1
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Dupont C, Blake B, Voss AA, Rich MM. BK channels promote action potential repolarization in skeletal muscle but contribute little to myotonia. Pflugers Arch 2024:10.1007/s00424-024-03005-z. [PMID: 39150500 DOI: 10.1007/s00424-024-03005-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2024] [Revised: 07/31/2024] [Accepted: 08/06/2024] [Indexed: 08/17/2024]
Abstract
Patients with myotonia congenita suffer from slowed relaxation of muscle (myotonia), due to hyperexcitability caused by loss-of-function mutations in the ClC-1 chloride channel. A recent study suggested that block of large-conductance voltage- and Ca2+- activated K+ channels (BK) may be effective as therapy. The mechanism underlying efficacy was suggested to be lessening of the depolarizing effect of build-up of K+ in t-tubules of muscle during repetitive firing. BK channels are widely expressed in the nervous system and have been shown to play a central role in regulation of excitability, but their contribution to muscle excitability has not been determined. We performed intracellular recordings as well as force measurements in both wild type and BK-/- mouse extensor digitorum longus muscles. Action potential width was increased in BK-/- muscle due to slowing of repolarization, consistent with the possibility K+ build-up in t-tubules is lessened by block of BK channels in myotonic muscle. However, there was no difference in the severity of myotonia triggered by block of muscle Cl- channels with 9-anthracenecarboxylic acid (9AC) in wild type and BK-/- muscle fibers. Further study revealed no difference in the interspike membrane potential during repetitive firing suggesting there was no reduction in K+ build-up in t-tubules of BK-/- muscle. Force recordings following block of muscle Cl- channels demonstrated little reduction in myotonia in BK-/- muscle. In contrast, the current standard of care, mexiletine, significantly reduced myotonia. Our data suggest BK channels regulate muscle excitability, but are not an attractive target for therapy of myotonia.
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Affiliation(s)
- Chris Dupont
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, OH, 45435, USA
| | - Brianna Blake
- Department of Biological Sciences, Wright State University, Dayton, OH, 45435, USA
| | - Andrew A Voss
- Department of Biological Sciences, Wright State University, Dayton, OH, 45435, USA
| | - Mark M Rich
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, OH, 45435, USA.
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2
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Tankisi H, Bostock H, Tan SV, Howells J, Ng K, Z'Graggen WJ. Muscle excitability testing. Clin Neurophysiol 2024; 164:1-18. [PMID: 38805900 DOI: 10.1016/j.clinph.2024.04.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2023] [Revised: 04/22/2024] [Accepted: 04/22/2024] [Indexed: 05/30/2024]
Abstract
Conventional electrophysiological methods, i.e. nerve conduction studies and electromyography are suitable methods for the diagnosis of neuromuscular disorders, however, they provide limited information about muscle fibre membrane properties and underlying disease mechanisms. Muscle excitability testing is a technique that provides in vivo information about muscle fibre membrane properties such as membrane potential and ion channel function. Since the 1960s, various methodologies have been suggested to examine muscle membrane properties but technical difficulties have limited its use. In 2009, an automated, fast and simple application, the so-called multi-fibre muscle velocity recovery cycles (MVRC) has accelerated the use of muscle excitability testing. Later, frequency ramp and repetitive stimulation protocols have been developed. Though this method has been used mainly in research for revealing disease mechanisms across a broad range of neuromuscular disorders, it may have additional diagnostic uses; value has been shown particularly in muscle channelopathies. This review will provide a description of the state-of-the art of methodological and clinical studies for muscle excitability testing.
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Affiliation(s)
- H Tankisi
- Department of Clinical Neurophysiology, Aarhus University Hospital, Aarhus, Denmark; Institute of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark.
