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Kötter S, Krüger M. Protein Quality Control at the Sarcomere: Titin Protection and Turnover and Implications for Disease Development. Front Physiol 2022; 13:914296. [PMID: 35846001 PMCID: PMC9281568 DOI: 10.3389/fphys.2022.914296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 06/10/2022] [Indexed: 11/26/2022] Open
Abstract
Sarcomeres are mainly composed of filament and signaling proteins and are the smallest molecular units of muscle contraction and relaxation. The sarcomere protein titin serves as a molecular spring whose stiffness mediates myofilament extensibility in skeletal and cardiac muscle. Due to the enormous size of titin and its tight integration into the sarcomere, the incorporation and degradation of the titin filament is a highly complex task. The details of the molecular processes involved in titin turnover are not fully understood, but the involvement of different intracellular degradation mechanisms has recently been described. This review summarizes the current state of research with particular emphasis on the relationship between titin and protein quality control. We highlight the involvement of the proteasome, autophagy, heat shock proteins, and proteases in the protection and degradation of titin in heart and skeletal muscle. Because the fine-tuned balance of degradation and protein expression can be disrupted under pathological conditions, the review also provides an overview of previously known perturbations in protein quality control and discusses how these affect sarcomeric proteins, and titin in particular, in various disease states.
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2
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Shi H, Verma M, Zhang L, Dong C, Flavell RA, Bennett AM. Improved regenerative myogenesis and muscular dystrophy in mice lacking Mkp5. J Clin Invest 2013; 123:2064-77. [PMID: 23543058 DOI: 10.1172/jci64375] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Accepted: 01/31/2013] [Indexed: 12/15/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) is a degenerative skeletal muscle disease caused by mutations in dystrophin. The degree of functional deterioration in muscle stem cells determines the severity of DMD. The mitogen-activated protein kinases (MAPKs), which are inactivated by MAPK phosphatases (MKPs), represent a central signaling node in the regulation of muscle stem cell function. Here we show that the dual-specificity protein phosphatase DUSP10/MKP-5 negatively regulates muscle stem cell function in mice. MKP-5 controlled JNK to coordinate muscle stem cell proliferation and p38 MAPK to control differentiation. Genetic loss of Mkp5 in mice improved regenerative myogenesis and dystrophin-deficient mdx mice lacking Mkp5 exhibited an attenuated dystrophic muscle phenotype. Hence, enhanced promyogenic MAPK activity preserved muscle stem cell function even in the absence of dystrophin and ultimately curtailed the pathogenesis associated with DMD. These results identify MKP-5 as an essential negative regulator of the promyogenic actions of the MAPKs and suggest that MKP-5 may serve as a target to promote muscle stem cell function in the treatment of degenerative skeletal muscle diseases.
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Affiliation(s)
- Hao Shi
- Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06520-8066, USA
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3
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Hayat Nosaeid M, Mahdian R, Jamali S, Maryami F, Babashah S, Maryami F, Karimipoor M, Zeinali S. Validation and comparison of two quantitative real-time PCR assays for direct detection of DMD/BMD carriers. Clin Biochem 2009; 42:1291-9. [DOI: 10.1016/j.clinbiochem.2009.04.016] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2009] [Revised: 04/12/2009] [Accepted: 04/24/2009] [Indexed: 10/20/2022]
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4
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Jaramillo MS, Lovato CV, Baca EM, Cripps RM. Crossveinless and the TGFbeta pathway regulate fiber number in the Drosophila adult jump muscle. Development 2009; 136:1105-13. [PMID: 19244280 DOI: 10.1242/dev.031567] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Skeletal muscles are readily characterized by their location within the body and by the number and composition of their constituent muscle fibers. Here, we characterize a mutation that causes a severe reduction in the number of fibers comprising the tergal depressor of the trochanter muscle (TDT, or jump muscle), which functions in the escape response of the Drosophila adult. The wild-type TDT comprises over 20 large muscle fibers and four small fibers. In crossveinless (cv) mutants, the number of large fibers is reduced by 50%, and the number of small fibers is also occasionally reduced. This reduction in fiber number arises from a reduction in the number of founder cells contributing to the TDT at the early pupal stage. Given the role of cv in TGFbeta signaling, we determined whether this pathway directly impacts TDT development. Indeed, gain- and loss-of-function manipulations in the TGFbeta pathway resulted in dramatic increases and decreases, respectively, in TDT fiber number. By identifying the origins of the TDT muscle, from founder cells specified in the mesothoracic leg imaginal disc, we also demonstrate that the TGFbeta pathway directly impacts the specification of founder cells for the jump muscle. Our studies define a new role for the TGFbeta pathway in the control of specific skeletal muscle characteristics.
