Voltage-dependent anion channel 1 and 2 are expressed in porcine oocytes
Résumé
The eukaryotic voltage-dependent anion channel (VDAC) is a pore-forming protein originally discovered in the outer membrane of mitochondria. It has been established as a key player in mitochondrial metabolite and ion signaling. In addition, in recent years, it has also been proposed that VDAC is present in extra-mitochondrial membranes, and it has been related to cytoskeletal structures. However, little is known about the presence and intracellular localization of VDAC subtypes in mammalian gametes. In this study we confirm the synthesis of VDAC1 and 2 subtypes in germinal vesicle (GV) and meiosis II (MII) stage porcine oocytes as well as their protein expression. A shift in the abundance of immunoreactive 32 kDa VDAC protein between GV and MII stage oocytes was observed with anti-VDAC2 antibody. Furthermore, subcellular localization by confocal laser microscopy demonstrated fluorescent labeling of VDAC1 over the entire oocyte surface, suggesting the presence of VDAC1 in the porcine oocyte plasma membrane and around the cortical area. Anti-VDAC2 immunostaining yielded ring-like clusters of structures distributed on the cortical area in some GV but not in MII stage oocytes. These results are the first data obtained for VDAC in mammalian female gametes and provide the basis for studying protein-protein interactions, distribution and possible functions of VDAC subtypes during maturation and fertilization of mammalian oocytes.
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