E-Poster Presentation ESA-SRB-ANZBMS 2021

Dysfunction of macroautophagy and mitophagy in the aged oocyte (#547)

Alexandra E Peters 1 2 , Shandelle J Caban 1 2 , Eileen A McLaughlin 1 2 3 4 , Shaun D Roman 1 2 5 , Kirsty G Pringle 1 2 , Elizabeth G Bromfield 1 2 6 , Brett Nixon 1 2 , Jessie M Sutherland 1 2
  1. Priority Research Centre for Reproductive Science, Schools of Biomedical Science & Pharmacy and Environmental & Life Sciences, University of Newcastle, Callaghan, New South Wales, Australia
  2. Pregnancy and Reproduction Program, Hunter Medical Research Institute, New Lambton Heights, New South Wales, Australia
  3. School of Science, Western Sydney University, Penrith , New South Wales, Australia
  4. School of Biological Sciences, Faculty of Science, The University of Auckland, Auckland, New Zealand
  5. Priority Research Centre for Drug Development, University of Newcastle, Callaghan, New South Wales, Australia
  6. Department of Biochemistry & Cell Biology, Faculty of Veterinary Medicine, Utrecht University , The Netherlands

The precipitous age-related decline in human female fertility is accompanied by an increase in poor-quality oocytes within the ovary. The autophagy pathways including macroautophagy, mitophagy, and chaperone-mediated autophagy are essential mechanisms of protein degradation responsible for maintaining cell health and promoting healthy ageing. However, there is a limited understanding of these pathways in the context of oocyte health, ageing, and ultimately human infertility. To investigate this, oocytes were collected at young (4 week-old) and aged (12 month-old) time points from C57BL/6 x CBA mice before being assessed for the presence and functional competence of autophagy pathways. Using comprehensive image analysis of macroautophagy pathway markers, we have previously demonstrated the impairment of the macroautophagy pathway in aged oocytes, harbouring a reduction of autophagosome and lysosome number. This was accompanied by an accumulation of large amphisomes (greater than 10 μm2 in area) in aged oocytes that was mimicked in young oocytes treated with lysosomal inhibitor chloroquine1. In this study we assess another autophagy pathway, mitophagy, by initially assessing the markers microtubule-associated protein 1 light chain 3B (LC3B; a constituent of the autophagosome membrane), and translocase of outer mitochondrial membrane 20 (TOMM20). Increased co-localisation of LC3B and TOMM20 markers in aged oocytes was evident indicating a potential increase in mitophagy with ageing (P < 0.05). These findings may provide a link between autophagy pathway dynamics and the known phenomenon of age-related mitochondrial dysfunction within oocytes. Overall, these data highlight dysfunctional autophagy pathways and lysosomal mechanisms as important contributors to the deterioration of oocyte quality in aged mice. Further characterisation of autophagy pathways and the mechanistic basis by which they regulate oocyte quality may ultimately inform the development of therapeutic strategies to maintain pre-ovulatory oocyte health, particularly in older women.

 

 

  1. 1. Peters, A. E., Caban, S. J., McLaughlin, E. A., Roman, S. D., Bromfield, E. G., Nixon, B., & Sutherland, J. M. (2021). The Impact of Aging on Macroautophagy in the Pre-ovulatory Mouse Oocyte. Frontiers in cell and developmental biology, 9, 691826. https://doi.org/10.3389/fcell.2021.691826