Pub Date : 2020-12-01DOI: 10.1080/19336950.2020.1730020
Shuo Wang, Chenhong Jia
The natural outcome of abdominal aortic aneurysm (AAA) is that of slow progression and ultimate rupture, then a life-threatening hemorrhage consequently. Ruptured AAA is a dramatic catastrophe and constitutes one of the leading causes of acute death in elderly men. However, the mechanism of AAA is still unclear. Transient receptor potential vanilloid (TRPV) family has protective effects in cardiovascular diseases. In this study, we revealed the expression and the pathogenesis of TRPV1 in a mouse AAA model. The results presented here identify TRPV1 could be a potential therapeutic target for AAA treatment.
{"title":"TRPV1 inhibits smooth muscle cell phenotype switching in a mouse model of abdominal aortic aneurysm.","authors":"Shuo Wang, Chenhong Jia","doi":"10.1080/19336950.2020.1730020","DOIUrl":"https://doi.org/10.1080/19336950.2020.1730020","url":null,"abstract":"<p><p>The natural outcome of abdominal aortic aneurysm (AAA) is that of slow progression and ultimate rupture, then a life-threatening hemorrhage consequently. Ruptured AAA is a dramatic catastrophe and constitutes one of the leading causes of acute death in elderly men. However, the mechanism of AAA is still unclear. Transient receptor potential vanilloid (TRPV) family has protective effects in cardiovascular diseases. In this study, we revealed the expression and the pathogenesis of TRPV1 in a mouse AAA model. The results presented here identify TRPV1 could be a potential therapeutic target for AAA treatment.</p>","PeriodicalId":72555,"journal":{"name":"Channels (Austin, Tex.)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/19336950.2020.1730020","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"37661596","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-01DOI: 10.1080/19336950.2020.1825894
Chihiro Uehara, Kota Takeda, Tatsuki Ibuki, Tadaomi Furuta, Naomi Hoshi, Ellen Tanudjaja, Nobuyuki Uozumi
Arabidopsis thaliana contains five tandem-pore domain potassium channels, TPK1-TPK5 and the related one-pore domain potassium channel, KCO3. Although KCO3 is unlikely to be an active channel, it still has a physiological role in plant cells. TPK2 is most similar to KCO3 and both are localized to the tonoplast. However, their function remains poorly understood. Here, taking advantage of the similarities between TPK2 and KCO3, we evaluated Ca2+ binding to the EF hands in TPK2, and the elements of KCO3 required for K+ channel activity. Presence of both EF-hand motifs in TPK2 resulted in Ca2+ binding, but EF1 or EF2 alone failed to interact with Ca2+. The EF hands were not required for K+ transport activity. EF1 contains two cysteines separated by two amino acids. Replacement of both cysteines with serines in TPK2 increased Ca2+ binding. We generated a two-pore domain chimeric K+ channel by replacing the missing pore region in KCO3 with a pore domain of TPK2. Alternatively, we generated two versions of simple one-pore domain K+ channels by removal of an extra region from KCO3. The chimera and one of the simple one-pore variants were functional channels. This strongly suggests that KCO3 is not a pseudogene and KCO3 retains components required for the formation of a functional K+ channel and oligomerization. Our results contribute to our understanding of the structural properties required for K+ channel activity.
