The Experts below are selected from a list of 63 Experts worldwide ranked by ideXlab platform
Charles A Thornton - One of the best experts on this subject based on the ideXlab platform.
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correction of clc 1 splicing eliminates Chloride Channelopathy and myotonia in mouse models of myotonic dystrophy
Journal of Clinical Investigation, 2007Co-Authors: Thurman M Wheeler, John D Lueck, Maurice S Swanson, Robert T Dirksen, Charles A ThorntonAbstract:In myotonic dystrophy (dystrophia myotonica [DM]), an increase in the excitability of skeletal muscle leads to repetitive action potentials, stiffness, and delayed relaxation. This constellation of features, collectively known as myotonia, is associated with abnormal alternative splicing of the muscle-specific Chloride channel (ClC-1) and reduced conductance of Chloride ions in the sarcolemma. However, the mechanistic basis of the Chloride Channelopathy and its relationship to the development of myotonia are uncertain. Here we show that a morpholino antisense oligonucleotide (AON) targeting the 3′ splice site of ClC-1 exon 7a reversed the defect of ClC-1 alternative splicing in 2 mouse models of DM. By repressing the inclusion of this exon, the AON restored the full-length reading frame in ClC-1 mRNA, upregulated the level of ClC-1 mRNA, increased the expression of ClC-1 protein in the surface membrane, normalized muscle ClC-1 current density and deactivation kinetics, and eliminated myotonic discharges. These observations indicate that the myotonia and Chloride Channelopathy observed in DM both result from abnormal alternative splicing of ClC-1 and that antisense-induced exon skipping offers a powerful method for correcting alternative splicing defects in DM.
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Chloride Channelopathy in myotonic dystrophy resulting from loss of posttranscriptional regulation for clcn1
American Journal of Physiology-cell Physiology, 2007Co-Authors: John D Lueck, Robert T Dirksen, Codrin Lungu, Ami Mankodi, Robert J Osborne, Stephen Welle, Charles A ThorntonAbstract:Transmembrane Chloride ion conductance in skeletal muscle increases during early postnatal development. A transgenic mouse model of myotonic dystrophy type 1 (DM1) displays decreased sarcolemmal Chloride conductance. Both effects result from modulation of Chloride channel 1 (CLCN1) expression, but the respective contributions of transcriptional vs. posttranscriptional regulation are unknown. Here we show that alternative splicing of CLCN1 undergoes a physiological splicing transition during the first 3 wk of postnatal life in mice. During this interval, there is a switch to production of CLCN1 splice products having an intact reading frame, an upregulation of CLCN1 mRNA encoding full-length channel protein, and an increase of CLCN1 function, as determined by patch-clamp analysis of single muscle fibers. In a transgenic mouse model of DM1, however, the splicing transition does not occur, CLCN1 channel function remains low throughout the postnatal interval, and muscle fibers display myotonic discharges. Thus alternative splicing is a posttranscriptional mechanism regulating Chloride conductance during muscle development, and the Chloride Channelopathy in a transgenic mouse model of DM1 results from a failure to execute a splicing transition for CLCN1.
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Chloride Channelopathy in myotonic dystrophy resulting from loss of posttranscriptional regulation for CLCN1
American Journal of Physiology-cell Physiology, 2006Co-Authors: John D Lueck, Robert T Dirksen, Codrin Lungu, Ami Mankodi, Robert J Osborne, Stephen Welle, Charles A ThorntonAbstract:Transmembrane Chloride ion conductance in skeletal muscle increases during early postnatal development. A transgenic mouse model of myotonic dystrophy type 1 (DM1) displays decreased sarcolemmal ch...
Thomas A Cooper - One of the best experts on this subject based on the ideXlab platform.
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regulation of Chloride ion conductance during skeletal muscle development and in disease focus on Chloride Channelopathy in myotonic dystrophy resulting from loss of posttranscriptional regulation for clcn1
American Journal of Physiology-cell Physiology, 2007Co-Authors: Thomas A CooperAbstract:productive investigations of disease mechanisms that also reveal new information about normal regulation elicit a particularly satisfying sense of a two-for-one deal. In the case of Lueck et al. (Ref. [13][1]; see page 1291 of this issue), a detailed study of the molecular basis for the myotonia (
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Regulation of Chloride ion conductance during skeletal muscle development and in disease. Focus on “Chloride Channelopathy in myotonic dystrophy resulting from loss of posttranscriptional regulation for CLCN1”
American Journal of Physiology-cell Physiology, 2007Co-Authors: Thomas A CooperAbstract:productive investigations of disease mechanisms that also reveal new information about normal regulation elicit a particularly satisfying sense of a two-for-one deal. In the case of Lueck et al. (Ref. [13][1]; see page 1291 of this issue), a detailed study of the molecular basis for the myotonia (
John D Lueck - One of the best experts on this subject based on the ideXlab platform.