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5
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Bae JS, Ki CS, Kim JW, Suh YL, Park MS, Kim BJ, Kim SJ. A novel in-frame deletion in the CAV3 gene in a Korean patient with rippling muscle disease. J Neurol Sci 2007; 260:275-8. [PMID: 17524427 DOI: 10.1016/j.jns.2007.04.023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2007] [Revised: 03/30/2007] [Accepted: 04/17/2007] [Indexed: 10/23/2022]
Abstract
Rippling muscle disease (RMD) is a rare form of myopathy that is characterized by percussion-induced rapid muscle contractions, muscle mounding, and rippling. Recently a caveolin-3 gene (CAV3) mutation was identified in patients suffering from autosomal dominant RMD. We encountered a Korean male patient with RMD who had suffered from muscle stiffness for 3 years. Mutation analysis of the CAV3 gene revealed the patient to be heterozygous for a novel in-frame deletion mutation (c.307_312delGTGGTG; Phe103_Phe104del). Further analysis of his family members showed that his mother and elder sister also have the same mutation. To the best of our knowledge, this is the first report of genetically confirmed RMD in Korea.
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Affiliation(s)
- Jong Seok Bae
- Department of Neurology, Inje University, College of Medicine, Busan, Republic of Korea
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6
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Current understanding of dystrophin-related muscular dystrophy and therapeutic challenges ahead. Chin Med J (Engl) 2006. [DOI: 10.1097/00029330-200608020-00011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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7
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Affiliation(s)
- Jeffrey A Towbin
- Department of Pediatrics (Cardiology), Baylor College of Medicine, Texas Children's Hospital, Houston, TX 77030, USA.
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8
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Roberts HL, Day B, Lo H, McLean C, North K. Rippling muscle disease. J Clin Neurosci 2006; 13:576-8. [PMID: 16723230 DOI: 10.1016/j.jocn.2005.06.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2005] [Accepted: 06/23/2005] [Indexed: 11/29/2022]
Abstract
A case of rippling muscle disease is presented and features of this rare condition, and its association with caveolin-3 are discussed.
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Affiliation(s)
- Helene L Roberts
- Department of Medicine (Neurosciences), Alfred Hospital, Monash University, P.O. Box 315, Prahran, Victoria 3181, Australia.
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9
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Silva WI, Maldonado HM, Velázquez G, Rubio-Dávila M, Miranda JD, Aquino E, Mayol N, Cruz-Torres A, Jardón J, Salgado-Villanueva IK. Caveolin isoform expression during differentiation of C6 glioma cells. Int J Dev Neurosci 2005; 23:599-612. [PMID: 16135403 DOI: 10.1016/j.ijdevneu.2005.07.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2005] [Revised: 07/18/2005] [Accepted: 07/19/2005] [Indexed: 12/01/2022] Open
Abstract
Caveolae, a specialized form of lipid rafts, are cholesterol- and sphingolipid-rich membrane microdomains implicated in potocytosis, endocytosis, transcytosis, and as platforms for signal transduction. One of the major constituents of caveolae are three highly homologous caveolin isoforms (caveolin-1, caveolin-2, and caveolin-3). The present study expands the analysis of caveolin isoform expression in C6 glioma cells. Three complementary approaches were used to assess their differential expression during the dibutyryl-cyclic AMP-induced differentiation of C6 cells into an astrocyte-like phenotype. Immunoblotting, conventional RT-PCR, and real-time RT-PCR analysis established the expression of the caveolin-3 isoform in C6 cells, in addition to caveolin-1 and caveolin-2. Similar to the other isoforms, caveolin-3 was associated with light-density, detergent-insoluble caveolae membrane fractions obtained using sucrose-density gradient centrifugation. The three caveolin isoforms display different temporal patterns of mRNA/protein expression during the differentiation of C6 cells. Western blot and real-time RT-PCR analysis demonstrate that caveolin-1 and caveolin-2 are up-regulated during the late stages of the differentiation of C6 cells. Meanwhile, caveolin-3 is gradually down-regulated during the differentiation process. Indirect immunofluorescence analysis via laser-scanning confocal microscopy reveals that the three caveolin isoforms display similar subcellular distribution patterns. In addition, co-localization of caveolin-1/caveolin-2 and caveolin-1/caveolin-3 was detected in both C6 glioma phenotypes. The findings reveal a differential temporal pattern of caveolin gene expression during phenotypic differentiation of C6 glioma cells, with potential implications to developmental and degenerative events in the brain.