| | - H Bostock
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, Queen Square, WC1N 3BG London, United Kingdom
| | - S V Tan
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, Queen Square, WC1N 3BG London, United Kingdom; Department of Neurology and Neurophysiology, Guys and St Thomas' NHS Foundation Trust, London, United Kingdom
| | - J Howells
- Central Clinical School, Faculty of Medicine and Health, University of Sydney, Sydney, Australia
| | - K Ng
- Department of Neurology and Neurophysiology, Royal North Shore Hospital, St Leonards, NSW, Australia; University of Sydney, Camperdown, NSW, Australia
| | - W J Z'Graggen
- Departments Neurology and Neurosurgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
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3
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Gaitán-Peñas H, Pérez-Rius C, Muhaisen A, Castellanos A, Errasti-Murugarren E, Barrallo-Gimeno A, Alcaraz-Pérez F, Estévez R. Characterization of ClC-1 chloride channels in zebrafish: a new model to study myotonia. J Physiol 2024; 602:3975-3994. [PMID: 39031529 DOI: 10.1113/jp286530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Accepted: 07/01/2024] [Indexed: 07/22/2024] Open
Abstract
The function of the chloride channel ClC-1 is crucial for the control of muscle excitability. Thus, reduction of ClC-1 functions by CLCN1 mutations leads to myotonia congenita. Many different animal models have contributed to understanding the myotonia pathophysiology. However, these models do not allow in vivo screening of potentially therapeutic drugs, as the zebrafish model does. In this work, we identified and characterized the two zebrafish orthologues (clc-1a and clc-1b) of the ClC-1 channel. Both channels are mostly expressed in the skeletal muscle as revealed by RT-PCR, western blot, and electrophysiological recordings of myotubes, and clc-1a is predominantly expressed in adult stages. Characterization in Xenopus oocytes shows that the zebrafish channels display similar anion selectivity and voltage dependence to their human counterparts. However, they show reduced sensitivity to the inhibitor 9-anthracenecarboxylic acid (9-AC), and acidic pH inverts the voltage dependence of activation. Reduction of clc-1a/b expression hampers spontaneous and mechanically stimulated movement, which could be reverted by expression of human ClC-1 but not by some ClC-1 containing myotonia mutations. Treatment of clc-1-depleted zebrafish with mexiletine, a typical drug used in human myotonia, improves the motor behaviour. Our work extends the repertoire of ClC channels to evolutionary structure-function studies and proposes the zebrafish clcn1 crispant model as a simple tool to find novel therapies for myotonia. KEY POINTS: We have identified two orthologues of ClC-1 in zebrafish (clc-1a and clc-1b) which are mostly expressed in skeletal muscle at different developmental stages. Functional characterization of the activity of these channels reveals many similitudes with their mammalian counterparts, although they are less sensitive to 9-AC and acidic pH inverts their voltage dependence of gating. Reduction of clc-1a/b expression hampers spontaneous and mechanically stimulated movement which could be reverted by expression of human ClC-1. Myotonia-like symptoms caused by clc-1a/b depletion can be reverted by mexiletine, suggesting that this model could be used to find novel therapies for myotonia.
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Affiliation(s)
- Héctor Gaitán-Peñas
- Physiology Unit, Department of Physiological Sciences, School of Medicine and Health Sciences, Institute of Neurosciences, University of Barcelona-IDIBELL, Barcelona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), ISCIII, Madrid, Spain
| | - Carla Pérez-Rius
- Physiology Unit, Department of Physiological Sciences, School of Medicine and Health Sciences, Institute of Neurosciences, University of Barcelona-IDIBELL, Barcelona, Spain
| | - Ashraf Muhaisen
- Physiology Unit, Department of Physiological Sciences, School of Medicine and Health Sciences, Institute of Neurosciences, University of Barcelona-IDIBELL, Barcelona, Spain
| | - Aida Castellanos
- Physiology Unit, Department of Physiological Sciences, School of Medicine and Health Sciences, Institute of Neurosciences, University of Barcelona-IDIBELL, Barcelona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), ISCIII, Madrid, Spain
| | - Ekaitz Errasti-Murugarren
- Physiology Unit, Department of Physiological Sciences, School of Medicine and Health Sciences, Institute of Neurosciences, University of Barcelona-IDIBELL, Barcelona, Spain
| | - Alejandro Barrallo-Gimeno
