Autophagy is not involved in the degradation of sperm mitochondria after fertilization in mice.

In almost all animals, mitochondrial DNA (mtDNA) is transmitted only from the female, while the paternal mitochondria and mtDNA are thought to be eliminated during early embryogenesis. Autophagy is involved in the elimination of sperm mitochondria and mtDNA in early embryos in Caenorhabditis elegans; however, solid evidence is still lacking in mammals. Recently, we found that despite the fact that some autophagy-related proteins, such as SQSTM1 and LC3 could localize nearby sperm mitochondria before the 2-cell stage, autophagy did not participate in the elimination of sperm mitochondria and mtDNA. Instead, the pre-elimination of sperm mtDNA before fertilization and the restriction of sperm mitochondria in one blastomere before 4-cell stage embryos are the most important mechanisms of maternal mitochondrial inheritance in mice.