Journal of General Physiology最新文献_第6页

A novel, patient-derived RyR1 mutation impairs muscle function and calcium homeostasis in mice. 一种源自患者的新型 RyR1 突变会损害小鼠的肌肉功能和钙稳态。

IF 3.3 2区医学

Journal of General Physiology Pub Date : 2024-04-01 Epub Date: 2024-03-04 DOI: 10.1085/jgp.202313486

Sofia Benucci, Alexis Ruiz, Martina Franchini, Lucia Ruggiero, Dario Zoppi, Rebecca Sitsapesan, Chris Lindsay, Pawel Pelczar, Laura Pietrangelo, Feliciano Protasi, Susan Treves, Francesco Zorzato

{"title":"A novel, patient-derived RyR1 mutation impairs muscle function and calcium homeostasis in mice.","authors":"Sofia Benucci, Alexis Ruiz, Martina Franchini, Lucia Ruggiero, Dario Zoppi, Rebecca Sitsapesan, Chris Lindsay, Pawel Pelczar, Laura Pietrangelo, Feliciano Protasi, Susan Treves, Francesco Zorzato","doi":"10.1085/jgp.202313486","DOIUrl":"10.1085/jgp.202313486","url":null,"abstract":"RYR1 is the most commonly mutated gene associated with congenital myopathies, a group of early-onset neuromuscular conditions of variable severity. The functional effects of a number of dominant RYR1 mutations have been established; however, for recessive mutations, these effects may depend on multiple factors, such as the formation of a hypomorphic allele, or on whether they are homozygous or compound heterozygous. Here, we functionally characterize a new transgenic mouse model knocked-in for mutations identified in a severely affected child born preterm and presenting limited limb movement. The child carried the homozygous c.14928C>G RYR1 mutation, resulting in the p.F4976L substitution. In vivo and ex vivo assays revealed that homozygous mice fatigued sooner and their muscles generated significantly less force compared with their WT or heterozygous littermates. Electron microscopy, biochemical, and physiological analyses showed that muscles from RyR1 p.F4976L homozygous mice have the following properties: (1) contain fewer calcium release units and show areas of myofibrillar degeneration, (2) contain less RyR1 protein, (3) fibers show smaller electrically evoked calcium transients, and (4) their SR has smaller calcium stores. In addition, single-channel recordings indicate that RyR1 p.F4976L exhibits higher Po in the presence of 100 μM [Ca2+]. Our mouse model partly recapitulates the clinical picture of the homozygous human patient and provides significant insight into the functional impact of this mutation. These results will help understand the pathology of patients with similar RYR1 mutations.","PeriodicalId":54828,"journal":{"name":"Journal of General Physiology","volume":"156 4","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10911087/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140040934","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

Phosphorylation of RyR2 simultaneously expands the dyad and rearranges the tetramers. RyR2 的磷酸化同时扩大了二联体并重新排列了四聚体。

IF 3.3 2区医学

Journal of General Physiology Pub Date : 2024-04-01 Epub Date: 2024-02-22 DOI: 10.1085/jgp.202213108

Parisa Asghari, David R L Scriven, Saba Shahrasebi, Hector H Valdivia, Katherina M Alsina, Carmen R Valdivia, J Alberto Navarro-Garcia, Xander H T Wehrens, Edwin D W Moore

{"title":"Phosphorylation of RyR2 simultaneously expands the dyad and rearranges the tetramers.","authors":"Parisa Asghari, David R L Scriven, Saba Shahrasebi, Hector H Valdivia, Katherina M Alsina, Carmen R Valdivia, J Alberto Navarro-Garcia, Xander H T Wehrens, Edwin D W Moore","doi":"10.1085/jgp.202213108","DOIUrl":"10.1085/jgp.202213108","url":null,"abstract":"We have previously demonstrated that type II ryanodine receptors (RyR2) tetramers can be rapidly rearranged in response to a phosphorylation cocktail. The cocktail modified downstream targets indiscriminately, making it impossible to determine whether phosphorylation of RyR2 was an essential element of the response. Here, we used the β-agonist isoproterenol and mice homozygous for one of the following clinically relevant mutations: S2030A, S2808A, S2814A, or S2814D. We measured the length of the dyad using transmission electron microscopy (TEM) and directly visualized RyR2 distribution using dual-tilt electron tomography. We found that the S2814D mutation, by itself, significantly expanded the dyad and reorganized the tetramers, suggesting a direct link between the phosphorylation state of the tetramer and its microarchitecture. S2808A and S2814A mutant mice, as well as wild types, had significant expansions of their dyads in response to isoproterenol, while S2030A mutants did not. In agreement with functional data from these mutants, S2030 and S2808 were necessary for a complete β-adrenergic response, unlike S2814 mutants. Additionally, all mutants had unique effects on the organization of their tetramer arrays. Lastly, the correlation of structural with functional changes suggests that tetramer-tetramer contacts play an important functional role. We thus conclude that both the size of the dyad and the arrangement of the tetramers are linked to the state of the channel tetramer and can be dynamically altered by a β-adrenergic receptor agonist.","PeriodicalId":54828,"journal":{"name":"Journal of General Physiology","volume":"156 4","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10883851/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139934365","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

