Journal of General Physiology最新文献_第7页

How PKA helps cardiomyocytes Navigate chronic stress. PKA 如何帮助心肌细胞驾驭慢性压力

IF 3.3 2区医学

Journal of General Physiology Pub Date : 2024-02-05 Epub Date: 2024-01-16 DOI: 10.1085/jgp.202313534

Ben Short

引用次数: 0

Mechanism of hydrophobic gating in the acetylcholine receptor channel pore. 乙酰胆碱受体通道孔的疏水门控机制。

IF 3.3 2区医学

Journal of General Physiology Pub Date : 2024-02-05 Epub Date: 2023-12-28 DOI: 10.1085/jgp.202213189

Monika Kumari, Nadira Khatoon, Rachita Sharma, Sushanth Adusumilli, Anthony Auerbach, Hemant K Kashyap, Tapan K Nayak

{"title":"Mechanism of hydrophobic gating in the acetylcholine receptor channel pore.","authors":"Monika Kumari, Nadira Khatoon, Rachita Sharma, Sushanth Adusumilli, Anthony Auerbach, Hemant K Kashyap, Tapan K Nayak","doi":"10.1085/jgp.202213189","DOIUrl":"10.1085/jgp.202213189","url":null,"abstract":"Neuromuscular acetylcholine receptors (AChRs) are hetero-pentameric, ligand-gated ion channels. The binding of the neurotransmitter acetylcholine (ACh) to two target sites promotes a global conformational change of the receptor that opens the channel and allows ion conduction through the channel pore. Here, by measuring free-energy changes from single-channel current recordings and using molecular dynamics simulations, we elucidate how a constricted hydrophobic region acts as a \"gate\" to regulate the channel opening in the pore of AChRs. Mutations of gate residues, including those implicated in congenital myasthenia syndrome, lower the permeation barrier of the channel substantially and increase the unliganded gating equilibrium constant (constitutive channel openings). Correlations between hydrophobicity and the observed free-energy changes, supported by calculations of water densities in the wild-type versus mutant channel pores, provide evidence for hydrophobic wetting-dewetting transition at the gate. The analysis of a coupled interaction network provides insight into the molecular mechanism of closed- versus open-state conformational changes at the gate. Studies of the transition state by \"phi\"(φ)-value analysis indicate that agonist binding serves to stabilize both the transition and the open state. Intersubunit interaction energy measurements and molecular dynamics simulations suggest that channel opening involves tilting of the pore-lining M2 helices, asymmetric outward rotation of amino acid side chains, and wetting transition of the gate region that lowers the barrier to ion permeation and stabilizes the channel open conformation. Our work provides new insight into the hydrophobic gate opening and shows why the gate mutations result in constitutive AChR channel activity.","PeriodicalId":54828,"journal":{"name":"Journal of General Physiology","volume":"156 2","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10757554/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139049805","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}

引用次数: 0

JGP in 2024. 2023 年的 JGP。

IF 3.3 2区医学

Journal of General Physiology Pub Date : 2024-02-05 Epub Date: 2024-01-09 DOI: 10.1085/jgp.202313527

David A Eisner

引用次数: 0

Asymmetric contribution of a selectivity filter gate in triggering inactivation of CaV1.3 channels. 选择性滤波门在触发 CaV1.3 通道失活过程中的不对称作用

IF 3.3 2区医学

Journal of General Physiology Pub Date : 2024-02-05 Epub Date: 2024-01-04 DOI: 10.1085/jgp.202313365

Pedro J Del Rivero Morfin, Audrey L Kochiss, Klaus R Liedl, Bernhard E Flucher, Monica L I Fernández-Quintero, Manu Ben-Johny