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Affiliation(s)
- W I Silva
- Department of Physiology, School of Medicine, University of Puerto Rico, Medical Sciences Campus, P.O. Box 365067, San Juan, PR.
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10
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Huebsch KA, Kudryashova E, Wooley CM, Sher RB, Seburn KL, Spencer MJ, Cox GA. Mdm muscular dystrophy: interactions with calpain 3 and a novel functional role for titin's N2A domain. Hum Mol Genet 2005; 14:2801-11. [PMID: 16115818 PMCID: PMC1350399 DOI: 10.1093/hmg/ddi313] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Human tibial muscular dystrophy and limb-girdle muscular dystrophy 2J are caused by mutations in the giant sarcomeric protein titin (TTN) adjacent to a binding site for the muscle-specific protease calpain 3 (CAPN3). Muscular dystrophy with myositis (mdm) is a recessive mouse mutation with severe and progressive muscular degeneration caused by a deletion in the N2A domain of titin (TTN-N2ADelta83), disrupting a putative binding site for CAPN3. To determine whether the muscular dystrophy in mutant mdm mice is caused by misregulation of CAPN3 activity, genetic crosses with CAPN3 overexpressing transgenic (C3Tg) and CAPN3 knockout (C3KO) mice were generated. Here, we report that overexpression of CAPN3 exacerbates the mdm disease, leading to a shorter life span and more severe muscular dystrophy. However, in a direct genetic test of CAPN3's role as a mediator of mdm pathology, C3KO;mdm double mutant mice showed no change in the progression or severity of disease indicating that aberrant CAPN3 activity is not a primary mechanism in this disease. To determine whether we could detect a functional deficit in titin in a non-disease state, we examined the treadmill locomotion of heterozygous +/mdm mice and detected a significant increase in stride time with a concomitant increase in stance time. Interestingly, these altered gait parameters were completely corrected by CAPN3 overexpression in transgenic C3Tg;+/mdm mice, supporting a CAPN3-dependent role for the N2A domain of TTN in the dynamics of muscle contraction.
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Affiliation(s)
| | - Elena Kudryashova
- Department of Neurology and Pediatrics, Duchenne Muscular Dystrophy Research Center, University of California, and, Los Angeles, CA 90095, USA
| | | | - Roger B. Sher
- The Jackson Laboratory, 600 Main Street, Bar Harbor, Maine 04609, USA
| | - Kevin L. Seburn
- The Jackson Laboratory, 600 Main Street, Bar Harbor, Maine 04609, USA
| | - Melissa J. Spencer
- Department of Neurology and Pediatrics, Duchenne Muscular Dystrophy Research Center, University of California, and, Los Angeles, CA 90095, USA
| | - Gregory A. Cox
- The Jackson Laboratory, 600 Main Street, Bar Harbor, Maine 04609, USA
- *To whom correspondence should be addressed. Fax: (207) 288-6073. E-mail:
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11
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Bogdanovich S, Perkins KJ, Krag TOB, Whittemore LA, Khurana TS. Myostatin propeptide‐mediated amelioration of dystrophic pathophysiology. FASEB J 2005; 19:543-9. [PMID: 15791004 DOI: 10.1096/fj.04-2796com] [Citation(s) in RCA: 189] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Mutations in myostatin (GDF8) cause marked increases in muscle mass, suggesting that this transforming growth factor-beta (TGF-beta) superfamily member negatively regulates muscle growth. Myostatin blockade therefore offers a strategy for reversing muscle wasting in Duchenne's muscular dystrophy (DMD) without resorting to genetic manipulation. Here, we demonstrate that pharmacological blockade using a myostatin propeptide stabilized by fusion to IgG-Fc improved pathophysiology of the mdx mouse model of DMD. Functional benefits evidenced by specific force improvement, exceeded those reported previously using myostatin antibody-mediated blockade. More importantly, use of a propeptide blockade strategy obviates possibilities of anti-idiotypic responses that could potentially limit the effectiveness of antibody-mediated myostatin blockade strategies over time. This study provides a novel pharmacological strategy for treatment of diseases associated with muscle wasting such as DMD and since it uses an endogenous inhibitor of myostatin should help circumvent technical hurdles and toxicity associated with conventional gene or cell based therapies.