{"title":"Analysis of Arabidopsis TPK2 and KCO3 reveals structural properties required for K<sup>+</sup> channel function.","authors":"Chihiro Uehara, Kota Takeda, Tatsuki Ibuki, Tadaomi Furuta, Naomi Hoshi, Ellen Tanudjaja, Nobuyuki Uozumi","doi":"10.1080/19336950.2020.1825894","DOIUrl":"https://doi.org/10.1080/19336950.2020.1825894","url":null,"abstract":"<p><p>Arabidopsis thaliana contains five tandem-pore domain potassium channels, TPK1-TPK5 and the related one-pore domain potassium channel, KCO3. Although KCO3 is unlikely to be an active channel, it still has a physiological role in plant cells. TPK2 is most similar to KCO3 and both are localized to the tonoplast. However, their function remains poorly understood. Here, taking advantage of the similarities between TPK2 and KCO3, we evaluated Ca<sup>2+</sup> binding to the EF hands in TPK2, and the elements of KCO3 required for K<sup>+</sup> channel activity. Presence of both EF-hand motifs in TPK2 resulted in Ca<sup>2+</sup> binding, but EF1 or EF2 alone failed to interact with Ca<sup>2+</sup>. The EF hands were not required for K<sup>+</sup> transport activity. EF1 contains two cysteines separated by two amino acids. Replacement of both cysteines with serines in TPK2 increased Ca<sup>2+</sup> binding. We generated a two-pore domain chimeric K<sup>+</sup> channel by replacing the missing pore region in KCO3 with a pore domain of TPK2. Alternatively, we generated two versions of simple one-pore domain K<sup>+</sup> channels by removal of an extra region from KCO3. The chimera and one of the simple one-pore variants were functional channels. This strongly suggests that <i>KCO3</i> is not a pseudogene and KCO3 retains components required for the formation of a functional K<sup>+</sup> channel and oligomerization. Our results contribute to our understanding of the structural properties required for K<sup>+</sup> channel activity.</p>","PeriodicalId":72555,"journal":{"name":"Channels (Austin, Tex.)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/19336950.2020.1825894","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"38454955","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-01DOI: 10.1080/19336950.2020.1841419
Mircea Iftinca, Christophe Altier
Transient receptor potential melastatin 8 (TRPM8) channels play a central role in the detection of environmental cold temperatures in the somatosensory system. TRPM8 is found in a subset of unmyelinated (C-type) afferents located in the dorsal root (DRG) and trigeminal ganglion (TG). Cold hypersensitivity is a common symptom of neuropathic pain conditions caused by cancer therapy, spinal cord injury, viral infection, multiple sclerosis, diabetes, or withdrawal symptoms associated with chronic morphine treatment. Therefore, TRPM8 has received great attention as a therapeutic target. However, as the activity of TRPM8 is unique in sensing cool temperature as well as warming, it is critical to understand the signaling transduction pathways that control modality-specific activity of TRPM8 in healthy versus pathological settings. This review summarizes recent advances in our understanding of the mechanisms involved in the regulation of the TRPM8 activity.
{"title":"The cool things to know about TRPM8!","authors":"Mircea Iftinca, Christophe Altier","doi":"10.1080/19336950.2020.1841419","DOIUrl":"https://doi.org/10.1080/19336950.2020.1841419","url":null,"abstract":"<p><p>Transient receptor potential melastatin 8 (TRPM8) channels play a central role in the detection of environmental cold temperatures in the somatosensory system. TRPM8 is found in a subset of unmyelinated (C-type) afferents located in the dorsal root (DRG) and trigeminal ganglion (TG). Cold hypersensitivity is a common symptom of neuropathic pain conditions caused by cancer therapy, spinal cord injury, viral infection, multiple sclerosis, diabetes, or withdrawal symptoms associated with chronic morphine treatment. Therefore, TRPM8 has received great attention as a therapeutic target. However, as the activity of TRPM8 is unique in sensing cool temperature as well as warming, it is critical to understand the signaling transduction pathways that control modality-specific activity of TRPM8 in healthy versus pathological settings. This review summarizes recent advances in our understanding of the mechanisms involved in the regulation of the TRPM8 activity.</p>","PeriodicalId":72555,"journal":{"name":"Channels (Austin, Tex.)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/19336950.2020.1841419","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"38573149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-01DOI: 10.1080/19336950.2020.1837439
Hani Alothaid, Mohammed S K Aldughaim, Karim El Bakkouri, Sufana AlMashhadi, Ahmed A Al-Qahtani
The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has prompted an urgent need to identify effective medicines for the prevention and treatment of the disease. A comparative analysis between SARS-CoV-2 and Hepatitis C Virus (HCV) can expand the available knowledge regarding the virology and potential drug targets against these viruses. Interestingly, comparing HCV with SARS-CoV-2 reveals major similarities between them, ranging from the ion channels that are utilized, to the symptoms that are exhibited by patients. Via this comparative analysis, and from what is known about HCV, the most promising treatments for COVID-19 can focus on the reduction of viral load, treatment of pulmonary system damages, and reduction of inflammation. In particular, the drugs that show most potential in this regard include ritonavir, a combination of peg-IFN, and lumacaftor-ivacaftor. This review anaylses SARS-CoV-2 from the perspective of the role of ion homeostasis and channels in viral pathomechanism. We also highlight other novel treatment approaches that can be used for both treatment and prevention of COVID-19. The relevance of this review is to offer high-quality evidence that can be used as the basis for the identification of potential solutions to the COVID-19 pandemic.
