Acute wound healing is associated with a reduction in the expression of the gap junction protein Connexin 43 (Cx43) at the leading wound edge. By contrast in chronic non-healing wounds Cx43 expression is significantly upregulated and associated with delayed wound closure. Thus targeting x43 with specific peptides or SiRNA strategies presents an attractive therapeutic target. Whether changes in cell proliferation and migration are linked with altered Cx43 expression or function remains unresolved. To address this we used two pharmacological tools, the histone deacetylase inhibitor sodium butyrate (0.5mM NaBu) and the Cx43-specific enhancing peptide AAP10 (50nM) to enhance Cx43 expression over 24 hour time periods in HeLa cells transfected to express Cx43 (HeLa43) and in primary human dermal fibroblasts (HFF) derived from child foreskins with parental consent and ethical approval. Connexin 43 function was blocked using 18-alpha-glycyrrhetinic acid (GA). Exposure of the cells to NaBu or AAP10 induced Cx43 expression with an associated increase in channel function, determined by the ability of cells to transfer small fluorescent dyes. Treatment with GA blocked channel function but maintained Cx43 expression levels irrespective of induction. Timelapse microscopy and fl ow cytometry of HeLa43 cells demonstrated that enhanced Cx43 expression resulted in reduced cell proliferation following a stall in the G1 stage of the cell cycle. This was linked to an increase in expression of the cell cycle inhibitor p21waf/cip1 and cyclinD1. Reductions in Cx43 channel activity did not abrogate these responses, indicating that connexin mediated communication was not a critical factor in reducing cell proliferation. Parallel studies in HFF cells illustrated that exposure to AAP10 was also associated with increased expression of Cx43 and p21waf/cip and delayed migration rates in in vitro scratch assays. Taken together we conclude that enhanced Cx43 expression and not communication is involved in regulation of cell migration and proliferation rates.
- Connexin 43
- cell–cell communication
- acute wound-healing
Johnstone, S. R., Wright, C. S., Errington, R. J., & Martin, P. (2009). Enhanced Connexin 43 expression mediates cell proliferation and migration independent of connexin mediated communication. In Journal of Investigative Dermatology (Vol. 129, pp. S82).  Elsevier B.V.. https://doi.org/10.1038/jid.2009.232