{"title":"Asymmetric contribution of a selectivity filter gate in triggering inactivation of CaV1.3 channels.","authors":"Pedro J Del Rivero Morfin, Audrey L Kochiss, Klaus R Liedl, Bernhard E Flucher, Monica L I Fernández-Quintero, Manu Ben-Johny","doi":"10.1085/jgp.202313365","DOIUrl":"10.1085/jgp.202313365","url":null,"abstract":"Voltage-dependent and Ca2+-dependent inactivation (VDI and CDI, respectively) of CaV channels are two biologically consequential feedback mechanisms that fine-tune Ca2+ entry into neurons and cardiomyocytes. Although known to be initiated by distinct molecular events, how these processes obstruct conduction through the channel pore remains poorly defined. Here, focusing on ultrahighly conserved tryptophan residues in the interdomain interfaces near the selectivity filter of CaV1.3, we demonstrate a critical role for asymmetric conformational changes in mediating VDI and CDI. Specifically, mutagenesis of the domain III-IV interface, but not others, enhanced VDI. Molecular dynamics simulations demonstrate that mutations in distinct selectivity filter interfaces differentially impact conformational flexibility. Furthermore, mutations in distinct domains preferentially disrupt CDI mediated by the N- versus C-lobes of CaM, thus uncovering a scheme of structural bifurcation of CaM signaling. These findings highlight the fundamental importance of the asymmetric arrangement of the pseudotetrameric CaV pore domain for feedback inhibition.","PeriodicalId":54828,"journal":{"name":"Journal of General Physiology","volume":"156 2","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10771039/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139089423","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}

引用次数: 0

Elucidating molecular mechanisms of protoxin-II state-specific binding to the human NaV1.7 channel. 阐明原毒素-II 与人类 NaV1.7 通道特异性结合的分子机制

IF 3.3 2区医学

Journal of General Physiology Pub Date : 2024-02-05 Epub Date: 2023-12-21 DOI: 10.1085/jgp.202313368

Khoa Ngo, Diego Lopez Mateos, Yanxiao Han, Kyle C Rouen, Surl-Hee Ahn, Heike Wulff, Colleen E Clancy, Vladimir Yarov-Yarovoy, Igor Vorobyov

{"title":"Elucidating molecular mechanisms of protoxin-II state-specific binding to the human NaV1.7 channel.","authors":"Khoa Ngo, Diego Lopez Mateos, Yanxiao Han, Kyle C Rouen, Surl-Hee Ahn, Heike Wulff, Colleen E Clancy, Vladimir Yarov-Yarovoy, Igor Vorobyov","doi":"10.1085/jgp.202313368","DOIUrl":"10.1085/jgp.202313368","url":null,"abstract":"Human voltage-gated sodium (hNaV) channels are responsible for initiating and propagating action potentials in excitable cells, and mutations have been associated with numerous cardiac and neurological disorders. hNaV1.7 channels are expressed in peripheral neurons and are promising targets for pain therapy. The tarantula venom peptide protoxin-II (PTx2) has high selectivity for hNaV1.7 and is a valuable scaffold for designing novel therapeutics to treat pain. Here, we used computational modeling to study the molecular mechanisms of the state-dependent binding of PTx2 to hNaV1.7 voltage-sensing domains (VSDs). Using Rosetta structural modeling methods, we constructed atomistic models of the hNaV1.7 VSD II and IV in the activated and deactivated states with docked PTx2. We then performed microsecond-long all-atom molecular dynamics (MD) simulations of the systems in hydrated lipid bilayers. Our simulations revealed that PTx2 binds most favorably to the deactivated VSD II and activated VSD IV. These state-specific interactions are mediated primarily by PTx2's residues R22, K26, K27, K28, and W30 with VSD and the surrounding membrane lipids. Our work revealed important protein-protein and protein-lipid contacts that contribute to high-affinity state-dependent toxin interaction with the channel. The workflow presented will prove useful for designing novel peptides with improved selectivity and potency for more effective and safe treatment of pain.","PeriodicalId":54828,"journal":{"name":"Journal of General Physiology","volume":"156 2","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10737443/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138833054","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}

引用次数: 0

Persistent PKA activation redistributes NaV1.5 to the cell surface of adult rat ventricular myocytes. 持续的 PKA 激活会将 NaV1.5 重新分配到成年大鼠心室肌细胞的细胞表面。

