Rapid communication: physical and linkage mapping of the porcine connexin 37 (CX37) gene

Cx37 C1019T polymorphism may contribute to the pathogenesis of coronary heart disease

OBJECTIVE

We conducted a meta-analysis of case-control studies to evaluate whether Cx37 C1019T (rs1764391 C>T) polymorphism may be implicated in the pathogenesis of coronary heart disease (CHD).

METHODS

The MEDLINE (1966-2013), the Cochrane Library Database (Issue 12, 2013), EMBASE (1980-2013), CINAHL (1982-2013), Web of Science (1945-2013), and the Chinese Biomedical Database (CBM) (1982-2013) were searched without language restrictions. Meta-analysis was performed with the use of the STATA statistical software. Odds ratios (ORs) with their 95% confidence intervals (95% CIs) were calculated.

RESULTS

Nine case-control studies with a total of 1426 CHD patients and 929 healthy controls met the inclusion criteria. Our results revealed that Cx37 C1019T polymorphism might be significantly correlated with the risk of CHD (T allele vs. C allele: OR=1.63, 95% CI=1.20-2.21, p=0.002; CT+TT vs. CC: OR=1.86, 95% CI=1.28-2.69, p=0.001; TT vs. CC+CT: OR=1.81, 95% CI=1.24-2.64, p=0.002; TT vs. CC: OR=2.50, 95% CI=1.46-4.27, p=0.001; TT vs. CT: OR=1.53, 95% CI=1.12-2.09, p=0.008; respectively). Further subgroup analysis by country indicated that Cx37 C1019T polymorphism might be closely linked to an increased risk of CHD among Chinese populations, while no positive associations were observed among non-Chinese populations (all p>0.05).

CONCLUSION

Our findings provide empirical evidence that Cx37 C1019T polymorphism may contribute to the pathogenesis of CHD, especially among Chinese populations.

Identification and expression analysis of connexin-45 and connexin-60 as major connexins in porcine oocytes

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 gap junction protein, alpha 10, which encodes connexin-60, and a porcine ortholog of mouse gap junction protein, gamma 1 encoding connexin-45, 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, gap junction protein, alpha 4, which encodes connexin-37 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.