Filamin C (FLNc) and Xin actin-binding repeat-containing proteins (XIRPs) are multi-adaptor proteins that are mainly expressed in cardiac and skeletal muscles and which play important roles in the assembly and repair of myofibrils and their attachment to the membrane. We identified the dystrophin-binding protein aciculin (also known as phosphoglucomutase-like protein 5, PGM5) as a new interaction partner of FLNc and Xin. All three proteins colocalized at intercalated discs of cardiac muscle and myotendinous junctions of skeletal muscle, whereas FLNc and aciculin also colocalized in mature Z-discs. Bimolecular fluorescence complementation experiments in developing cultured mammalian skeletal muscle cells demonstrated that Xin and aciculin also interact in FLNc-containing immature myofibrils and areas of myofibrillar remodeling and repair induced by electrical pulse stimulation (EPS). Fluorescence recovery after photobleaching (FRAP) experiments showed that aciculin is a highly dynamic and mobile protein. Aciculin knockdown in myotubes led to failure in myofibril assembly, alignment and membrane attachment, and a massive reduction in myofibril number. A highly similar phenotype was found upon depletion of aciculin in zebrafish embryos. Our results point to a thus far unappreciated, but essential, function of aciculin in myofibril formation, maintenance and remodeling.
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http://dx.doi.org/10.1242/jcs.152157 | DOI Listing |
Hum Mol Genet
July 2016
Department of Molecular Cell Biology, Institute for Cell Biology, University of Bonn, D53121 Bonn, Germany
Filamin c (FLNc) is a large dimeric actin-binding protein located at premyofibrils, myofibrillar Z-discs and myofibrillar attachment sites of striated muscle cells, where it is involved in mechanical stabilization, mechanosensation and intracellular signaling. Mutations in the gene encoding FLNc give rise to skeletal muscle diseases and cardiomyopathies. Here, we demonstrate by fluorescence recovery after photobleaching that a large fraction of FLNc is highly mobile in cultured neonatal mouse cardiomyocytes and in cardiac and skeletal muscles of live transgenic zebrafish embryos.
View Article and Find Full Text PDFJ Cell Sci
August 2014
Institute for Cell Biology, University of Bonn, 53121 Bonn, Germany
Filamin C (FLNc) and Xin actin-binding repeat-containing proteins (XIRPs) are multi-adaptor proteins that are mainly expressed in cardiac and skeletal muscles and which play important roles in the assembly and repair of myofibrils and their attachment to the membrane. We identified the dystrophin-binding protein aciculin (also known as phosphoglucomutase-like protein 5, PGM5) as a new interaction partner of FLNc and Xin. All three proteins colocalized at intercalated discs of cardiac muscle and myotendinous junctions of skeletal muscle, whereas FLNc and aciculin also colocalized in mature Z-discs.
View Article and Find Full Text PDFActa Neuropathol
June 2000
Department of Medicine, Showa University Fujigaoka Hospital, Yokohama, Japan.
Aciculin is a novel adherens junction antigen extracted from human uterine smooth muscle that is reported to associate biochemically with dystrophin. We attempted to determine (i) the immunostainability of anti-aciculin antibody for the 6 histochemically normal human muscles and seven muscles from boys with Duchenne muscular dystrophy (DMD) and 11 disease control muscles, (ii) the ultrastructural localization of aciculin in normal skeletal myofibers, (iii) aciculin's spacial relationship with dystrophin and beta-spectrin, and (iv) if the aciculin is ultrastructurally colocalized with dystrophin, the distance from the aciculin epitope to the epitope of the dystrophin N- or C-terminal domain. For this, rabbit anti-aciculin antibody was generated against the synthetic peptide of aciculin fragment D [4].
View Article and Find Full Text PDFCell Adhes Commun
November 1996
Dept. of Cell Biology and Anatomy, Univ. of North Carolina, Chapel Hill 27599-7090, USA.
We report that cranin (dystroglycan) can become recruited to focal adhesions of cultured rat REF 52 fibroblasts and human aortic smooth muscle cells. Within mature focal adhesions, cranin was present within the plaque region defined by beta 1 integrin, vinculin and phosphotyrosine staining, but occupied a larger domain corresponding to the terminal segments of stress fibers that was more precisely co-extensive with the cytoskeletal proteins alpha-actinin, utrophin and aciculin. When REF 52 fibroblasts were plated on different substrata in the absence of protein synthesis and secretion in serum-free medium, focal clusters of cranin readily formed within 2 hours on matrix proteins that bind cranin directly (laminin or agrin) which were maintained as the focal adhesions became mature.
View Article and Find Full Text PDFEur J Biochem
January 1996
Department of Biochemistry, University of Leicester, UK.
A 60-kDa protein localised in adherens-type cellular junctions, and previously called aciculin, has been found to interact with the cytoskeletal proteins dystrophin and utrophin [Belkin, A. M. & Burridge, K.
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