IF 3.3 2区医学

Journal of General Physiology Pub Date : 2024-02-05 Epub Date: 2024-01-16 DOI: 10.1085/jgp.202313436

Tytus Bernas, John Seo, Zachary T Wilson, Bi-Hua Tan, Isabelle Deschenes, Christiane Carter, Jinze Liu, Gea-Ny Tseng

{"title":"Persistent PKA activation redistributes NaV1.5 to the cell surface of adult rat ventricular myocytes.","authors":"Tytus Bernas, John Seo, Zachary T Wilson, Bi-Hua Tan, Isabelle Deschenes, Christiane Carter, Jinze Liu, Gea-Ny Tseng","doi":"10.1085/jgp.202313436","DOIUrl":"10.1085/jgp.202313436","url":null,"abstract":"During chronic stress, persistent activation of cAMP-dependent protein kinase (PKA) occurs, which can contribute to protective or maladaptive changes in the heart. We sought to understand the effect of persistent PKA activation on NaV1.5 channel distribution and function in cardiomyocytes using adult rat ventricular myocytes as the main model. PKA activation with 8CPT-cAMP and okadaic acid (phosphatase inhibitor) caused an increase in Na+ current amplitude without altering the total NaV1.5 protein level, suggesting a redistribution of NaV1.5 to the myocytes' surface. Biotinylation experiments in HEK293 cells showed that inhibiting protein trafficking from intracellular compartments to the plasma membrane prevented the PKA-induced increase in cell surface NaV1.5. Additionally, PKA activation induced a time-dependent increase in microtubule plus-end binding protein 1 (EB1) and clustering of EB1 at myocytes' peripheral surface and intercalated discs (ICDs). This was accompanied by a decrease in stable interfibrillar microtubules but an increase in dynamic microtubules along the myocyte surface. Imaging and coimmunoprecipitation experiments revealed that NaV1.5 interacted with EB1 and β-tubulin, and both interactions were enhanced by PKA activation. We propose that persistent PKA activation promotes NaV1.5 trafficking to the peripheral surface of myocytes and ICDs by providing dynamic microtubule tracks and enhanced guidance by EB1. Our proposal is consistent with an increase in the correlative distribution of NaV1.5, EB1, and β-tubulin at these subcellular domains in PKA-activated myocytes. Our study suggests that persistent PKA activation, at least during the initial phase, can protect impulse propagation in a chronically stressed heart by increasing NaV1.5 at ICDs.","PeriodicalId":54828,"journal":{"name":"Journal of General Physiology","volume":"156 2","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10791559/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139472932","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}

引用次数: 0

Na+/Ca2+ exchange in enamel cells is dominated by the K+-dependent NCKX exchanger. 釉质细胞中Na+/Ca2+的交换主要由K+依赖性NCKX交换剂控制。

IF 3.8 2区医学

Journal of General Physiology Pub Date : 2024-01-01 Epub Date: 2023-11-10 DOI: 10.1085/jgp.202313372

Guilherme Henrique Souza Bomfim, Erna Mitaishvili, Paul P M Schnetkamp, Rodrigo S Lacruz

