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1.
Pflugers Arch ; 473(3): 417-434, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33638008

RESUMO

Store-operated Ca2+ entry (SOCE) is an ancient and ubiquitous Ca2+ signaling pathway that is present in virtually every cell type. Over the last two decades, many studies have implicated this non-voltage dependent Ca2+ entry pathway in cardiac physiology. The relevance of the SOCE pathway in cardiomyocytes is often questioned given the well-established role for excitation contraction coupling. In this review, we consider the evidence that STIM1 and SOCE contribute to Ca2+ dynamics in cardiomyocytes. We discuss the relevance of this pathway to cardiac growth in response to developmental and pathologic cues. We also address whether STIM1 contributes to Ca2+ store refilling that likely impacts cardiac pacemaking and arrhythmogenesis in cardiomyocytes.


Assuntos
Sinalização do Cálcio/fisiologia , Proteínas Sensoras de Cálcio Intracelular/metabolismo , Miócitos Cardíacos/metabolismo , Molécula 1 de Interação Estromal/metabolismo , Animais , Acoplamento Excitação-Contração/fisiologia , Humanos
2.
Proc Natl Acad Sci U S A ; 113(19): E2665-74, 2016 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-27044086

RESUMO

Clustering of voltage-gated sodium channels (VGSCs) within the neuronal axon initial segment (AIS) is critical for efficient action potential initiation. Although initially inserted into both somatodendritic and axonal membranes, VGSCs are concentrated within the axon through mechanisms that include preferential axonal targeting and selective somatodendritic endocytosis. How the endocytic machinery specifically targets somatic VGSCs is unknown. Here, using knockdown strategies, we show that noncanonical FGF13 binds directly to VGSCs in hippocampal neurons to limit their somatodendritic surface expression, although exerting little effect on VGSCs within the AIS. In contrast, homologous FGF14, which is highly concentrated in the proximal axon, binds directly to VGSCs to promote their axonal localization. Single-point mutations in FGF13 or FGF14 abrogating VGSC interaction in vitro cannot support these specific functions in neurons. Thus, our data show how the concerted actions of FGF13 and FGF14 regulate the polarized localization of VGSCs that supports efficient action potential initiation.


Assuntos
Potenciais de Ação , Canais de Sódio Disparados por Voltagem/metabolismo , Axônios/metabolismo , Humanos , Neurônios/metabolismo , Sódio/metabolismo , Canais de Sódio/genética
3.
Proc Natl Acad Sci U S A ; 112(40): 12528-33, 2015 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-26392562

RESUMO

Nav channels are essential for metazoan membrane depolarization, and Nav channel dysfunction is directly linked with epilepsy, ataxia, pain, arrhythmia, myotonia, and irritable bowel syndrome. Human Nav channelopathies are primarily caused by variants that directly affect Nav channel permeability or gating. However, a new class of human Nav channelopathies has emerged based on channel variants that alter regulation by intracellular signaling or cytoskeletal proteins. Fibroblast growth factor homologous factors (FHFs) are a family of intracellular signaling proteins linked with Nav channel regulation in neurons and myocytes. However, to date, there is surprisingly little evidence linking Nav channel gene variants with FHFs and human disease. Here, we provide, to our knowledge, the first evidence that mutations in SCN5A (encodes primary cardiac Nav channel Nav1.5) that alter FHF binding result in human cardiovascular disease. We describe a five*generation kindred with a history of atrial and ventricular arrhythmias, cardiac arrest, and sudden cardiac death. Affected family members harbor a novel SCN5A variant resulting in p.H1849R. p.H1849R is localized in the central binding core on Nav1.5 for FHFs. Consistent with these data, Nav1.5 p.H1849R affected interaction with FHFs. Further, electrophysiological analysis identified Nav1.5 p.H1849R as a gain-of-function for INa by altering steady-state inactivation and slowing the rate of Nav1.5 inactivation. In line with these data and consistent with human cardiac phenotypes, myocytes expressing Nav1.5 p.H1849R displayed prolonged action potential duration and arrhythmogenic afterdepolarizations. Together, these findings identify a previously unexplored mechanism for human Nav channelopathy based on altered Nav1.5 association with FHF proteins.


