Article

Dystrophin is a microtubule-associated protein

Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA.
The Journal of Cell Biology (Impact Factor: 9.83). 09/2009; 186(3):363-9. DOI: 10.1083/jcb.200905048
Source: PubMed

ABSTRACT

Cytolinkers are giant proteins that can stabilize cells by linking actin filaments, intermediate filaments, and microtubules (MTs) to transmembrane complexes. Dystrophin is functionally similar to cytolinkers, as it links the multiple components of the cellular cytoskeleton to the transmembrane dystroglycan complex. Although no direct link between dystrophin and MTs has been documented, costamere-associated MTs are disrupted when dystrophin is absent. Using tissue-based cosedimentation assays on mice expressing endogenous dystrophin or truncated transgene products, we find that constructs harboring spectrinlike repeat 24 through the first third of the WW domain cosediment with MTs. Purified Dp260, a truncated isoform of dystrophin, bound MTs with a K(d) of 0.66 microM, a stoichiometry of 1 Dp260/1.4 tubulin heterodimer at saturation, and stabilizes MTs from cold-induced depolymerization. Finally, alpha- and beta-tubulin expression is increased approximately 2.5-fold in mdx skeletal muscle without altering the tubulin-MT equilibrium. Collectively, these data suggest dystrophin directly organizes and/or stabilizes costameric MTs and classifies dystrophin as a cytolinker in skeletal muscle.

Download full-text

Full-text

Available from: Kurt Prins
  • Source
    • "Therapies that produce internally deleted dystrophins are based on observations that patients with the milder BMD can harbor large deletions in the central rod domain. In addition to conferring elasticity or flexibility to dystrophin[5,41,42], it is known that the central rod domain encodes a second actin binding domain[6,43,44], as well as domains for localizing nNOS to the sarcolemma[38,39], for in vitro binding to phospholipids[45,46], intermediate filaments[9], and microtubules[11,12]. The biophysical properties of individual and tandem repeats of the rod domain have been extensively investigated , and these findings demonstrate a wide range of stabilities45464748, whereas full-length dystrophin has remarkable cooperative stability[21]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: The X-linked recessive disease Duchenne muscular dystrophy (DMD) is caused by mutations in the gene encoding the protein dystrophin. Despite its large size, dystrophin is a highly stable protein, demonstrating cooperative unfolding during thermal denaturation as monitored by circular dichroism spectroscopy. In contrast, internal sequence deletions have been associated with a loss of the cooperative unfolding and cause in vitro protein aggregation. Several emerging therapy options for DMD utilize internally deleted micro-dystrophins and multi-exon-skipped dystrophins that produce partially functional proteins, but the stability of such internally truncated proteins has not been investigated. In this study, we analyzed the in vitro stability of human dystrophin constructs skipped around exon 45 or exon 51, several dystrophin gene therapy constructs, as well as human full-length and micro-utrophin. Constructs were expressed in insect cells using the baculovirus system, purified by affinity chromatography, and analyzed by high-speed sedimentation, circular dichroism spectroscopy, and differential scanning fluorimetry. Our results reveal that not all gene therapy constructs display stabilities consistent with full-length human dystrophin. However, all dystrophins skipped in-frame around exon 45 or exon 51 show stability profiles congruent with intact human dystrophin. Similar to previous studies of mouse proteins, full-length human utrophin also displays stability similar to human dystrophin and does not appear to be affected by a large internal deletion. Our results suggest that the in vitro stability of human dystrophin is less sensitive to smaller deletions at natural exon boundaries than larger, more complex deletions present in some gene therapy constructs.
    Full-text · Article · Dec 2015 · Skeletal Muscle
  • Source
    • "The central part of dystrophin coded by exons 8 to 61 is made of 24 spectrin-like repeats interspaced by four hinges H1 to H4 and at the origin of the rod-shaped filament nature of dystrophin [23]. This long domain interacts with a high number of proteins among which they are the filamentous actin [24], intermediate filaments [25] [26] and microtubules [27] [28] and finally the muscular isoform of nitric oxide synthase (nNOS)[29] [30] [31] and PAR1-b [32]. In addition, this domain interacts with membrane phospholipids[33-35]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Mutations of the dystrophin DMD gene, essentially deletions of one or several exons, are the cause of two devastating and to date incurable diseases, Duchenne (DMD) and Becker (BMD) muscular dystrophies. Depending upon the preservation or not of the reading frame, dystrophin is completely absent in DMD, or present in either a mutated or a truncated form in BMD. DMD is a severe disease which leads to a premature death of the patients. Therapy approaches are evolving with the aim to transform the severe DMD in the BMD form of the disease by restoring the expression of a mutated or truncated dystrophin. These therapies are based on the assumption that BMD is a mild disease. However, this is not completely true as BMD patients are more or less severely affected and no molecular basis of this heterogeneity of the BMD form of the disease is yet understood. The aim of this review is to report for the correlation between dystrophin structures in BMD deletions in view of this heterogeneity and to emphasize that examining BMD patients in details is highly relevant to anticipate for DMD therapy effects.
    Preview · Article · Aug 2015 · Bosnian journal of basic medical sciences / Udruzenje basicnih mediciniskih znanosti = Association of Basic Medical Sciences
  • Source
    • "To explain the orthogonal grid of MTs, we must involve dystrophin, the protein missing in DMD. Dystrophin is a MAP (Prins et al., 2009) Figure 4. MTs are nucleated on Golgi elements that concentrate -tubulin and pericentrin . To investigate MT nucleation, plated FDB fibers were treated with NZ to depolymerize MTs and fixed after different periods of recovery . "
    [Show abstract] [Hide abstract]
    ABSTRACT: Skeletal muscle microtubules (MTs) form a nonclassic grid-like network, which has so far been documented in static images only. We have now observed and analyzed dynamics of GFP constructs of MT and Golgi markers in single live fibers and in the whole mouse muscle in vivo. Using confocal, intravital, and superresolution microscopy, we find that muscle MTs are dynamic, growing at the typical speed of ∼9 µm/min, and forming small bundles that build a durable network. We also show that static Golgi elements, associated with the MT-organizing center proteins γ-tubulin and pericentrin, are major sites of muscle MT nucleation, in addition to the previously identified sites (i.e., nuclear membranes). These data give us a framework for understanding how muscle MTs organize and how they contribute to the pathology of muscle diseases such as Duchenne muscular dystrophy.
    Full-text · Article · Oct 2013 · The Journal of Cell Biology
Show more