Andrew F Mead, Neil B Wood, Shane R Nelson, Bradley M Palmer, Lin Yang, Samantha Beck Previs, Angela Ploysangngam, Guy G Kennedy, Jennifer F McAdow, Sarah M Tremble, Marcus A Zimmermann, Marilyn J Cipolla, Alicia M Ebert, Aaron N Johnson, Christina A Gurnett, Michael J Previs, David M Warshaw
{"title":"Correction: Functional role of myosin-binding protein H in thick filaments of developing vertebrate fast-twitch skeletal muscle.","authors":"Andrew F Mead, Neil B Wood, Shane R Nelson, Bradley M Palmer, Lin Yang, Samantha Beck Previs, Angela Ploysangngam, Guy G Kennedy, Jennifer F McAdow, Sarah M Tremble, Marcus A Zimmermann, Marilyn J Cipolla, Alicia M Ebert, Aaron N Johnson, Christina A Gurnett, Michael J Previs, David M Warshaw","doi":"10.1085/jgp.20241360411072024c","DOIUrl":"10.1085/jgp.20241360411072024c","url":null,"abstract":"","PeriodicalId":54828,"journal":{"name":"Journal of General Physiology","volume":"156 12","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11561551/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142632902","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Maarten M Steinz, Nicole Beard, Emily Shorter, Johanna T Lanner
{"title":"Stable oxidative posttranslational modifications alter the gating properties of RyR1.","authors":"Maarten M Steinz, Nicole Beard, Emily Shorter, Johanna T Lanner","doi":"10.1085/jgp.202313515","DOIUrl":"10.1085/jgp.202313515","url":null,"abstract":"<p><p>The ryanodine receptor type 1 (RyR1) is a Ca2+ release channel that regulates skeletal muscle contraction by controlling Ca2+ release from the sarcoplasmic reticulum (SR). Posttranslational modifications (PTMs) of RyR1, such as phosphorylation, S-nitrosylation, and carbonylation are known to increase RyR1 open probability (Po), contributing to SR Ca2+ leak and skeletal muscle dysfunction. PTMs on RyR1 have been linked to muscle dysfunction in diseases like breast cancer, rheumatoid arthritis, Duchenne muscle dystrophy, and aging. While reactive oxygen species (ROS) and oxidative stress induce PTMs, the impact of stable oxidative modifications like 3-nitrotyrosine (3-NT) and malondialdehyde adducts (MDA) on RyR1 gating remains unclear. Mass spectrometry and single-channel recordings were used to study how 3-NT and MDA modify RyR1 and affect Po. Both modifications increased Po in a dose-dependent manner, with mass spectrometry identifying 30 modified residues out of 5035 amino acids per RyR1 monomer. Key modifications were found in domains critical for protein interaction and channel activation, including Y808/3NT in SPRY1, Y1081/3NT and H1254/MDA in SPRY2&3, and Q2107/MDA and Y2128/3NT in JSol, near the binding site of FKBP12. Though these modifications did not directly overlap with FKBP12 binding residues, they promoted FKBP12 dissociation from RyR1. These findings provide detailed insights into how stable oxidative PTMs on RyR1 residues alter channel gating, advancing our understanding of RyR1-mediated Ca2+ release in conditions associated with oxidative stress and muscle weakness.</p>","PeriodicalId":54828,"journal":{"name":"Journal of General Physiology","volume":"156 12","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11540854/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142583565","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A new stress test for ryanodine receptors.","authors":"Ben Short","doi":"10.1085/jgp.202413716","DOIUrl":"10.1085/jgp.202413716","url":null,"abstract":"<p><p>JGP study (Steinz et al. https://doi.org/10.1085/jgp.202313515) reveals that oxidative stress can induce stable posttranslational modifications of RyR1 that increase the channel's open probability and could therefore disrupt muscle contractility.</p>","PeriodicalId":54828,"journal":{"name":"Journal of General Physiology","volume":"156 12","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11577274/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142669450","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Arnaldo Mercado-Perez, Jeric P Hernandez, Yaroslav Fedyshyn, Anthony J Treichel, Vikram Joshi, Kimberlee Kossick, Kalpana R Betageri, Gianrico Farrugia, Brooke Druliner, Arthur Beyder