{"title":"Similarities between the effect of SARS-CoV-2 and HCV on the cellular level, and the possible role of ion channels in COVID19 progression: a review of potential targets for diagnosis and treatment.","authors":"Hani Alothaid, Mohammed S K Aldughaim, Karim El Bakkouri, Sufana AlMashhadi, Ahmed A Al-Qahtani","doi":"10.1080/19336950.2020.1837439","DOIUrl":"https://doi.org/10.1080/19336950.2020.1837439","url":null,"abstract":"<p><p>The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has prompted an urgent need to identify effective medicines for the prevention and treatment of the disease. A comparative analysis between SARS-CoV-2 and Hepatitis C Virus (HCV) can expand the available knowledge regarding the virology and potential drug targets against these viruses. Interestingly, comparing HCV with SARS-CoV-2 reveals major similarities between them, ranging from the ion channels that are utilized, to the symptoms that are exhibited by patients. Via this comparative analysis, and from what is known about HCV, the most promising treatments for COVID-19 can focus on the reduction of viral load, treatment of pulmonary system damages, and reduction of inflammation. In particular, the drugs that show most potential in this regard include ritonavir, a combination of peg-IFN, and lumacaftor-ivacaftor. This review anaylses SARS-CoV-2 from the perspective of the role of ion homeostasis and channels in viral pathomechanism. We also highlight other novel treatment approaches that can be used for both treatment and prevention of COVID-19. The relevance of this review is to offer high-quality evidence that can be used as the basis for the identification of potential solutions to the COVID-19 pandemic.</p>","PeriodicalId":72555,"journal":{"name":"Channels (Austin, Tex.)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/19336950.2020.1837439","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"38615057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-01DOI: 10.1080/19336950.2020.1750189
Jingyuan Li, Siqi Wang, Jie Zhang, Yan Liu, Xi Zheng, Fan Ding, Xuefei Sun, Meimi Zhao, Liying Hao
Residue Thr1604 in the CaV1.2 channel is a Ca2+/calmodulin dependent protein kinase II (CaMKII) phosphorylation site, and its phosphorylation status maintains the basic activity of the channel. However, the role of CaV1.2 phosphorylation at Thr1604 in myocardial hypertrophy is incompletely understood. Isoproterenol (ISO) was used to induce cardiomyocyte hypertrophy, and autocamtide-2-related inhibitory peptide (AIP) was added as a treatment. Rats in a myocardial hypertrophy development model were subcutaneously injected with ISO for two or three weeks. The heart and left ventricle weights, each of which were normalized to the body weight and cross-sectional area of the myocardial cells, were used to describe the degree of hypertrophy. Protein expression levels were detected by western blotting. CaMKII-induced CaV1.2 (Thr1604) phosphorylation (p-CaV1.2) was assayed by coimmunoprecipitation. The results showed that CaMKII, HDAC, MEF2 C, and atrial natriuretic peptide (ANP) expression was increased in the ISO group and downregulated by AIP treatment in vitro. There was no difference in the expression of these proteins between the ISO 2-week group and the ISO 3-week group in vivo. CaV1.2 channel expression did not change, but p-CaV1.2 expression was increased after ISO stimulation and decreased by AIP. In the rat model, p-CaV1.2 levels and CaMKII activity were much higher in the ISO 3-week group than in the ISO 2-week group. CaMKII-induced CaV1.2 channel phosphorylation at residue Thr1604 may be one of the key features of myocardial hypertrophy and disease development.Abbreviations: CaMKII: Ca2+/calmodulin dependent protein kinase II; p-CaMKII: autophosphorylated Ca2+/calmodulin dependent protein kinase II; CaM: calmodulin; AIP: autocamtide-2-related inhibitory peptide; ECC: excitation-contraction coupling; ISO: isoproterenol; BW: body weight; HW: heart weight; LVW: left ventricle weight; HDAC: histone deacetylase; p-HDAC: phosphorylated histone deacetylase; MEF2C: myocyte-specific enhancer factor 2C; ANP: atrial natriuretic peptide; PKC: protein kinase C.
