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Analysis of sperm mitophagy after in vitro fertilization

Grant number: 18/25907-2
Support type:Scholarships in Brazil - Master
Effective date (Start): May 01, 2019
Effective date (End): January 31, 2021
Field of knowledge:Biological Sciences - Morphology
Principal Investigator:Mariana Camargo
Grantee:Karla Pacheco de Melo
Home Institution: Escola Paulista de Medicina (EPM). Universidade Federal de São Paulo (UNIFESP). Campus São Paulo. São Paulo , SP, Brazil

Abstract

It has been described that the mechanism of mitophagy is essential to ensure the uniparental transmission of mtDNA and participating in this mitochondrial degradation we find ubiquitin binding proteins such as E3 ubiquitin ligase Parkin. This protein is responsible for the ubiquitination of the proteins presents in the mitochondrial membrane so that they are directed to the proteasomal protein recycling system. After the decoupling of the mitochondrial proteins, the formation of a double membrane complex occurs around the mitochondria to be degraded (autophagosomes), followed by the lysosomal fusion to the conclusion of the mitophagy. In this way, autophagy and the ubiquitin-proteasome system act together to keep the maternal mitochondrial DNA in the offspring single. Some groups argue that in addition to these pathways of degradation, mitochondrial segregation is also very important to avoid heteroplasmy in embryos, which is responsible for most mitochondrial diseases. Thus, knowing the importance of parkin in the mitophagy that begins in the testicle with the ubiquitination of the intermediate piece and is finished in the embryo, this study aims to contribute to the clarification of mitochondrial degradation and maintenance of sperm functionality in case of mutation of the gene encoding Parkin. Thus, the objective of this work is to evaluate the pathways of paternal mitochondrial degradation in animal model with the mutation of the Parkin gene, after in vitro fertilization. For this, normal and mutated mice will be used in PARK2 to promote Parkin deletion. Spermatozoa were collected from males to evaluate the sperm function (concentration, motility and fragmentation of sperm DNA and mitochondrial activity) and analysis of the ubiquitination, in addition to sperm collection for in vitro fertilization. Females will be stimulated with hormones for the production of gametes and from them the oocytes will be collected for in vitro fertilization. With fertilization, we intend to evaluate mitochondrial segregation and if the mutation generates deficits in the degradation of paternal mitochondria through the degradation pathway of the parkin. (AU)