Centre for Regenerative Medicine, Mawson Institute, University of South Australia, Adelaide, Australia; Women's and Children's Health Research Institute, Adelaide, Australia.
J Pathol. 2014 Apr;232(5):541-52. doi: 10.1002/path.4323. Epub 2014 Feb 5.
Development of an intact epidermis is critical for maintaining the integrity of the skin. Patients with epidermolysis bullosa (EB) experience multiple erosions, which breach the epidermal barrier and lead to increased microbial colocalization of wounds, infections and sepsis. The cytoskeletal protein Flightless I (Flii) is a known regulator of both development and wound healing. Using Flii(+/-), WT and Flii(Tg/Tg) mice, we investigated the effect of altering Flii levels in embryos and adult mice on the development of the epidermal barrier and, consequently, how this affects the integrity of the skin in EB. Flii over-expression resulted in delayed formation of the epidermal barrier in embryos and decreased expression of tight junction (TJ) proteins Claudin-1 and ZO-2. Increased intercellular space and transepidermal water loss was observed in Flii(Tg)(/Tg) adult mouse skin, while Flii(Tg/Tg) keratinocytes showed altered TJ protein localization and reduced transepithelial resistance. Flii is increased in the blistered skin of patients with EB, and over-expression of Flii in experimental EBA showed impaired Claudin-1 and -4 TJ protein expression and delayed recovery of functional barrier post-blistering. Immunoprecipitation confirmed Flii associated with TJ proteins and in vivo actin assays showed that the effect of Flii on actin polymerization underpinned the impaired barrier function observed in Flii(Tg/Tg) mice. These results therefore demonstrate an important role for Flii in the development and regulation of the epidermal barrier, which may contribute to the impaired healing and skin fragility of EB patients.
完整的表皮层对于维持皮肤的完整性至关重要。患有大疱性表皮松解症（EB）的患者会经历多次糜烂，这会破坏表皮屏障，并导致伤口、感染和败血症中微生物的定植增加。无翅型 I （Flii）是一种已知的细胞骨架蛋白，它可以调节发育和伤口愈合。我们使用 Flii(+/-)、WT 和 Flii(Tg/Tg)小鼠，研究了在胚胎和成年小鼠中改变 Flii 水平对表皮屏障发育的影响，以及这如何影响 EB 皮肤的完整性。Flii 的过度表达导致胚胎表皮屏障形成延迟，紧密连接（TJ）蛋白 Claudin-1 和 ZO-2 的表达减少。在 Flii(Tg)(/Tg)成年小鼠皮肤中观察到细胞间空间增加和经表皮水分丢失增加，而 Flii(Tg/Tg)角质形成细胞显示 TJ 蛋白定位改变和跨上皮电阻降低。EB 患者的水疱皮肤中 Flii 增加，实验性 EBA 中的 Flii 过度表达显示 Claudin-1 和 -4 TJ 蛋白表达受损，水疱后功能屏障恢复延迟。免疫沉淀证实 Flii 与 TJ 蛋白相关，体内肌动蛋白测定表明 Flii 对肌动蛋白聚合的影响是 Flii(Tg/Tg)小鼠观察到的屏障功能受损的基础。因此，这些结果表明 Flii 在表皮屏障的发育和调节中起着重要作用，这可能导致 EB 患者愈合受损和皮肤脆弱。
