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Role of the outer pore domain in transient receptor potential vanilloid 1 dynamic permeability to large cations.

ABSTRACT: Transient receptor potential vanilloid 1 (TRPV1) has been shown to alter its ionic selectivity profile in a time- and agonist-dependent manner. One hallmark of this dynamic process is an increased permeability to large cations such as N-methyl-D-glucamine (NMDG). In this study, we mutated residues throughout the TRPV1 pore domain to identify loci that contribute to dynamic large cation permeability. Using resiniferatoxin (RTX) as the agonist, we identified multiple gain-of-function substitutions within the TRPV1 pore turret (N628P and S629A), pore helix (F638A), and selectivity filter (M644A) domains. In all of these mutants, maximum NMDG permeability was substantially greater than that recorded in wild type TRPV1, despite similar or even reduced sodium current density. Two additional mutants, located in the pore turret (G618W) and selectivity filter (M644I), resulted in significantly reduced maximum NMDG permeability. M644A and M644I also showed increased and decreased minimum NMDG permeability, respectively. The phenotypes of this panel of mutants were confirmed by imaging the RTX-evoked uptake of the large cationic fluorescent dye YO-PRO1. Whereas none of the mutations selectively altered capsaicin-induced changes in NMDG permeability, the loss-of-function phenotypes seen with RTX stimulation of G618W and M644I were recapitulated in the capsaicin-evoked YO-PRO1 uptake assay. Curiously, the M644A substitution resulted in a loss, rather than a gain, in capsaicin-evoked YO-PRO1 uptake. Modeling of our mutations onto the recently determined TRPV1 structure revealed several plausible mechanisms for the phenotypes observed. We conclude that side chain interactions at a few specific loci within the TRPV1 pore contribute to the dynamic process of ionic selectivity.

SUBMITTER: Munns CH

PROVIDER: S-EPMC4342482 | biostudies-literature | 2015 Feb

REPOSITORIES: biostudies-literature

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Role of the outer pore domain in transient receptor potential vanilloid 1 dynamic permeability to large cations.

Munns Clare H CH Chung Man-Kyo MK Sanchez Yuly E YE Amzel L Mario LM Caterina Michael J MJ

The Journal of biological chemistry 20150107 9

Transient receptor potential vanilloid 1 (TRPV1) has been shown to alter its ionic selectivity profile in a time- and agonist-dependent manner. One hallmark of this dynamic process is an increased permeability to large cations such as N-methyl-D-glucamine (NMDG). In this study, we mutated residues throughout the TRPV1 pore domain to identify loci that contribute to dynamic large cation permeability. Using resiniferatoxin (RTX) as the agonist, we identified multiple gain-of-function substitutions ...[more]

PMID: 25568328

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Project description:The transient receptor potential vanilloid (TRPV) ion channel family is involved in multiple sensory and physiological functions including thermosensing and temperature-dependent neuroendocrine regulation. The objective of the present study was to investigate the number, origin and evolution of TRPV genes in metazoans, with special focus on the impact of the vertebrate whole-genome duplications (WGD). Gene searches followed by phylogenetic and synteny analyses revealed multiple previously undescribed TRPV genes. The common ancestor of Cnidaria and Bilateria had three TRPV genes that became four in the deuterostome ancestor. Two of these were lost in the vertebrate ancestor. The remaining two genes gave rise to two TRPV subfamilies in vertebrates, consisting of subtypes 1, 2, 3, 4, 9 and 5, 6, 7, 8, respectively. This gene expansion resulted from the two basal vertebrate WGD events (1R and 2R) and three local duplications before the radiation of gnathostomes. TRPV1, 4 and 5 have been retained in all gnathostomes investigated, presumably reflecting important functions. TRPV7 and 8 have been lost independently in various lineages but are still retained in cyclostomes, actinistians (coelacanth), amphibians, prototherians and basal actinopterygians (Polypteridae). TRPV3 and 9 are present in extant elasmobranchs, while TRPV9 was lost in the osteichthyan ancestor and TRPV3 in the actinopterygian ancestor. The coelacanth has retained the ancestral osteichthyan repertoire of TRPV1, 3, 4, 5, 7 and 8. TRPV2 arose in the tetrapod ancestor. Duplications of TRPV5 occurred independently in various lineages, such as cyclostomes, chondrichthyans, anuran amphibians, sauropsids, mammals (where the duplicate is called TRPV6), and actinopterygians (Polypteridae and Esocidae). After the teleost-specific WGD (3R) only TRPV1 retained its duplicate, whereas TRPV4 and 5 remained as single genes. Both 3R-paralogs of TRPV1 were kept in some teleost species, while one paralog was lost in others. The salmonid-specific WGD (4R) duplicated TRPV1, 4, and 5 leading to six TRPV genes. The largest number was found in Xenopus tropicalis with no less than 15 TRPV genes. This study provides a comprehensive evolutionary scenario for the vertebrate TRPV family, revealing additional TRPV types and proposing a phylogeny-based classification of TRPV across metazoans.

Dataset Information

Role of the outer pore domain in transient receptor potential vanilloid 1 dynamic permeability to large cations.

Publications

Role of the outer pore domain in transient receptor potential vanilloid 1 dynamic permeability to large cations.

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