- Physiology Unit, Department of Physiological Sciences, School of Medicine and Health Sciences, Institute of Neurosciences, University of Barcelona-IDIBELL, Barcelona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), ISCIII, Madrid, Spain
| | - Francisca Alcaraz-Pérez
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), ISCIII, Madrid, Spain
- Department of Surgery, Telomerase, Cancer and Aging Group (TCAG), Hospital Clínico Universitario Virgen de la Arrixaca, Murcia, Spain
- Instituto Murciano de Investigación Biosanitaria-Arrixaca (IMIB-Arrixaca), Murcia, Spain
| | - Raúl Estévez
- Physiology Unit, Department of Physiological Sciences, School of Medicine and Health Sciences, Institute of Neurosciences, University of Barcelona-IDIBELL, Barcelona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), ISCIII, Madrid, Spain
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Jama A, Alshudukhi AA, Burke S, Dong L, Kamau JK, Morris B, Alkhomsi IA, Finck BN, Voss AA, Ren H. Exploring lipin1 as a promising therapeutic target for the treatment of Duchenne muscular dystrophy. J Transl Med 2024; 22:664. [PMID: 39014470 PMCID: PMC11253568 DOI: 10.1186/s12967-024-05494-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Accepted: 07/10/2024] [Indexed: 07/18/2024] Open
Abstract
BACKGROUND Duchenne muscular dystrophy (DMD) is a progressive and devastating muscle disease, resulting from the absence of dystrophin. This leads to cell membrane instability, susceptibility to contraction-induced muscle damage, subsequent muscle degeneration, and eventually disability and early death of patients. Currently, there is no cure for DMD. Our recent studies identified that lipin1 plays a critical role in maintaining myofiber stability and integrity. However, lipin1 gene expression levels are dramatically reduced in the skeletal muscles of DMD patients and mdx mice. METHODS To identify whether increased lipin1 expression could prevent dystrophic pathology, we employed unique muscle-specific mdx:lipin1 transgenic (mdx:lipin1Tg/0) mice in which lipin1 was restored in the dystrophic muscle of mdx mice, intramuscular gene delivery, as well as cell culture system. RESULTS We found that increased lipin1 expression suppressed muscle degeneration and inflammation, reduced fibrosis, strengthened membrane integrity, and resulted in improved muscle contractile and lengthening force, and muscle performance in mdx:lipin1Tg/0 compared to mdx mice. To confirm the role of lipin1 in dystrophic muscle, we then administered AAV1-lipin1 via intramuscular injection in mdx mice. Consistently, lipin1 restoration inhibited myofiber necroptosis and lessened muscle degeneration. Using a cell culture system, we further found that differentiated primary mdx myoblasts had elevated expression levels of necroptotic markers and medium creatine kinase (CK), which could be a result of sarcolemmal damage. Most importantly, increased lipin1 expression levels in differentiated myoblasts from mdx:lipin1Tg/0 mice substantially inhibited the elevation of necroptotic markers and medium CK levels. CONCLUSIONS Overall, our data suggest that lipin1 is a promising therapeutic target for the treatment of dystrophic muscles.
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Affiliation(s)
- Abdulrahman Jama
- Department of Biochemistry and Molecular Biology, Wright State University, 3640 Colonel Glenn Hwy., Dayton, OH, 45435-0001, USA
| | - Abdullah A Alshudukhi
- Department of Biochemistry and Molecular Biology, Wright State University, 3640 Colonel Glenn Hwy., Dayton, OH, 45435-0001, USA
- Department of Medical Laboratories, College of Applied Medical Sciences, Qassim University, Buraydah, Saudi Arabia
| | - Steve Burke
- Department of Biological Sciences, Wright State University, Dayton, OH, USA
| | - Lixin Dong
- Mumetel LLC, University Technology Park at IIT, Chicago, IL, USA
| | - John Karanja Kamau
- Department of Biochemistry and Molecular Biology, Wright State University, 3640 Colonel Glenn Hwy., Dayton, OH, 45435-0001, USA
| | - Brooklyn Morris
- Department of Biochemistry and Molecular Biology, Wright State University, 3640 Colonel Glenn Hwy., Dayton, OH, 45435-0001, USA
| | - Ibrahim A Alkhomsi
- Department of Biochemistry and Molecular Biology, Wright State University, 3640 Colonel Glenn Hwy., Dayton, OH, 45435-0001, USA
| | - Brian N Finck
- Division of Geriatrics & Nutritional Science, Washington University School of Medicine, St. Louis, USA
| | - Andrew Alvin Voss
- Department of Biological Sciences, Wright State University, Dayton, OH, USA
| | - Hongmei Ren
- Department of Biochemistry and Molecular Biology, Wright State University, 3640 Colonel Glenn Hwy., Dayton, OH, 45435-0001, USA.
