Peroxiredoxin 6 is essential to fight oxidative stress in human spermatozoa

MARÍA CELIA FERNÁNDEZ; ADEL R. MOAWAD; CRISTIAN O´FLAHERTY

Encuentro; CHHD annual retreat; 2017

Background: Our laboratory is pioneer in characterizing the family of antioxidant called peroxiredoxins(PRDXs) and establishing their role in the antioxidant protection of human spermatozoa. Indeed, we foundthat spermatozoa from infertile men have low amount of PRDXs, particularly PRDX1 and 6. However, it isunknown whether human spermatozoa is able to re-activate PRDXs when facing an oxidative stress.Objective: We aimed to determine the impact of the inhibition of different players of the PRDX system onthe reactive oxygen species (ROS) levels, viability, DNA oxidation and 4-hydroxynonenal (4-HNE) productionin human spermatozoa.Materials and Methods: Highly motile spermatozoa from healthy donors were incubated with inhibitors ofthe PRDX system and viability, mitochondrial membrane potential (MMP), ROS levels, DNA oxidation and4HNE production were assessed by flow cytometry using Calcein-AM, JC-1, MitoSOX-Red (O2?-), APF (HO?,)and H2DCFDA (ONOO-, ROO?), the anti-8-OHdG, and anti-4HNE antibodies, respectively.Results: We observed that the inhibition of the calcium independent phospholipase A2 (iPLA2) activity ofPRDX6 with MJ33 significantly decreased viability, and increased ROS levels and DNA oxidation inspermatozoa. Moreover, the peroxidase activity of PRDX6 was proven to be essential to scavenge ONOO-.Although the inhibition of the 2-Cys PRDXs decreased viability and significant increased mitochondrial O2?-production, the sole inhibition of PRDX6-PLA2 activity generated cytotoxic aldehydes like 4-HNE, a knownlipid peroxidation product, and a decrease of MMP.Conclusion: PRDXs, and especially the PRDX6 iPLA2 activity, are essential in maintaining viability and DNAintegrity in spermatozoa. This study will help to design new diagnostic tools and personalized therapy totreat male infertility