Correction: A dual-clock-driven model of lymphatic muscle cell pacemaking to emulate knock-out of Ano1 or IP3R. 更正：双时钟驱动的淋巴肌细胞起搏模型，以模拟敲除 Ano1 或 IP3R。

IF 3.8 2区医学

Journal of General Physiology Pub Date : 2024-03-04 Epub Date: 2024-01-31 DOI: 10.1085/jgp.20231335501222024c

Edward J Hancock, Scott D Zawieja, Charlie Macaskill, Michael J Davis, Christopher D Bertram

引用次数: 0

SMR transporters meet the challenge of metformin metabolites. SMR 转运体迎接二甲双胍代谢物的挑战。

IF 3.3 2区医学

Journal of General Physiology Pub Date : 2024-03-04 Epub Date: 2024-02-07 DOI: 10.1085/jgp.202413549

Ben Short

引用次数: 0

Effect of a sensing charge mutation on the deactivation of KV7.2 channels. 感应电荷突变对 KV7.2 通道失活的影响

IF 3.8 2区医学

Journal of General Physiology Pub Date : 2024-03-04 Epub Date: 2024-01-18 DOI: 10.1085/jgp.202213284

Baharak Mehrdel, Carlos A Villalba-Galea

{"title":"Effect of a sensing charge mutation on the deactivation of KV7.2 channels.","authors":"Baharak Mehrdel, Carlos A Villalba-Galea","doi":"10.1085/jgp.202213284","DOIUrl":"10.1085/jgp.202213284","url":null,"abstract":"Potassium-selective, voltage-gated channels of the KV7 family are critical regulators of electrical excitability in many cell types. Removing the outermost putative sensing charge (R198) of the human KV7.2 shifts its activation voltage dependence toward more negative potentials. This suggests that removing a charge \"at the top\" of the fourth (S4) segment of the voltage-sensing domain facilitates activation. Here, we hypothesized that restoring that charge would bring back the activation to its normal voltage range. We introduced the mutation R198H in KV7.2 with the idea that titrating the introduced histidine with protons would reinstate the sensing charge. As predicted, the mutant's activation voltage dependence changed as a function of the external pH (pHEXT) while modest changes in the activation voltage dependence were observed with the wild-type (WT) channel. On the other hand, the deactivation kinetics of the R198H mutant was remarkably sensitive to pHEXT changes, readily deactivating at pHEXT 6, while becoming slower to deactivate at pHEXT 8. In contrast, the KV7.2 WT displayed modest changes in the deactivation kinetics as a function of pHEXT. This suggested that the charge of residue 198 was critical for deactivation. However, in a surprising turn, the mutant R198Q-a non-titratable mutation-also displayed a high pHEXT sensitivity activity. We thus concluded that rather than the charge at position 198, the protonation status of the channel's extracellular face modulates the open channel stabilization and that the charge of residue 198 is required for the voltage sensor to effectively deactivate the channel, overcoming the stabilizing effect of high pHEXT.","PeriodicalId":54828,"journal":{"name":"Journal of General Physiology","volume":"156 3","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10796215/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139486753","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

Evaluating sequential and allosteric activation models in IKs channels with mutated voltage sensors. 评估具有突变电压传感器的 IKs 通道的顺序激活和异位激活模型

IF 3.3 2区医学

Journal of General Physiology Pub Date : 2024-03-04 Epub Date: 2024-01-31 DOI: 10.1085/jgp.202313465

