title: Dysferlin interacts with affixin (beta-parvin) at the sarcolemma.
abstract: The dysferlin gene is defective in Miyoshi myopathy (MM) and limb girdle muscular dystrophy type 2B (LGMD2B). Dysferlin is a sarcolemmal protein that is implicated in calcium-dependent membrane repair. Affixin (beta-parvin) is a novel, integrin-linked kinase-binding protein that is involved in the linkage between integrin and the cytoskeleton. Here we show that affixin is a dysferlin binding protein that colocalizes with dysferlin at the sarcolemma of normal human skeletal muscle. The immunoreactivity of affixin was reduced in sarcolemma of MM and LGMD2B muscles, although the total amount of the affixin protein was normal. Altered immunoreactivity of affixin was also observed in other muscle diseases including LGMD1C, where both affixin and dysferlin showed quite similar changes with a reduction of sarcolemmal staining with or without cytoplasmic accumulations. Colocalization of dysferlin and affixin was confirmed by immunofluorescence analysis using dysferlin-expressing C2 myoblasts. Wild-type and mutant dysferlin colocalized with endogenous affixin. The interaction of dysferlin and affixin was confirmed by immunoprecipitation study using normal human and mouse skeletal muscles. Using immunoprecipitation with deletion mutants of dysferlin, we have identified that C-terminal region of dysferlin is an apparent binding site for affixin. We also found N-terminal calponin homology domain of affixin as a binding site for dysferlin. Our results suggest that affixin may participate in membrane repair with dysferlin.
authors.affiliation: Research Institute of Neurobiology, Neuroscience Research Institute, AIST, Central 6, Tsukuba, Ibaraki, Japan. c-matsuda@aist.go.jp
authors.forename: Chie
authors.initials: C
authors.lastname: Matsuda
authors.forename: Kimihiko
authors.initials: K
authors.lastname: Kameyama
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Tagawa
authors.forename: Megumu
authors.initials: M
authors.lastname: Ogawa
authors.forename: Atsushi
authors.initials: A
authors.lastname: Suzuki
authors.forename: Satoshi
authors.initials: S
authors.lastname: Yamaji
authors.forename: Harumasa
authors.initials: H
authors.lastname: Okamoto
authors.forename: Ichizo
authors.initials: I
authors.lastname: Nishino
authors.forename: Yukiko K
authors.initials: YK
authors.lastname: Hayashi
mesh_terms: D000185:Actinin / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D000073939:Dysferlin; D006801:Humans; D007150:Immunohistochemistry; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism / Q000473:pathology; D009136:Muscular Dystrophies / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D012508:Sarcolemma / Q000737:chemistry / Q000378:metabolism*
chemical_list: C114839:DYSF protein, human; D000073939:Dysferlin; D008565:Membrane Proteins; D009124:Muscle Proteins; C486591:PARVB protein, human; C500559:Parvb protein, mouse; D000185:Actinin