{"title":"Piezo2 interacts with E-cadherin in specialized gastrointestinal epithelial mechanoreceptors.","authors":"Arnaldo Mercado-Perez, Jeric P Hernandez, Yaroslav Fedyshyn, Anthony J Treichel, Vikram Joshi, Kimberlee Kossick, Kalpana R Betageri, Gianrico Farrugia, Brooke Druliner, Arthur Beyder","doi":"10.1085/jgp.202213324","DOIUrl":"10.1085/jgp.202213324","url":null,"abstract":"<p><p>Piezo2 is a mechanically gated ion channel most commonly expressed by specialized mechanoreceptors, such as the enteroendocrine cells (EECs) of the gastrointestinal epithelium. A subpopulation of EECs expresses Piezo2 and functionally resembles the skin's touch sensors, called Merkel cells. Low-magnitude mechanical stimuli delivered to the mucosal layer are primarily sensed by mechanosensitive EECs in a process we term \"gut touch.\" Piezo2 transduces cellular forces into ionic currents, a process that is sensitive to bilayer tension and cytoskeletal depolymerization. E-cadherin is a widely expressed protein that mediates cell-cell adhesion in epithelia and interacts with scaffold proteins that anchor it to actin fibers. E-cadherin was shown to interact with Piezo2 in immortalized cell models. We hypothesized that the Piezo2-E-cadherin interaction is important for EEC mechanosensitivity. To test this, we used super-resolution imaging, co-immunoprecipitation, and functional assays in primary tissues from mice and gut organoids. In tissue EECs and intestinal organoids, we observed multiple Piezo2 cellular pools, including one that overlaps with actin and E-cadherin at the cells' lateral walls. Further, E-cadherin co-immunoprecipitated with Piezo2 in the primary colonic epithelium. We found that E-cadherin knockdown decreases mechanosensitive calcium responses in mechanically stimulated primary EECs. In all, our results demonstrate that Piezo2 localizes to the lateral wall of EECs, where it physically interacts with E-cadherin and actin. They suggest that the Piezo2-E-cadherin-actin interaction is important for mechanosensitivity in the gut epithelium and possibly in tissues where E-cadherin and Piezo2 are co-expressed in epithelial mechanoreceptors, such as skin, lung, and bladder.</p>","PeriodicalId":54828,"journal":{"name":"Journal of General Physiology","volume":"156 12","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11536063/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142570381","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Mechanism of acid-sensing ion channel modulation by Hi1a.","authors":"Kyle D Berger, David M MacLean","doi":"10.1085/jgp.202313519","DOIUrl":"10.1085/jgp.202313519","url":null,"abstract":"<p><p>Acid-sensing ion channels (ASICs) are trimeric cation-selective channels activated by extracellular acidification. Amongst many pathological roles, ASICs are an important mediator of ischemic cell death and hence an attractive drug target for stroke treatment as well as other conditions. A peptide called Hi1a, isolated from Australian funnel web spider venom, inhibits ASIC1a and attenuates cell death in a stroke model up to 8 h after stroke induction. Here, we set out to understand the molecular basis for Hi1a's action. Hi1a is a bivalent toxin with two inhibitory cystine knot domains joined by a short linker. We found that both Hi1a domains modulate human ASIC1a gating with the N-terminal domain impairing channel activation while the C-terminal domain produces a \"pro-open\" phenotype even at submicromolar concentrations. Interestingly, both domains bind at the same site since a single point mutation, F352A, abolishes functional effects and reduces toxin affinity in surface plasmon resonance measurements. Therefore, the action of Hi1a at ASIC1a appears to arise through a mutually exclusive binding model where either the N or C domain of a single Hi1a binds one ASIC1a subunit. An ASIC1a trimer may bind several inhibitory N domains and one or more pro-open C domains at any one time, accounting for the incomplete inhibition of wild type Hi1a. We also found that the functional differences between these two domains are partially transferred by mutagenesis, affording new insight into the channel function and possible novel avenues of drug design.</p>","PeriodicalId":54828,"journal":{"name":"Journal of General Physiology","volume":"156 12","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11513431/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142513210","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dmytro V Vasylyev, Peng Zhao, Betsy R Schulman, Stephen G Waxman
{"title":"Interplay of Nav1.8 and Nav1.7 channels drives neuronal hyperexcitability in neuropathic pain.","authors":"Dmytro V Vasylyev, Peng Zhao, Betsy R Schulman, Stephen G Waxman","doi":"10.1085/jgp.202413596","DOIUrl":"10.1085/jgp.202413596","url":null,"abstract":"<p><p>While voltage-gated sodium channels Nav1.7 and Nav1.8 both contribute to electrogenesis in dorsal root ganglion (DRG) neurons, details of their interactions have remained unexplored. Here, we studied the functional contribution of Nav1.8 in DRG neurons using a dynamic clamp to express Nav1.7L848H, a gain-of-function Nav1.7 mutation that causes inherited erythromelalgia (IEM), a human genetic model of neuropathic pain, and demonstrate a profound functional interaction of Nav1.8 with Nav1.7 close to the threshold for AP generation. At the voltage threshold of -21.9 mV, we observed that Nav1.8 channel open-probability exceeded Nav1.7WT channel open-probability ninefold. Using a kinetic model of Nav1.8, we showed that a reduction of Nav1.8 current by even 25-50% increases rheobase and reduces