title: Microtubules underlie dysfunction in duchenne muscular dystrophy.
abstract: Duchenne muscular dystrophy (DMD) is a fatal X-linked degenerative muscle disease caused by the absence of the microtubule-associated protein dystrophin, which results in a disorganized and denser microtubule cytoskeleton. In addition, mechanotransduction-dependent activation of calcium (Ca(2+)) and reactive oxygen species (ROS) signaling underpins muscle degeneration in DMD. We show that in muscle from adult mdx mice, a model of DMD, a brief physiologic stretch elicited microtubule-dependent activation of NADPH (reduced-form nicotinamide adenine dinucleotide phosphate) oxidase-dependent production of ROS, termed X-ROS. Further, X-ROS amplified Ca(2+) influx through stretch-activated channels in mdx muscle. Consistent with the importance of the microtubules to the dysfunction in mdx muscle, muscle cells with dense microtubule structure, such as those from adult mdx mice or from young wild-type mice treated with Taxol, showed increased X-ROS production and Ca(2+) influx, whereas cells with a less dense microtubule network, such as young mdx or adult mdx muscle treated with colchicine or nocodazole, showed little ROS production or Ca(2+) influx. In vivo treatments that disrupted the microtubule network or inhibited NADPH oxidase 2 reduced contraction-induced injury in adult mdx mice. Furthermore, transcriptome analysis identified increased expression of X-ROS-related genes in human DMD skeletal muscle. Together, these data show that microtubules are the proximate element responsible for the dysfunction in Ca(2+) and ROS signaling in DMD and could be effective therapeutic targets for intervention.
authors.affiliation: Center for Biomedical Engineering and Technology and Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
authors.forename: Ramzi J
authors.initials: RJ
authors.lastname: Khairallah
authors.forename: Guoli
authors.initials: G
authors.lastname: Shi
authors.forename: Francesca
authors.initials: F
authors.lastname: Sbrana
authors.forename: Benjamin L
authors.initials: BL
authors.lastname: Prosser
authors.forename: Carlos
authors.initials: C
authors.lastname: Borroto
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Mazaitis
authors.forename: Eric P
authors.initials: EP
authors.lastname: Hoffman
authors.forename: Anup
authors.initials: A
authors.lastname: Mahurkar
authors.forename: Fredrick
authors.initials: F
authors.lastname: Sachs
authors.forename: Yezhou
authors.initials: Y
authors.lastname: Sun
authors.forename: Yi-Wen
authors.initials: YW
authors.lastname: Chen
authors.forename: Roberto
authors.initials: R
authors.lastname: Raiteri
authors.forename: W Jonathan
authors.initials: WJ
authors.lastname: Lederer
authors.forename: Susan G
authors.initials: SG
authors.lastname: Dorsey
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Ward
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D007223:Infant; D008297:Male; D051379:Mice; D018101:Mice, Inbred mdx; D008870:Microtubules / Q000378:metabolism*; D018485:Muscle Fibers, Skeletal / Q000378:metabolism / Q000502:physiology; D018482:Muscle, Skeletal / Q000378:metabolism / Q000503:physiopathology*; D009137:Muscular Dystrophy, Animal / Q000378:metabolism / Q000503:physiopathology*; D020388:Muscular Dystrophy, Duchenne / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology*; D019255:NADPH Oxidases / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D059467:Transcriptome / Q000235:genetics; D050257:Tubulin Modulators / Q000494:pharmacology
chemical_list: D017382:Reactive Oxygen Species; D050257:Tubulin Modulators; D019255:NADPH Oxidases; D002118:Calcium