Bradykinin can modulate focal contacts assembly

MÁRQUEZ MARÍA G; SERRANO DIEGO; STERIN-SPEZIALE N

Carlos Paz, Cordoba

Congreso; XXXVIII REUNIÓN DE LA SOCIEDAD ARGENTINA DE INVESTIGACIONES BIOQUÍMICAS Y BIOLOGÍA MOLECULAR; 2002

SOCIEDAD ARGENTINA DE INVESTIGACIONES BIOQUÍMICAS Y BIOLOGÍA MOLECULAR

In previous works we found that lipid?detergent?resistant membrane? rafts (DRMs) associated vinculin (V) is observed in microsomal but not in nuclear membranes, denoting its participation in the assembly of focal contacts (FC) - dynamic cytoskeletal structures where the cell membrane attaches to the extracellular matrix. In the present work, we have investigated renal papilla in adult rat: a) to which membrane domain the FC proteins talin (T) and paxilin (P) are associated, by ultracentrifugation and immunoblotting, b) the interaction of V,T and P with phosphatidylinositol-4,5-bisphosphate (PIP2), by immunoprecipitation with an antibody (Ab) to PIP2 and subsequent immunoblotting with Ab to V, T and P, and c) the dynamic of binding between V and PIP2 in DMRs, by incubating papilla slices with bradykinin (BK) for 1, 5 and 10 minutes. Results: T and P are associated with DMRs. V and T, but not P, co-immunoprecipitate with PIP2 in DMRs, indicating an interaction between them, and this binding is so tight and stable that they remain bound even after electrophoresis on SDS-PAGE. BK induced a decrease in V binding with PIP2 after 10 minutes. As it is known that BK stimulates PIP2 hydrolysis by activating phospholipaseC, we can speculate that BK can regulate the assembly of FC in renal papilla altering the interaction between PIP2 and the cytoskeletal proteins V and T.