Assuntos
Arritmias Cardíacas/genética , Fatores de Crescimento de Fibroblastos/metabolismo , Mutação de Sentido Incorreto , Canal de Sódio Disparado por Voltagem NAV1.5/genética , Potenciais de Ação/genética , Potenciais de Ação/fisiologia , Animais , Arritmias Cardíacas/metabolismo , Arritmias Cardíacas/fisiopatologia , Células Cultivadas , Canalopatias/genética , Canalopatias/metabolismo , Canalopatias/fisiopatologia , Saúde da Família , Feminino , Predisposição Genética para Doença/genética , Células HEK293 , Humanos , Immunoblotting , Masculino , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/fisiologia , Canal de Sódio Disparado por Voltagem NAV1.5/metabolismo , Técnicas de Patch-Clamp , Linhagem , Ligação Proteica
4.
Arch Gynecol Obstet ; 293(6): 1309-17, 2016 06.
Artigo em Inglês | MEDLINE | ID: mdl-26446578

RESUMO

PURPOSE: This preliminary study aimed at investigating the feasibility and effective of multi-scale hyperspectral imaging in detecting cervical neoplasia at both tissue and cellular levels. METHODS: In this paper, we describe a noninvasive diagnosis method with a hyperspectral imager for detection and location of cervical intraepithelial neoplasia (CIN) at multiple scales. At the macroscopic level, the hyperspectral imager was applied to capture the reflectance images of the entire cervix in vivo at a series of wavelengths. At the microscopic level, the hyperspectral imager was coupled with a microscope to collect the transmittance images of the pathological slide. The collected image data were calibrated. A wide-gap second derivative analysis was applied to differentiate CIN from other types of tissue. RESULTS: At both macroscopic and microscopic levels, hyperspectral imaging analysis results were consistent with those of histopathological analysis, indicating the technical feasibility of multi-scale hyperspectral imaging for cervical neoplasia detection with accuracy and efficacy. CONCLUSION: We propose a multi-scale hyperspectral imaging method for noninvasive detection of cervical neoplasia. Comparison of the imaging results with those of gold standard histologic measurements demonstrates that the hyperspectral diagnostic imaging system can distinguish CIN at both tissue and cellular levels.


Assuntos
Interpretação de Imagem Assistida por Computador/métodos , Análise Espectral/métodos , Displasia do Colo do Útero/diagnóstico por imagem , Neoplasias do Colo do Útero/diagnóstico por imagem , Feminino , Humanos , Neoplasias do Colo do Útero/patologia , Displasia do Colo do Útero/patologia
5.
PLoS One ; 19(5): e0301293, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38743677

RESUMO

Bicycle safety has emerged as a pressing concern within the vulnerable transportation community. Numerous studies have been conducted to identify the significant factors that contribute to the severity of cyclist injuries, yet the findings have been subject to uncertainty due to unobserved heterogeneity and class imbalance. This research aims to address these issues by developing a model to examine the impact of key factors on cyclist injury severity, accounting for data heterogeneity and imbalance. To incorporate unobserved heterogeneity, a total of 3,895 bicycle accidents were categorized into three homogeneous sub-accident clusters using Latent Class Cluster Analysis (LCA). Additionally, five over-sampling techniques were employed to mitigate the effects of data imbalance in each accident cluster category. Subsequently, Bayesian Network (BN) structure learning algorithms were utilized to construct 32 BN models after pairing the accident data from the four accident cluster types before and after sampling. The optimal BN models for each accident cluster type provided insights into the key factors associated with cyclist injury severity. The results indicate that the key factors influencing serious cyclist injuries vary heterogeneously across different accident clusters. Female cyclists, adverse weather conditions such as rain and snow, and off-peak periods were identified as key factors in several subclasses of accident clusters. Conversely, factors such as the week of the accident, characteristics of the trafficway, the season, drivers failing to yield to the right-of-way, distracted cyclists, and years of driving experience were found to be key factors in only one subcluster of accident clusters. Additionally, factors such as the time of the crash, gender of the cyclist, and weather conditions exhibit varying levels of heterogeneity across different accident clusters, and in some cases, exhibit opposing effects.


Assuntos
Acidentes de Trânsito , Teorema de Bayes , Ciclismo , Ciclismo/lesões , Humanos , Feminino , Masculino , Acidentes de Trânsito/estatística & dados numéricos , Adulto , Análise por Conglomerados , Lesões Acidentais/epidemiologia , Lesões Acidentais/etiologia , Pessoa de Meia-Idade , Adulto Jovem , Adolescente , Fatores de Risco
6.
J Clin Invest ; 134(7)2024 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-38300705

