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1.
Genes Brain Behav ; : e12625, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31730264

RESUMO

Temperature sensing is an important adaptive mechanism for warm-blooded animals such as humans. ThermoTRP ion channels are activated by distinct but overlapping physiological temperatures. Our previous research demonstrated that sorting nexin 11 (SNX11) regulates lysosomal degradation of plasma membrane TRPV3, one of ThermoTRP ion channel proteins. Here, we found that SNX11, a vesicular trafficking protein, modulates mouse behaviour in response to temperature changes. Snx11-knockout mice exhibit a stronger preference for mild temperatures along with enhanced sensitivity to harmful heat. Mechanistically, keratinocytes from Snx11-knockout mice exhibit a larger temperature-gated TRPV3 membrane current and have enhanced thermoTRPV3 expression in the plasma membrane compared to wild-type keratinocytes. Additionally, Snx11-knockout mice show higher endogenous TRPV3 protein levels in skin tissues than wild-type mice do. Therefore, our results indicate that SNX11 may regulate thermal perception via alteration of functional thermoTRPV3 on the plasma membrane of thermally sensitive cells, which is the first link between vesicular trafficking and thermal transduction.

2.
Traffic ; 17(5): 500-14, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-26818531

RESUMO

The trafficking of ion channels to/from the plasma membrane is considered an important mechanism for cellular activity and an interesting approach for disease therapies. The transient receptor potential vanilloid 3 (TRPV3) ion channel is widely expressed in skin keratinocytes, and its trafficking mechanism to/from the plasma membrane is unknown. Here, we report that the vesicular trafficking protein sorting nexin 11 (SNX11) downregulates the level of the TRPV3 plasma membrane protein. Overexpression of SNX11 causes a decrease in the level of TRPV3 current and TRPV3 plasma membrane protein in TRPV3-transfected HEK293T cells. Subcellular localizations and western blots indicate that SNX11 interacts with TRPV3 and targets it to lysosomes for degradation, which is blocked by the lysosomal inhibitors chloroquine and leupeptin. Both TRPV3 and SNX11 are highly expressed in HaCaT cells. We show that TRPV3 agonists-activated Ca(2+) influxes and the level of native TRPV3 total protein in HaCaT cells are decreased by overexpression of SNX11 and increased by knockdown of SNX11. Our findings reveal that SNX11 promotes the trafficking of TRPV3 from the plasma membrane to lysosomes for degradation via protein-protein interactions, which demonstrates a previously unknown function of SNX11 as a regulator of TRPV3 trafficking from the plasma membrane to lysosomes.


Assuntos
Lisossomos/metabolismo , Nexinas de Classificação/fisiologia , Canais de Cátion TRPV/metabolismo , Células HEK293 , Células HeLa , Humanos , Proteólise
3.
Free Radic Biol Med ; 89: 1003-13, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26456053

RESUMO

Oxidative stress is important for the initiation and progression of cancers, which confers the cells with a survival advantage by inducing oxidative adaption and drug resistance. Therefore, developing strategies to promote oxidative stress-induced cytotoxicity could be important for cancer therapy. Herein, we found that H2O2-mediated oxidative stress increases TRPV2 expression in human hepatoma (HepG2 and Huh-7) cells. This occurred at the mRNA and protein levels in a dose-dependent manner. The significance of TRPV2 in promoting H2O2-induced cell death was demonstrated in gain and loss of function studies with overexpression and knockdown of TRPV2, respectively. Mechanistically, H2O2-induced cell death involves inhibition of pro-survival signaling proteins (Akt, Nrf2) and activation of pro-death signaling proteins (p38, JNK1). Overexpression of TRPV2 in H2O2-treated hepatoma cells aggravates the inhibition of Akt and Nrf2, while it enhances the activation of p38 and JNK1 at the early stage of cell death. Interestingly, increased expression of TRPV2 in HepG2 cells improved the efficacy of stress-associated chemicals to induce cell death. Our findings suggest that TRPV2 acts as an important enhancer for H2O2-induced cytotoxicity. This process occurred by the inhibition of Akt and Nrf2 as well as the early activation of p38 and JNK1. These findings have important implications for inhibition of oxidative adaption and drug resistance.