{"title":"The CaMKII phosphorylation site Thr1604 in the Ca<sub>V</sub>1.2 channel is involved in pathological myocardial hypertrophy in rats.","authors":"Jingyuan Li, Siqi Wang, Jie Zhang, Yan Liu, Xi Zheng, Fan Ding, Xuefei Sun, Meimi Zhao, Liying Hao","doi":"10.1080/19336950.2020.1750189","DOIUrl":"https://doi.org/10.1080/19336950.2020.1750189","url":null,"abstract":"<p><p>Residue Thr1604 in the Ca<sub>V</sub>1.2 channel is a Ca<sup>2+</sup>/calmodulin dependent protein kinase II (CaMKII) phosphorylation site, and its phosphorylation status maintains the basic activity of the channel. However, the role of Ca<sub>V</sub>1.2 phosphorylation at Thr1604 in myocardial hypertrophy is incompletely understood. Isoproterenol (ISO) was used to induce cardiomyocyte hypertrophy, and autocamtide-2-related inhibitory peptide (AIP) was added as a treatment. Rats in a myocardial hypertrophy development model were subcutaneously injected with ISO for two or three weeks. The heart and left ventricle weights, each of which were normalized to the body weight and cross-sectional area of the myocardial cells, were used to describe the degree of hypertrophy. Protein expression levels were detected by western blotting. CaMKII-induced Ca<sub>V</sub>1.2 (Thr1604) phosphorylation (p-Ca<sub>V</sub>1.2) was assayed by coimmunoprecipitation. The results showed that CaMKII, HDAC, MEF2 C, and atrial natriuretic peptide (ANP) expression was increased in the ISO group and downregulated by AIP treatment <i>in vitro</i>. There was no difference in the expression of these proteins between the ISO 2-week group and the ISO 3-week group <i>in vivo</i>. Ca<sub>V</sub>1.2 channel expression did not change, but p-Ca<sub>V</sub>1.2 expression was increased after ISO stimulation and decreased by AIP. In the rat model, p-Ca<sub>V</sub>1.2 levels and CaMKII activity were much higher in the ISO 3-week group than in the ISO 2-week group. CaMKII-induced Ca<sub>V</sub>1.2 channel phosphorylation at residue Thr1604 may be one of the key features of myocardial hypertrophy and disease development.<b>Abbreviations:</b> CaMKII: Ca2+/calmodulin dependent protein kinase II; p-CaMKII: autophosphorylated Ca2+/calmodulin dependent protein kinase II; CaM: calmodulin; AIP: autocamtide-2-related inhibitory peptide; ECC: excitation-contraction coupling; ISO: isoproterenol; BW: body weight; HW: heart weight; LVW: left ventricle weight; HDAC: histone deacetylase; p-HDAC: phosphorylated histone deacetylase; MEF2C: myocyte-specific enhancer factor 2C; ANP: atrial natriuretic peptide; PKC: protein kinase C.</p>","PeriodicalId":72555,"journal":{"name":"Channels (Austin, Tex.)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/19336950.2020.1750189","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"37834057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-01DOI: 10.1080/19336950.2020.1724759
Marie-Christine Klein, Monika Lerner, Duy Nguyen, Stefan Pfeffer, Johanna Dudek, Friedrich Förster, Volkhard Helms, Sven Lang, Richard Zimmermann
In mammalian cells, one-third of all polypeptides is transported into or through the ER-membrane via the Sec61-channel. While the Sec61-complex facilitates the transport of all polypeptides with amino-terminal signal peptides (SP) or SP-equivalent transmembrane helices (TMH), the translocating chain-associated membrane protein (now termed TRAM1) was proposed to support transport of a subset of precursors. To identify possible determinants of TRAM1 substrate specificity, we systematically identified TRAM1-dependent precursors by analyzing cellular protein abundance changes upon TRAM1 depletion in HeLa cells using quantitative label-free proteomics. In contrast to previous analysis after TRAP depletion, SP and TMH analysis of TRAM1 clients did not reveal any distinguishing features that could explain its putative substrate specificity. To further address the TRAM1 mechanism, live-cell calcium imaging was carried out after TRAM1 depletion in HeLa cells. In additional contrast to previous analysis after TRAP depletion, TRAM1 depletion did not affect calcium leakage from the ER. Thus, TRAM1 does not appear to act as SP- or TMH-receptor on the ER-membrane's cytosolic face and does not appear to affect the open probability of the Sec61-channel. It may rather play a supportive role in protein transport, such as making the phospholipid bilayer conducive for accepting SP and TMH in the vicinity of the lateral gate of the Sec61-channel.Abbreviations: ER, endoplasmic reticulum; OST, oligosaccharyltransferase; RAMP, ribosome-associated membrane protein; SP, signal peptide; SR, SRP-receptor; SRP, signal recognition particle; TMH, signal peptide-equivalent transmembrane helix; TRAM, translocating chain-associated membrane protein; TRAP, translocon-associated protein.