David Fedida, Daniel Sastre, Ying Dou, Maartje Westhoff, Jodene Eldstrom

{"title":"Evaluating sequential and allosteric activation models in IKs channels with mutated voltage sensors.","authors":"David Fedida, Daniel Sastre, Ying Dou, Maartje Westhoff, Jodene Eldstrom","doi":"10.1085/jgp.202313465","DOIUrl":"10.1085/jgp.202313465","url":null,"abstract":"The ion-conducting IKs channel complex, important in cardiac repolarization and arrhythmias, comprises tetramers of KCNQ1 α-subunits along with 1-4 KCNE1 accessory subunits and calmodulin regulatory molecules. The E160R mutation in individual KCNQ1 subunits was used to prevent activation of voltage sensors and allow direct determination of transition rate data from complexes opening with a fixed number of 1, 2, or 4 activatable voltage sensors. Markov models were used to test the suitability of sequential versus allosteric models of IKs activation by comparing simulations with experimental steady-state and transient activation kinetics, voltage-sensor fluorescence from channels with two or four activatable domains, and limiting slope currents at negative potentials. Sequential Hodgkin-Huxley-type models approximately describe IKs currents but cannot explain an activation delay in channels with only one activatable subunit or the hyperpolarizing shift in the conductance-voltage relationship with more activatable voltage sensors. Incorporating two voltage sensor activation steps in sequential models and a concerted step in opening via rates derived from fluorescence measurements improves models but does not resolve fundamental differences with experimental data. Limiting slope current data that show the opening of channels at negative potentials and very low open probability are better simulated using allosteric models of activation with one transition per voltage sensor, which implies that movement of all four sensors is not required for IKs conductance. Tiered allosteric models with two activating transitions per voltage sensor can fully account for IKs current and fluorescence activation kinetics in constructs with different numbers of activatable voltage sensors.","PeriodicalId":54828,"journal":{"name":"Journal of General Physiology","volume":"156 3","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10829594/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139643436","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

On the link between antibiotic resistance, diabetes, and wastewater. 抗生素耐药性、糖尿病和废水之间的联系。

IF 3.3 2区医学

Journal of General Physiology Pub Date : 2024-03-04 Epub Date: 2024-01-31 DOI: 10.1085/jgp.202313533

Shimon Schuldiner

引用次数: 0

Transport of metformin metabolites by guanidinium exporters of the small multidrug resistance family. 二甲双胍代谢物通过小型多药耐药性家族的胍类输出体转运。

IF 3.3 2区医学

Journal of General Physiology Pub Date : 2024-03-04 Epub Date: 2024-01-31 DOI: 10.1085/jgp.202313464

Rachael M Lucero, Kemal Demirer, Trevor Justin Yeh, Randy B Stockbridge

{"title":"Transport of metformin metabolites by guanidinium exporters of the small multidrug resistance family.","authors":"Rachael M Lucero, Kemal Demirer, Trevor Justin Yeh, Randy B Stockbridge","doi":"10.1085/jgp.202313464","DOIUrl":"10.1085/jgp.202313464","url":null,"abstract":"Proteins from the small multidrug resistance (SMR) family are frequently associated with horizontally transferred multidrug resistance gene arrays found in bacteria from wastewater and the human-adjacent biosphere. Recent studies suggest that a subset of SMR transporters might participate in the metabolism of the common pharmaceutical metformin by bacterial consortia. Here, we show that both genomic and plasmid-associated transporters of the SMRGdx functional subtype export byproducts of microbial metformin metabolism, with particularly high export efficiency for guanylurea. We use solid-supported membrane electrophysiology to evaluate the transport kinetics for guanylurea and native substrate guanidinium by four representative SMRGdx homologs. Using an internal reference to normalize independent electrophysiology experiments, we show that transport rates are comparable for genomic and plasmid-associated SMRGdx homologs, and using a proteoliposome-based transport assay, we show that 2 proton:1 substrate transport stoichiometry is maintained. Additional characterization of guanidinium and guanylurea export properties focuses on the structurally characterized homolog, Gdx-Clo, for which we examined the pH dependence and thermodynamics of substrate binding and solved an x-ray crystal structure with guanylurea bound. Together, these experiments contribute in two main ways. By providing the first detailed kinetic examination of the structurally characterized SMRGdx homolog Gdx-Clo, they provide a functional framework that will inform future mechanistic studies of this model transport protein. Second, this study casts light on a potential role for SMRGdx transporters in microbial handling of metformin and its microbial metabolic byproducts, providing insight into how native transport physiologies are co-opted to contend with new selective pressures.","PeriodicalId":54828,"journal":{"name":"Journal of General Physiology","volume":"156 3","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10829512/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139643438","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

