Differential Tight Junction Expression In Skin And Mucosal Wounds
Junhe Shi, Luisa A. DiPietro, Lin Chen.
Center for Wound Healing and Tissue Regeneration, College of Dentistry, University of Illinois at Chicago, Chicago, IL, USA.
Background: Oral mucosal wounds heal more rapidly with significantly less inflammation, faster re-epithelialization, more refined angiogenesis, and less scar formation than skin wounds. Tight junctions (TJ) are intercellular junctions between adjacent cells that play pivotal roles in barrier function and cell polarity as well as in innate immunity. Methods: Using microarray, we compared the expression of TJ related genes in mouse skin and tongue wounds at 6, 12, and 24 hours and day 3, 5, 7, and 10 post-wounding. Using qPCR, the expression of occludin, claudins 1 and 4, ZO-1, and JAM-1 was compared between a wounded human skin keratinocyte cell line, HACAT and an immortalized human gingival epithelial cell line, TIGK. Results: The gene expression of multiple TJ molecules including occludin, claudins 1, 3, 4, 7, 10-12, 14, and 23, and ZOs 1-3, and JAMs 1-3 was found to change significantly over the course of healing process in skin wounds. By comparison, tongue wounds showed an overlapping but different pattern of expression that included occludin, claudins 1, 2, 4, 5, 10-13, 15, 18, 19, and 23, and ZO-2 and JAMs 1-3 (p<0.05, One-way Anova analysis). Since epithelial cells are one of the primary cell types to express TJ, we next investigated the in vitro gene expression of a subset of the TJ molecules that were differentially expressed in skin and tongue wounds. The expression of occludin and claudin 1 was significantly higher in HACAT than in TIGK after injury; Claudin 4 and JAM-1 were significantly higher in TIGK than in HACAT. No significant difference was observed in ZO-1 expression between these two cell lines after injury. Conclusions: The results suggest that certain TJ molecules are differentially expressed in skin and oral tissues. This differential expression may contribute to the distinct healing phenotypes seen between skin and oral mucosal wounds.
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