ADHERENS JUNCTION (AJ) INTEGRITY DEPENDS ON DRM-LIPID COMPOSITION IN RAT RENAL PAPILLA.

MARÍA G MARQUEZ; FRANCISCO LEOCATA NIETO; NICOLÁS FAVALE; MARÍA DEL CARMEN FERNANDEZ; NORMA B STERIN-SPEZIALE

San Miguel del Tucumán

Congreso; XLIV Reunión de la Sociedad Argentina de Investigaciones Bioquímicas y Biología Molecular; 2009

SAIB

In epithelial tissues, AJ mediate cell-cell adhesion by using proteins called E-cadherin that span the cell membrane, contact E-cadherin on other cells and connect with the actin cytoskeleton inside the cell. In previous work we described, in rat renal papilla, a specific DRM, that contained focal adhesion (FA) proteins. Changes in DRM lipid composition provoked by cyclodextrin (CD), neomycin (Neo) and LiCl induced dissipation of FA structures from cultured collecting duct cells. Now, we show that this specific DRM also contains E-cadherin and b-catenin. Wes-tern blot analysis showed that changes in DRM lipid composition induced by CD provokes a 10% and 50% decrease in the amount of E-cadherin and b-catenin present in DRM, respectively. Neo induces a more important decrease in b-catenin than in E-cadherin, while no significant changes were induced by LiCl. Immunofluorescence analysis showed that CD and Neo provoked a delocalization of E-cadherin and b-catenin from the plasma membrane, and F-actin was found as a cortical network, typical of isolated cells. After LiCl, both proteins remained in the plasma membrane. These results demonstrate that AJ are located in DRM microdomains, and the preservation of lipid DRM composition is essential to maintain epithelial cell adhesion structures.