IDENTIFICATION OF PROTEIN TYROSINE PHOSPHATASE 1B (PTP1B) INTERACTORS INVOLVED IN CELL MOTILITY

MARÍA EUGENIA PEREZ COLLADO; ANA E. GONZÁLEZ WUSENER; CARLOS O. ARREGUI

Ciudad de Buenos Aires

Congreso; REUNIÓN CONJUNTA DE SOCIEDADES DE BIOCIENCIAS - LIII REUNIÓN ANUAL DE LA SOCIEDAD ARGENTINA DE INVESTIGACIÓN BIOQUÍMICA Y BIOLOGÍA MOLECULAR (SAIB); 2017

PTP1B is an ER-bound protein tyrosine phosphatase implicated inthe dynamics of cell-matrix adhesions. This regulation relates to apositive role of PTP1B in directional cell migration and attenuation ofcell contractility. The aim of the current study is to identify and characterizepotential substrates and interactors of PTP1B involved incell motility. To this end we used a Bimolecular Fluorescence Complementation(BiFC) approach for direct visualization and analysis ofPTP1B interactors in intact cells. BiFC is based on complementationand restoration of fluorescence when two non-fluorescent fragmentsof a native fluorescent protein are a few nanometers apart. Thesefragments were fused to PTP1B and the potential substrates/interactors,chosen on the basis of previous phosphoproteomic data andtheir relevance in cell motility. We observed BiFC between PTP1Band epidermal growth factor receptor (EGFR), the scaffold proteinMena and the focal adhesion tyrosine kinase FAK. PTP1B/EGFRinteraction was revealed as puncta with increasing size and densityin internal locations compared to the cell periphery. The colocalizationwith cell-matrix markers was not evident. In contrast, PTP1B/FAK and PTP1B/Mena interactions were prominent at peripheraladhesions. FAK BiFC fluorescent signal was attenuated when usinga FAK mutant (Y4-9F-FAK) in which tyrosine phosphorylation sitesTyr 407, 576, 577, 861, and 925 were mutated to phenylalanine. Therole of individual mutations on FAK, as well as on putative interactingmotifs on EGFR and Mena are currently investigated. Our resultssuggest a dual role of PTP1B on integrin and EGFR signaling drivingthe cell motility machinery. Supported by CONICET and ANPCyT.