Investigating the role of connexin 43 in oocyte developmental competence

Abstract

In this study we are committed to understanding the role of connexin 43 (CXx43)-based, cumulus cell cellular coupling and its relationship to bovine embryo development. Several studies have provided clear evidence that CXx43-based coupling between the cumulus cells is critical for producing a healthy oocyte. Previously, the expression and localization of CXx43 has been linked to resulting embryo outcomes in several studies. However, the relationship has largely remained undefined due to limitations inherent in group culture in vitro fertilization (IVF). To better associate the expression and localization of CX43 with in vitro embryo outcomes we first developed a bovine single cumulus-oocyte-complex (COC) IVF and embryo culture system. Furthermore, all-trans retinoic acid (ATRA) signaling has been shown in a number of studies to enhance Cx43 expression and cellular coupling in a variety of cell types. Along with this, ATRA has been shown to have beneficial effects on oocyte maturation, fertilization, and embryo development in a number of species. Therefore, we investigated the ability of ATRA to enhance cumulus cell coupling and influence bovine embryo production. Clarifying the relationship between cumulus CX43 expression and embryo outcomes has the potential to allow for the selection of COCs with higher developmental capacities, limiting the current inefficiency of bovine IVF systems. Furthermore, the enhancement of CX43 expression may allow for improvements in the number of COCs available for use in advanced reproductive technologies.