Oral Presentation The Joint Annual Scientific Meetings of the Endocrine Society of Australia and the Society for Reproductive Biology 2017

The targeted disruption of lipoxygenase enzymes prevents oxidative stress in the male germline (#122)

Elizabeth Bromfield 1 , Jessica LH Walters 1 , Bettina P Mihalas 1 , Matthew D Dun 2 , Eileen A McLaughlin 3 , John Aitken 1 , Brett Nixon 1
  1. The University of Newcastle, Callaghan, NSW, Australia
  2. Priority Research Centre for Cancer Research, The University of Newcastle, Callaghan, New South Wales, Australia
  3. Biological Sciences, The University of Auckland, Auckland, New Zealand

Germline oxidative stress is responsible for an extensive range of infertile pathologies. Not least of these is a failure of sperm-egg recognition, a distressingly common cause of clinical fertilization failure. Recently, we have established that the lipid peroxidation product 4-hydroxynonenal (4HNE) reduces sperm-egg recognition as it modifies the function and stability of the molecular chaperone, Heat Shock Protein A2 (HSPA2), a protein that facilitates important sperm membrane remodeling events that precede fertilization. The enzymatic generation of 4HNE in somatic cells relies on the action of lipoxygenase enzymes for the oxygenation and degradation of ω-6 polyunsaturated fatty acids (PUFAs). Furthermore, 15-arachidonate lipoxygenase (ALOX15) activity appears to be intrinsically linked with the production of 4HNE. This study sought to develop a new strategy for the prevention of oxidative stress through the targeted inhibition of ALOX15. This work has established that inhibition of ALOX15 using the indole based inhibitor 6,11-dihydro [1] benzothiopyrano [4,3-b] indole (PD146176) in developing germ cells results in a significant reduction in cytoplasmic (P < 0.01) and mitochondrial reactive oxygen species (ROS) (P < 0.001), as well as in the bioavailability of 4HNE (P < 0.001). This in turn ameliorated 4HNE-induced damage to the chaperone HSPA2 and prevented its proteolysis in the testis. Excitingly, our pilot data also reveal extremely positive outcomes for sperm function as the inactivation of ALOX15 resulted in a complete recovery of human sperm-oocyte interaction under conditions of oxidative stress (P < 0.001). This research provides the impetus to explore lipoxygenase-targeted therapeutic interventions to prevent oxidative stress-mediated male infertility.