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General Comment |
NCBI Summary:
Connexins, such as GJA10, are involved in the formation of gap junctions, intercellular conduits that directly connect the cytoplasms of contacting cells. Each gap junction channel is formed by docking of 2 hemichannels, each of which contains 6 connexin subunits (Sohl et al., 2003 [PubMed 12881038]).[supplied by OMIM]
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Comment |
Identification and expression analysis of CX45 and CX60 as major connexins in porcine oocytes. Nitta M et al. During mammalian oogenesis, intercellular communication between oocytes and the surrounding follicle cells through gap junction channels is crucial for oocyte development and maturation. The channel properties of gap junctions may be affected by the composition or combination of connexins, the expression of which is regulated by gonadotropins and other factors. Thus, identification and expression analysis of connexin genes in oocytes and follicle cells will help us to better understand how oogenesis and folliculogenesis are regulated in a species-specific manner in mammals. We previously reported the spatiotemporal expression of multiple connexin genes in porcine follicle cells. Here, we searched for connexin genes specifically expressed in porcine oocytes that may be involved in the formation of gap junctions between oocytes and follicle cells. To achieve this, we constructed an oocyte-specific cDNA library to identify which connexin genes are expressed in these cells, and found that GJA10, which encodes Connexin-60 (CX60), and a porcine ortholog of mouse Gjc1 encoding Connexin-45 (CX45), are the major connexins expressed in porcine oocytes during folliculogenesis. Immunostaining and in situ hybridization of sectioned porcine ovaries confirmed oocyte expression of these genes at 3 different stages of ovary development. Furthermore, their gap junction channel activity was assessed using a heterologous cell system. However, GJA4, which encodes CX37 and is expressed in the oocytes of several other mammals, was undetectable. We demonstrate that there is diversity in the connexin genes expressed in mammalian oocytes, and hence in the gap junctions connecting oocytes and cumulus cells.
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