firing probability in small DRG neurons expressing Nav1.7L848H. Nav1.8 subtraction also reduces the amplitudes of subthreshold membrane potential oscillations in these cells. Our results show that within DRG neurons that express peripheral sodium channel Nav1.7, the Nav1.8 channel amplifies excitability at a broad range of membrane voltages with a predominant effect close to the AP voltage threshold, while Nav1.7 plays a major role at voltages closer to resting membrane potential. Our data show that dynamic-clamp reduction of Nav1.8 conductance by 25-50% can reverse hyperexcitability of DRG neurons expressing a gain-of-function Nav1.7 mutation that causes pain in humans and suggests, more generally, that full inhibition of Nav1.8 may not be required for relief of pain due to DRG neuron hyperexcitability.</p>","PeriodicalId":54828,"journal":{"name":"Journal of General Physiology","volume":"156 11","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11465073/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142395402","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lina Kraujaliene, Tadas Kraujalis, Mindaugas Snipas, Vytas K Verselis
{"title":"An Ala/Glu difference in E1 of Cx26 and Cx30 contributes to their differential anionic permeabilities.","authors":"Lina Kraujaliene, Tadas Kraujalis, Mindaugas Snipas, Vytas K Verselis","doi":"10.1085/jgp.202413600","DOIUrl":"10.1085/jgp.202413600","url":null,"abstract":"<p><p>Two closely related connexins, Cx26 and Cx30, share widespread expression in the cochlear cellular networks. Gap junction channels formed by these connexins have been shown to have different permeability profiles, with Cx30 showing a strongly reduced preference for anionic tracers. The pore-forming segment of the first extracellular loop, E1, identified by computational studies of the Cx26 crystal structure to form a parahelix and a narrowed region of the pore, differs at a single residue at position 49. Cx26 contains an Ala and Cx30, a charged Glu at this position, and cysteine scanning in hemichannels identified this position to be pore-lining. To assess whether the Ala/Glu difference affects permeability, we modeled and quantified Lucifer Yellow transfer between HeLa cell pairs expressing WT Cx26 and Cx30 and variants that reciprocally substituted Glu and Ala at position 49. Cx26(A49E) and Cx30(E49A) substitutions essentially reversed the Lucifer Yellow permeability profile when accounting for junctional conductance. Moreover, by using a calcein efflux assay in single cells, we observed a similar reduced anionic preference in undocked Cx30 hemichannels and a reversal with reciprocal Ala/Glu substitutions. Thus, our data indicate that Cx26 and Cx30 gap junction channels and undocked hemichannels retain similar permeability characteristics and that a single residue difference in their E1 domains can largely account for their differential permeabilities to anionic tracers. The higher anionic permeability of Cx26 compared with Cx30 suggests that these connexins may serve distinct signaling functions in the cochlea, perhaps reflected in the vastly higher prevalence of Cx26 mutations in human deafness.</p>","PeriodicalId":54828,"journal":{"name":"Journal of General Physiology","volume":"156 11","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11415307/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142301291","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Helmuth A Sanchez, Lina Kraujaliene, Vytas K Verselis
{"title":"A pore locus in the E1 domain differentially regulates Cx26 and Cx30 hemichannel function.","authors":"Helmuth A Sanchez, Lina Kraujaliene, Vytas K Verselis","doi":"10.1085/jgp.202313502","DOIUrl":"https://doi.org/10.1085/jgp.202313502","url":null,"abstract":"<p><p>Connexins (Cxs) function as gap junction (GJ) channels and hemichannels that mediate intercellular and transmembrane signaling, respectively. Here, we investigated the proximal segment of the first extracellular loop, E1, of two closely related Cxs, Cx26 and Cx30, that share widespread expression in the cochlea. Computational studies of Cx26 proposed that this segment of E1 contains a parahelix and functions in gating. The sequence of the parahelix is identical between Cx26 and Cx30 except for an Ala/Glu difference at position 49. We show through cysteine-scanning and mutational analyses that position 49 is pore-lining and interacts with the adjacent Asp50 residue to impact hemichannel functionality. When both positions 49 and 50 are charged, as occurs naturally in Cx30, the hemichannel function is dampened. Co-expression of Cx30 with Cx26(D50N), the most common mutation associated with keratitis-ichthyosis-deafness syndrome, results in robust hemichannel currents indicating that position 49-50 interactions are relevant in heteromerically assembled hemichannels. Cysteine substitution at position 49 in either Cx26 or Cx30 results in tonic inhibition of hemichannels, both through disulfide formation and high-affinity metal coordination, suggestive of a flexible region of the pore that can narrow substantially. These effects are absent in GJ channels, which exhibit wild-type functionality. Examination of postnatal cochlear explants suggests that Cx30 expression is associated with reduced propagation of Ca2+ waves. Overall, these data identify a pore locus in E1 of Cx26 and Cx30 that impacts hemichannel functionality and provide new considerations for understanding the roles of these connexins in cochlear function.