RESUMO

Stromal interaction molecule 1 (STIM1) is a Ca2+ sensor located in the sarcoplasmic reticulum (SR) of skeletal muscle, where it is best known for its role in store-operated Ca2+ entry (SOCE). Genetic syndromes resulting from STIM1 mutations are recognized as a cause of muscle weakness and atrophy. Here, we focused on a gain-of-function mutation that occurs in humans and mice (STIM1+/D84G mice), in which muscles exhibited constitutive SOCE. Unexpectedly, this constitutive SOCE did not affect global Ca2+ transients, SR Ca2+ content, or excitation-contraction coupling (ECC) and was therefore unlikely to underlie the reduced muscle mass and weakness observed in these mice. Instead, we demonstrate that the presence of D84G STIM1 in the nuclear envelope of STIM1+/D84G muscle disrupted nuclear-cytosolic coupling, causing severe derangement in nuclear architecture, DNA damage, and altered lamina A-associated gene expression. Functionally, we found that D84G STIM1 reduced the transfer of Ca2+ from the cytosol to the nucleus in myoblasts, resulting in a reduction of [Ca2+]N. Taken together, we propose a novel role for STIM1 in the nuclear envelope that links Ca2+ signaling to nuclear stability in skeletal muscle.


Assuntos
Debilidade Muscular , Membrana Nuclear , Molécula 1 de Interação Estromal , Animais , Humanos , Camundongos , Cálcio/metabolismo , Sinalização do Cálcio , Debilidade Muscular/genética , Debilidade Muscular/metabolismo , Músculo Esquelético/metabolismo , Mutação , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/metabolismo , Membrana Nuclear/genética , Membrana Nuclear/metabolismo , Proteína ORAI1/genética , Molécula 1 de Interação Estromal/genética , Molécula 1 de Interação Estromal/metabolismo
7.
Circ Res ; 109(7): 775-82, 2011 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-21817159

RESUMO

RATIONALE: Fibroblast growth factor homologous factors (FHFs), a subfamily of fibroblast growth factors (FGFs) that are incapable of functioning as growth factors, are intracellular modulators of Na(+) channels and have been linked to neurodegenerative diseases. Although certain FHFs have been found in embryonic heart, they have not been reported in adult heart, and they have not been shown to regulate endogenous cardiac Na(+) channels or to participate in cardiac pathophysiology. OBJECTIVE: We tested whether FHFs regulate Na(+) channels in murine heart. METHODS AND RESULTS: We demonstrated that isoforms of FGF13 are the predominant FHFs in adult mouse ventricular myocytes. FGF13 binds directly to, and colocalizes with, the Na(V)1.5 Na(+) channel in the sarcolemma of adult mouse ventricular myocytes. Knockdown of FGF13 in adult mouse ventricular myocytes revealed a loss of function of Na(V)1.5-reduced Na(+) current density, decreased Na(+) channel availability, and slowed Na(V)1.5-reduced Na(+) current recovery from inactivation. Cell surface biotinylation experiments showed ≈45% reduction in Na(V)1.5 protein at the sarcolemma after FGF13 knockdown, whereas no changes in whole-cell Na(V)1.5 protein or in mRNA level were observed. Optical imaging in neonatal rat ventricular myocyte monolayers demonstrated slowed conduction velocity and a reduced maximum capture rate after FGF13 knockdown. CONCLUSION: These findings show that FHFs are potent regulators of Na(+) channels in adult ventricular myocytes and suggest that loss-of-function mutations in FHFs may underlie a similar set of cardiac arrhythmias and cardiomyopathies that result from Na(V)1.5 loss-of-function mutations.


Assuntos
Fatores de Crescimento de Fibroblastos/metabolismo , Ventrículos do Coração/metabolismo , Ativação do Canal Iônico , Miócitos Cardíacos/metabolismo , Canais de Sódio/metabolismo , Sódio/metabolismo , Potenciais de Ação , Animais , Animais Recém-Nascidos , Biotinilação , Células Cultivadas , Fatores de Crescimento de Fibroblastos/genética , Cinética , Camundongos , Camundongos Endogâmicos C57BL , Mutação , Canal de Sódio Disparado por Voltagem NAV1.5 , Técnicas de Patch-Clamp , Ligação Proteica , Interferência de RNA , RNA Mensageiro/metabolismo , Ratos , Ratos Sprague-Dawley , Sarcolema/metabolismo , Canais de Sódio/genética , Transfecção , Imagens com Corantes Sensíveis à Voltagem
8.
bioRxiv ; 2023 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-37205564

