Defense Date

2008

Document Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Biochemistry

First Advisor

Robert M. Tombes

Abstract

Transient elevations in Ca2+ have previously been shown to promote focal adhesion disassembly and cell motility. Yet the targets of these Ca2+ transients have not been fully examined. In this study, we demonstrate that CaMK-II, a Ca2+/calmodulin dependent protein kinase, is activated in response to β1 integrin engagement with fibronectin to influence fibroblast adhesion and motility. We also show that CaMK-II is dynamically localized to the cell surface using Total Internal Reflection Fluorescence microscopy (TIRFm) and that inhibition of CaMK-II with two mechanistically distinct, membrane permeant inhibitors accelerates spreading on fibronectin, enlarges paxillin-containing focal adhesions and blocks cell motility. On the other hand, expression of constitutively active CaMK-II reduces cell attachment, eliminates paxillin from focal adhesions and decreases the phospho-tyrosine levels of both FAK and paxillin. Cell spreading, paxillin incorporation into focal adhesions and phospho-tyrosine levels of FAK and paxillin are restored when cells expressing constitutively active CaMK-II are subsequently treated with myr-AIP, a specific CaMK-II catalytic inhibitor. Like CaMK-II inhibition, constitutively active CaMK-II blocks cell motility. Thus, both CaMK-II inhibition and constitutive activation block cell motility through over-stabilization or destabilization of focal adhesions, respectively. These findings provide the first direct evidence that CaMK-II promotes focal adhesion turnover and thus enables cell motility by stimulating tyrosine dephosphorylation of focal adhesion proteins.

Rights

© The Author

Is Part Of

VCU University Archives

Is Part Of

VCU Theses and Dissertations

Date of Submission

8-21-2008

easleyca_lamininpaper.pdf (577 kB)
pdf on in press paper

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