{"title":"Na+/Ca2+ exchange in enamel cells is dominated by the K+-dependent NCKX exchanger.","authors":"Guilherme Henrique Souza Bomfim, Erna Mitaishvili, Paul P M Schnetkamp, Rodrigo S Lacruz","doi":"10.1085/jgp.202313372","DOIUrl":"10.1085/jgp.202313372","url":null,"abstract":"Calcium (Ca2+) extrusion is an essential function of the enamel-forming ameloblasts, providing Ca2+ for extracellular mineralization. The plasma membrane Ca2+ ATPases (PMCAs) remove cytosolic Ca2+ (cCa2+) and were recently shown to be efficient when ameloblasts experienced low cCa2+ elevation. Sodium-calcium (Na+/Ca2+) exchange has higher capacity to extrude cCa2+, but there is limited evidence on the function of the two main families of Na+/Ca2+ exchangers in enamel formation. The purpose of this study was to analyze the function of the NCX (coded by SLC8) and the K+-dependent NCKX (coded by SLC24) exchangers in rat ameloblasts and to compare their efficacy in the two main stages of enamel formation: the enamel forming secretory stage and the mineralizing or maturation stage. mRNA expression profiling confirmed the expression of Slc8 and Slc24 genes in enamel cells, Slc24a4 being the most highly upregulated transcript during the maturation stage, when Ca2+ transport increases. Na+/Ca2+ exchange was analyzed in the Ca2+ influx mode in Fura-2 AM-loaded ameloblasts. We show that maturation-stage ameloblasts have a higher Na+/Ca2+ exchange capacity than secretory-stage cells. We also show that Na+/Ca2+ exchange in both stages is dominated by NCKX over NCX. The importance of NCKX function in ameloblasts may partly explain why mutations in the SLC24A4 gene, but not in SLC8 genes, result in enamel disease. Our results demonstrate that Na+/Ca2+ exchangers are fully operational in ameloblasts and that their contribution to Ca2+ homeostasis increases in the maturation stage, when Ca2+ transport need is higher.","PeriodicalId":54828,"journal":{"name":"Journal of General Physiology","volume":"156 1","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10637953/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72016202","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}

引用次数: 0

Analogs of FTY720 inhibit TRPM7 but not S1PRs and exert multimodal anti-inflammatory effects. FTY720的类似物抑制TRPM7，但不抑制S1PR，并发挥多模式抗炎作用。

IF 3.8 2区医学

Journal of General Physiology Pub Date : 2024-01-01 Epub Date: 2023-11-09 DOI: 10.1085/jgp.202313419

Gregory W Busey, Mohan C Manjegowda, Tao Huang, Wesley H Iobst, Shardul S Naphade, Joel A Kennedy, Catherine A Doyle, Philip V Seegren, Kevin R Lynch, Bimal N Desai

{"title":"Analogs of FTY720 inhibit TRPM7 but not S1PRs and exert multimodal anti-inflammatory effects.","authors":"Gregory W Busey, Mohan C Manjegowda, Tao Huang, Wesley H Iobst, Shardul S Naphade, Joel A Kennedy, Catherine A Doyle, Philip V Seegren, Kevin R Lynch, Bimal N Desai","doi":"10.1085/jgp.202313419","DOIUrl":"10.1085/jgp.202313419","url":null,"abstract":"TRPM7, a TRP channel with ion conductance and kinase activities, has emerged as an attractive drug target for immunomodulation. Reverse genetics and cell biological studies have already established a key role for TRPM7 in the inflammatory activation of macrophages. Advancing TRPM7 as a viable molecular target for immunomodulation requires selective TRPM7 inhibitors with in vivo tolerability and efficacy. Such inhibitors have the potential to interdict inflammatory cascades mediated by systemic and tissue-specialized macrophages. FTY720, an FDA-approved drug for multiple sclerosis inhibits TRPM7. However, FTY720 is a prodrug and its metabolite, FTY720-phosphate, is a potent agonist of sphingosine-1-phosphate (S1P) receptors. In this study, we test non-phosphorylatable FTY720 analogs, which are inert against S1PRs and well tolerated in vivo, for activity against TRPM7 and tissue bioavailability. Using patch clamp electrophysiology, we show that VPC01091.4 and AAL-149 block TRPM7 current at low micromolar concentrations. In culture, they act directly on macrophages to blunt LPS-induced inflammatory cytokine expression, though this likely occurrs through multiple molecular targets. We found that VPC01091.4 has significant and rapid accumulation in the brain and lungs, along with direct anti-inflammatory action on alveolar macrophages and microglia. Finally, using a mouse model of endotoxemia, we show VPC01091.4 to be an efficacious anti-inflammatory agent that arrests systemic inflammation in vivo. Together, these findings identify novel small molecule inhibitors that allow TRPM7 channel inhibition independent of S1P receptor targeting which demonstrate potent, polymodal anti-inflammatory activities ex vivo and in vivo.","PeriodicalId":54828,"journal":{"name":"Journal of General Physiology","volume":"156 1","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10635799/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71523425","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}