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correction of clc 1 splicing eliminates Chloride Channelopathy and myotonia in mouse models of myotonic dystrophy
Journal of Clinical Investigation, 2007Co-Authors: Thurman M Wheeler, John D Lueck, Maurice S Swanson, Robert T Dirksen, Charles A ThorntonAbstract:In myotonic dystrophy (dystrophia myotonica [DM]), an increase in the excitability of skeletal muscle leads to repetitive action potentials, stiffness, and delayed relaxation. This constellation of features, collectively known as myotonia, is associated with abnormal alternative splicing of the muscle-specific Chloride channel (ClC-1) and reduced conductance of Chloride ions in the sarcolemma. However, the mechanistic basis of the Chloride Channelopathy and its relationship to the development of myotonia are uncertain. Here we show that a morpholino antisense oligonucleotide (AON) targeting the 3′ splice site of ClC-1 exon 7a reversed the defect of ClC-1 alternative splicing in 2 mouse models of DM. By repressing the inclusion of this exon, the AON restored the full-length reading frame in ClC-1 mRNA, upregulated the level of ClC-1 mRNA, increased the expression of ClC-1 protein in the surface membrane, normalized muscle ClC-1 current density and deactivation kinetics, and eliminated myotonic discharges. These observations indicate that the myotonia and Chloride Channelopathy observed in DM both result from abnormal alternative splicing of ClC-1 and that antisense-induced exon skipping offers a powerful method for correcting alternative splicing defects in DM.
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Chloride Channelopathy in myotonic dystrophy resulting from loss of posttranscriptional regulation for clcn1
American Journal of Physiology-cell Physiology, 2007Co-Authors: John D Lueck, Robert T Dirksen, Codrin Lungu, Ami Mankodi, Robert J Osborne, Stephen Welle, Charles A ThorntonAbstract:Transmembrane Chloride ion conductance in skeletal muscle increases during early postnatal development. A transgenic mouse model of myotonic dystrophy type 1 (DM1) displays decreased sarcolemmal Chloride conductance. Both effects result from modulation of Chloride channel 1 (CLCN1) expression, but the respective contributions of transcriptional vs. posttranscriptional regulation are unknown. Here we show that alternative splicing of CLCN1 undergoes a physiological splicing transition during the first 3 wk of postnatal life in mice. During this interval, there is a switch to production of CLCN1 splice products having an intact reading frame, an upregulation of CLCN1 mRNA encoding full-length channel protein, and an increase of CLCN1 function, as determined by patch-clamp analysis of single muscle fibers. In a transgenic mouse model of DM1, however, the splicing transition does not occur, CLCN1 channel function remains low throughout the postnatal interval, and muscle fibers display myotonic discharges. Thus alternative splicing is a posttranscriptional mechanism regulating Chloride conductance during muscle development, and the Chloride Channelopathy in a transgenic mouse model of DM1 results from a failure to execute a splicing transition for CLCN1.
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Chloride Channelopathy in myotonic dystrophy resulting from loss of posttranscriptional regulation for CLCN1
American Journal of Physiology-cell Physiology, 2006Co-Authors: John D Lueck, Robert T Dirksen, Codrin Lungu, Ami Mankodi, Robert J Osborne, Stephen Welle, Charles A ThorntonAbstract:Transmembrane Chloride ion conductance in skeletal muscle increases during early postnatal development. A transgenic mouse model of myotonic dystrophy type 1 (DM1) displays decreased sarcolemmal ch...
Robert T Dirksen - One of the best experts on this subject based on the ideXlab platform.
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correction of clc 1 splicing eliminates Chloride Channelopathy and myotonia in mouse models of myotonic dystrophy
Journal of Clinical Investigation, 2007Co-Authors: Thurman M Wheeler, John D Lueck, Maurice S Swanson, Robert T Dirksen, Charles A ThorntonAbstract:In myotonic dystrophy (dystrophia myotonica [DM]), an increase in the excitability of skeletal muscle leads to repetitive action potentials, stiffness, and delayed relaxation. This constellation of features, collectively known as myotonia, is associated with abnormal alternative splicing of the muscle-specific Chloride channel (ClC-1) and reduced conductance of Chloride ions in the sarcolemma. However, the mechanistic basis of the Chloride Channelopathy and its relationship to the development of myotonia are uncertain. Here we show that a morpholino antisense oligonucleotide (AON) targeting the 3′ splice site of ClC-1 exon 7a reversed the defect of ClC-1 alternative splicing in 2 mouse models of DM. By repressing the inclusion of this exon, the AON restored the full-length reading frame in ClC-1 mRNA, upregulated the level of ClC-1 mRNA, increased the expression of ClC-1 protein in the surface membrane, normalized muscle ClC-1 current density and deactivation kinetics, and eliminated myotonic discharges. These observations indicate that the myotonia and Chloride Channelopathy observed in DM both result from abnormal alternative splicing of ClC-1 and that antisense-induced exon skipping offers a powerful method for correcting alternative splicing defects in DM.
