N-WASP has been reported to exist in a self-folded auto-inhibited

conformation. When activated, conformational changes occur facilitating the interaction with the Arp2/3 complex and subsequent nucleation [37]. The Rho-associated serine-threonine protein kinase, ROCK, is ubiquitously expressed in mammalian tissues and it is directly linked, after activation, with numerous processes related to actin-myosin, LY294002 mw such as actin cytoskeletal reorganisation and the formation of focal adhesions. It also has an important role in cell migration by promoting the contraction of the cell body and is required for tail retraction in cancer cells [38]. The transfected and control cells were treated with the N-WASP inhibitor, responsible for stabilising the R788 mw auto-inhibited conformation of the N-WASP protein [39], and their rate of speed was measured using ECIS after wounding. Results showed an inhibition in their motility, however, this inhibition was marginally reduced in knockdown cells. The effect of the ROCK inhibitor (Y-27632) was also studied in our cells. The inhibitor specificity is, however, questioned as in vitro studies revealed that it not

only exerts an inhibitory effect on ROCK proteins but also on other kinases [40]. Nevertheless, the control cells responded to its inhibition showing a lower rate of migration; conversely both transfected cells did not respond to its inhibitory effects. Thus far we have shown that the absence of Claudin-5 clearly caused an alteration in cell motility as the ROCK inhibitors were no longer inhibiting cell motility in MDACL5rib2. Additionally, in the case of MDACL5rib2 ifenprodil cells treated with N-WASP inhibitor, we

observed some inhibition, but at a considerably reduced manner compared to N-WASP inhibitor in control and MDACl5exp cells. The next question to be addressed following the ECIS results, was to investigate any possible protein-protein interaction between Claudin-5 and N-WASP or Claudin-5 and ROCK 1 as well as whether any direct effect was occurring at the protein level of these molecules in the control and transfected cells. Co-immunoprecipitation with Claudin-5, followed by immunoblotting with either N-WASP or ROCK 1 demonstrated an interaction between Claudin-5 and N-WASP as well as with ROCK 1. To confirm these interactions, a co-immunoprecipitation with either N-WASP or ROCK 1 followed by immunoblotting with Claudin-5 was carried out confirming the interactions between these protein pairs. Previously, studies have already linked TJ with N-WASP. The intestinal epithelial cells, T84, when treated with N-WASP inhibitor showed an inhibition in the formation of TJ [41].