scholarly journals Beyond Hot and Spicy: TRPV Channels and their Pharmacological Modulation

2021 ◽  
Vol 55 (S3) ◽  
pp. 108-130

Transient receptor potential vanilloid (TRPV) channels are part of the TRP channel superfamily and named after the first identified member TRPV1, that is sensitive to the vanillylamide capsaicin. Their overall structure is similar to the structure of voltage gated potassium channels (Kv) built up as homotetramers from subunits with six transmembrane helices (S1-S6). Six TRPV channel subtypes (TRPV1-6) are known, that can be subdivided into the thermoTRPV (TRPV1-4) and the Ca2+-selective TRPV channels (TRPV5, TRPV6). Contrary to Kv channels, TRPV channels are not primary voltage gated. All six channels have distinct properties and react to several endogenous ligands as well as different gating stimuli such as heat, pH, mechanical stress, or osmotic changes. Their physiological functions are highly diverse and subtype as well as tissue specific. In many tissues they serve as sensors for different pain stimuli (heat, pressure, pH) and contribute to the homeostasis of electrolytes, the maintenance of barrier functions and the development of macrophages. Due to their fundamental role in manifold physiological and pathophysiological processes, TRPV channels are promising targets for drug development. However, drugs targeting specific TRPV channels, that are suitable for drug therapy, are rare. Moreover, selective and potent compounds for further research at TRPV channels are often lacking. In this review different aspects of the structure, the different gating stimuli, the expression pattern, the physiological and pathophysiological roles as well as the modulating mechanisms of synthetic, natural and endogenous ligands are summarized.

Pharmaceutics ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 334
Author(s):  
Huilong Luo ◽  
Xavier Declèves ◽  
Salvatore Cisternino

The gliovascular unit (GVU) is composed of the brain microvascular endothelial cells forming blood–brain barrier and the neighboring surrounding “mural” cells (e.g., pericytes) and astrocytes. Modulation of the GVU/BBB features could be observed in a variety of vascular, immunologic, neuro-psychiatric diseases, and cancers, which can disrupt the brain homeostasis. Ca2+ dynamics have been regarded as a major factor in determining BBB/GVU properties, and previous studies have demonstrated the role of transient receptor potential vanilloid (TRPV) channels in modulating Ca2+ and BBB/GVU properties. The physiological role of thermosensitive TRPV channels in the BBB/GVU, as well as their possible therapeutic potential as targets in treating brain diseases via preserving the BBB are reviewed. TRPV2 and TRPV4 are the most abundant isoforms in the human BBB, and TRPV2 was evidenced to play a main role in regulating human BBB integrity. Interspecies differences in TRPV2 and TRPV4 BBB expression complicate further preclinical validation. More studies are still needed to better establish the physiopathological TRPV roles such as in astrocytes, vascular smooth muscle cells, and pericytes. The effect of the chronic TRPV modulation should also deserve further studies to evaluate their benefit and innocuity in vivo.


2007 ◽  
Vol 292 (3) ◽  
pp. H1390-H1397 ◽  
Author(s):  
Sean P. Marrelli ◽  
Roger G. O'Neil ◽  
Rachel C. Brown ◽  
Robert M. Bryan

We previously demonstrated that endothelium-derived hyperpolarizing factor (EDHF)-mediated dilations in cerebral arteries are significantly reduced by inhibitors of PLA2. In this study we examined possible mechanisms by which PLA2 regulates endothelium-dependent dilation, specifically whether PLA2 is involved in endothelial Ca2+ regulation through stimulation of TRPV4 channels. Studies were carried out with middle cerebral arteries (MCA) or freshly isolated MCA endothelial cells (EC) of male Long-Evans rats. Nitro-l-arginine methyl ester (l-NAME) and indomethacin were present throughout. In pressurized MCA, luminally delivered UTP produced increased EC intracellular Ca2+ concentration ([Ca2+]i) and MCA dilation. Incubation with PACOCF3, a PLA2 inhibitor, significantly reduced both EC [Ca2+]i and dilation responses to UTP. EC [Ca2+]i was also partially reduced by a transient receptor potential vanilloid (TRPV) channel blocker, ruthenium red. Manganese quenching experiments demonstrated Ca2+ influx across the luminal and abluminal face of the endothelium in response to UTP. Interestingly, PLA2-sensitive Ca2+ influx occurred primarily across the abluminal face. Luminal application of arachidonic acid, the primary product of PLA2 and a demonstrated activator of certain TRPV channels, increased both EC [Ca2+]i and MCA diameter. TRPV4 mRNA and protein was demonstrated in the endothelium by RT-PCR and immunofluorescence, respectively. Finally, application of 4α-phorbol 12,13-didecanoate (4αPDD), a TRPV4 channel activator, produced an increase in EC [Ca2+]i that was significantly reduced in the presence of ruthenium red. We conclude that PLA2 is involved in EC Ca2+ regulation through its regulation of TRPV4 channels. Furthermore, the PLA2-sensitive component of Ca2+ influx may be polarized to the abluminal face of the endothelium.