RESUMO

Stromal interaction molecule 1 (STIM1) is a Ca 2+ sensor located in the sarcoplasmic reticulum (SR) of skeletal muscle where it is best known for its role in store operated Ca 2+ entry (SOCE). Genetic syndromes resulting from STIM1 mutations are recognized as a cause of muscle weakness and atrophy. Here, we focus on a gain of function mutation that occurs in humans and mice (STIM1 +/D84G mice) where muscles exhibit constitutive SOCE. Unexpectedly, this constitutive SOCE did not affect global Ca 2+ transients, SR Ca 2+ content or excitation contraction coupling (ECC) and was therefore unlikely to underlie the reduced muscle mass and weakness observed in these mice. Instead, we demonstrate that the presence of D84G STIM1 in the nuclear envelope of STIM1 +/D84G muscle disrupts nuclear-cytosolic coupling causing severe derangement in nuclear architecture, DNA damage, and altered lamina A associated gene expression. Functionally, we found D84G STIM1 reduced the transfer of Ca 2+ from the cytosol to the nucleus in myoblasts resulting in a reduction of [Ca 2+ ] N . Taken together, we propose a novel role for STIM1 in the nuclear envelope that links Ca 2+ signaling to nuclear stability in skeletal muscle.

9.
Mol Ther Nucleic Acids ; 31: 662-673, 2023 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-36910716

RESUMO

Acute lung injury (ALI) is a syndrome of acute inflammation, barrier disruption, and hypoxemic respiratory failure associated with high morbidity and mortality. Diverse conditions lead to ALI, including inhalation of toxic substances, aspiration of gastric contents, infection, and trauma. A shared mechanism of acute lung injury is cellular toxicity from damage-associated molecular patterns (DAMPs), including extracellular histones. We recently described the selection and efficacy of a histone-binding RNA aptamer (HBA7). The current study aimed to identify the effects of extracellular histones in the lung and determine if HBA7 protected mice from ALI. Histone proteins decreased metabolic activity, induced apoptosis, promoted proinflammatory cytokine production, and caused endothelial dysfunction and platelet activation in vitro. HBA7 prevented these effects. The oropharyngeal aspiration of histone proteins increased neutrophil and albumin levels in bronchoalveolar lavage fluid (BALF) and precipitated neutrophil infiltration, interstitial edema, and barrier disruption in alveoli in mice. Similarly, inhaling wood smoke particulate matter, as a clinically relevant model, increased lung inflammation and alveolar permeability. Treatment by HBA7 alleviated lung injury in both models of ALI. These findings demonstrate the pulmonary delivery of HBA7 as a nucleic acid-based therapeutic for ALI.

10.
J Biol Chem ; 286(27): 24253-63, 2011 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-21566136

RESUMO

Fibroblast growth factor homologous factors (FHFs, FGF11-14) bind to the C termini (CTs) of specific voltage-gated sodium channels (VGSC) and thereby regulate their function. The effect of an individual FHF on a specific VGSC varies greatly depending upon the individual FHF isoform. How individual FHFs impart distinctive effects on specific VGSCs is not known and the specificity of these pairwise interactions is not understood. Using several biochemical approaches combined with functional analysis, we mapped the interaction site for FGF12B on the Na(V)1.5 C terminus and discovered previously unknown determinants necessary for FGF12 interaction. Also, we demonstrated that FGF12B binds to some, but not all Na(V)1 CTs, suggesting specificity of interaction. Exploiting a human single nucleotide polymorphism in the core domain of FGF12 (P149Q), we identified a surface proline that contributes a part of this pairwise specificity. This proline is conserved among all FHFs, and mutation of the homologous residue in FGF13 also leads to loss of interaction with a specific VGSC CT (Na(V)1.1) and loss of modulation of the resultant Na(+) channel function. We hypothesized that some of the specificity mediated by this proline may result from differences in the affinity of the binding partners. Consistent with this hypothesis, surface plasmon resonance data showed that the P149Q mutation decreased the binding affinity between FHFs and VGSC CTs. Moreover, immunocytochemistry revealed that the mutation prevented proper subcellular targeting of FGF12 to the axon initial segment in neurons. Together, these results give new insights into details of the interactions between FHFs and Na(V)1.x CTs, and the consequent regulation of Na(+) channels.