Blood flow-bearing physical forces, endothelial glycocalyx, and liver enzyme mobilization: A hypothesis. 血流承载的物理力、内皮糖萼和肝酶动员：一个假设

IF 3.8 2区医学

Journal of General Physiology Pub Date : 2024-03-04 Epub Date: 2024-01-17 DOI: 10.1085/jgp.202313462

Lorena Carmina Hernández-Espinosa, Rolando Hernández-Muñoz

{"title":"Blood flow-bearing physical forces, endothelial glycocalyx, and liver enzyme mobilization: A hypothesis.","authors":"Lorena Carmina Hernández-Espinosa, Rolando Hernández-Muñoz","doi":"10.1085/jgp.202313462","DOIUrl":"10.1085/jgp.202313462","url":null,"abstract":"Numerous elements involved in shear stress-induced signaling have been identified, recognizing their functions as mechanotransducing ion channels situated at cellular membranes. This form of mechanical signaling relies on transmembrane proteins and cytoplasmic proteins that restructure the cytoskeleton, contributing to mechanotransduction cascades. Notably, blood flow generates mechanical forces that significantly impact the structure and remodeling of blood vessels. The primary regulation of blood vessel responses occurs through hemodynamic forces acting on the endothelium. These mechanical events intricately govern endothelial biophysical, biochemical, and genetic responses. Endothelial cells, positioned on the intimal surface of blood vessels, have the capability to express components of the glycocalyx. This endothelial structure emerges as a pivotal factor in mechanotransduction and the regulation of vascular tone. The endothelial glycocalyx assumes diverse roles in both health and disease. Our findings propose a connection between the release of specific enzymes from the rat liver and variations in the hepatic blood flow/mass ratio. Importantly, this phenomenon is not correlated with liver necrosis. Consequently, this review serves as an exploration of the potential involvement of membrane proteins in a hypothetical mechanotransducing phenomenon capable of controlling the release of liver enzymes.","PeriodicalId":54828,"journal":{"name":"Journal of General Physiology","volume":"156 3","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10794122/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139479377","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

Electro-metabolic signaling. 电代谢信号

IF 3.3 2区医学

Journal of General Physiology Pub Date : 2024-02-05 Epub Date: 2024-01-10 DOI: 10.1085/jgp.202313451

Thomas A Longden, W Jonathan Lederer

{"title":"Electro-metabolic signaling.","authors":"Thomas A Longden, W Jonathan Lederer","doi":"10.1085/jgp.202313451","DOIUrl":"10.1085/jgp.202313451","url":null,"abstract":"Precise matching of energy substrate delivery to local metabolic needs is essential for the health and function of all tissues. Here, we outline a mechanistic framework for understanding this critical process, which we refer to as electro-metabolic signaling (EMS). All tissues exhibit changes in metabolism over varying spatiotemporal scales and have widely varying energetic needs and reserves. We propose that across tissues, common signatures of elevated metabolism or increases in energy substrate usage that exceed key local thresholds rapidly engage mechanisms that generate hyperpolarizing electrical signals in capillaries that then relax contractile elements throughout the vasculature to quickly adjust blood flow to meet changing needs. The attendant increase in energy substrate delivery serves to meet local metabolic requirements and thus avoids a mismatch in supply and demand and prevents metabolic stress. We discuss in detail key examples of EMS that our laboratories have discovered in the brain and the heart, and we outline potential further EMS mechanisms operating in tissues such as skeletal muscle, pancreas, and kidney. We suggest that the energy imbalance evoked by EMS uncoupling may be central to cellular dysfunction from which the hallmarks of aging and metabolic diseases emerge and may lead to generalized organ failure states-such as diverse flavors of heart failure and dementia. Understanding and manipulating EMS may be key to preventing or reversing these dysfunctions.","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/PMC10783436/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139405297","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