{"title":"TRAM1 protein may support ER protein import by modulating the phospholipid bilayer near the lateral gate of the Sec61-channel.","authors":"Marie-Christine Klein, Monika Lerner, Duy Nguyen, Stefan Pfeffer, Johanna Dudek, Friedrich Förster, Volkhard Helms, Sven Lang, Richard Zimmermann","doi":"10.1080/19336950.2020.1724759","DOIUrl":"https://doi.org/10.1080/19336950.2020.1724759","url":null,"abstract":"<p><p>In mammalian cells, one-third of all polypeptides is transported into or through the ER-membrane via the Sec61-channel. While the Sec61-complex facilitates the transport of all polypeptides with amino-terminal signal peptides (SP) or SP-equivalent transmembrane helices (TMH), the translocating chain-associated membrane protein (now termed TRAM1) was proposed to support transport of a subset of precursors. To identify possible determinants of TRAM1 substrate specificity, we systematically identified TRAM1-dependent precursors by analyzing cellular protein abundance changes upon TRAM1 depletion in HeLa cells using quantitative label-free proteomics. In contrast to previous analysis after TRAP depletion, SP and TMH analysis of TRAM1 clients did not reveal any distinguishing features that could explain its putative substrate specificity. To further address the TRAM1 mechanism, live-cell calcium imaging was carried out after TRAM1 depletion in HeLa cells. In additional contrast to previous analysis after TRAP depletion, TRAM1 depletion did not affect calcium leakage from the ER. Thus, TRAM1 does not appear to act as SP- or TMH-receptor on the ER-membrane's cytosolic face and does not appear to affect the open probability of the Sec61-channel. It may rather play a supportive role in protein transport, such as making the phospholipid bilayer conducive for accepting SP and TMH in the vicinity of the lateral gate of the Sec61-channel.<b>Abbreviations:</b> ER, endoplasmic reticulum; OST, oligosaccharyltransferase; RAMP, ribosome-associated membrane protein; SP, signal peptide; SR, SRP-receptor; SRP, signal recognition particle; TMH, signal peptide-equivalent transmembrane helix; TRAM, translocating chain-associated membrane protein; TRAP, translocon-associated protein.</p>","PeriodicalId":72555,"journal":{"name":"Channels (Austin, Tex.)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/19336950.2020.1724759","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"37605904","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-01DOI: 10.1080/19336950.2020.1818509
Angela M Schlegel, Elizabeth S Haswell
Mechanosensitive (MS) ion channels are widespread mechanisms for cellular mechanosensation that can be directly activated by increasing membrane tension. The well-studied MscS family of MS ion channels is found in bacteria, archaea, and plants. MscS-Like (MSL)1 is localized to the inner mitochondrial membrane of Arabidopsis thaliana, where it is required for normal mitochondrial responses to oxidative stress. Like Escherichia coli MscS, MSL1 has a pore-lining helix that is kinked. However, in MSL1 this kink is comprised of two charged pore-lining residues, R326 and D327. Using single-channel patch-clamp electrophysiology in E. coli, we show that altering the size and charge of R326 and D327 leads to dramatic changes in channel kinetics. Modest changes in gating pressure were also observed while no effects on channel rectification or conductance were detected. MSL1 channel variants had differing physiological function in E. coli hypoosmotic shock assays, without clear correlation between function and particular channel characteristics. Taken together, these results demonstrate that altering pore-lining residue charge and size disrupts normal channel state stability and gating transitions, and led us to propose the "sweet spot" model. In this model, the transition to the closed state is facilitated by attraction between R326 and D327 and repulsion between R326 residues of neighboring monomers. In the open state, expansion of the channel reduces inter-monomeric repulsion, rendering open state stability influenced mainly by attractive forces. This work provides insight into how unique charge-charge interactions can be combined with an otherwise conserved structural feature to help modulate MS channel function.