引用次数: 0

Interpretation of presynaptic phenotypes of synaptic plasticity in terms of a two-step priming process. 从两步启动过程解读突触可塑性的突触前表型

IF 3.3 2区医学

Journal of General Physiology Pub Date : 2024-01-01 Epub Date: 2023-12-19 DOI: 10.1085/jgp.202313454

Erwin Neher

{"title":"Interpretation of presynaptic phenotypes of synaptic plasticity in terms of a two-step priming process.","authors":"Erwin Neher","doi":"10.1085/jgp.202313454","DOIUrl":"10.1085/jgp.202313454","url":null,"abstract":"Studies on synaptic proteins involved in neurotransmitter release often aim at distinguishing between their roles in vesicle priming (the docking of synaptic vesicles to the plasma membrane and the assembly of a release machinery) as opposed to the process of vesicle fusion. This has traditionally been done by estimating two parameters, the size of the pool of fusion-competent vesicles (the readily releasable pool, RRP) and the probability that such vesicles are released by an action potential, with the aim of determining how these parameters are affected by molecular perturbations. Here, it is argued that the assumption of a homogeneous RRP may be too simplistic and may blur the distinction between vesicle priming and fusion. Rather, considering priming as a dynamic and reversible multistep process allows alternative interpretations of mutagenesis-induced changes in synaptic transmission and suggests mechanisms for variability in synaptic strength and short-term plasticity among synapses, as well as for interactions between short- and long-term plasticity. In many cases, assigned roles of proteins or causes for observed phenotypes are shifted from fusion- to priming-related when considering multistep priming. Activity-dependent enhancement of priming is an essential element in this alternative view and its variation among synapse types can explain why some synapses show depression and others show facilitation at low to intermediate stimulation frequencies. Multistep priming also suggests a mechanism for frequency invariance of steady-state release, which can be observed in some synapses involved in sensory processing.","PeriodicalId":54828,"journal":{"name":"Journal of General Physiology","volume":"156 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10730358/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138813209","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}

引用次数: 0

Permeant cations modulate pore dynamics and gating of TRPV1 ion channels. 渗透性阳离子调节 TRPV1 离子通道的孔动力学和门控。

IF 3.8 2区医学

Journal of General Physiology Pub Date : 2024-01-01 Epub Date: 2023-12-06 DOI: 10.1085/jgp.202313422

Miriam García-Ávila, Javier Tello-Marmolejo, Tamara Rosenbaum, León D Islas

{"title":"Permeant cations modulate pore dynamics and gating of TRPV1 ion channels.","authors":"Miriam García-Ávila, Javier Tello-Marmolejo, Tamara Rosenbaum, León D Islas","doi":"10.1085/jgp.202313422","DOIUrl":"10.1085/jgp.202313422","url":null,"abstract":"The transient receptor vanilloid 1 (TRPV1) is a non-selective ion channel, which is activated by several chemical ligands and heat. We have previously shown that activation of TRPV1 by different ligands results in single-channel openings with different conductance, suggesting that the selectivity filter is highly dynamic. TRPV1 is weakly voltage dependent; here, we sought to explore whether the permeation of different monovalent ions could influence the voltage dependence of this ion channel. By using single-channel recordings, we show that TRPV1 channels undergo rapid transitions to closed states that are directly connected to the open state, which may result from structural fluctuations of their selectivity filter. Moreover, we demonstrate that the rates of these transitions are influenced by the permeant ion, suggesting that ion permeation regulates the voltage dependence of these channels. Our data could be the basis for more detailed MD simulations exploring the permeation mechanism and how the occupancy of different ions alters the three-dimensional structure of the pore of TRPV1 channels.","PeriodicalId":54828,"journal":{"name":"Journal of General Physiology","volume":"156 1","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10760480/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138489128","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}

引用次数: 0