TRPV3 in keratinocytes transmits temperature information to sensory neurons via ATP

Transient receptor potential V3 (TRPV3) and TRPV4 are heat-activated cation channels expressed in keratinocytes. It has been proposed that heat-activation of TRPV3 and/or TRPV4 in the skin may release diffusible molecules which would then activate termini of neighboring dorsal root ganglion (DRG) neurons. Here we show that adenosine triphosphate (ATP) is such a candidate molecule released from keratinocytes upon heating in the co-culture systems. Using TRPV1-deficient DRG neurons, we found that increase in cytosolic Ca(2+)-concentration in DRG neurons upon heating was observed only when neurons were co-cultured with keratinocytes, and this increase was blocked by P2 purinoreceptor antagonists, PPADS and suramin. In a co-culture of keratinocytes with HEK293 cells (transfected with P2X(2) cDNA to serve as a bio-sensor), we observed that heat-activated keratinocytes secretes ATP, and that ATP release is compromised in keratinocytes from TRPV3-deficient mice. This study provides evidence that ATP is a messenger molecule for mainly TRPV3-mediated thermotransduction in skin. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00424-009-0703-x) contains supplementary material, which is available to authorized users

DIP/WISH deficiency enhances synaptic function and performance in the Barnes maze

<p>Abstract</p> <p>Background</p> <p>DIP (diaphanous interacting protein)/WISH (WASP interacting SH3 protein) is a protein involved in cytoskeletal signaling which regulates actin cytoskeleton dynamics and/or microtubules mainly through the activity of Rho-related proteins. Although it is well established that: 1) spine-head volumes change dynamically and reflect the strength of the synapse accompanying long-term functional plasticity of glutamatergic synaptic transmission and 2) actin organization is critically involved in spine formation, the involvement of DIP/WISH in these processes is unknown.</p> <p>Results</p> <p>We found that DIP/WISH-deficient hippocampal CA1 neurons exhibit enhanced long-term potentiation via modulation of both pre- and post-synaptic events. Consistent with these electrophysiological findings, DIP/WISH-deficient mice, particularly at a relatively young age, found the escape hole more rapidly in the Barnes maze test.</p> <p>Conclusions</p> <p>We conclude that DIP/WISH deletion improves performance in the Barnes maze test in mice probably through increased hippocampal long-term potentiation.</p

HIV-1 Nef Disrupts the Podocyte Actin Cytoskeleton by Interacting with Diaphanous Interacting Protein*

The ability of the human immunodeficiency virus, type 1 (HIV-1) protein Nef to induce cytoskeleton changes in infected host cells is a key event in viral replication. In renal podocytes, we found that Nef induced loss of stress fibers and increased lamellipodia, pathological changes leading to proteinuria in HIV-associated nephropathy. These morphological changes were mediated by Nef-induced Rac1 activation and RhoA inhibition. We identified a new interaction between Nef and diaphanous interacting protein (DIP), a recently described regulator of Rho and Rac signaling. We found that the Src homology 3 binding domain of DIP and the Nef PXXP motif were required for this interaction. Nef also interacts with Vav2 in podocytes. DIP and Vav2 both interact directly with Nef in a competitive manner. DIP interacts with p190RhoGAP, and intact DIP was required for Nef-induced phosphorylation of p190RhoGAP. DIP also interacts with Vav2, and although DIP enhanced baseline phosphorylation of Vav2, it was not required for Nef-induced Vav2 activation. In Nef-infected podocytes, Src kinase induces phosphorylation of DIP, p190RhoGAP, and Vav2, leading to RhoA inhibition and Rac1 activation. Inhibition of the Nef-induced signaling pathway by using a dominant negative of either Src or DIP or siRNA for DIP or p190RhoAGAP restored RhoA activity and stress fiber formation in Nef-infected podocytes, whereas siRNA for Vav2 reduced Rac1 activity and formation of lamellipodia. We conclude that in HIV-infected podocytes, Nef, through the recruitment of DIP and p190RhoAGAP to Nef-Src complex, activates p190RhoAGAP and down-regulates RhoA activity