{"title":"Charged pore-lining residues are required for normal channel kinetics in the eukaryotic mechanosensitive ion channel MSL1.","authors":"Angela M Schlegel, Elizabeth S Haswell","doi":"10.1080/19336950.2020.1818509","DOIUrl":"https://doi.org/10.1080/19336950.2020.1818509","url":null,"abstract":"<p><p>Mechanosensitive (MS) ion channels are widespread mechanisms for cellular mechanosensation that can be directly activated by increasing membrane tension. The well-studied MscS family of MS ion channels is found in bacteria, archaea, and plants. MscS-Like (MSL)1 is localized to the inner mitochondrial membrane of <i>Arabidopsis thaliana</i>, where it is required for normal mitochondrial responses to oxidative stress. Like <i>Escherichia coli</i> MscS, MSL1 has a pore-lining helix that is kinked. However, in MSL1 this kink is comprised of two charged pore-lining residues, R326 and D327. Using single-channel patch-clamp electrophysiology in <i>E. coli</i>, we show that altering the size and charge of R326 and D327 leads to dramatic changes in channel kinetics. Modest changes in gating pressure were also observed while no effects on channel rectification or conductance were detected. MSL1 channel variants had differing physiological function in <i>E. coli</i> hypoosmotic shock assays, without clear correlation between function and particular channel characteristics. Taken together, these results demonstrate that altering pore-lining residue charge and size disrupts normal channel state stability and gating transitions, and led us to propose the \"sweet spot\" model. In this model, the transition to the closed state is facilitated by attraction between R326 and D327 and repulsion between R326 residues of neighboring monomers. In the open state, expansion of the channel reduces inter-monomeric repulsion, rendering open state stability influenced mainly by attractive forces. This work provides insight into how unique charge-charge interactions can be combined with an otherwise conserved structural feature to help modulate MS channel function.</p>","PeriodicalId":72555,"journal":{"name":"Channels (Austin, Tex.)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/19336950.2020.1818509","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"38530677","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-01DOI: 10.1080/19336950.2020.1803552
Xiling Zhang, Zhimin Mao, Yanru Huang, Zhen Zhang, Jian Yao
The elevated intracellular Ca2+ and oxidative stress are well-reported mechanisms behind renal tubular epithelial injury initiated by various insults. Given that TRPV4 and connexin43 (Cx43) channels are activated by a wide range of stimuli and regulate both intracellular Ca2+ and redox status, we speculated an involvement of these channels in renal tubular cell injury. Here, we tested this possibility and explored the potential underlying mechanisms. Our results demonstrated that exposure of renal tubular epithelial cells to aminoglycoside G418 led to cell death, which was attenuated by both TRPV4 and gap junction (Gj) inhibitor. Activation of TRPV4 caused cell damage, which was associated with an early increase in Cx43 expression and function. Inhibition of Cx43 with chemical inhibitor or siRNA largely prevented TRPV4 activation-induced cell damage. Further analysis revealed that TRPV4 agonists elicited a rise in intracellular Ca2+ and caused a Ca2+-dependent elevation in TXNIP (a negative regulator of the antioxidant thioredoxin). In the presence of Gj inhibitor, however, these effects of TRPV4 were largely prevented. The depletion of intracellular Ca2+ with Ca2+ chelator BAPTA-AM or downregulation of TXNIP with siRNA significantly alleviated TRPV4 activation-initiated cell injury. Collectively, our results point to a critical involvement of TRPV4/Cx43 channel interaction in renal tubular cell injury through mechanisms involving a synergetic induction of intracellular Ca2+ and oxidative stress. Channel interactions could be an important mechanism underlying cell injury. Targeting channels could have therapeutic potential for the treatment of acute tubular cell injury.
