Membrane Traffic and Muscle: Lessons from Human Disease
James J. Dowling, Elizabeth M. Gibbs, Eva L. Feldman
Traffic, Volume 9 Issue 7: 1035 - 1043, Abstract
Like all mammalian tissues, skeletal muscle is dependent on membrane traffic for proper development and homeostasis. This fact is underscored by the observation that several human diseases of the skeletal muscle are caused by mutations in gene products of the membrane trafficking machinery. An examination of these diseases and the proteins that underlie them is ...

The Sarcoplasmic Reticulum: An Organized Patchwork of Specialized Domains
Daniela Rossi, Virginia Barone, Emiliana Giacomello, Vincenza Cusimano, Vincenzo Sorrentino
Traffic, Volume 9 Issue 7: 1044 - 1049, Abstract
The sarcoplasmic reticulum (SR) of skeletal muscle cells is a convoluted structure composed of a variety of tubules and cisternae, which share a continuous lumen delimited by a single continuous membrane, branching to form a network that surrounds each myofibril. In this network, some specific domains basically represented by the longitudinal SR and the junctional SR can ...

Myoblast Fusion in Fly and Vertebrates: New Genes, New Processes and New Perspectives
Brian E. Richardson, Scott J. Nowak, Mary K. Baylies
Traffic, Volume 9 Issue 7: 1050 - 1059, Abstract
Muscle formation and repair depends critically on the fusion of myoblasts. Despite the importance of this process, little is known about the cellular and molecular mechanisms regulating fusion. Forward genetic screens in Drosophila melanogaster have uncovered genes that, when mutated, prevent myoblast fusion. Analyses of these gene products have indicated that the actin ...

Clathrin-Dependent and Independent Endocytosis of Glucose Transporter 4 (GLUT4) in Myoblasts: Regulation by Mitochondrial Uncoupling
Costin N. Antonescu, Mònica Díaz, Guiseppe Femia, Josep V. Planas, Amira Klip
Traffic, Volume 9 Issue 7: 1173 - 1190, Abstract
n myocytes and adipocytes, insulin increases glucose transporter 4 (GLUT4) exocytosis by promoting GLUT4 vesicle docking/fusion with the membrane. Less is known about the mechanism and regulation of GLUT4 endocytosis, particularly in myocytes. Here, we show that GLUT4 internalization in L6 myoblasts was inhibited in part by hypertonicity or clathrin heavy chain knockdown and ...

Similar [DE]XXXL[LI] Motifs Differentially Target GLUT8 and GLUT12 in Chinese Hamster Ovary Cells
Lauren B. Flessner, Kelle H. Moley
Traffic, Volume 10 Issue 3: 324 - 333, Abstract
The transport of glucose across cell membranes is mediated by facilitative glucose transporters (GLUTs). The recently identified class III GLUT12 is predominantly expressed in insulin-sensitive tissues such as heart, fat and skeletal muscle. We examined the subcellular localization of GLUT12 in Chinese hamster ovary and human embryonic kidney 293 cells stably expressing murine ...

Membrane Traffic in Skeletal Muscle
Mhairi C. Towler, Stephen J. Kaufman, Frances M. Brodsky
Traffic, Volume 5 Issue 3: 129 - 139, 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 ...

Insulin Stimulates the Entry of GLUT4 into the Endosomal Recycling Pathway by a Quantal Mechanism
Adelle C. F. Coster, Roland Govers, David E. James
Traffic, Volume 5 Issue 10: 763 - 771, Abstract
The insulin-sensitive glucose transporter GLUT4 mediates the uptake of glucose into adipocytes and muscle cells. In this study we have used a novel 96-well plate fluorescence assay to study the kinetics of GLUT4 trafficking in 3T3-L1 adipocytes. We have found evidence for a graded release mechanism whereby GLUT4 is released into the plasma membrane recycling system in a ...

Munc 18-1 and Granuphilin Collaborate During Insulin Granule Exocytosis
Alejandra Tomas, Paolo Meda, Romano Regazzi, Jeffrey E. Pessin, Philippe A. Halban
Traffic, Volume 9 Issue 5: 813 - 832, Abstract
Munc 18-1 is a member of the Sec/Munc family of syntaxin-binding proteins known to bind to the plasma membrane Q-SNARE syntaxin1 and whose precise role in regulated exocytosis remains controversial. Here, we show that Munc 18-1 plays a positive role in regulated insulin secretion from pancreatic beta cells. Munc 18-1 depletion caused a loss in the secretory capacity of both ...

Cytoplasmic Targeting of Mutant Poly(A)-Binding Protein Nuclear 1 Suppresses Protein Aggregation and Toxicity in Oculopharyngeal Muscular Dystrophy
Aida Abu-Baker, Simon Laganiere, Xueping Fan, Janet Laganiere, Bernard Brais, Guy A. Rouleau
Traffic, Volume 6 Issue 9: 766 - 779, Abstract
Oculopharyngeal muscular dystrophy (OPMD) is an adult-onset disorder characterized by progressive eyelid drooping, swallowing difficulties and proximal limb weakness. The autosomal dominant form of this disease is caused by a polyalanine expansion from 10 to 12–17 residues, located at the N-terminus of the poly(A)-binding protein nuclear 1 (PABPN1). A distinct pathological ...

a-Sarcoglycan is Recycled from the Plasma Membrane in the Absence of Sarcoglycan Complex Assembly
Romesh A. Draviam, Bing Wang, Stuart H. Shand, Xiao Xiao, Simon C. Watkins
Traffic, Volume 7 Issue 7: 793 - 810, Abstract
The sarcoglycan complex consists of four subunits in skeletal muscle (a, ß, ?, and d-SG). Mutations in a-sarcoglycan (a-SG) result in the most common form of limb girdle muscular dystrophy. However, the function of a-SG remains unknown. In this report we attempt to clarify its function by delineating the trafficking pathway of a-SG in live cells. We present evidence, utilizing total ...

