Cx31.1 is associated with apoptosis in scrape-wounded ‘diabetic’ skin models

Modulating Cx43-mediated communication via gap junctions and/or hemichannels increases skin wound-healing capacity. Cx31.1 expression is associated with apoptosis in eye and ovary. We investigated Cx31.1 and its association with apoptosis in HaCaT scrape-wounded monolayers cultured in normal or ‘diabetic’ levels of glucose and insulin. HaCaTs were treated for 5 days with normal glucose (5.5 mM) and insulin (1 nM; termed NGI) or high glucose (25 mM) and insulin (10 nM; termed HGI). Scrape-wounds (600 µm) were introduced and monitored over 48 hours. Cx31.1 levels were determined by qPCR and immunocytochemistry. Caspase 3/7 activity and cell viability were determined, with some cells pre-exposed to UV. Cx31.1 protein expression was increased in HGI compared to NGI, and was higher in apoptotic than healthy cells in both conditions. Cx31.1 increased in cells at scrape-wound edges over 48 hours. Caspase activity in conditioned media from scrape-wounded cells was higher in HGI than NGI at 0 hours (P < 0.05), but not at later time points. UV exposure significantly increased caspase in both NGI and HGI (P < 0.05), while there was less caspase activity in HGI treated cells pre-UV (P < 0.01). In parallel, cell viability was reduced post-UV exposure in NGI treated cells (P < 0.001), although not in HGI. Cx31.1 expression was modulated in HaCaT scrape-wound closure and was associated with apoptosis, and with ‘diabetic’ levels of glucose and insulin. We propose that Cx31.1 is associated with tissue turn-over in diabetic wounds.