the regulation of gluconeogenesis and other pathways. The text also presents our views on potentially important new directions for research involving this enzyme in a variety of metabolic adaptations (e.g. diapause), discussing enzyme isoforms, roles during arthropod embryogenesis, as well as involvement in vector-pathogen interactions, contributing to a better understanding of insect vectors of diseases and their control.

Wolbachia pipientis modulates metabolism and immunity during Aedes fluviatilis oogenesis.

Wolbachia pipientis is a maternally transmitted bacterium that mostly colonizes arthropods, including the mosquito Aedes fluviatilis, potentially affecting different aspects of host physiology. This intracellular bacterium prefers gonadal tissue cells, interfering with the reproductive cycle of insects, arachnids, crustaceans, and nematodes. Wolbachia's ability to modulate the host's reproduction is related to its success in prevalence and frequency. Infecting oocytes is essential for vertical propagation, ensuring its presence in the germline. The mosquito Ae. fluviatilis is a natural host for this bacterium and therefore represents an excellent experimental model in the effort to understand host-symbiont interactions and the mutual metabolic regulation. The aim of this study was to comparatively describe metabolic changes in naturally Wolbachia-infected and uninfected ovaries of Ae. fluviatilis during the vitellogenic period of oogenesis, thus increasing the knowledge about Wolbachia parasitic/symbiotic mechanisms.

Redox imbalance induces remodeling of glucose metabolism in Rhipicephalus microplus embryonic cell line.

Carbohydrate metabolism not only functions in supplying cellular energy but also has an important role in maintaining physiological homeostasis and in preventing oxidative damage caused by reactive oxygen species. Previously, we showed that arthropod embryonic cell lines have high tolerance to H2O2 exposure. Here, we describe that Rhipicephalus microplus tick embryonic cell line (BME26) employs an adaptive glucose metabolism mechanism that confers tolerance to hydrogen peroxide at concentrations too high for other organisms. This adaptive mechanism sustained by glucose metabolism remodeling promotes cell survival and redox balance in BME26 cell line after millimolar H2O2 exposure. The present work shows that this tick cell line could tolerate high H2O2 concentrations by initiating a carbohydrate-related adaptive response. We demonstrate that gluconeogenesis was induced as a compensation strategy that involved, among other molecules, the metabolic enzymes NADP-ICDH, G6PDH, and PEPCK. We also found that this phenomenon was coupled to glycogen accumulation and glucose uptake, supporting the pentose phosphate pathway to sustain NADPH production and leading to cell survival and proliferation. Our findings suggest that the described response is not atypical, being also observed in cancer cells, which highlights the importance of this model to all proliferative cells. We propose that these results will be useful in generating basic biological information to support the development of new strategies for disease treatment and parasite control.