title: In vitro analysis of rod composition and actin dynamics in inherited myopathies.
abstract: Rods are the pathological hallmark of nemaline myopathy, but they can also occur as a secondary phenomenon in other disorders, including mitochondrial myopathies such as complex I deficiency. The mechanisms of rod formation are not well understood, particularly when rods occur in diverse disorders with very different structural and metabolic defects. We compared the characteristics of rods associated with abnormalities in structural components of skeletal muscle thin filament (3 mutations in the skeletal actin gene ACTA1) with those of rods induced by the metabolic cell stress of adenosine triphosphate depletion. C2C12 and NIH/3T3 cell culture models and immunocytochemistry were used to study rod composition and conformation. Fluorescent recovery after photobleaching was used to measure actin dynamics inside the rods. We demonstrate that not all rods are the same. Rods formed under different conditions contain a unique fingerprint of actin-binding proteins (cofilin and alpha-actinin) and display differences in actin dynamics that are specific to the mutation, to the cellular location of the rods (intranuclear vs cytoplasmic), and/or to the underlying pathological process (i.e. mutant actin or adenosine triphosphate depletion). Thus, rods likely represent a common morphological end point of a variety of different pathological processes, either structural or metabolic.
authors.affiliation: Institute for Neuroscience and Muscle Research, The Children's Hospital at Westmead, Westmead, Australia.
authors.forename: Aurélie
authors.initials: A
authors.lastname: Vandebrouck
authors.forename: Ana
authors.initials: A
authors.lastname: Domazetovska
authors.forename: Nancy
authors.initials: N
authors.lastname: Mokbel
authors.forename: Sandra T
authors.initials: ST
authors.lastname: Cooper
authors.forename: Biljana
authors.initials: B
authors.lastname: Ilkovski
authors.forename: Kathryn N
authors.initials: KN
authors.lastname: North
mesh_terms: D000185:Actinin / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002461:Cell Line, Transformed; D051340:Cofilin 2 / Q000378:metabolism*; D003593:Cytoplasm / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D049452:Green Fluorescent Proteins / Q000235:genetics; D045586:Intranuclear Inclusion Bodies / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D009135:Muscular Diseases / Q000378:metabolism* / Q000473:pathology*; D009154:Mutation / Q000235:genetics*; D017711:Nonlinear Dynamics; D038761:Photobleaching; D014162:Transfection / Q000379:methods
chemical_list: D051340:Cofilin 2; C485184:enhanced green fluorescent protein; D000185:Actinin; D049452:Green Fluorescent Proteins; D000255:Adenosine Triphosphate