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Cisco LA, Sipple MT, Edwards KM, Thornton CA, Lueck JD. Verapamil mitigates chloride and calcium bi-channelopathy in a myotonic dystrophy mouse model. J Clin Invest 2024; 134:e173576. [PMID: 38165038 PMCID: PMC10760957 DOI: 10.1172/jci173576] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 10/23/2023] [Indexed: 01/03/2024] Open
Abstract
Myotonic dystrophy type 1 (DM1) involves misregulated alternative splicing for specific genes. We used exon or nucleotide deletion to mimic altered splicing of genes central to muscle excitation-contraction coupling in mice. Mice with forced skipping of exon 29 in the CaV1.1 calcium channel combined with loss of ClC-1 chloride channel function displayed markedly reduced lifespan, whereas other combinations of splicing mimics did not affect survival. The Ca2+/Cl- bi-channelopathy mice exhibited myotonia, weakness, and impairment of mobility and respiration. Chronic administration of the calcium channel blocker verapamil rescued survival and improved force generation, myotonia, and respiratory function. These results suggest that Ca2+/Cl- bi-channelopathy contributes to muscle impairment in DM1 and is potentially mitigated by common clinically available calcium channel blockers.
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Affiliation(s)
| | | | | | - Charles A. Thornton
- Department of Neurology
- Center for RNA Biology, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA
| | - John D. Lueck
- Department of Pharmacology and Physiology
- Department of Neurology
- Center for RNA Biology, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA
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6
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Cisco LA, Sipple MT, Edwards KM, Thornton CA, Lueck JD. Combinatorial chloride and calcium channelopathy in myotonic dystrophy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.29.542752. [PMID: 37398406 PMCID: PMC10312834 DOI: 10.1101/2023.05.29.542752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Myotonic dystrophy type 1 (DM1) involves misregulated alternative splicing for specific genes. We used exon or nucleotide deletion to mimic altered splicing of genes central to muscle excitation-contraction coupling processes in mice. Mice with forced-skipping of exon 29 in CaV1.1 calcium channel combined with loss of ClC-1 chloride channel function showed a markedly reduced lifespan, whereas other combinations of splicing mimics did not affect survival. The Ca2+/Cl- bi-channelopathy mice exhibited myotonia, weakness, and impairment of mobility and respiration. Chronic administration of the calcium channel blocker verapamil rescued survival and improved force generation, myotonia, and respiratory function. These results suggest that Ca2+/Cl- bi-channelopathy contributes to muscle impairment in DM1 and is potentially mitigated by common clinically available calcium channel blockers.
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Affiliation(s)
- Lily A. Cisco
- Department of Pharmacology and Physiology, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
| | - Matthew T. Sipple
- Department of Pharmacology and Physiology, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
| | - Katherine M. Edwards
- Department of Pharmacology and Physiology, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
| | - Charles A. Thornton
- Department of Neurology, University of Rochester School of Medicine and Dentistry, Rochester, Rochester, NY 14642, USA
- Center for RNA Biology, University of Rochester School of Medicine and Dentistry, Rochester, Rochester, NY 14642, USA
| | - John D. Lueck
- Department of Pharmacology and Physiology, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
- Department of Neurology, University of Rochester School of Medicine and Dentistry, Rochester, Rochester, NY 14642, USA
- Center for RNA Biology, University of Rochester School of Medicine and Dentistry, Rochester, Rochester, NY 14642, USA
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Wang X, Dupont C, Grant D, Voss AA, Rich MM. Plateau potentials contribute to myotonia in mouse models of myotonia congenita. Exp Neurol 2023; 361:114303. [PMID: 36563835 PMCID: PMC9892346 DOI: 10.1016/j.expneurol.2022.114303] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 12/12/2022] [Accepted: 12/17/2022] [Indexed: 12/24/2022]
Abstract
It has long been accepted that myotonia (muscle stiffness) in patients with muscle channelopathies is due to myotonic discharges (involuntary firing of action potentials). In a previous study, we identified a novel phenomenon in myotonic muscle: development of plateau potentials, transient depolarizations to near -35 mV lasting for seconds to minutes. In the current study we examined whether plateau potentials contribute to myotonia. A recessive genetic model (ClCadr mice) with complete loss of muscle chloride channel (ClC-1) function was used to model severe myotonia congenita with complete loss of ClC-1 function and a pharmacologic model using anthracene-9-carboxylic acid (9 AC) was used to model milder myotonia congenita with incomplete loss of ClC-1 function. Simultaneous measurements of action potentials and myoplasmic Ca2+ from individual muscle fibers were compared to recordings of whole muscle force generation. In ClCadr muscle both myotonia and plateau potentials lasted 10s of seconds to minutes. During plateau potentials lasting 1-2 min, there was a gradual transition from high to low intracellular Ca2+, suggesting a transition in individual fibers from myotonia to flaccid paralysis in severe myotonia congenita. In 9 AC-treated muscles, both myotonia and plateau potentials lasted only a few seconds and Ca2+ remained elevated during the plateau potentials, suggesting plateau potentials contribute to myotonia without causing weakness. We propose, that in myotonic muscle, there is a novel state in which there is contraction in the absence of action potentials. This discovery provides a mechanism to explain reports of patients with myotonia who suffer from electrically silent muscle contraction lasting minutes.
