Molecular regulation of N-cadherin precursor trafficking: role of protein tyrosine phosphatase PTP1B and p120.

WEHRENDT D. P; CARMONA F; ARREGUI C. O

Congreso; SAIB; 2010

N-cadherin, a cell-cell adhesion molecule, is synthesized as a precursor protein, with a prodomain that is cleaved post-Golgi. Our previous data suggest that PTP1B promotes ER-Golgi trafficking of the precursor, likely by ensuring its binding to p120 catenin. To confirm the role of p120 in traffic, we analyzed endo H sensitive profiles of the precursor in cells knocked down for p120 expression. Preliminary results did not show differences with the control, suggesting that additional components bound to the precursor are involved in trafficking. In a search for relevant proteins, we analyzed the array of proteins associated with the wild type and a mutant precursor unable to bind p120. Immunoprecipitation/Western blot analysis showed that N-ethylmaleimide sensitive factor, an ATPase that regulates vesicle fusion, associates with the WT precursor, but at lower levels with the mutant. Mass spectrometry analysis also revealed a reduction of spectrins alpha2/beta1 and alpha-actinin 4 in the mutant complex, and in the complex of the WT precursor expressed in PTP1B KO cells. Spectrin interacts with the motor dynein, which mediates ER-Golgi transport, and with ankyrin G, a protein that binds to the precursor in a region overlapping with the p120 binding site. Thus, PTP1B and p120 may contribute to recruit components involved in transport and fusion to the N-cadherin precursor. Supported by ANPCYT.