title: Reducing dynamin 2 expression rescues X-linked centronuclear myopathy.
abstract: Centronuclear myopathies (CNM) are congenital disorders associated with muscle weakness and abnormally located nuclei in skeletal muscle. An autosomal dominant form of CNM results from mutations in the gene encoding dynamin 2 (DNM2), and loss-of-function mutations in the gene encoding myotubularin (MTM1) result in X-linked CNM (XLCNM, also called myotubular myopathy), which promotes severe neonatal hypotonia and early death. Currently, no effective treatments exist for XLCNM. Here, we found increased DNM2 levels in XLCNM patients and a mouse model of XLCNM (Mtm1(-/y)). Generation of Mtm1(-/y) mice that were heterozygous for Dnm2 revealed that reduction of DNM2 in XLCNM mice restored life span, whole-body strength, and diaphragm function and increased muscle strength. Additionally, classic CNM-associated histological features, including fiber atrophy and nuclei mispositioning, were absent or reduced. Ultrastructural analysis revealed improvement of sarcomere organization and triad structures. Skeletal muscle-specific decrease of Dnm2 during embryogenesis or in young mice after disease onset revealed that the rescue associated with downregulation of Dnm2 is cell autonomous and is able to stop and potentially revert XLCNM progression. These data indicate that MTM1 and DNM2 regulate muscle organization and force through a common pathway. Furthermore, despite DNM2 being a key mechanoenzyme, its reduction is beneficial for XLCNM and represents a potential therapeutic approach for patients.
authors.forename: Belinda S
authors.initials: BS
authors.lastname: Cowling
authors.forename: Thierry
authors.initials: T
authors.lastname: Chevremont
authors.forename: Ivana
authors.initials: I
authors.lastname: Prokic
authors.forename: Christine
authors.initials: C
authors.lastname: Kretz
authors.forename: Arnaud
authors.initials: A
authors.lastname: Ferry
authors.forename: Catherine
authors.initials: C
authors.lastname: Coirault
authors.forename: Olga
authors.initials: O
authors.lastname: Koutsopoulos
authors.forename: Vincent
authors.initials: V
authors.lastname: Laugel
authors.forename: Norma B
authors.initials: NB
authors.lastname: Romero
authors.forename: Jocelyn
authors.initials: J
authors.lastname: Laporte
mesh_terms: D000818:Animals; D003964:Diaphragm / Q000503:physiopathology; D015536:Down-Regulation; D034285:Dynamin II / Q000235:genetics* / Q000378:metabolism; D005260:Female; D015870:Gene Expression; D006801:Humans; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D009119:Muscle Contraction; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology; D020914:Myopathies, Structural, Congenital / Q000378:metabolism* / Q000473:pathology / Q000628:therapy; D010641:Phenotype; D054558:Protein Tyrosine Phosphatases, Non-Receptor / Q000378:metabolism
chemical_list: D054558:Protein Tyrosine Phosphatases, Non-Receptor; C099588:myotubularin; D034285:Dynamin II