Assuntos
Fatores de Crescimento de Fibroblastos/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Neurônios/metabolismo , Canais de Sódio/metabolismo , Substituição de Aminoácidos , Fatores de Crescimento de Fibroblastos/genética , Células HEK293 , Humanos , Mutação de Sentido Incorreto , Canal de Sódio Disparado por Voltagem NAV1.1 , Canal de Sódio Disparado por Voltagem NAV1.5 , Proteínas do Tecido Nervoso/genética , Polimorfismo de Nucleotídeo Único , Estrutura Terciária de Proteína , Canais de Sódio/genética
11.
Circ Res ; 104(12): 1382-9, 2009 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-19461043

RESUMO

Complex modulation of voltage-gated Ca2+ currents through the interplay among Ca2+ channels and various Ca(2+)-binding proteins is increasingly being recognized. The K+ channel interacting protein 2 (KChIP2), originally identified as an auxiliary subunit for K(V)4.2 and a component of the transient outward K+ channel (I(to)), is a Ca(2+)-binding protein whose regulatory functions do not appear restricted to K(V)4.2. Consequently, we hypothesized that KChIP2 is a direct regulator of the cardiac L-type Ca2+ current (I(Ca,L)). We found that I(Ca,L) density from KChIP2(-/-) myocytes is reduced by 28% compared to I(Ca,L) recorded from wild-type myocytes (P<0.05). This reduction in current density results from loss of a direct effect on the Ca2+ channel current, as shown in a transfected cell line devoid of confounding cardiac ion currents. I(Ca,L) regulation by KChIP2 was independent of Ca2+ binding to KChIP2. Biochemical analysis suggested a direct interaction between KChIP2 and the Ca(V)1.2 alpha(1C) subunit N terminus. We found that KChIP2 binds to the N-terminal inhibitory module of alpha(1C) and augments I(Ca,L) current density without increasing Ca(V)1.2 protein expression or trafficking to the plasma membrane. We propose a model in which KChIP2 impedes the N-terminal inhibitory module of Ca(V)1.2, resulting in increased I(Ca,L). In the context of recent reports that KChIP2 modulates multiple K(V) and Na(V) currents, these results suggest that KChIP2 is a multimodal regulator of cardiac ionic currents.


Assuntos
Cálcio/metabolismo , Membrana Celular/metabolismo , Proteínas Interatuantes com Canais de Kv/metabolismo , Potenciais da Membrana/fisiologia , Proteínas Musculares/metabolismo , Animais , Canais de Cálcio Tipo L/genética , Canais de Cálcio Tipo L/metabolismo , Membrana Celular/genética , Células Cultivadas , Transporte de Íons/fisiologia , Proteínas Interatuantes com Canais de Kv/genética , Masculino , Camundongos , Camundongos Knockout , Proteínas Musculares/genética , Estrutura Terciária de Proteína/fisiologia , Canais de Potássio Shal/genética , Canais de Potássio Shal/metabolismo
12.
JCI Insight ; 6(17)2021 09 08.
Artigo em Inglês | MEDLINE | ID: mdl-34494555

RESUMO

Stromal interaction molecule 1 (STIM1), the sarcoplasmic reticulum (SR) transmembrane protein, activates store-operated Ca2+ entry (SOCE) in skeletal muscle and, thereby, coordinates Ca2+ homeostasis, Ca2+-dependent gene expression, and contractility. STIM1 occupies space in the junctional SR membrane of the triads and the longitudinal SR at the Z-line. How STIM1 is organized and is retained in these specific subdomains of the SR is unclear. Here, we identified desmin, the major type III intermediate filament protein in muscle, as a binding partner for STIM1 based on a yeast 2-hybrid screen. Validation of the desmin-STIM1 interaction by immunoprecipitation and immunolocalization confirmed that the CC1-SOAR domains of STIM1 interact with desmin to enhance STIM1 oligomerization yet limit SOCE. Based on our studies of desmin-KO mice, we developed a model wherein desmin connected STIM1 at the Z-line in order to regulate the efficiency of Ca2+ refilling of the SR. Taken together, these studies showed that desmin-STIM1 assembles a cytoskeletal-SR connection that is important for Ca2+ signaling in skeletal muscle.


Assuntos
Desmina/genética , Regulação da Expressão Gênica , Músculo Esquelético/metabolismo , RNA/genética , Molécula 1 de Interação Estromal/genética , Animais , Sinalização do Cálcio , Células Cultivadas , Desmina/biossíntese , Proteínas de Membrana/biossíntese , Proteínas de Membrana/genética , Camundongos , Microscopia Eletrônica de Transmissão , Modelos Animais , Músculo Esquelético/ultraestrutura , Retículo Sarcoplasmático/metabolismo , Molécula 1 de Interação Estromal/biossíntese
13.
JCI Insight ; 5(19)2020 10 02.
Artigo em Inglês | MEDLINE | ID: mdl-32870823

