DUB3/USP17 regulates cell growth and movement, and ras-like GTPase processing and activation

Abstract

The deubiquitinating enzyme DUB3IUSPl7 CUSPI 7) is a cytokine inducible gene that blocks cell proliferation. In this study we have shown that the RasIERKI/2 MAP Kinase pathway and cell proliferation were perturbed in the presence ofUSPI7. Specifically, we have found that USPl7 targets the Ras converting enzyme RCEI and alters its protease activity. Furthennore, over-expression ofUSPl7 disrupted the localization ofRas and modulation of .: USPl7 lead to aberrant Ras GTP-binding. 00 RCEI also processes geranyl-gei~~lated Ras-like GTPases such as Rapl, RhoA, Racl, and Cdc42. These GTPases are critically hivolved in chemotaxis, adhesion, and inyasion. Her.~ we show !hat USPI7. is inducible upon chemokine·stimulation which activates GTPases. ~d their downstream functions. Utilizing USPl7shRNAwe have investigated the r -. '.' ': • •• . ..., • : - • .'' .. '. role ofUSP17.in 9hemokine driven GTPase dependent event~. ';We show that chemokine stimulation led to aberrant GTPase activation -i~ USPl7 knockdoWn cells indicating a role for USPl7 in the regulation of GTPase activation. USPl7 depletion also strongly inhibited cell adhesion, cell migration, matrix degradation, cell invasion, and cell proliferation. Moreover, confocal analysis indicated that USPl7shRNA blocked cell morphology, cytoskeletal dynamics and chemokine induced cell polarization. These findings identify USPl7 as an important regul~tor·ofGTPase-driven cellular events such as cell proliferation and chemotaxis and suggest that this USP is a therapeutic target for cancer cell invasion, inflammatory disease and other pathologies ofaberrant cell movement and cell proliferation.EThOS - Electronic Theses Online ServiceGBUnited Kingdo