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MESH Headings
- Animals
- Antibodies, Monoclonal
- Immunoglobulin Fc Fragments/chemistry
- Immunoglobulin G/chemistry
- Injections, Intraperitoneal
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Inbred mdx
- Muscle, Skeletal/chemistry
- Muscle, Skeletal/pathology
- Muscular Dystrophy, Animal/pathology
- Muscular Dystrophy, Animal/physiopathology
- Muscular Dystrophy, Animal/therapy
- Myostatin
- Protein Precursors/administration & dosage
- Protein Precursors/chemistry
- Protein Precursors/immunology
- RNA, Messenger/analysis
- Recombinant Fusion Proteins
- Transforming Growth Factor beta/antagonists & inhibitors
- Transforming Growth Factor beta/immunology
- Utrophin/genetics
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Affiliation(s)
- Sasha Bogdanovich
- Department of Physiology and Pennsylvania Muscle Institute, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6085, USA
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12
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Niederländer N, Raynaud F, Astier C, Chaussepied P. Regulation of the actin-myosin interaction by titin. ACTA ACUST UNITED AC 2005; 271:4572-81. [PMID: 15560799 DOI: 10.1111/j.1432-1033.2004.04429.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Titin is known to interact with actin thin filaments within the I-band region of striated muscle sarcomeres. In this study, we have used a titin fragment of 800 kDa (T800) purified from striated skeletal muscle to measure the effect of this interaction on the functional properties of the actin-myosin complex. MALDI-TOF MS revealed that T800 contains the entire titin PEVK (Pro, Glu, Val, Lys-rich) domain. In the presence of tropomyosin-troponin, T800 increased the sliding velocity (both average and maximum values) of actin filaments on heavy-meromyosin (HMM)-coated surfaces and dramatically decreased the number of stationary filaments. These results were correlated with a 30% reduction in actin-activated HMM ATPase activity and with an inhibition of HMM binding to actin N-terminal residues as shown by chemical cross-linking. At the same time, T800 did not affect the efficiency of the Ca(2+)-controlled on/off switch, nor did it alter the overall binding energetics of HMM to actin, as revealed by cosedimentation experiments. These data are consistent with a competitive effect of PEVK domain-containing T800 on the electrostatic contacts at the actin-HMM interface. They also suggest that titin may participate in the regulation of the active tension generated by the actin-myosin complex.
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13
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Sugie K, Murayama K, Noguchi S, Murakami N, Mochizuki M, Hayashi YK, Nonaka I, Nishino I. Two novel CAV3 gene mutations in Japanese families. Neuromuscul Disord 2005; 14:810-4. [PMID: 15564037 DOI: 10.1016/j.nmd.2004.08.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2004] [Revised: 08/16/2004] [Accepted: 08/27/2004] [Indexed: 11/22/2022]
Abstract
Caveolin-3 deficiency is a rare, autosomal dominant, muscle disorder caused by caveolin-3 gene (CAV3) mutations and consists of four clinical phenotypes: limb-girdle muscular dystrophy type 1C (LGMD-1C), rippling muscle disease, distal myopathy, and familial hyperCKemia. So far, only 13 mutations have been reported. We here report two novel heterozygous mutations, 96C>G (N32K) and 128T>A (V43E), in the CAV3 gene in two unrelated Japanese families with LGMD-1C. Both probands presented with elevated serum CK level with calf muscle hypertrophy in their childhood but without apparent muscle weakness. However, their mothers showed mild limb-girdle weakness in addition to high CK level. Caveolin-3 was deficient and caveolae were lacking in muscles from both patients. Our data confirm that caveolin-3 deficiency causes LGMD-1C and expand the variability in CAV3 gene mutations.
