The connexin mimetic peptide Gap27 increases human dermal fibroblast migration in hyperglycemic and hyperinsulinemic conditions in vitro

Abstract

Significant increases in skin wound healing rates occur by reducing connexin-mediated communication (CMC). Gap27, a connexin (Cx) mimetic peptide targeted to the second extracellular loop of Cx43, which inhibits CMC, increases migration of human keratinocytes and dermal fibroblasts. To examine the efficacy of Gap27 in a hyperglycemic and hyperinsulinemic in vitro environment, cell migration, gap junction, and Cx hemichannel functionality and cell-substrate adhesion assays were performed on human dermal fibroblasts and diabetic fibroblast and keratinocytes. To investigate fibroblast genes involved in these processes, extra-cellular matrix (ECM) and adhesion gene expression was determined with a PCR array. Gap27 increased fibroblast migration in both euglycemia/euinsulinemia and hyperglycemia/hyperinsulinemia, and influenced migration in diabetic keratinocytes. Hyperglycemia/hyperinsulinemia reduced gap junction coupling in fibroblasts and Gap27 reduced CMC and cell adhesion to substrata in fibroblasts cultured in high glucose. Migrating dermal fibroblast ECM and cell adhesion genes were found to be differentially regulated by Gap27 in euglycemia and hyperglycemia. The PCR array showed that Gap27 upregulated 34 genes and downregulated 1 gene in euglycemic migrating fibroblasts. By contrast in hyperglycemia, Gap27 upregulated 1 gene and downregulated 9 genes. In euglycemic conditions, Gap27 induced upregulation of genes associated with ECM remodeling, whereas in hyperglycemia, ECM component genes were downregulated by Gap27. Thus, Gap27 improves cell migration during scrape-wound repair in hyperglycemia/hyperinsulinemia conditions in vitro, although migration of diabetic cells is less influenced. Our results suggest that this increase in motility may occur by decreasing gap junction and hemichannel activity and altering gene expression in the adhesion and ECM pathway.

Connexin 43 deficiency accelerates skin wound healing and extracellular matrix remodeling in mice

“…Gap27 hereby blocks both Cx43-mediated gap junctional [34] and hemichannel [6] activity, and increases proliferation and migration rates of keratinocytes and dermal fibroblasts [6,34]. Moreover, Gap27 upregulates genes associated with extracellular matrix remodeling [35], which is reminiscent of our observations. Collectively, these reports thus demonstrate that Cx43 signaling represents a promising therapeutic target in wound healing, a finding that is clearly underscored by the results of the present study.…”

Connexins and pannexins in the integumentary system: the skin and appendages

“…Evidence continues to mount that targeting Cx43 to inhibit function and or expression with antisense technologies, to block expression [37] or peptidomimetics to inhibit function [38,39] and/or Cx43 protein interactions are effective in translational applications to improve wound repair rates in normal and diabetic individuals [40,41]. Recent studies reveal that both connexin channel and nonchannel functions are important mediators in these events.…”

Porokeratotic Eccrine Nevus May Be Caused by Somatic Connexin26 Mutations

“…Total protein was measured using the Bio-Rad Laboratories D C protein assay kit (Bio-Rad Laboratories, Hemel Hempstead, UK) following the manufacturer's instructions. Results were then standardized against protein concentration and results presented as a fold change compared with the control (Wright et al , 2012). …”