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Oxidation of methionine residues activates the high-threshold heat-sensitive ion channel TRPV2.

ABSTRACT: Thermosensitive transient receptor potential (TRP) ion channels detect changes in ambient temperature to regulate body temperature and temperature-dependent cellular activity. Rodent orthologs of TRP vanilloid 2 (TRPV2) are activated by nonphysiological heat exceeding 50 °C, and human TRPV2 is heat-insensitive. TRPV2 is required for phagocytic activity of macrophages which are rarely exposed to excessive heat, but what activates TRPV2 in vivo remains elusive. Here we describe the molecular mechanism of an oxidation-induced temperature-dependent gating of TRPV2. While high concentrations of H2O2 induce a modest sensitization of heat-induced inward currents, the oxidant chloramine-T (ChT), ultraviolet A light, and photosensitizing agents producing reactive oxygen species (ROS) activate and sensitize TRPV2. This oxidation-induced activation also occurs in excised inside-out membrane patches, indicating a direct effect on TRPV2. The reducing agent dithiothreitol (DTT) in combination with methionine sulfoxide reductase partially reverses ChT-induced sensitization, and the substitution of the methionine (M) residues M528 and M607 to isoleucine almost abolishes oxidation-induced gating of rat TRPV2. Mass spectrometry on purified rat TRPV2 protein confirms oxidation of these residues. Finally, macrophages generate TRPV2-like heat-induced inward currents upon oxidation and exhibit reduced phagocytosis when exposed to the TRP channel inhibitor ruthenium red (RR) or to DTT. In summary, our data reveal a methionine-dependent redox sensitivity of TRPV2 which may be an important endogenous mechanism for regulation of TRPV2 activity and account for its pivotal role for phagocytosis in macrophages.

SUBMITTER: Fricke TC

PROVIDER: S-EPMC6883831 | biostudies-literature | 2019 Nov

REPOSITORIES: biostudies-literature

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Oxidation of methionine residues activates the high-threshold heat-sensitive ion channel TRPV2.

Fricke Tabea C TC Echtermeyer Frank F Zielke Johannes J de la Roche Jeanne J Filipovic Milos R MR Claverol Stéphane S Herzog Christine C Tominaga Makoto M Pumroy Ruth A RA Moiseenkova-Bell Vera Y VY Zygmunt Peter M PM Leffler Andreas A Eberhardt Mirjam J MJ

Proceedings of the National Academy of Sciences of the United States of America 20191112 48

Thermosensitive transient receptor potential (TRP) ion channels detect changes in ambient temperature to regulate body temperature and temperature-dependent cellular activity. Rodent orthologs of TRP vanilloid 2 (TRPV2) are activated by nonphysiological heat exceeding 50 °C, and human TRPV2 is heat-insensitive. TRPV2 is required for phagocytic activity of macrophages which are rarely exposed to excessive heat, but what activates TRPV2 in vivo remains elusive. Here we describe the molecular mecha ...[more]

PMID: 31719194

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Project description:The cation channel TRPV2 is known to be expressed by murine macrophages and is crucially involved in their functionality. Macrophages are frequent cells of the mouse testis, an immune-privileged and steroid-producing organ. TRPV2 expression by testicular macrophages and possible changes associated with age or inflammation have not been investigated yet. Therefore, we studied testes of young adult and old wild-type (WT) and AROM+ mice, i.e., transgenic mice overexpressing aromatase. In these animals, inflammatory changes are described in the testis, involving active macrophages, which increase with age. This is associated with impaired spermatogenesis and therefore AROM+ mice are a model for male infertility associated with sterile inflammation. In WT animals, testicular TRPV2 expression was mapped to interstitial CD206+ and peritubular MHC II+ macrophages, with higher levels in CD206+ cells. Expression levels of TRPV2 and most macrophage markers did not increase significantly in old mice, with the exception of CD206. As the number of TRPV2+ testicular macrophages was relatively small, their possible involvement in testicular functions and in aging in WT mice remains to be further studied. In AROM+ testis, TRPV2 was readily detected and levels increased significantly with age, together with macrophage markers and TNF-α. TRPV2 co-localized with F4/80 in macrophages and further studies showed that TRPV2 is mainly expressed by unusual CD206+MHC II+ macrophages, arising in the testis of these animals. Rescue experiments (aromatase inhibitor treatment and crossing with ERαKO mice) restored the testicular phenotype and also abolished the elevated expression of TRPV2, macrophage and inflammation markers. This suggests that TRPV2+ macrophages of the testis are part of an inflammatory cascade initiated by an altered sex hormone balance in AROM+ mice. The changes in testis are distinct from the described alterations in other organs of AROM+, such as prostate and spleen. When we monitored TRPV2 levels in another immune-privileged organ, namely the brain, we found that levels of TRPV2 were not elevated in AROM+ and remained stable during aging. In the adrenal, which similar to the testis produces steroids, we found slight, albeit not significant increases in TRPV2 in both AROM+ and WT mice, which were associated with age. Thus, the changes in the testis are specific for this organ.

Dataset Information

Oxidation of methionine residues activates the high-threshold heat-sensitive ion channel TRPV2.

Publications

Oxidation of methionine residues activates the high-threshold heat-sensitive ion channel TRPV2.

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