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MESH Headings
- Adult
- Caveolin 3
- Caveolins/deficiency
- Caveolins/genetics
- Child
- Child, Preschool
- Creatine Kinase/metabolism
- DNA Mutational Analysis
- Dysferlin
- Dystrophin/metabolism
- Family Health
- Female
- Genes, Dominant
- Genetic Predisposition to Disease/genetics
- Genetic Testing
- Genetic Variation/genetics
- Humans
- Hypertrophy/genetics
- Hypertrophy/pathology
- Japan
- Male
- Membrane Proteins/metabolism
- Microscopy, Electron, Transmission
- Middle Aged
- Muscle Proteins/metabolism
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/pathology
- Muscle, Skeletal/ultrastructure
- Muscular Dystrophies, Limb-Girdle/genetics
- Muscular Dystrophies, Limb-Girdle/metabolism
- Muscular Dystrophies, Limb-Girdle/pathology
- Mutation, Missense/genetics
- Up-Regulation/genetics
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Affiliation(s)
- Kazuma Sugie
- Department of Neuromuscular Research, National Center of Neurology and Psychiatry (NCNP), National Institute of Neuroscience, 4-1-1 Ogawahigashi-cho, Kodaira, Tokyo 187-8502, Japan
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14
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Cohn RD. Dystroglycan: important player in skeletal muscle and beyond. Neuromuscul Disord 2005; 15:207-17. [PMID: 15725582 DOI: 10.1016/j.nmd.2004.11.005] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2004] [Revised: 08/02/2004] [Accepted: 11/24/2004] [Indexed: 10/25/2022]
Abstract
Dystroglycan is a transmembrane protein that connects the extracellular matrix to the cytoskeleton. Given the ubiquitous tissue expression of dystroglycan, different functional roles in various organ systems have been characterized during the past decade. More recently, aberrant glycosylation of dystroglycan has been identified as a novel pathogenetic mechanism in several forms of congenital and late onset muscular dystrophy syndromes. The current review summarizes the recent scientific achievements as they relate to the function of dystroglycan under normal and pathophysiological conditions.
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Affiliation(s)
- Ronald D Cohn
- Johns Hopkins Hospital, Children's Center, McKusick-Nathans Institute of Genetic Medicine, 600 N Wolfe Street, Blalock 1008, Baltimore, MD 21287, USA.
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15
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Abstract
Skeletal muscle tissue is made up of highly organized multinuclear cells. The internal organization of the muscle cell is dictated by the necessary regular arrangement of repeated units within the protein myofibrils that mediate muscle contraction. Skeletal muscle cells have the usual membrane traffic pathways for partitioning newly synthesized proteins, internalizing cell surface receptors for hormones and nutrients, and mediating membrane repair. However, in muscle, these pathways must be further specialized to deal with targeting to and organizing muscle-specific membrane structures, satisfying the unique metabolic requirements of muscle and meeting the high demand for membrane repair in a tissue that is constantly under mechanical stress. Specialized membrane traffic pathways in muscle also play a role in the formation of muscle through fusion of myoblast membranes and the development of internal muscle-specific membrane structures during myogenesis and regeneration. It has recently become apparent that muscle-specific isoforms of proteins that are known to mediate ubiquitous membrane traffic pathways, as well as novel muscle-specific proteins, are involved in tissue-specific aspects of muscle membrane traffic. Here we describe the specialized membrane structures of skeletal muscle, how these are developed, maintained and repaired by specialized and generic membrane traffic pathways, and how defects in these pathways result in muscle disease.
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Affiliation(s)
- Mhairi C Towler
- Department of Microbiology and Immunology, University of California, San Francisco, CA, USA
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16
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Abstract
PURPOSE OF REVIEW Congenital disorders of glycosylation are caused by defects in the synthesis of the glycan moiety of glycoproteins or other glycoconjugates. There has been a great explosion in the number of neuromuscular diseases caused by mutations in genes that affect carbohydrate metabolism or protein glycosylation. A common defect in these disorders is the defective processing of alpha-dystroglycan. RECENT FINDINGS Recent advances demonstrating mutations in glycosyltransferases and dysfunction of the alpha-beta dystroglycan axis causing different forms of muscular dystrophy, especially with brain involvement, shows clearly that muscle integrity is dependent on glycosylation. We first review the newly identified muscular dystrophies, with a focus on the hypoglycosylation of alpha-dystroglycan, from a clinical, biochemical and genetic standpoint, and second hereditary inclusion body myopathies caused by mutations in the gene that encodes an enzyme responsible for the protein's posttranslational modification that cause sialidation defects. It is shown very recently that molecular recognition of dystroglycan by LARGE is a key determinant in the biosynthetic pathway to produce mature and functional dystroglycan. Gene transfer of LARGE into the cells of individuals with congenital muscular dystrophies restores alpha-dystroglycan function. SUMMARY The clinical spectrum of congenital disorders of glycosylation is becoming increasingly broad. A demonstration of mutations in glycosyltransferases will further help to design diagnostic tools and therapeutic approaches. Recent findings which show that molecular recognition by LARGE is essential for expression of functional dystroglycan and LARGE can functionally bypass alpha-dystroglycan glycosylation defects in distinct congenital muscular dystrophies, indicate a new therapeutic strategy.
