Pannexins and Connexins: Their Relevance for Oocyte Developmental Competence

Abstract

The oocyte is the major determinant of embryo developmental competence in all mammalian species. Although fundamental advances have been generated in the field of reproductive medicine and assisted reproductive technologies in the past three decades, researchers and clinicians are still trying to elucidate molecular factors and pathways, which could be pivotal for the oocyte’s developmental competence. The cell-to-cell and cell-to-matrix communications are crucial not only for oocytes but also for multicellular organisms in general. This latter mentioned communication is among others possibly due to the Connexin and Pannexin families of large-pore forming channels. Pannexins belong to a protein group of ATP-release channels, therefore of high importance for the oocyte due to its requirements of high energy supply. An increasing body of studies on Pannexins provided evidence that these channels not only play a role during physiological processes of an oocyte but also during pathological circumstances which could lead to the development of diseases or infertility. Connexins are proteins that form membrane channels and gap-junctions, and more precisely, these proteins enable the exchange of some ions and molecules, and therefore they do play a fundamental role in the communication between the oocyte and accompanying cells. Herein, the role of Pannexins and Connexins for the processes of oogenesis, folliculogenesis, oocyte maturation and fertilization will be discussed and, at the end of this review, Pannexin and Connexin related pathologies and their impact on the developmental competence of oocytes will be provided.

Age-associated aberrations of cumulus-oocyte interaction and microfilamentous structure in the zona pellucida decline female fertility

“…The fate of premature oocytes goes to either atresia or failure of ovulation. Replacing Cx37-null mutant mice by specific expression of Cx43 in the oocytes restored the formation of gap junctions and resumed oocyte maturation in follicles, suggesting that the physical linkages between cumulus cells and oocytes are essential (Kordowitzki et al, 2021; Li et al, 2007). However, it remained unclear how aging is associated with the expression of connexin proteins.…”

Influences of Supplementing Selective Members of the Interleukin-6 Cytokine Family on Bovine Oocyte Competency

“…The expression profiling study utilized previously validated cumulus markers of COC competency to describe whether any of the cytokines under investigation affect cumulus cell activity during IVM [ 20 , 29 , 43 ]. Protein products for CX37 and CX43 play pivotal roles in controlling granulosa and cumulus–oocyte gap-junctional communication [ 44 ], HAS2 is involved with cumulus expansion [ 45 ], and AREG transduces gonadotrophin effects within the COC [ 46 ]. Both LIF and IL11 increased AREG transcript abundance at 4 h. This may indicate that these cytokines can enhance the effects of LH and FSH during maturation [ 47 ].…”

Oogenesis in Women: From Molecular Regulatory Pathways and Maternal Age to Stem Cells

“…This special communication allows a fast signal exchange between the oocyte and the surrounding follicular cells and is possible due to several connexins and pannexins. The detailed role of these two latter mentioned proteins has been reviewed recently elsewhere [ 74 ].…”