TRPV4 Regulates Cytoskeleton Figure 5. Activation of TRPV4 results in reorganization of actin cytoskeleton. Shown are the confocal images of live F11 cells expressing TRPV4-GFP (green) and Actin-RFP (red). a. Activation of TRPV4 results in merging of several actin-ribs at the tips and further transition of lamellipodial structures to filopodial structures. The arrow indicates the region and direction of the cell retraction at the same time. b. Activation of TRPV4 results in lateral initiation of filopodial structures from neurites and further elongation of them. doi:10.1371/journal.pone.0011654.g005 cytoskeleton components interact directly and functionally with a mechanosensitive ion channel, namely TRPV4. The C-terminus of TRPV4 interacts directly with actin and microtubule cytoskeletal components The C-terminus of various TRP channels has been shown to be of importance. For example, a recent study reported that the deletion of the C-terminal cytoplasmic domain of TRPV4 strongly inhibits membrane localization [63]. And also the C-terminus of TRPC4 interacts with another cytoskeletal component, spectrin, which is essential for the surface expression of the receptor [64]. In this work we now demonstrate that TRPV4-Ct is sufficient for the interaction with tubulin and actin as well as signaling-components. The interaction of MBP-TRPV4-Ct to tubulin and actin appears to be very strong as these interactions withstand the presence of high salt concentrations (500 mM NaCl, data not shown). If the N- terminal cytoplasmic domain of TRPV4 can also interact with the cytoskeleton has not been established yet. We observed that TRPV4 co-localized with actin-enriched structures, such as focal adhesion points, filopodial and lamellipo- dial structures. These results fit well with the previously described subcellular localizations of TRPV4 in actin cytoskeleton-enriched structures like dendritic spines [65]. This also accords well with the reported presence of a2 integrin, an actin binding protein in the TRPV4 complex [66]. We show that TRPV4 physically interacts with soluble actin as well as with polymerised actin filaments via its PLoS ONE | www.plosone.org 8 July 2010 | Volume 5 | Issue 7 | e11654