Journal of General Physiology最新文献_第2页

Interplay of Nav1.8 and Nav1.7 channels drives neuronal hyperexcitability in neuropathic pain. Nav1.8和Nav1.7通道的相互作用驱动了神经元在神经病理性疼痛中的过度兴奋。

IF 3.3 2区医学

Journal of General Physiology Pub Date : 2024-11-04 Epub Date: 2024-10-08 DOI: 10.1085/jgp.202413596

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":"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.","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}

引用次数: 0

An Ala/Glu difference in E1 of Cx26 and Cx30 contributes to their differential anionic permeabilities. Cx26 和 Cx30 E1 中的 Ala/Glu 差异导致了它们不同的阴离子渗透性。

IF 3.3 2区医学

Journal of General Physiology Pub Date : 2024-11-04 Epub Date: 2024-09-20 DOI: 10.1085/jgp.202413600

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":"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.","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}

引用次数: 0

A pore locus in the E1 domain differentially regulates Cx26 and Cx30 hemichannel function. E1 结构域中的一个孔位置对 Cx26 和 Cx30 半通道的功能起着不同的调节作用。

IF 3.3 2区医学

Journal of General Physiology Pub Date : 2024-11-04 Epub Date: 2024-09-20 DOI: 10.1085/jgp.202313502

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":"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.","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}

引用次数: 0

Calcium has a direct effect on thick filament activation in porcine myocardium. 钙对猪心肌的粗丝活化有直接影响。

IF 3.3 2区医学

Journal of General Physiology Pub Date : 2024-11-04 Epub Date: 2024-09-20 DOI: 10.1085/jgp.202413545

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":"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.","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}

引用次数: 0

The artificial intelligence revolution...in unethical publishing: Will AI worsen our dysfunctional publishing system? 人工智能革命......不道德的出版业：人工智能会恶化我们功能失调的出版系统吗？

IF 3.3 2区医学

Journal of General Physiology Pub Date : 2024-11-04 Epub Date: 2024-10-07 DOI: 10.1085/jgp.202413654

Thiago F A França, José Maria Monserrat

{"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":"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.","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}

引用次数: 0

Connecting the dots on connexin function. 连接连接蛋白功能的点。

IF 3.3 2区医学

Journal of General Physiology Pub Date : 2024-11-04 Epub Date: 2024-10-14 DOI: 10.1085/jgp.202413675

Ben Short

引用次数: 0

Light induces a rapid increase in cAMP and activates PKA in rod outer segments of the frog retina. 光能诱导 cAMP 快速增加，并激活蛙视网膜视杆细胞外节的 PKA。

IF 3.3 2区医学

Journal of General Physiology Pub Date : 2024-11-04 Epub Date: 2024-10-22 DOI: 10.1085/jgp.202313530

Olga Chernyshkova, Natalia Erofeeva, Darya Meshalkina, Anna Balykina, Stepan Gambaryan, Michael Belyakov, Michael Firsov

{"title":"Light induces a rapid increase in cAMP and activates PKA in rod outer segments of the frog retina.","authors":"Olga Chernyshkova, Natalia Erofeeva, Darya Meshalkina, Anna Balykina, Stepan Gambaryan, Michael Belyakov, Michael Firsov","doi":"10.1085/jgp.202313530","DOIUrl":"10.1085/jgp.202313530","url":null,"abstract":"The phototransduction cascade enables the photoreceptor to detect light over a wide range of intensities without saturation. The main second messenger of the cascade is cGMP and the primary regulatory mechanism is calcium feedback. However, some experimental data suggest that cAMP may also play a role in regulating the phototransduction cascade, but this would require changes in cAMP on a time scale of seconds. Currently, there is a lack of data on the dynamics of changes in intracellular cAMP levels on this timescale. This is largely due to the specificity of the sensory modality of photoreceptors, which makes it practically impossible to use conventional experimental approaches based on fluorescence methods. In this study, we employed the method of rapid cryofixation of retinal samples after light stimulation and subsequent isolation of outer segment preparations. The study employed highly sensitive metabolomics approaches to measure levels of cAMP. Additionally, PKA activity was measured in the samples using a western blot. The results indicate that when exposed to near-saturating but still moderate light, cAMP levels increase transiently within the first second and then return to pre-stimulus levels. The increase in cAMP activates PKA, resulting in the phosphorylation of PKA-specific substrates in frog retinal outer segments.","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/PMC11498274/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142481289","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

What happened to the pursuit of truth? 追求真理怎么了？

IF 3.3 2区医学

Journal of General Physiology Pub Date : 2024-11-04 Epub Date: 2024-10-23 DOI: 10.1085/jgp.202413672

Eve Marder

引用次数: 0

Modeling the mechanism of Ca2+ release in skeletal muscle by DHPRs easing inhibition at RyR I1-sites. 通过 DHPRs 缓解 RyR I1 位点的抑制作用，模拟骨骼肌中 Ca2+ 释放的机制。

IF 3.3 2区医学

Journal of General Physiology Pub Date : 2024-10-07 Epub Date: 2024-09-04 DOI: 10.1085/jgp.202213113

D George Stephenson

{"title":"Modeling the mechanism of Ca2+ release in skeletal muscle by DHPRs easing inhibition at RyR I1-sites.","authors":"D George Stephenson","doi":"10.1085/jgp.202213113","DOIUrl":"10.1085/jgp.202213113","url":null,"abstract":"Ca2+ release from the sarcoplasmic reticulum (SR) plays a central role in excitation-contraction coupling (ECC) in skeletal muscles. However, the mechanism by which activation of the voltage-sensors/dihydropyridine receptors (DHPRs) in the membrane of the transverse tubular system leads to activation of the Ca2+-release channels/ryanodine receptors (RyRs) in the SR is not fully understood. Recent observations showing that a very small Ca2+ leak through RyR1s in mammalian skeletal muscle can markedly raise the background [Ca2+] in the junctional space (JS) above the Ca2+ level in the bulk of the cytosol indicate that there is a diffusional barrier between the JS and the cytosol at large. Here, I use a mathematical model to explore the hypothesis that a sudden rise in Ca2+ leak through DHPR-coupled RyR1s, caused by reduced inhibition at the RyR1 Ca2+/Mg2+ inhibitory I1-sites when the associated DHPRs are activated, is sufficient to enable synchronized responses that trigger a regenerative rise of Ca2+ release that remains under voltage control. In this way, the characteristic response to Ca2+ of RyR channels is key not only for the Ca2+ release mechanism in cardiac muscle and other tissues, but also for the DHPR-dependent Ca2+ release in skeletal muscle.","PeriodicalId":54828,"journal":{"name":"Journal of General Physiology","volume":"156 10","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11390858/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142127393","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

Grammotoxin increases its toxic behavior. 革兰氏毒素会增加其毒性。

IF 3.3 2区医学

Journal of General Physiology Pub Date : 2024-10-07 Epub Date: 2024-09-25 DOI: 10.1085/jgp.202413665

Ben Short

引用次数: 0