Tracking the ancestral functions of erythropoietin: neuroprotection & mitochondria

Abstract

It has long been thought that erythropoietin (Epo) is exclusively involved in erythropoiesis, allowing erythroid progenitor cells to survive and mature through their antiapoptotic action. We now know that Epo in mammals has also other functions in the brain, playing key roles in the development, maintenance, protection, and repair of the nervous system. However, the recombinant human Epo (rhEpo) has neuroprotective effects in orthoptera insects (such as grasshoppers), and this effect appears to be mediated by the cytokine receptor‐like factor 3 (CRLF3), raising interesting questions about the evolutionary origin of the Epo signaling pathway and its role in invertebrate species. Taking into account that: 1) Epo in mammals modulates the mitochondrial oxidative phosphorylation and the production of reactive oxygen species (ROS) in several tissues, including the brain; and 2) that insects appeared during a geological period (Cambrian explosion) in which the atmospheric O 2 was increasing and required the implementation of antioxidant systems at the cellular level; here we tested the hypothesis that activation of the “Epo‐like” system in the brain domestic crickets ( Acheta domesticus ) exposed to 6 % of hypoxia during 5 days , modulates mitochondrial functions for preventing against oxidative damages. To do so, we used our oxygraph‐2K system (OROBOROS) that measures the mitochondrial bioenergetics in saponin‐permeabilized tissue of 2 mg weight. Our preliminary results showed that rhEpo increased the survival of domestic crickets exposed to hypoxia by 20%. We showed also that, in normoxic animals, rhEpo increased the mitochondrial O2 consumption rate (OCR), but in hypoxic animals, rhEPO limited the increase of mitochondrial OCR. In parallel, rhEpo significantly decreased the production of ROS in hypoxia. These preliminary results suggest that rhEpo significantly improves cricket’s survival under hypoxia, by promoting a robust antioxidant effect through mitochondria. Our data also suggest that a neuroprotective “Epo‐like” endogenous molecule evolved during the “Cambrian explosion” from a urbilaterian (common to vertebrates and invertebrates) ancestor. Support or Funding Information Natural Sciences and Engineering Research Council of Canada