Assuntos
Apoptose/efeitos dos fármacos , Carcinoma Hepatocelular/patologia , Peróxido de Hidrogênio/farmacologia , Neoplasias Hepáticas/patologia , Oxidantes/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Canais de Cátion TRPV/metabolismo , Western Blotting , Carcinoma Hepatocelular/tratamento farmacológico , Carcinoma Hepatocelular/metabolismo , Proliferação de Células/efeitos dos fármacos , Citometria de Fluxo , Humanos , Neoplasias Hepáticas/tratamento farmacológico , Neoplasias Hepáticas/metabolismo , Fator 2 Relacionado a NF-E2/genética , Fator 2 Relacionado a NF-E2/metabolismo , Fosfatidilinositol 3-Quinases/genética , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , RNA Mensageiro/genética , Reação em Cadeia da Polimerase em Tempo Real , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transdução de Sinais/efeitos dos fármacos , Canais de Cátion TRPV/genética , Células Tumorais Cultivadas , Proteínas Quinases p38 Ativadas por Mitógeno/genética , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismo
4.
Biochemistry ; 53(18): 3012-9, 2014 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-24762105

RESUMO

P2X receptors are trimeric ATP-gated cation permeable ion channels. When ATP binds, the extracellular head and dorsal fin domains are predicted to move closer to each other. However, there are scant functional data corroborating the role of the dorsal fin in ligand binding. Here using site-directed mutagenesis and electrophysiology, we show that a dorsal fin leucine, L214, contributes to ATP binding. Mutant receptors containing a single substitution of alanine, serine, glutamic acid, or phenylalanine at L214 of the rat P2X4 receptor exhibited markedly reduced sensitivities to ATP. Mutation of other dorsal fin side chains, S216, T223, and D224, did not significantly alter ATP sensitivity. Exposure of L214C to sodium (2-sulfonatoethyl) methanethiosulfonate (MTSES(-)) or (2-aminoethyl) methanethiosulfonate hydrobromide in the absence of ATP blocked responses evoked by subsequent ATP application. In contrast, when MTSES(-) was applied in the presence of ATP, no current inhibition was observed. Furthermore, L214A also slightly reduced the inhibitory effect of the antagonist 2',3'-O-(2,4,6-trinitrophenyl)-ATP, and the blockade was more rapidly reversible after washout. Certain L214 mutants also showed effects on current desensitization in the continued presence of ATP. L214I exhibited an accelerated current decline, whereas L214M exhibited a slower rate. Taken together, these data reveal that position L214 participates in both ATP binding and conformational changes accompanying channel opening and desensitization, providing compelling evidence that the dorsal fin domain indeed has functional properties that are similar to those previously reported for the body domains.


Assuntos
Trifosfato de Adenosina/metabolismo , Leucina/química , Receptores Purinérgicos P2X4/química , Substituição de Aminoácidos , Animais , Células HEK293 , Humanos , Ativação do Canal Iônico/efeitos dos fármacos , Ativação do Canal Iônico/genética , Ivermectina/farmacologia , Leucina/genética , Leucina/metabolismo , Ligantes , Modelos Moleculares , Mutagênese Sítio-Dirigida , Técnicas de Patch-Clamp , Estrutura Terciária de Proteína , Ratos , Receptores Purinérgicos P2X4/efeitos dos fármacos , Transdução de Sinais
5.
PLoS One ; 8(8): e70629, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23936459

RESUMO

The transition from the closed to open state greatly alters the intra- and inter-subunit interactions of the P2X receptor (P2XR). The interactions that occur in the transmembrane domain of the P2X2R remain unclear. We used substituted cysteine mutagenesis disulfide mapping to identify pairs of residues that are in close proximity within the transmembrane domain of rP2X2R and compared our results to the predicted positions of these amino acids obtained from a rat P2X2R homology model of the available open and closed zebrafish P2X4R structures. Alternations in channel function were measured as a change in the ATP-gated current before and after exposure to dithiothreitol. Thirty-six pairs of double mutants of rP2X2R expressed in HEK293 cells produced normal functioning channels. Thirty-five pairs of these mutants did not exhibit a functionally detectable disulfide bond. The double mutant H33C/S345C formed redox-dependent cross-links in the absence of ATP. Dithiothreitol ruptured the disulfide bond of H33C/S345C and induced a 2 to 3-fold increase in current. The EC50 for H33C/S345C before dithiothreitol treatment was ~2-fold higher than that after dithiothreitol treatment. Dithiothreitol reduced the EC50 to wild-type levels. Furthermore, expression of trimeric concatamer receptors with Cys mutations at some but not all six positions showed that the more disulfide bond formation sites within the concatamer, the greater current potentiation after dithiothreitol incubation. Immunoblot analysis of H33C/S345C revealed one monomer band under nonreducing conditions strongly suggesting that disulfide bonds are formed within single subunits (intra-subunit) and not between two subunits (inter-subunit). Taken together, these data indicate that His33 and Ser345 are proximal to each other across an intra-subunit interface. The relative movement between the first transmembrane and the second transmembrane in the intra-subunit is likely important for transmitting the action of ATP binding to the opening of the channel.


Assuntos
Membrana Celular/metabolismo , Receptores Purinérgicos P2X2/química , Receptores Purinérgicos P2X2/metabolismo , Animais , Cádmio/metabolismo , Cisteína , Dissulfetos/química , Células HEK293 , Humanos , Modelos Moleculares , Mutagênese , Mutação , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Ratos , Receptores Purinérgicos P2X2/genética , Homologia de Sequência de Aminoácidos
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