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Chloride Channelopathy in myotonic dystrophy resulting from loss of posttranscriptional regulation for clcn1
American Journal of Physiology-cell Physiology, 2007Co-Authors: John D Lueck, Robert T Dirksen, Codrin Lungu, Ami Mankodi, Robert J Osborne, Stephen Welle, Charles A ThorntonAbstract:Transmembrane Chloride ion conductance in skeletal muscle increases during early postnatal development. A transgenic mouse model of myotonic dystrophy type 1 (DM1) displays decreased sarcolemmal Chloride conductance. Both effects result from modulation of Chloride channel 1 (CLCN1) expression, but the respective contributions of transcriptional vs. posttranscriptional regulation are unknown. Here we show that alternative splicing of CLCN1 undergoes a physiological splicing transition during the first 3 wk of postnatal life in mice. During this interval, there is a switch to production of CLCN1 splice products having an intact reading frame, an upregulation of CLCN1 mRNA encoding full-length channel protein, and an increase of CLCN1 function, as determined by patch-clamp analysis of single muscle fibers. In a transgenic mouse model of DM1, however, the splicing transition does not occur, CLCN1 channel function remains low throughout the postnatal interval, and muscle fibers display myotonic discharges. Thus alternative splicing is a posttranscriptional mechanism regulating Chloride conductance during muscle development, and the Chloride Channelopathy in a transgenic mouse model of DM1 results from a failure to execute a splicing transition for CLCN1.
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Chloride Channelopathy in myotonic dystrophy resulting from loss of posttranscriptional regulation for CLCN1
American Journal of Physiology-cell Physiology, 2006Co-Authors: John D Lueck, Robert T Dirksen, Codrin Lungu, Ami Mankodi, Robert J Osborne, Stephen Welle, Charles A ThorntonAbstract:Transmembrane Chloride ion conductance in skeletal muscle increases during early postnatal development. A transgenic mouse model of myotonic dystrophy type 1 (DM1) displays decreased sarcolemmal ch...
Julio L Vergara - One of the best experts on this subject based on the ideXlab platform.
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the Chloride Channelopathy in knockout mice of muscleblind like proteins
Biophysical Journal, 2013Co-Authors: Carl Yu, Marino Difranco, Sita Reddy, Warunee Dansithong, Julio L VergaraAbstract:Myotonic dystrophy (DM) is the most prevalent human dystrophy; it results from a spliceopathy in which muscleblind-like (MBNL) regulatory proteins are sequestered by expanded CUG triplet repeats. In order to investigate the specific role that MBNL proteins play on the functional expression of Chloride (ClC-1) channels, we studied the Chloride currents (ICl) in fibers isolated from FDB muscles of adult knockout (KO) mice lacking MBNL1, MBNL3, or both (MBNL1/3 DKO). ICl were recorded in fibers voltage clamped with 2 microelectrodes, internally equilibrated with 70 mM intracellular Chloride, and bathed in TEA-Cl solution. We found that ICl records in fibers from the three knockout strains display kinetic and voltage-dependent properties comparable to those in control fibers (129SV mice). However, the maximal peak ICl (peak-IClmax), and the maximal conductance calculated from them (gClmax), varied markedly among strains. Both peak-IClmax and gClmax are significantly smaller (∼34%, p<005) in fibers of adult MBNL1 KO mice, than in those of the controls. The persistently impaired functional expression of ClC-1 channels contrasts with the transient Chloride Channelopathy of the HSALR model of DM. Furthermore, while ICl records in fibers of MBNL3 KO mice are identical to those from their control counterparts, peak-IClmax in fibers of MBNL1/3 DKO mice show more severe reductions (∼50%, p<005) than those of MBNL1 KO. These interesting results suggest novel synergistic regulatory interactions between MBNL proteins which ultimately affect the functional expression of ClC-1 channels. This work was supported by NIH grants AR047664, AR041802, and AR054816. Precursors of MBNL1 mice were kindly provided by Dr. M. Swanson, University of Florida.