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Affiliation(s)
- Xueyong Wang
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, OH 45435, USA
| | - Chris Dupont
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, OH 45435, USA
| | - Delaney Grant
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, OH 45435, USA
| | - Andrew A Voss
- Department of Biology, Wright State University, Dayton, OH 45435, USA
| | - Mark M Rich
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, OH 45435, USA.
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8
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Jama A, Alshudukhi AA, Burke S, Dong L, Kamau JK, Voss AA, Ren H. Lipin1 plays complementary roles in myofibre stability and regeneration in dystrophic muscles. J Physiol 2023; 601:961-978. [PMID: 36715084 PMCID: PMC9992338 DOI: 10.1113/jp284085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 01/23/2023] [Indexed: 01/31/2023] Open
Abstract
Duchenne muscular dystrophy (DMD) is a severe muscle wasting disorder caused by dystrophin mutations, leading to the loss of sarcolemmal integrity, and resulting in progressive myofibre necrosis and impaired muscle function. Our previous studies suggest that lipin1 is important for skeletal muscle regeneration and myofibre integrity. Additionally, we discovered that mRNA expression levels of lipin1 were significantly reduced in skeletal muscle of DMD patients and the mdx mouse model. To understand the role of lipin1 in dystrophic muscle, we generated dystrophin/lipin1 double knockout (DKO) mice, and compared the limb muscle pathology and function of wild-type B10, muscle-specific lipin1 deficient (lipin1Myf5cKO ), mdx and DKO mice. We found that further knockout of lipin1 in dystrophic muscle exhibited a more severe phenotype characterized by increased necroptosis, fibrosis and exacerbated membrane damage in DKO compared to mdx mice. In barium chloride-induced muscle injury, both lipin1Myf5cKO and DKO showed prolonged regeneration at day 14 post-injection, suggesting that lipin1 is critical for muscle regeneration. In situ contractile function assays showed that lipin1 deficiency in dystrophic muscle led to reduced specific force production. Using a cell culture system, we found that lipin1 deficiency led to elevated expression levels of necroptotic markers and medium creatine kinase, which could be a result of sarcolemmal damage. Most importantly, restoration of lipin1 inhibited the elevation of necroptotic markers in differentiated primary lipin1-deficient myoblasts. Overall, our data suggests that lipin1 plays complementary roles in myofibre stability and muscle function in dystrophic muscles, and overexpression of lipin1 may serve as a potential therapeutic strategy for dystrophic muscles. KEY POINTS: We identified that lipin1 mRNA expression levels are significantly reduced in skeletal muscles of Duchenne muscular dystrophy patients and mdx mice. We found that further depletion of lipin1 in skeletal muscles of mdx mice induces more severe dystrophic phenotypes, including enhanced myofibre sarcolemma damage, muscle necroptosis, inflammation, fibrosis and reduced specific force production. Lipin1 deficiency leads to elevated expression levels of necroptotic markers, whereas restoration of lipin1 inhibits their expression. Our results suggest that lipin1 is functionally complementary to dystrophin in muscle membrane integrity and muscle regeneration.