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Affiliation(s)
- Göknur Haliloğlu
- Department of Child Neurology, Hacettepe Children's Hospital, 06100 Ankara, Turkey
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Agarkova I, Ehler E, Lange S, Schoenauer R, Perriard JC. M-band: a safeguard for sarcomere stability? J Muscle Res Cell Motil 2004; 24:191-203. [PMID: 14609030 DOI: 10.1023/a:1026094924677] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The sarcomere of striated muscle is a very efficient machine transforming chemical energy into movement. However, a wrong distribution of the generated forces may lead to self-destruction of the engine itself. A well-known example for this is eccentric contraction (elongation of the sarcomere in the activated state), which damages sarcomeric structure and leads to a reduced muscle performance. The goal of this review is to discuss the involvement of different cytoskeletal systems, in particular the M-band filaments, in the mechanisms that provide stability during sarcomeric contraction. The M-band is the transverse structure in the center of the sarcomeric A-band, which is responsible both for the regular packing of thick filaments and for the uniform distribution of the tension over the myosin filament lattice in the activated sarcomere. Although some proteins from the Ig-superfamily, like myomesin and M-protein, are the major candidates for the role of M-band bridges, the exact molecular organisation of the M-band is not clear. However, the protein composition of the M-band seems to modulate the mechanical characteristics of the thick filament lattice, in particular its stiffness, adjusting it to the specific demands in different muscle types. The special M-band design in slow fibers might be part of structural adaptations, favouring sarcomere stability for a continuous contractile activity over a broad working range. In conclusion, we discuss why the interference with M-band structure might have fatal consequences for the integrity of the working sarcomere.
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Affiliation(s)
- Irina Agarkova
- Institute of Cell Biology, ETH-Zurich Hoenggerberg, CH-8093 Zurich, Switzerland
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18
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Haslett JN, Sanoudou D, Kho AT, Han M, Bennett RR, Kohane IS, Beggs AH, Kunkel LM. Gene expression profiling of Duchenne muscular dystrophy skeletal muscle. Neurogenetics 2003; 4:163-71. [PMID: 12698323 DOI: 10.1007/s10048-003-0148-x] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2003] [Accepted: 03/03/2003] [Indexed: 10/26/2022]
Abstract
The primary cause of Duchenne muscular dystrophy (DMD) is a mutation in the dystrophin gene, leading to absence of the corresponding protein, disruption of the dystrophin-associated protein complex, and substantial changes in skeletal muscle pathology. Although the primary defect is known and the histological pathology well documented, the underlying molecular pathways remain in question. To clarify these pathways, we used expression microarrays to compare individual gene expression profiles for skeletal muscle biopsies from DMD patients and unaffected controls. We have previously published expression data for the 12,500 known genes and full-length expressed sequence tags (ESTs) on the Affymetrix HG-U95Av2 chips. Here we present comparative expression analysis of the 50,000 EST clusters represented on the remainder of the Affymetrix HG-U95 set. Individual expression profiles were generated for biopsies from 10 DMD patients and 10 unaffected control patients. Two methods of statistical analysis were used to interpret the resulting data (t-test analysis to determine the statistical significance of differential expression and geometric fold change analysis to determine the extent of differential expression). These analyses identified 183 probe sets (59 of which represent known genes) that differ significantly in expression level between unaffected and disease muscle. This study adds to our knowledge of the molecular pathways that are altered in the dystrophic state. In particular, it suggests that signaling pathways might be substantially involved in the disease process. It also highlights a large number of unknown genes whose expression is altered and whose identity therefore becomes important in understanding the pathogenesis of muscular dystrophy.
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Affiliation(s)
- Judith N Haslett
- Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA
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