Centrosomally localized EVI5 is a novel GTPase activator of the small GTPase Rab11 and may play crucial roles in cytokinesis and neuroblastoma development
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Neuroblastoma is a disease that develops due to the failure of neural crest cells to migrate and differentiate properly. The human EV15 gene was isolated and characterized as a result of its location at the breakpoint junction of a t(1;10)(p21;q21) constitutional chromosome translocation in a patient with stage 4S neuroblastoma. The N-terminal portion of the EV15 protein contains a TBC domain, which is the catalytic domain of many Rab-activating GTPase activators. A series of cell and molecular biology approaches were used to explore possible roles and functions of EV15 and how EV15 may affect the development of neuroblastoma. An antibody was raised against EV15 and used in immunocytochemistry assays to determine its localization within the cell. Additionally, microarray based gene expression assays and GST pull-downs, in combination with mass spectroscopy were performed in order to determine the genes affected by the overexpression of the TBC region of EV15 and partners of interaction for the EV15 protein. A small population of EV15 protein was found to localize to the centrosome of the cell and thereby activate Rab11 GTPase activity. Overexpression of the TBC region of EV15 led to the upregulation of many extracellular matrix genes. Extracellular matrix proteins are critical for the proper migration and differentiation of neural crest cells. Rab11 is responsible for the recycling of several extracellular matrix proteins. We suggest that aberrant regulation of Rab11 by EV15 leads to improper recycling of extracellular matrix genes critical for proper neural crest cell migration thus leading to the development of neuroblastoma.