title: Bin1 SRC homology 3 domain acts as a scaffold for myofiber sarcomere assembly.
abstract: In skeletal muscle development, the genes and regulatory factors that govern the specification of myocytes are well described. Despite this knowledge, the mechanisms that regulate the coordinated assembly of myofiber proteins into the functional contractile unit or sarcomere remain undefined. Here we explored the hypothesis that modular domain proteins such as Bin1 coordinate protein interactions to promote sarcomere formation. We demonstrate that Bin1 facilitates sarcomere organization through protein-protein interactions as mediated by the Src homology 3 (SH3) domain. We observed a profound disorder in myofiber size and structural organization in a murine model expressing the Bin1 SH3 region. In addition, satellite cell-derived myogenesis was limited despite the accumulation of skeletal muscle-specific proteins. Our experiments revealed that the Bin1 SH3 domain formed transient protein complexes with both actin and myosin filaments and the pro-myogenic kinase Cdk5. Bin1 also associated with a Cdk5 phosphorylation domain of titin. Collectively, these observations suggest that Bin1 displays protein scaffold-like properties and binds with sarcomeric factors important in directing sarcomere protein assembly and myofiber maturation.
authors.affiliation: The Sprott Center for Stem Cell Research, Regenerative Medicine Program, Ottawa, Ontario K1H 8L6, Canada. pasan.fernando@mdsinc.com
authors.forename: Pasan
authors.initials: P
authors.lastname: Fernando
authors.forename: Jacqueline S
authors.initials: JS
authors.lastname: Sandoz
authors.forename: Wen
authors.initials: W
authors.lastname: Ding
authors.forename: Yves
authors.initials: Y
authors.lastname: de Repentigny
authors.forename: Steve
authors.initials: S
authors.lastname: Brunette
authors.forename: John F
authors.initials: JF
authors.lastname: Kelly
authors.forename: Rashmi
authors.initials: R
authors.lastname: Kothary
authors.forename: Lynn A
authors.initials: LA
authors.lastname: Megeney
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002454:Cell Differentiation; D002460:Cell Line; D018507:Gene Expression Regulation, Developmental; D051379:Mice; D008822:Mice, Transgenic; D018485:Muscle Fibers, Skeletal / Q000166:cytology* / Q000378:metabolism / Q000648:ultrastructure; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D012518:Sarcomeres / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D018909:src Homology Domains
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C109221:Bin1 protein, mouse; D009419:Nerve Tissue Proteins; D025521:Tumor Suppressor Proteins