</p>","PeriodicalId":54828,"journal":{"name":"Journal of General Physiology","volume":"156 11","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11415306/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142301290","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Saffie Mohran, Timothy S McMillen, Christian Mandrycky, An-Yue Tu, Kristina B Kooiker, Wenjing Qian, Stephanie Neys, Brayan Osegueda, Farid Moussavi-Harami, Thomas C Irving, Michael Regnier, Weikang Ma
{"title":"Calcium has a direct effect on thick filament activation in porcine myocardium.","authors":"Saffie Mohran, Timothy S McMillen, Christian Mandrycky, An-Yue Tu, Kristina B Kooiker, Wenjing Qian, Stephanie Neys, Brayan Osegueda, Farid Moussavi-Harami, Thomas C Irving, Michael Regnier, Weikang Ma","doi":"10.1085/jgp.202413545","DOIUrl":"10.1085/jgp.202413545","url":null,"abstract":"<p><p>Sarcomere activation in striated muscle requires both thin filament-based and thick filament-based activation mechanisms. Recent studies have shown that myosin heads on the thick filaments undergo OFF to ON structural transitions in response to calcium (Ca2+) in permeabilized porcine myocardium in the presence of a small molecule inhibitor that eliminated active force. The changes in X-ray diffraction signatures of OFF to ON transitions were interpreted as Ca2+ acting to activate the thick filaments. Alternatively, Ca2+ binding to troponin could initiate a Ca2+-dependent crosstalk from the thin filament to the thick filament via interfilament connections such as the myosin binding protein-C. Here, we exchanged native troponin in permeabilized porcine myocardium for troponin containing the cTnC D65A mutation, which disallows the activation of troponin through Ca2+ binding to determine if Ca2+-dependent thick filament activation persists in the absence of thin filament activation. After the exchange protocol, over 95% of the Ca2+-activated force was eliminated. Equatorial intensity ratio increased significantly in both WT and D65A exchanged myocardium with increasing Ca2+ concentration. The degree of helical ordering of the myosin heads decreased by the same amount in WT and D65A myocardium when Ca2+ concentration increased. These results are consistent with a direct effect of Ca2+ in activating the thick filament rather than an indirect effect due to Ca2+-mediated crosstalk between the thick and thin filaments.</p>","PeriodicalId":54828,"journal":{"name":"Journal of General Physiology","volume":"156 11","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11415303/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142301292","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The artificial intelligence revolution...in unethical publishing: Will AI worsen our dysfunctional publishing system?","authors":"Thiago F A França, José Maria Monserrat","doi":"10.1085/jgp.202413654","DOIUrl":"10.1085/jgp.202413654","url":null,"abstract":"<p><p>Scholarly publishing has been shaped by the pressure of a liquid economy to become an exercise in branding more than a vehicle for the advancement of science. The current revolution in artificial intelligence (AI) is poised to make matters worse. The new generation of large language models (LLMs) have shown impressive capabilities in text generation and are already being used to write papers, grants, peer review reports, code for analyses, and even perform literature reviews. Although these models can be used in positive ways, the metrics and pressures of academia, along with our dysfunctional publishing system, stimulate their indiscriminate and uncritical use to speed up research outputs. Thus, LLMs are likely to amplify the worst incentives of academia, greatly increasing the volume of scientific literature while diluting its quality. At present, no effective solutions are evident to overcome this grim scenario, and nothing short of a cultural revolution within academia will be needed to realign the practice of science with its traditional ideal of a rigorous search for truth.</p>","PeriodicalId":54828,"journal":{"name":"Journal of General Physiology","volume":"156 11","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11461141/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142382485","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}