RESUMO

The Ca2+-binding protein calmodulin has emerged as a pivotal player in tuning Na+ channel function, although its impact in vivo remains to be resolved. Here, we identify the role of calmodulin and the NaV1.5 interactome in regulating late Na+ current in cardiomyocytes. We created transgenic mice with cardiac-specific expression of human NaV1.5 channels with alanine substitutions for the IQ motif (IQ/AA). The mutations rendered the channels incapable of binding calmodulin to the C-terminus. The IQ/AA transgenic mice exhibited normal ventricular repolarization without arrhythmias and an absence of increased late Na+ current. In comparison, transgenic mice expressing a lidocaine-resistant (F1759A) human NaV1.5 demonstrated increased late Na+ current and prolonged repolarization in cardiomyocytes, with spontaneous arrhythmias. To determine regulatory factors that prevent late Na+ current for the IQ/AA mutant channel, we considered fibroblast growth factor homologous factors (FHFs), which are within the NaV1.5 proteomic subdomain shown by proximity labeling in transgenic mice expressing NaV1.5 conjugated to ascorbate peroxidase. We found that FGF13 diminished late current of the IQ/AA but not F1759A mutant cardiomyocytes, suggesting that endogenous FHFs may serve to prevent late Na+ current in mouse cardiomyocytes. Leveraging endogenous mechanisms may furnish an alternative avenue for developing novel pharmacology that selectively blunts late Na+ current.


Assuntos
Potenciais de Ação , Arritmias Cardíacas/patologia , Calmodulina/metabolismo , Fatores de Crescimento de Fibroblastos/metabolismo , Mutação , Miócitos Cardíacos/patologia , Canal de Sódio Disparado por Voltagem NAV1.5/metabolismo , Animais , Arritmias Cardíacas/genética , Arritmias Cardíacas/metabolismo , Sinalização do Cálcio , Calmodulina/genética , Feminino , Fatores de Crescimento de Fibroblastos/genética , Humanos , Masculino , Camundongos , Camundongos Transgênicos , Miócitos Cardíacos/metabolismo , Canal de Sódio Disparado por Voltagem NAV1.5/genética , Ligação Proteica , Sódio/metabolismo
14.
J Neurosci ; 28(8): 1865-70, 2008 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-18287503

RESUMO

Ca2+ influx through NMDA receptors (NMDARs) leads to channel inactivation, which limits Ca2+ entry and protects against excitotoxicity. Extensive functional data suggests that this Ca2+-dependent inactivation (CDI) requires both calmodulin (CaM) binding to the C0 cassette of the NR1 subunit's C terminus (CT) and regulation by alpha-actinin-2, but a molecular understanding of CDI has been elusive. Here we used a number of methods to analyze the molecular nature of the interaction among CaM, alpha-actinin-2, and the NR1 CT. We found that a single CaM binds to two NR1 CTs in a Ca2+-dependent manner and promotes their reversible "dimerization." Expressed NMDARs containing NR1 concatamers in which the NR1 C termini are "uncoupled" display markedly reduced CDI. In contrast to current models, alpha-actinin-2 does not bind to the NR1 CT. We propose a new model for CDI in which the noncanonical Ca2+/CaM-dependent dimerization of the two NR1 subunits inactivates the channel by propagating a conformational change from the short NR1 CT to the nearby channel pore.


Assuntos
Cálcio/metabolismo , Calmodulina/metabolismo , Receptores de N-Metil-D-Aspartato/química , Receptores de N-Metil-D-Aspartato/metabolismo , Sítios de Ligação/fisiologia , Linhagem Celular , Dimerização , Humanos , Receptores de N-Metil-D-Aspartato/antagonistas & inibidores
15.
J Muscle Res Cell Motil ; 30(1-2): 67-72, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19381846

RESUMO

Phosphorylation of cardiac troponin is a key mechanism involved in regulation of contractile function. In vitro kinase assays revealed that lysates prepared from resting cardiomyocytes contain cardiac troponin I (cTnI) and cTnT kinase activity. cTnI phosphorylation is inhibited by pharmacologic inhibitors of PKA, PKC, Rho kinase and PKC effectors such as RSK and PKD; these kinase inhibitors do not inhibit phosphorylation of cTnT. Rather, cTnT phosphorylation is decreased by the Raf inhibitor GW5074. In vitro kinase assays show that recombinant Raf phosphorylates cTnT, and that Raf-dependent cTnT phosphorylation is abrogated by a T206E substitution; Raf does not phosphorylate cTnI. These studies identify Raf-dependent cTnT-Thr(206) phosphorylation as a novel mechanism that would link growth factor-dependent signaling pathways to dynamic changes in cardiac contractile function.


