Transient receptor potential V2 (TRPV2) has been proposed to be a high-threshold thermosensor. However, further elucidation of the channel properties and physiological role of TRPV2 have been hindered by the lack of selective pharmacological tools as well as by the species-dependent differences in the activation of this channel. In the present study, we have used cell-based calcium mobilization and electrophysiological assays to identify and characterize several novel cannabinoid TRPV2 agonists. Among these, cannabidiol was found to be the most robust and potent (EC 50 ϭ 3.7 M), followed by ⌬ 9 -tetrahydrocannabinol (EC 50 ϭ 14 M) and cannabinol (EC 50 ϭ 77.7 M). We also demonstrated that cannabidiol evoked a concentration-dependent release of calcitonin gene-related peptide (CGRP) from cultured rat dorsal root ganglion neurons in a cannabinoid receptor-and TRPV1-independent manner. Moreover, the cannabidiolevoked CGRP release depended on extracellular calcium and was blocked by the nonselective TRP channel blocker, ruthenium red. We further provide evidence through the use of small interfering RNA knockdown and repetitive stimulation studies, to show that cannabidiol-evoked CGRP release is mediated, at least in part, by TRPV2. Together, these data suggest not only that TRPV2 may comprise a mechanism whereby cannabidiol exerts its clinically beneficial effects in vivo, but also that TRPV2 may constitute a viable, new drug target.

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TRPV2 has been proposed as a potential pain target, in part due to its relatedness to the nociceptor TRPV1 and to its reported activation by noxious high temperatures (>52°C). However, TRPV2 responses to heat as well as to the nonselective agonist 2-aminoethoxydiphenyl borate (2-APB) have not been universally reproduced in other laboratories, leading to debate about the activation properties of this channel. Here, we report the expression of rat, mouse, and human TRPV2 in HEK293 cells and the differential properties of their responses to heat and 2-APB. Expression of mouse or rat TRPV2 in HEK293 cells resulted in robust channel activation when induced by either temperature (>53°C) or 2-APB. By contrast, expression of human TRPV2 did not lead to detectable activation by either of these stimuli. Human TRPV2 protein was expressed at levels comparable with those of rat TRPV2, exhibited similar surface localization and responded to a novelly identified TRPV2 agonist, ⌬ 9 -tetrahydrocannabinol, indicating that human TRPV2 is functionally expressed on the cell surface. Studies using deletion mutants and chimeras between rat and human TRPV2 indicated that both amino-and carboxyl-cytoplasmic termini of rat TRPV2 are important for responses to heat and 2-APB but can be supplied in trans to form an active channel. The present study not only confirms and extends previous reports demonstrating that rat and mouse TRPV2 respond to 2-APB and noxious heat but also indicates that further investigation will be required to elucidate TRPV2 activation and regulatory mechanisms.TRP (transient receptor potential) proteins comprise a large family of nonselective cation channels responsible for diverse cellular functions, including the transduction of thermal, chemical, and mechanical stimuli, as well as the regulation of cellular calcium levels. Named after the Drosophila phototransduction pathway mutant trp, with which they share common structural homology (1), these proteins are characterized by a six-transmembrane domain region, including a pore and cytosolically oriented NH 2 and COOH termini, the former of which typically includes one or more ankyrin domain repeats (for a review, see Ref.2). Recent studies have provided evidence that there are at least six distinct TRP channels that are temperature sensors (3). These thermo-TRPs are believed to be important transducers of temperature to the nervous system, including the sensation of pain due to noxious heat and cold. TRPV1, the most extensively characterized member of the TRP family, is activated by moderate heat (ϳ43°C), capsaicin, protons, and certain lipidic mediators, such as anandamide (4, 5). Moreover, numerous studies using a variety of experimental approaches have implicated TRPV1 in the transduction of pain signals in animal models of hyperalgesia (6, 7); hence, this TRP has been aggressively pursued as a target for the alleviation of certain types of pain.The TRP vanilloid subfamily, type 2 channel (TRPV2; also known as vanilloid receptor-like 1, or VRL-1), is closely rel...

It has been shown previously that immunization of animals with recombinant virus-like particles (VLPs) consisting of the viral capsid proteins L1 or L1 plus L2 protected animals against experimental viral challenge. However, none of these experimental models addresses the issue of whether systemic immunization with VLPs elicits a neutralizing antibody response in the genital mucosa. Such a response may be necessary to protect the uterine cervix against infection with genital human papillomavirus (HPV) types. African green monkeys systemically immunized with HPV-11 VLPs expressed in Saccharomyces cerevisiae and formulated on aluminum adjuvant elicited high-titered HPV-11 VLP-specific serum antibody responses. Sera from these immunized monkeys neutralized HPV-11 in the athymic mouse xenograft system. Significant levels of HPV-11-neutralizing antibodies also were observed in cervicovaginal secretions. These findings suggest that protection against HPV infection of the uterine cervix may be possible through systemic immunization with HPV VLPs.