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MAGP2 binding to α v β 3 integrins affects levels of microfibril formation
Author(s) -
Daniels Ryan,
Valdivia Michael,
Perez Andrew,
Miyamoto Alison
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.622.1
Subject(s) - integrin , rgd motif , microfibril , extracellular matrix , microbiology and biotechnology , glycoprotein , chemistry , matrix metalloproteinase , cell adhesion , disintegrin , biology , cell , metalloproteinase , biochemistry , cellulose
Matrix metalloproteases (MMPs) are secreted proteins that degrade extracellular matrix (ECM) proteins and are thought to play a major role in cancer cell motility, invasion, and angiogenesis. Activation of α v β 3 integrins has been shown to increase expression or activation of MMPs. Microfibril‐associated glycoprotein 2 (MAGP2) is a small secreted protein that binds to microfibrils in the ECM, and overexpression of MAGP2 in human papillary serous ovarian carcinomas correlates to poor prognosis. MAGP2 has an RGD integrin binding motif in the amino‐terminal half (NT). This motif was shown to be necessary to stimulate cell motility in an an α v β 3 integrin dependent manner. The carboxy‐terminal half of MAGP2 contains a matrix binding domain that is necessary and sufficient for MAGP2 to associate with microfibrils. Direct transfection of a construct expressing the NT‐MAGP2 shows a decrease in extracellular fibers via immunocytochemistry (ICC). This construct can bind to α v β 3 integrins but not microfibrils, suggesting that this effect is mediated by the MAGP2 RGD integrin binding motif. Therefore, we hypothesize that NT‐MAGP2 binding to α v β 3 integrin promotes the activity of MMPs to degrade the ECM in order for the cell to be motile during metastasis. To test the requirement for the RGD motif two mutant constructs were generated in the RGD integrin binding motif of the NT‐MAGP2 construct with a conservative (RGE) and non‐conservative (RGA) mutation to assess levels of cell‐associated MAGP2 and microfibril levels via ICC. As expected, the wild type NT‐MAGP2 construct had the most cell association and greatest loss of microfibrils, followed by the RGE mutant, and lastly the RGA mutant. These preliminary results suggest that there is an inverse relationship between amount of cell associated MAGP2 and amount of microfibrils present. Current studies are testing whether the NT‐MAGP2 treatment increases MMP activity via zymography. These studies could provide insights for possible anti‐MAGP2 treatments of ovarian cancer. Support or Funding Information Howard Hughes Medical School Two‐Year Undergraduate Research Scholars Programs (RD), California Institute of Regenerative Medicine Bridges to Stem Cell Research Program (MV, AP), Department of Biological Science, CSUF (AM).