Oocyte mitochondria: role on fertility and disease transmission

Abstract

Oocyte mitochondria are increased in number, smaller, and rounder in appearance than mitochondria in somatic cells. Moreover, mitochondrial numbers and activity are narrowly tied with oocyte quality because of the key role of mitochondria to oocyte maturation. During oocyte maturation, mitochondria display great mobility and cluster at specific sites to meet the high energy demand. Conversely, oocyte mitochondria are not required during early oogenesis as coupling with granulosa cells is sufficient to support gamete's needs. In part, this might be explained by the importance of protecting mitochondria from oxidative damage that result in mutations in mitochondrial DNA (mtDNA). Considering mitochondria are transmitted exclusively by the mother, oocytes with mtDNA mutations may lead to diseases in offspring. Thus, to counterbalance mutation expansion, the oocyte has developed specific mechanisms to filter out deleterious mtDNA molecules. Herein, we discuss the role of mitochondria on oocyte developmental potential and recent evidence supporting a purifying filter against deleterious mtDNA mutations in oocytes.

The mitochondrial protease LONP1 maintains oocyte development and survival by suppressing nuclear translocation of AIFM1 in mammals

“…During meiosis in oocyte maturation, mitochondria appear to undergo fission more frequently than fusion. 33 In contrast, LONP1 deletion in oocytes alters the balance of mitochondrial dynamics and leads to mitochondrial dysfunction. Similarly, Lonp1 knockout in the heart affects Opa1, as we reported previously, causing an imbalance between fission and fusion.…”

The Pre-Conception Maternal Exposure To Sofosbuvir Impacts The Mitochondrial Biogenesis In Prenatal Fetal Tissues: Experimental Study On Rats

“…The low ovarian mtDNA-CN is a marker of poor oocyte quality, which may lead to poor embryonic development [16] . The maternal mitochondrial dysfunctions and impaired biogenesis may be transmitted to following generations and may cause many diseases [17] . Also, the possible direct effects of the Sofosbuvir administered before pregnancy cannot be ruled out since animal studies prove that Sofosbuvir metabolites cross the placenta and are excreted in the milk of nursing animals [18] .…”

Mitochondria in reproduction

“…The reconstituted zygote contains the original parental nuclear DNA and a mixture of mtDNA from the recipient and donor oocytes [21,[65][66][67][68]. The donor ooplasm is thought to contain healthy mitochondria and other beneficial cytosolic factors that promote development and embryogenesis [41,69,70]. Although this technique was initially developed to improve oocytes with poor-quality cytoplasm using animal models, it has been employed as an ART and led to clinical outcomes [21,66].…”

“…There are more mitochondria in oocytes than in somatic cells, and mitochondria are smaller and rounder in the former than in the latter [ 41 ]. Moreover, the number and activity of mitochondria are tightly linked with oocyte quality owing to the key role of mitochondria in oocyte maturation [ 33 ].…”