2019 ◽  
Vol 116 (18) ◽  
pp. 8869-8878 ◽  
Author(s):  
Shangyu Dang ◽  
Mark K. van Goor ◽  
Daniel Asarnow ◽  
YongQiang Wang ◽  
David Julius ◽  
...  

TRPV5 (transient receptor potential vanilloid 5) is a unique calcium-selective TRP channel essential for calcium homeostasis. Unlike other TRPV channels, TRPV5 and its close homolog, TRPV6, do not exhibit thermosensitivity or ligand-dependent activation but are constitutively open at physiological membrane potentials and modulated by calmodulin (CaM) in a calcium-dependent manner. Here we report high-resolution electron cryomicroscopy structures of truncated and full-length TRPV5 in lipid nanodiscs, as well as of a TRPV5 W583A mutant and TRPV5 in complex with CaM. These structures highlight the mechanism of calcium regulation and reveal a flexible stoichiometry of CaM binding to TRPV5.


2016 ◽  
Vol 21 (4) ◽  
pp. 268-274 ◽  
Author(s):  
Takefumi Kamakura ◽  
Makoto Kondo ◽  
Yoshihisa Koyama ◽  
Yukiko Hanada ◽  
Yusuke Ishida ◽  
...  

Transient receptor potential vanilloid (TRPV) 4 is a nonselective cation channel expressed in sensory neurons such as those in the dorsal root and trigeminal ganglia, kidney, and inner ear. TRPV4 is activated by mechanical stress, heat, low osmotic pressure, low pH, and phorbol derivatives such as 4α-phorbol 12,13-didecanoate (4α-PDD). We investigated the expression of TRPV4 in rat vestibular ganglion (VG) neurons. The TRPV4 gene was successfully amplified from VG neuron mRNA using reverse-transcription polymerase chain reaction. Furthermore, immunoblotting showed positive expression of TRPV4 protein in VG neurons. Immunohistochemistry indicated that TRPV4 was localized predominantly on the plasma membrane of VG neurons. Calcium (Ca2+) imaging of VG neurons showed that 4α-PDD and/or hypotonic stimuli caused an increase in intracellular Ca2+ concentration ([Ca2+]i) that was almost completely inhibited by ruthenium red, a selective antagonist of TRPV channels. Interestingly, a [Ca2+]i increase was evoked by both hypotonic stimuli and 4α-PDD in approximately 38% of VG neurons. These data indicate that TRPV4 is functionally expressed in VG neurons as an ion channel and that TRPV4 likely participates in VG neurons for vestibular neurotransmission as an osmoreceptor and/or mechanoreceptor.


2006 ◽  
Vol 191 (3) ◽  
pp. 515-523 ◽  
Author(s):  
Wolfgang Liedtke

In signal transduction of metazoan cells, ion channels of the family of transient receptor potential (TRP) have been identified to respond to diverse external and internal stimuli, amongst them osmotic stimuli. This review will highlight findings on the TRPV subfamily, both vertebrate and invertebrate members. Out of the six mammalian TRP vanilloid (TRPV) channels, TRPV1, TRPV2, and TRPV4 were demonstrated to function in transduction of osmotic stimuli. TRPV channels have been found to function in cellular as well as systemic osmotic homeostasis in vertebrates. Invertebrate TRPV channels, five in Caenorhabditis elegans and two in Drosophila, have been shown to play a role in mechanosensation, such as hearing and proprioception in Drosophila and nose touch in C. elegans, and in the response to osmotic stimuli in C. elegans. In a striking example of evolutionary conservation of function, mammalian TRPV4 has been found to rescue osmo-and mechanosensory deficits of the TRPV mutant strain osm-9 in C. elegans, despite not more than 26% orthology of the respective proteins.


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