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Mechanisms of epidermal growth factor receptor activation after epithelial wounding

Block, Ethan Robert (2010) Mechanisms of epidermal growth factor receptor activation after epithelial wounding. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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Wounding disrupts the primary function of an epithelium, which is to provide a barrier to the outside environment. The longer the epithelial defect remains unhealed, the greater the risks of morbidity and mortality from infection, loss of tissue homeostasis, and fibrosis. Normally, epithelial cells restore barrier function by becoming highly motile and migrating to cover the defect, but in many situations cells do not move fast enough to prevent tissue malfunction. This is especially true in the cornea, where even minor wounds can impair vision. Therefore, there is considerable therapeutic interest in identifying signals that induce epithelial migration. Activation of the epidermal growth factor receptor (EGFR) is a key signaling event that promotes cells to move and cover wounds in many epithelia. The broad goal of this dissertation research was to identify mechanisms of wound-induced EGFR activation so that therapies may be developed to improve normal and pathological healing.I hypothesized that mechanisms of EGFR activation may differ with respect to distance from the wound, so I developed wounding models to analyze signaling specifically in cells near to or far from "wounds" in a human corneal epithelial cell line. I have examined the involvement of extracellular ATP, phospholipase D, Src-family kinases (SFKs), and the focal adhesion kinase Pyk2, all of which are signals that have been hypothesized to be stimulated by environmental cues related to wounding and to activate the EGFR.I have found that the proximal mechanism of EGFR activation is the proteolytic release of membrane-bound ligands, which is regulated by activation of SFKs. After wounding, multiple pathways converge on SFKs to regulate EGFR activation and cell motility. In one pathway, extracellular ATP transactivates the EGFR through phospholipase D2. In a distinct pathway that functions specifically near the wound edge, Pyk2 triggers SFK and EGFR activation. Finally, my data suggest the presence of a third distinct pathway that promotes SFK and EGFR activation in response to a physically unconstrained edge. By delineating signaling pathways that stimulate EGFR activation, I have identified potential therapeutic targets for modulating EGFR signaling and cell motility in wound healing and other pathologies.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Block, Ethan
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairWalker, William H.walkerw@pitt.eduWALKERW
Committee MemberWells, Alan H.wellsa@upmc.eduAHW6
Committee MemberHebda, Patricia
Committee MemberHughey, Rebecca P.hughey@dom.pitt.eduHUGHEYR
Committee MemberMurray, Sandra A.smurray@pitt.eduSMURRAY
Date: 12 February 2010
Date Type: Completion
Defense Date: 19 January 2010
Approval Date: 12 February 2010
Submission Date: 7 February 2010
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Institution: University of Pittsburgh
Schools and Programs: School of Medicine > Cell Biology and Molecular Physiology
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: atp; cornea; EGFR; epithelial; phospholipase D; purinergic; Src; wound healing
Other ID:, etd-02072010-112053
Date Deposited: 10 Nov 2011 19:31
Last Modified: 19 Dec 2016 14:34


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