Regulation of mitochondrial polarity in mouse and human oocytes: the influence of cumulus derived nitric oxide

Abstract

Whether exogenous factors influenced the level of mitochondrial polarity (DeltaPsim) in the subplasmalemmal cytoplasm of the oocyte was investigated with denuded and cumulus-enclosed human and mouse oocytes between the germinal vesicle and metaphase II stage. Co-culture of denuded oocytes with cumulus masses or primary cumulus cell cultures demonstrated a 'proximity' effect with respect to the detectable level of DeltaPsim in the oocyte. The specificity and reversibility of this effect on subplasmalemmal mitochondria were shown by repeated repositioning between cellular and acellular regions, which sequentially down- or up-regulated DeltaPsim. Experimental studies with a nitric oxide (NO) donor and inhibitor of NO synthase indicate that NO produced by cumulus cells has a regulatory influence on DeltaPsim in the subplasmalemmal cytoplasm of the corresponding oocyte. Culture of denuded and cumulus-enclosed (intact) oocytes in low and high oxygen atmospheres suggests that competition between oxygen and NO at the mitochondrial level may regulate the level of DeltaPsim and maintain mitochondria homeostasis in the pre-ovulatory oocyte, with a shift to higher polarity occurring after ovulation. The role of exogenous influences on oocyte DeltaPsim is discussed with respect to the regulation of developmental processes in the oocyte and early embryo.

The Association of Mitochondrial Potential and Copy Number with Pig Oocyte Maturation and Developmental Potential

“…Sequential analysis of individual oocytes and embryos indicates that mitochondria with a high Δφm remain spatially stable during oocyte maturation, fertilization, and initial cleavage [39]. It is likely that FCCP slows the rate of early embryo development.…”

Sperm attachment and penetration competence in the human oocyte: a possible aetiology of fertilization failure involving the organization of oolemmal lipid raft microdomains influenced by the ΔΨm of subplasmalemmal mitochondria

“…While distinct patterns of GM1 lipid raft aggregation seem to correlate with DWm in the corresponding subplasmalemmal cytoplasm, these phenotypes may represent a spectrum of mitochondrial states that establish cell surface conditions that, for some oocytes, are positive for fertilization while not for others. In this context, it may be useful to determine how spatial changes in DWm that occur during preovulatory maturation (Van Blerkom et al, 2008) relate to GM1 lipid raft micro-and macro-domain distribution and density and how they temporally and spatially relate to the acquisition of fertilization competence in the corresponding oolemma. An alternative possibility worthy of investigation is whether the differential organization of lipid raft microdomains in the oolemma, such as those detectable with CTB, influence DWm in the subplasmalemmal domain.…”

Improvement in embryo quality and pregnancy rates by using autologous cumulus body during icsi cycles

“…The interaction and close contact between the cumulus cells and developing oocyte are characterized by the presence of secreted factors (10). The interaction between the oocyte and surrounding cumulus cells is controlled by the oocyte, and this interaction ultimately determines oocyte quality (11), while the cumulus cells play a significant role in the protection of the developing embryo (12). In addition, there is a T cell population detected inside the cumulus cell mass which enhances embryo development (13).…”

“…Signalling interactions between the granulosa, cumulus cells, local extracellular matrix, and oocytes have been well documented in studies on humans, rat, mouse, bovine, and swine. In most of these studies, a genetic site for this interaction was revealed (15), and some of the benefits of this relationship were found to be due to the antioxidant effect of cumulus cells (12). There is a study in the literature (16) using cumulus cells for coculture and embryo transfer, but in their study they separated cumulus cells with hyaluronidase enzyme treatment and so used monolayer cultivation.…”