Insulin-Regulated Aminopeptidase Marks an Antigen-Stimulated Recycling Compartment in Mast Cells
Haini Liao, Susanna R. Keller, J. David Castle
Traffic, Volume 7 Issue 2: 155 - 167, Abstract
Insulin-regulated aminopeptidase (IRAP) is a marker for insulin-sensitive recycling compartments of fat and muscle cells that contain the glucose transporter isoform GLUT4. Unlike GLUT4, IRAP is expressed in many other cell types. Thus, it is a potential marker for regulated recycling compartments that are analogous to GLUT4 vesicles. In bone marrow-derived mast cells, IRAP is highly ...

Myotubularin Lipid Phosphatase Binds the hVPS15/hVPS34 Lipid Kinase Complex on Endosomes
Canhong Cao, Jocelyn Laporte, Jonathan M. Backer, Angela Wandinger-Ness, Mary-Pat Stein
Traffic, Volume 8 Issue 8: 1052 - 1067, Abstract
Myotubularins constitute a ubiquitous family of phosphatidylinositol (PI) 3-phosphatases implicated in several neuromuscular disorders. Myotubularin [myotubular myopathy 1 (MTM1)] PI 3-phosphatase is shown associated with early and late endosomes. Loss of endosomal phosphatidylinositol 3-phosphate [PI(3)P] upon overexpression of wild-type MTM1, but not a phosphatase- ...

Dysferlin in Membrane Trafficking and Patch Repair
Louise Glover, Robert H. Brown Jr
Traffic, Volume 8 Issue 7: 785 - 794, Abstract
The muscular dystrophies are a heterogeneous group of inherited disorders, defined by progressive muscle weakness and atrophy. Following the discovery of dystrophin, remarkable progress has been made in defining the molecular properties of proteins involved in the various dystrophies. This has underlined the importance of the dystrophin-associated protein complex as a cell ...

Golgi Complex Organization in Skeletal Muscle: A Role for Golgi-Mediated Glycosylation in Muscular Dystrophies?
Justin M. Percival, Stanley C. Froehner
Traffic, Volume 8 Issue 3: 184 - 194, Abstract
The Golgi complex (GC) is the central organelle of the classical secretory pathway, and it receives, modifies and packages proteins and lipids en route to their intracellular or extracellular destinations. Recent studies of congenital muscular dystrophies in skeletal muscle suggest an exciting new role for an old and well-established function of the GC: glycosylation. Glycosylation is ...

Processing and Assembly of the Dystrophin Glycoprotein Complex
Michael J. Allikian, Elizabeth M. McNally
Traffic, Volume 8 Issue 3: 177 - 183, Abstract
The assembly, processing and translocation of proteins occur constantly in all cells, and these processes also take place during the genesis, maintenance and repair of skeletal muscle. Skeletal muscle fibers are composed of myofibrils and are surrounded by a muscle plasma membrane, the sarcolemma. The sarcolemma serves as a docking location for many proteins. These proteins ...

rAAV6-Microdystrophin Rescues Aberrant Golgi Complex Organization in mdx Skeletal Muscles
Justin M. Percival, Paul Gregorevic, Guy L. Odom, Glen B. Banks, Jeffrey S. Chamberlain, Stanley C. Froehner
Traffic, Volume 8 Issue 10: 1424 - 1439, Abstract
Muscular dystrophies are a diverse group of severe degenerative muscle diseases. Recent interest in the role of the Golgi complex (GC) in muscle disease has been piqued by findings that several dystrophies result from mutations in putative Golgi-resident glycosyltransferases. Given this new role of the Golgi in sarcolemmal stability, we hypothesized that abnormal Golgi ...

Patients with a Non-dysferlin Miyoshi Myopathy have a Novel Membrane Repair Defect
Jyoti K. Jaiswal, Gareth Marlow, Gillian Summerill, Ibrahim Mahjneh, Sebastian Mueller, Maria Hill, Katsuya Miyake, Hannelore Haase, Louise V. B. Anderson, Isabelle Richard, Sari Kiuru-Enari, Paul L. McNeil, Sanford M. Simon, Rumaisa Bashir
Traffic, Volume 8 Issue 1: 77 - 88, Abstract
Two autosomal recessive muscle diseases, limb girdle muscular dystrophy type 2B (LGMD2B) and Miyoshi myopathy (MM), are caused by mutations in the dysferlin gene. These mutations result in poor ability to repair cell membrane damage, which is suggested to be the cause for this disease. However, many patients who share clinical features with MM-type muscular dystrophy do not ...

Insulin-Regulated Aminopeptidase Marks an Antigen-Stimulated Recycling Compartment in Mast Cells
Haini Liao, Susanna R. Keller, J. David Castle
Traffic, Volume 7 Issue 2: 155 - 167, Abstract
Insulin-regulated aminopeptidase (IRAP) is a marker for insulin-sensitive recycling compartments of fat and muscle cells that contain the glucose transporter isoform GLUT4. Unlike GLUT4, IRAP is expressed in many other cell types. Thus, it is a potential marker for regulated recycling compartments that are analogous to GLUT4 vesicles. In bone marrow-derived mast cells, IRAP is highly ...