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Affiliation(s)
- Abdulrahman Jama
- Department of Biochemistry and Molecular Biology, Wright State University, Dayton, OH, USA
| | - Abdullah A. Alshudukhi
- Department of Biochemistry and Molecular Biology, Wright State University, Dayton, OH, USA
| | - Steve Burke
- Department of Biological Sciences, Wright State University, Dayton, OH, USA
| | - Lixin Dong
- Mumetel LLC, University Technology Park at IIT, Chicago, IL, USA
| | - John Karanja Kamau
- Department of Biochemistry and Molecular Biology, Wright State University, Dayton, OH, USA
| | - Andrew Alvin Voss
- Department of Biological Sciences, Wright State University, Dayton, OH, USA
| | - Hongmei Ren
- Department of Biochemistry and Molecular Biology, Wright State University, Dayton, OH, USA
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9
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Ranolazine: An Old Drug with Emerging Potential; Lessons from Pre-Clinical and Clinical Investigations for Possible Repositioning. Pharmaceuticals (Basel) 2021; 15:ph15010031. [PMID: 35056088 PMCID: PMC8777683 DOI: 10.3390/ph15010031] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 12/16/2021] [Accepted: 12/20/2021] [Indexed: 02/07/2023] Open
Abstract
Ischemic heart disease is a significant public health problem with high mortality and morbidity. Extensive scientific investigations from basic sciences to clinics revealed multilevel alterations from metabolic imbalance, altered electrophysiology, and defective Ca2+/Na+ homeostasis leading to lethal arrhythmias. Despite the recent identification of numerous molecular targets with potential therapeutic interest, a pragmatic observation on the current pharmacological R&D output confirms the lack of new therapeutic offers to patients. By contrast, from recent trials, molecules initially developed for other fields of application have shown cardiovascular benefits, as illustrated with some anti-diabetic agents, regardless of the presence or absence of diabetes, emphasizing the clear advantage of “old” drug repositioning. Ranolazine is approved as an antianginal agent and has a favorable overall safety profile. This drug, developed initially as a metabolic modulator, was also identified as an inhibitor of the cardiac late Na+ current, although it also blocks other ionic currents, including the hERG/Ikr K+ current. The latter actions have been involved in this drug’s antiarrhythmic effects, both on supraventricular and ventricular arrhythmias (VA). However, despite initial enthusiasm and promising development in the cardiovascular field, ranolazine is only authorized as a second-line treatment in patients with chronic angina pectoris, notwithstanding its antiarrhythmic properties. A plausible reason for this is the apparent difficulty in linking the clinical benefits to the multiple molecular actions of this drug. Here, we review ranolazine’s experimental and clinical knowledge on cardiac metabolism and arrhythmias. We also highlight advances in understanding novel effects on neurons, the vascular system, skeletal muscles, blood sugar control, and cancer, which may open the way to reposition this “old” drug alone or in combination with other medications.
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10
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Maggi L, Bonanno S, Altamura C, Desaphy JF. Ion Channel Gene Mutations Causing Skeletal Muscle Disorders: Pathomechanisms and Opportunities for Therapy. Cells 2021; 10:cells10061521. [PMID: 34208776 PMCID: PMC8234207 DOI: 10.3390/cells10061521] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 06/03/2021] [Accepted: 06/10/2021] [Indexed: 02/06/2023] Open
Abstract
Skeletal muscle ion channelopathies (SMICs) are a large heterogeneous group of rare genetic disorders caused by mutations in genes encoding ion channel subunits in the skeletal muscle mainly characterized by myotonia or periodic paralysis, potentially resulting in long-term disabilities. However, with the development of new molecular technologies, new genes and new phenotypes, including progressive myopathies, have been recently discovered, markedly increasing the complexity in the field. In this regard, new advances in SMICs show a less conventional role of ion channels in muscle cell division, proliferation, differentiation, and survival. Hence, SMICs represent an expanding and exciting field. Here, we review current knowledge of SMICs, with a description of their clinical phenotypes, cellular and molecular pathomechanisms, and available treatments.
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Affiliation(s)
- Lorenzo Maggi
- Neuroimmunology and Neuromuscular Disorders Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133 Milan, Italy;
- Correspondence:
| | - Silvia Bonanno
- Neuroimmunology and Neuromuscular Disorders Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133 Milan, Italy;
| | - Concetta Altamura
- Department of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari Aldo Moro, 70124 Bari, Italy; (C.A.); (J.-F.D.)
| | - Jean-François Desaphy
- Department of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari Aldo Moro, 70124 Bari, Italy; (C.A.); (J.-F.D.)
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