Cell migration is a complex process that requires the coordination of signaling events that take place in distinct locations within the cell. Adaptor proteins are emerging as key modulators of spatially integrated processes because of their ability to localize to different subcellular compartments and bring together important signaling proteins at these sites. However, the role that adaptor proteins play in regulating cell migration is not well understood. Here, we show a novel function for the adaptor protein containing a pleckstrin homology (PH), phosphotyrosine binding (PTB), and leucine zipper motif 1 (APPL1) in modulating cell migration. APPL1 impairs the turnover of adhesions at the leading edge of cells thereby inhibiting their migration. The ability of APPL1 to impair migration is dependent on its PTB domain, which interacts with Akt, suggesting the interaction of APPL1 with Akt is important for its effect on migration. Interestingly, APPL1 decreases the amount of active Akt in cells. We show that APPL1 modulates migration and adhesion dynamics via a mechanism that involves regulation of Akt function. Src has been shown to regulate Akt function through the phosphorylation of two Akt tyrosine residues, and intriguingly, we have found that APPL1 reduces Src-mediated tyrosine phosphorylation of Akt. Therefore, we propose a model in which APPL1 regulates adhesion dynamics and cell migration by altering Src-mediated tyrosine phosphorylation of Akt. Our results further underscore the importance of adaptor proteins in modulating the flow of information through signaling pathways by demonstrating a critical new function for APPL1 in regulating cell migration and adhesion turnover.
In addition, we provide the first comprehensive phosphorylation map of APPL1. Using mass spectrometry, we identify 13 phosphorylated residues within APPL1. Four of these sites are located in important functional domains; one within the BAR domain, two cluster near the edge of the PH domain, and one within the PTB domain. These phosphorylation sites may control APPL1 function by regulating the ability of APPL1 domains to interact with other proteins and membranes.
| Identifer | oai:union.ndltd.org:VANDERBILT/oai:VANDERBILTETD:etd-06182012-165410 |
| Date | 19 June 2012 |
| Creators | Broussard, Joshua Allen |
| Contributors | Katherine L. Friedman, Donna J. Webb, Lilianna Solnica-Krezel, Christopher J. Janetopoulos, James R. Goldenring, Irina Kaverina |
| Publisher | VANDERBILT |
| Source Sets | Vanderbilt University Theses |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.vanderbilt.edu/available/etd-06182012-165410/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to Vanderbilt University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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