Neurofibromatosis Type II (NF2) is a neurological disorder arising from mutations in the rif2 gene. NF2 is characterized by formation of bilateral vestibular schwannomas. These tumors arise from Schwann cells, the myelin-forming glia in nerves. Schwannoma cells lose the characteristic bipolar, spindle morphology and assume a round fibroblast-like phenotype. Phenotypic de-differentiation of schwannomas has been attributed to increased levels of Cdc42/Rac-GTP and activation of downstream pathways. The n/2 gene encodes the tumor suppressor called merlin. It is targeted to the plasma membrane by direct binding to paxillin at paxillin-binding domain 1, encoded by exon 2 of the nj2 gene. At the plasma membrane, merlin associates with B1-integrin and erbB2/3 receptors and actin regulating proteins. We hypothesize that merlin modulates actin polymerization, and thus cell shape, by controlling the activity of actin filament regulating proteins. We developed an in vitro model ofNF2 using ad-ere ( ad-Cre) viral mediated deletion of nj2 exon 2 in primary mouse Schwann cells. Within 5 days of ad-Cre infection, merlin levels fall to 40% of normal levels in Schwann cells. Moreover, the expressed merlin protein has the expected lower molecular weight and does not target to the plasma membrane. Schwann cells expressing this mutant merlin lose their characteristic bipolar shape. We tested the activation levels of2 candidate Cdc42/Rac dependent-actin regulating proteins in these cells. Using immunofluorescence, we found that the activity of these proteins increased dramatically within 4 days of n/2 inactivation. This increase in activity was then confirmed with western blotting. We conclude that the function of these actin-filament regulating proteins could contribute to changes in morphology associated with schwannoma formation in NF2.
| Identifer | oai:union.ndltd.org:ucf.edu/oai:stars.library.ucf.edu:honorstheses1990-2015-2052 |
| Date | 01 January 2010 |
| Creators | Sparrow, Nicklaus A. |
| Publisher | STARS |
| Source Sets | University of Central Florida |
| Language | English |
| Detected Language | English |
| Type | text |
| Source | HIM 1990-2015 |
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