Molecular regulation of corneal epithelial wound healing.

摘要

Corneal epithelial wound healing is vital to maintaining a clear healthy cornea and preserving vision. Rapid and successful wound repair involves a wide variety of cellular processes such as cell migration, proliferation, differentiation, adhesion, and matrix remodeling. Ectodomain shedding of heparin-binding EGF-like growth factor (HB-EGF) by a disintegrin and metalloprotease (ADAM) and subsequent epidermal growth factor receptor (EGFR) activation have been established as pivotal regulators of injury recovery. EGFR transactivation by ligands for G-protein-coupled receptors (GPCR) has also emerged as a key scenario during wound healing.; The purpose of this dissertation is to elucidate the roles of adenosine triphosphate (ATP), extracellular signal-regulated kinases 1/2 (ERK1/2), and Small GTPase Rho/Rho kinases pathways during corneal epithelial wound healing and to examine the mechanisms underlying their actions with an emphasis on their interactions with EGFR.; We first demonstrated that ATP, released upon epithelial injury, enhances corneal epithelial wound healing by functioning as an early signal to trigger cell responses including an increase in HB-EGF shedding, subsequent EGFR transactivation and its downstream signaling. We then showed that ERK1/2, in addition to acting as an EGFR downstream effector, mediate HB-EGF shedding and EGFR transactivation via regulating ADAM17 activities in response to wounding and GPCR ligands ATP and lysophosphatidic acid.; The roles of Rho and its major effectors Rho Kinases (ROCK) were also investigated. Wounding induces Rho activation via an EGFR-independent pathway. Rho activity is required for modulating both cell migration and proliferation, through cytoskeleton reorganization and focal adhesion formation in response to wounding. Activation of ROCK enhances cell proliferation, promote epithelial differentiation, but negatively modulate cell migration and cell adhesion in corneal epithelial wound healing.; In summary, studies in this dissertation identified ATP and ERK pathways as mediators of wounding-induced EGFR activation and elucidated the role of EGFR-independent Rho/ROCK pathway in corneal epithelial wound healing. The conclusions are relevant to therapeutic intervention and drug development for wound healing-related diseases in the cornea and other tissues.