Assuntos
Miócitos Cardíacos/enzimologia , Proteínas Proto-Oncogênicas c-raf/metabolismo , Troponina T/metabolismo , Animais , Células Cultivadas , Indóis/farmacologia , Contração Miocárdica , Miócitos Cardíacos/fisiologia , Fenóis/farmacologia , Fosforilação/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-raf/antagonistas & inibidores , Ratos , Ratos Wistar , Proteínas Recombinantes/metabolismo , Treonina/metabolismo , Troponina I/metabolismo , Troponina T/química
16.
J Neurosci ; 27(34): 9086-93, 2007 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-17715345

RESUMO

As the Ca2+-sensor for Ca2+-dependent inactivation, calmodulin (CaM) has been proposed, but never definitively demonstrated, to be a constitutive Ca(V)1.2 Ca2+ channel subunit. Here we show that CaM is associated with the Ca(V)1.2 pore-forming alpha1C subunit in brain in a Ca2+-independent manner. Within its CaM binding pocket, alpha1C has been proposed to contain a membrane targeting domain. Because ion channel subunits assemble early during channel biosynthesis, we postulated that this association with CaM could afford the opportunity for Ca2+-dependent regulation of membrane targeting. We showed that the isolated domain functioned as a Ca2+/CaM regulated trafficking determinant for CD8 (a model transmembrane protein) using fluorescent-activated cell sorting analysis and, using green fluorescent protein-tagged alpha1C subunits expressed in cultured hippocampal neurons, that Ca2+/CaM interaction with this domain accelerated trafficking of Ca(V)1.2 channels to distal regions of the dendritic arbor. Furthermore, this Ca2+/CaM-accelerated trafficking was activity dependent. Thus, CaM imparts Ca2+-dependent regulation not only to mature Ca(V)1.2 channels at the cell surface but also to steps during channel biosynthesis.


Assuntos
Canais de Cálcio Tipo L/metabolismo , Cálcio/metabolismo , Calmodulina/fisiologia , Hipocampo/citologia , Neurônios/metabolismo , Animais , Animais Recém-Nascidos , Cálcio/farmacologia , Canais de Cálcio Tipo L/genética , Células Cultivadas , Relação Dose-Resposta a Droga , Proteínas de Fluorescência Verde/biossíntese , Proteínas de Fluorescência Verde/metabolismo , Humanos , Imunoprecipitação/métodos , Modelos Biológicos , Mutação/fisiologia , Neurônios/efeitos dos fármacos , Transporte Proteico/efeitos dos fármacos , Transporte Proteico/fisiologia , Ratos , Ratos Sprague-Dawley , Transfecção
17.
J Gen Physiol ; 149(2): 277-293, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-28087622

RESUMO

Increased "persistent" current, caused by delayed inactivation, through voltage-gated Na+ (NaV) channels leads to cardiac arrhythmias or epilepsy. The underlying molecular contributors to these inactivation defects are poorly understood. Here, we show that calmodulin (CaM) binding to multiple sites within NaV channel intracellular C-terminal domains (CTDs) limits persistent Na+ current and accelerates inactivation across the NaV family. Arrhythmia or epilepsy mutations located in NaV1.5 or NaV1.2 channel CTDs, respectively, reduce CaM binding either directly or by interfering with CTD-CTD interchannel interactions. Boosting the availability of CaM, thus shifting its binding equilibrium, restores wild-type (WT)-like inactivation in mutant NaV1.5 and NaV1.2 channels and likewise diminishes the comparatively large persistent Na+ current through WT NaV1.6, whose CTD displays relatively low CaM affinity. In cerebellar Purkinje neurons, in which NaV1.6 promotes a large physiological persistent Na+ current, increased CaM diminishes the persistent Na+ current, suggesting that the endogenous, comparatively weak affinity of NaV1.6 for apoCaM is important for physiological persistent current.


Assuntos
Arritmias Cardíacas/genética , Calmodulina/metabolismo , Epilepsia/genética , Canais de Sódio Disparados por Voltagem/metabolismo , Sítios de Ligação , Células HEK293 , Humanos , Mutação , Ligação Proteica , Canais de Sódio Disparados por Voltagem/química , Canais de Sódio Disparados por Voltagem/genética
18.
PLoS One ; 11(3): e0152355, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27028743