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The Chloride Channelopathy in Knockout Mice of Muscleblind-Like Proteins
Biophysical Journal, 2013Co-Authors: Carl Yu, Marino Difranco, Sita Reddy, Warunee Dansithong, Julio L VergaraAbstract:Myotonic dystrophy (DM) is the most prevalent human dystrophy; it results from a spliceopathy in which muscleblind-like (MBNL) regulatory proteins are sequestered by expanded CUG triplet repeats. In order to investigate the specific role that MBNL proteins play on the functional expression of Chloride (ClC-1) channels, we studied the Chloride currents (ICl) in fibers isolated from FDB muscles of adult knockout (KO) mice lacking MBNL1, MBNL3, or both (MBNL1/3 DKO). ICl were recorded in fibers voltage clamped with 2 microelectrodes, internally equilibrated with 70 mM intracellular Chloride, and bathed in TEA-Cl solution. We found that ICl records in fibers from the three knockout strains display kinetic and voltage-dependent properties comparable to those in control fibers (129SV mice). However, the maximal peak ICl (peak-IClmax), and the maximal conductance calculated from them (gClmax), varied markedly among strains. Both peak-IClmax and gClmax are significantly smaller (∼34%, p
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Age‐dependent Chloride channel expression in skeletal muscle fibres of normal and HSALR myotonic mice
The Journal of Physiology, 2012Co-Authors: Marino Difranco, Carl Yu, Marbella Quinonez, Julio L VergaraAbstract:Key points • The role that the age-dependent expression of Chloride channels (ClC-1) plays on the electrical properties of muscle fibres from normal and human skeletal actin (HSA)LR mice (a model of myotonic dystrophy) was studied using a combination of electrophysiological and optical techniques. • Chloride currents (ICl) are significantly smaller in fibres isolated from young (2 weeks old) HSALR mice than from aged-matched control mice, but become statistically undistinguishable in adult (17 weeks old) mice. Thus, the severe ClC-1 Channelopathy in young HSALR animals slowly reverses with aging. • The maximal Chloride conductance (gCl,max) is uniformly depressed in fibres of young HSALR mice, but fibres from older animals show a wide range of gCl,max values suggestive of a mosaic expression of ClC-1 channels in FDB muscles of these animals. • Regardless of the age of the animals, the Chloride Channelopathy does not affect the normal expression of ClC-1 channels at the sarcolemma and transverse tubular system membranes. • The membrane resistance (Rm) is lower than expected in young HSALR animals due to an upregulation of an Rb-sensitive K conductance. In adult animals, differences in Rm are negligible between fibres of both animal strains. • It is proposed that, while the hyperexcitability in young HSALR mice can be accounted for by the reduction in gCl,max, a mosaic expression of ClC-1 channels and/or alterations of other conductances may be the underlying causes in adult animals. Abstract We combine electrophysiological and optical techniques to investigate the role that the expression of Chloride channels (ClC-1) plays on the age-dependent electrical properties of mammalian muscle fibres. To this end, we comparatively evaluate the magnitude and voltage dependence of Chloride currents (ICl), as well as the resting resistance, in fibres isolated from control and human skeletal actin (HSA)LR mice (a model of myotonic dystrophy) of various ages. In control mice, the maximal peak Chloride current ([peak-ICl]max) increases from −583 ± 126 to −956 ± 260 μA cm−2 (mean ± SD) between 3 and 6 weeks old. Instead, in 3-week-old HSALR mice, ICl are significantly smaller (−153 ± 33 μA cm−2) than in control mice, but after a long period of ∼14 weeks they reach statistically comparable values. Thus, the severe ClC-1 Channelopathy in young HSALR animals is slowly reversed with aging. Frequency histograms of the maximal Chloride conductance (gCl,max) in fibres of young HSALR animals are narrow and centred in low values; alternatively, those from older animals show broad distributions, centred at larger gCl,max values, compatible with mosaic expressions of ClC-1 channels. In fibres of both animal strains, optical data confirm the age-dependent increase in gCl, and additionally suggest that ClC-1 channels are evenly distributed between the sarcolemma and transverse tubular system membranes. Although gCl is significantly depressed in fibres of young HSALR mice, the resting membrane resistance (Rm) at −90 mV is only slightly larger than in control mice due to upregulation of a Rb-sensitive resting conductance (gK,IR). In adult animals, differences in Rm are negligible between fibres of both strains, and the contributions of gCl and gK,IR are less altered in HSALR animals. We surmise that while hyperexcitability in young HSALR mice can be readily explained on the basis of reduced gCl, myotonia in adult HSALR animals may be explained on the basis of a mosaic expression of ClC-1 channels in different fibres and/or on alterations of other conductances.