{"title":"Gap junctions amplify TRPV4 activation-initiated cell injury via modification of intracellular Ca<sup>2+</sup> and Ca<sup>2+</sup>-dependent regulation of TXNIP.","authors":"Xiling Zhang, Zhimin Mao, Yanru Huang, Zhen Zhang, Jian Yao","doi":"10.1080/19336950.2020.1803552","DOIUrl":"https://doi.org/10.1080/19336950.2020.1803552","url":null,"abstract":"<p><p>The elevated intracellular Ca<sup>2+</sup> and oxidative stress are well-reported mechanisms behind renal tubular epithelial injury initiated by various insults. Given that TRPV4 and connexin43 (Cx43) channels are activated by a wide range of stimuli and regulate both intracellular Ca<sup>2+</sup> and redox status, we speculated an involvement of these channels in renal tubular cell injury. Here, we tested this possibility and explored the potential underlying mechanisms. Our results demonstrated that exposure of renal tubular epithelial cells to aminoglycoside G418 led to cell death, which was attenuated by both TRPV4 and gap junction (Gj) inhibitor. Activation of TRPV4 caused cell damage, which was associated with an early increase in Cx43 expression and function. Inhibition of Cx43 with chemical inhibitor or siRNA largely prevented TRPV4 activation-induced cell damage. Further analysis revealed that TRPV4 agonists elicited a rise in intracellular Ca<sup>2+</sup> and caused a Ca<sup>2+</sup>-dependent elevation in TXNIP (a negative regulator of the antioxidant thioredoxin). In the presence of Gj inhibitor, however, these effects of TRPV4 were largely prevented. The depletion of intracellular Ca<sup>2+</sup> with Ca<sup>2+</sup> chelator BAPTA-AM or downregulation of TXNIP with siRNA significantly alleviated TRPV4 activation-initiated cell injury. Collectively, our results point to a critical involvement of TRPV4/Cx43 channel interaction in renal tubular cell injury through mechanisms involving a synergetic induction of intracellular Ca<sup>2+</sup> and oxidative stress. Channel interactions could be an important mechanism underlying cell injury. Targeting channels could have therapeutic potential for the treatment of acute tubular cell injury.</p>","PeriodicalId":72555,"journal":{"name":"Channels (Austin, Tex.)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/19336950.2020.1803552","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"38229391","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-01DOI: 10.1080/19336950.2020.1730019
James Osei-Owusu, Junhua Yang, Maria Del Carmen Vitery, Mengnan Tian, Zhaozhu Qiu
Severe local acidosis causes tissue damage and pain, and is associated with many diseases, including cerebral and cardiac ischemia, cancer, infection, and inflammation. However, the molecular mechanisms of the cellular response to extracellular acidic environment are not fully understood. We recently identified a novel and evolutionarily conserved membrane protein, PAC (also known as PACC1 or TMEM206), encoding the proton-activated chloride (Cl-) channel, whose activity is widely observed in human cell lines. We demonstrated that genetic deletion of Pac abolished the proton-activated Cl- currents in mouse neurons and also attenuated the acid-induced neuronal cell death and brain damage after ischemic stroke. Here, we show that the proton-activated Cl- currents are also conserved in primary rat cortical neurons, with characteristics similar to those observed in human and mouse cells. Pac gene knockdown nearly abolished the proton-activated Cl- currents in rat neurons and reduced the neuronal cell death triggered by acid treatment. These data further support the notion that activation of the PAC channel and subsequent Cl- entry into neurons during acidosis play a pathogenic role in acidotoxicity and brain injury.