RESUMO

Drug-induced long-QT syndrome (diLQTS) is often due to drug block of IKr, especially in genetically susceptible patients with subclinical mutations in the IKr-encoding KCHN2. Few variants in the cardiac NaV1.5 Na+ channel complex have been associated with diLQTS. We tested whether a novel SNTA1 (α1-syntrophin) variant (p.E409Q) found in a patient with diLQTS increases late sodium current (INa-L), thereby providing a disease mechanism. Electrophysiological studies were performed in HEK293T cells co-expressing human NaV1.5/nNOS/PMCA4b with either wild type (WT) or SNTA1 variants (A390V-previously reported in congenital LQTS; and E409Q); and in adult rat ventricular cardiomyocytes infected with SNTA1 expressing adenoviruses (WT or one of the two SNTA1 variants). In HEK293T cells and in cardiomyocytes, there was no significant difference in the peak INa densities among the SNTA1 WT and variants. However, both variants increased INa-L (% of peak current) in HEK293T cells (0.58 ± 0.10 in WT vs. 0.90 ± 0.11 in A390V, p = 0.048; vs. 0.88 ± 0.07 in E409Q, p = 0.023). In cardiomyocytes, INa-L was significantly increased by E409Q, but not by A390V compared to WT (0.49 ± 0.14 in WT vs.0.94 ± 0.23 in A390V, p = 0.099; vs. 1.12 ± 0.24 in E409Q, p = 0.019). We demonstrated that a novel SNTA1 variant is likely causative for diLQTS by augmenting INa-L. These data suggest that variants within the NaV1.5-interacting α1-syntrophin are a potential mechanism for diLQTS, thereby expanding the concept that variants within congenital LQTS loci can cause diLQTS.


Assuntos
Proteínas de Ligação ao Cálcio/genética , Síndrome do QT Longo/genética , Proteínas de Membrana/genética , Proteínas Musculares/genética , Adulto , Animais , Estudos de Associação Genética , Predisposição Genética para Doença , Células HEK293 , Humanos , Masculino , Potenciais da Membrana , Mutação de Sentido Incorreto , Miócitos Cardíacos/metabolismo , Ratos Sprague-Dawley , Sódio/metabolismo
19.
J Biomed Opt ; 20(12): 121303, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26220210

RESUMO

Hyperspectral reflectance imaging technique has been used for in vivo detection of cervical intraepithelial neoplasia. However, the clinical outcome of this technique is suboptimal owing to multiple limitations such as nonuniform illumination, high-cost and bulky setup, and time-consuming data acquisition and processing. To overcome these limitations, we acquired the hyperspectral data cube in a wavelength ranging from 600 to 800 nm and processed it by a wide gap second derivative analysis method. This method effectively reduced the image artifacts caused by nonuniform illumination and background absorption. Furthermore, with second derivative analysis, only three specific wavelengths (620, 696, and 772 nm) are needed for tissue classification with optimal separability. Clinical feasibility of the proposed image analysis and classification method was tested in a clinical trial where cervical hyperspectral images from three patients were used for classification analysis. Our proposed method successfully classified the cervix tissue into three categories of normal, inflammation and high-grade lesion. These classification results were coincident with those by an experienced gynecology oncologist after applying acetic acid. Our preliminary clinical study has demonstrated the technical feasibility for in vivo and noninvasive detection of cervical neoplasia without acetic acid. Further clinical research is needed in order to establish a large-scale diagnostic database and optimize the tissue classification technique.


Assuntos
Aumento da Imagem/métodos , Interpretação de Imagem Assistida por Computador/métodos , Microscopia/métodos , Análise Espectral/métodos , Displasia do Colo do Útero/patologia , Neoplasias do Colo do Útero/patologia , Algoritmos , Feminino , Humanos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
20.
Artigo em Inglês | MEDLINE | ID: mdl-26640496

RESUMO

The Feng Gou Zhen (sharp-hook acupuncture) as a traditional form of ancient acupuncture is said to be particularly effective for managing periarthritis of shoulder. We conducted this randomized controlled trial to evaluate the effectiveness of Feng Gou Zhen as an add-on compared to conventional analgesics for patients with PAS. 132 patients were randomly assigned in a 1 : 1 ratio to either a acupuncture group receiving sharp-hook acupuncture plus acupoint injection with conventional analgesics or a control group. Patients from both groups were evaluated at week 0 (baseline), week 1, and week 4. The primary outcome measure was the change from baseline shoulder pain, measured by Visual Analogue Scale at 7 days after treatment. Secondary outcome measures include the (i) function of shoulder joint and (ii) McGill pain questionnaire. The results showed that patients in acupuncture group had better pain relief and function recovery compared with control group (P < 0.05) at 1 week after treatment. Moreover, there were statistical differences between two groups in VAS and shoulder joint function and McGill pain questionnaire at 4 weeks after treatment (P < 0.05). Therefore, the sharp-hook acupuncture helps to relieve the pain and restore the shoulder function for patients with periarthritis of shoulder.

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