Chapter category: Development
Structure and Function of the Dystrophin-Glycoprotein Complex
Molecular Mechanisms of Muscular Dystrophies
Edited by: Steve J. WinderISBN: 1-58706-264-X
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Chapter authors:
James M. Ervasti
Duchenne muscular dystrophy (DMD) is the most prevalent and severe form of human muscular dystrophy. While clinical descriptions of DMD date back to the 1850’s, over 100 years passed before evidence suggested that the muscle cell plasma membrane, or sarcolemma, is compromised in DMD muscle. The molecular basis for DMD and its associated sarcolemmal instability became more clear with landmark studies published in the mid-to-late 1980’s which identified the gene defective in DMD.1 The DMD locus spans over 2.5 million bases distinguishing it as the largest gene in the human genome. The array of transcripts expressed from the DMD gene is complex due to the presence of multiple promoters and alternative splicing. The largest transcripts encode a four-domain protein with a predicted molecular weight of 427,000, named dystrophin. Dystrophin is the predominant DMD transcript expressed in striated muscle and DMD gene mutations, deletions or duplications most frequently result in a loss of dystrophin expression in muscle of patients afflicted with DMD. Based on its localization to the cytoplasmic face of the sarcolemma and sequence similarity with domains/motifs common to proteins of the actin-based cytoskeleton, dystrophin was hypothesized early on to play a structural role in anchoring the sarcolemma to the underlying cytoskeleton and protect the sarcolemma against stress imposed during muscle contraction or stretch. Biochemical studies aimed at confirming the hypothesized structure and function of dystrophin revealed its tight association with a multi-subunit complex, the so-named dystrophin-glycoprotein complex. Since its description, the dystrophin-glycoprotein complex has emerged as an important structural unit of muscle and also as a critical nexus for understanding muscular dystrophies arising from defects in several distinct genes.
Additional chapters from this book:
Utrophin in the Therapy of Duchenne Muscular Dystrophy
Qing Bai, Edward A. Burton and Kay E. Davies
Duchenne muscular dystrophy (DMD) is a devastating muscle wasting disease caused by the lack of the cytoskeletal protein dystrophin in muscle. The dystrophin-related protein, utrophin, shows a high ...
Sarcomeric Proteins in LGMD
Olli Carpen
Limb girdle muscular dystrophies are caused by mutations in several genes that encode for proteins with divergent functions. The most common LGMD forms result from sarcolemmal adhesion complex defec...
The Structure and Function of Dystrophin
Simone Abmayr and Jeff Chamberlain
Duchenne muscular dystrophy (DMD) and the allelic Becker muscular dystrophy (BMD) are X-linked recessive disorders caused by mutations in the dystrophin gene. The dystrophin gene spans 2.4 MB on the...
Glycosylation and Muscular Dystrophy
Susan C. Brown and Francesco Muntoni
The congenital muscular dystrophies (CMD) are a heterogeneous group of autosomal recessive disorders a number of which have recently been shown to be associated with mutations in the genes encoding ...
The Pathophysiological Role of Impaired Calcium Handling in Muscular Dystrophy
Kay Ohlendieck
Although the primary deficiency in dystrophin and the concomitant reduction in surface glycoproteins are well established factors in the molecular pathogenesis of Duchenne muscular dystrophy, the pa...
Overview of the Limb-Girdle Muscular Dystrophies and Dysferlinopathy
KMD Bushby and SH Laval
The limb-girdle muscular dystrophies (LGMD) comprise a group of disorders now known to reflect the whole spectrum of molecular pathogenesis of muscle disease. Initially identified as a heterogeneous...
Gene Therapies for Muscular Dystrophies
Dominic J. Wells
Gene therapy for the muscular dystrophies aims to restore the normal biochemistry by either modifying the damaged gene (or mRNA) or by expression of a therapeutic transgene. Animal models, mostly mi...
Distinct Mechanisms Downstream of the Repeat Expansion are Implicated in the Molecular Basis of Myotonic Dystrophy Type 1
Keith Johnson and Rami Jarjour
Myotonic dystrophy type 1 (DM1) is the most common inherited muscular dystrophy affecting adults. The underlying mutation is the same in all patients with DM1, namely a trinucleotide (CTG) repeat ex...
Syntrophin: A Molecular Adaptor Conferring a Signaling Role to the Dystrophin-Associated Protein Complex
Justin M. Percival, Marvin E. Adams and Stanley C. Froehner
The dystrophin-associated protein complex (DAPC) plays a critical role in maintaining the structural integrity of the sarcolemma of skeletal muscle. In addition, several regulatory molecules, includ...
The Sarcoglycans
Elizabeth M. McNally
The sarcoglycans are transmembrane proteins found as a plasma membrane-associated complex. First characterized as a subunit of the dystrophin glycoprotein complex in skeletal muscle, the sarcoglycan...
Molecular and Functional Diversity of Dystrobrevin-containing Complexes
Derek J. Blake and Roy V. Sillitoe
It is now well established that mutations in the gene encoding the large sarcolemmal-associated protein dystrophin cause Duchenne and Becker muscular dystrophies (DMD and BMD). The core dystrophin g...
Cell Adhesion and Signalling in the Muscular Dystrophies
Steven J. Winder
Many of the muscular dystrophies are caused by defects in proteins involved in main taining connections between the cytoskeleton and extracellular matrix – cell adhe sion complexes. Cell adhesion co...
Spinal Muscular Atrophy
Robert Olaso, Jeremie Vitte, Nouzha Salah and Judith Melki
Spinal muscular atrophies (SMA) are characterized by degeneration of lower motor neurons and occasionally bulbar motor neurons leading to progressive limb and trunk paralysis associated with muscula...
Structure and Function of the Dystrophin-Glycoprotein Complex
James M. Ervasti
Duchenne muscular dystrophy (DMD) is the most prevalent and severe form of human muscular dystrophy. While clinical descriptions of DMD date back to the 1850’s, over 100 years passed before evidence...
Lamins and Emerin in Muscular Dystrophy: The Nuclear Envelope Connection
Josef Gotzmann and Roland Foisner
Lamins are nuclear intermediate filaments, which form a network like structure underneath the nuclear membrane, the nuclear lamina, as well as complexes in the nuclear interior. Lamins associate wit...
Caveolin-3 and Limb-Girdle Muscular Dystrophy
Ferruccio Galbiati and Michael P. Lisanti
Caveolin-3 is the principal structural protein component of caveolae membrane domains in skeletal muscle cells. Caveolae are plasma membrane invaginations implicated in the regulation of signal tran...
Commonalities and Differences in Muscular Dystrophies: Mechanisms and Molecules Involved in Merosin-Deficient Congenital Muscular Dystrophy
Markus A. Ruegg
Congenital muscular dystrophies are autosomal recessive diseases characterized by generalized hypotonia, delayed motor milestones and involvement of the brain. A large subgroup of this rather hetero...