{"title":"PAC proton-activated chloride channel contributes to acid-induced cell death in primary rat cortical neurons.","authors":"James Osei-Owusu, Junhua Yang, Maria Del Carmen Vitery, Mengnan Tian, Zhaozhu Qiu","doi":"10.1080/19336950.2020.1730019","DOIUrl":"https://doi.org/10.1080/19336950.2020.1730019","url":null,"abstract":"<p><p>Severe local acidosis causes tissue damage and pain, and is associated with many diseases, including cerebral and cardiac ischemia, cancer, infection, and inflammation. However, the molecular mechanisms of the cellular response to extracellular acidic environment are not fully understood. We recently identified a novel and evolutionarily conserved membrane protein, PAC (also known as PACC1 or TMEM206), encoding the proton-activated chloride (Cl<sup>-</sup>) channel, whose activity is widely observed in human cell lines. We demonstrated that genetic deletion of <i>Pac</i> abolished the proton-activated Cl<sup>-</sup> currents in mouse neurons and also attenuated the acid-induced neuronal cell death and brain damage after ischemic stroke. Here, we show that the proton-activated Cl<sup>-</sup> currents are also conserved in primary rat cortical neurons, with characteristics similar to those observed in human and mouse cells. <i>Pac</i> gene knockdown nearly abolished the proton-activated Cl<sup>-</sup> currents in rat neurons and reduced the neuronal cell death triggered by acid treatment. These data further support the notion that activation of the PAC channel and subsequent Cl<sup>-</sup> entry into neurons during acidosis play a pathogenic role in acidotoxicity and brain injury.</p>","PeriodicalId":72555,"journal":{"name":"Channels (Austin, Tex.)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/19336950.2020.1730019","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"37673526","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-01DOI: 10.1080/19336950.2020.1747803
Chenyang Zhang, Lifang Ye, Qinggang Zhang, Fei Wu, Lihong Wang
Transient receptor potential vanilloid subfamily member 1 (TRPV1) is a nonselective cation channel, that is mainly distributed in sensory nerve endings and can release a variety of neurotransmitters after activation. Early studies showed that it mainly conducts pain sensation, but research has demonstrated that it also plays an important role in cardiovascular diseases. Notably, in atherosclerosis, the activation of TRPV1 can regulate lipid metabolism, reduce foam cell formation, protect endothelial cells, inhibit smooth muscle cell proliferation and inhibit inflammation and oxidation. In this review, the role of the TRPV1 channel in atherosclerosis was discussed to provide new ideas for the prevention and treatment of atherosclerotic diseases.
瞬时受体电位香草蛋白亚家族成员1 (Transient receptor potential vanilloid subfamily member 1, TRPV1)是一种非选择性阳离子通道,主要分布于感觉神经末梢,激活后可释放多种神经递质。早期的研究表明,它主要负责疼痛感觉,但研究表明,它在心血管疾病中也起着重要作用。值得注意的是,在动脉粥样硬化中,激活TRPV1可以调节脂质代谢,减少泡沫细胞形成,保护内皮细胞,抑制平滑肌细胞增殖,抑制炎症和氧化。本文就TRPV1通道在动脉粥样硬化中的作用进行综述,以期为预防和治疗动脉粥样硬化性疾病提供新的思路。
{"title":"The role of TRPV1 channels in atherosclerosis.","authors":"Chenyang Zhang, Lifang Ye, Qinggang Zhang, Fei Wu, Lihong Wang","doi":"10.1080/19336950.2020.1747803","DOIUrl":"https://doi.org/10.1080/19336950.2020.1747803","url":null,"abstract":"<p><p>Transient receptor potential vanilloid subfamily member 1 (TRPV1) is a nonselective cation channel, that is mainly distributed in sensory nerve endings and can release a variety of neurotransmitters after activation. Early studies showed that it mainly conducts pain sensation, but research has demonstrated that it also plays an important role in cardiovascular diseases. Notably, in atherosclerosis, the activation of TRPV1 can regulate lipid metabolism, reduce foam cell formation, protect endothelial cells, inhibit smooth muscle cell proliferation and inhibit inflammation and oxidation. In this review, the role of the TRPV1 channel in atherosclerosis was discussed to provide new ideas for the prevention and treatment of atherosclerotic diseases.</p>","PeriodicalId":72555,"journal":{"name":"Channels (Austin, Tex.)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/19336950.2020.1747803","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"37820856","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}