title: BPAG1a and b associate with EB1 and EB3 and modulate vesicular transport, Golgi apparatus structure, and cell migration in C2.7 myoblasts.
abstract: BPAG1a and BPAG1b (BPAG1a/b) constitute two major isoforms encoded by the dystonin (Dst) gene and show homology with MACF1a and MACF1b. These proteins are members of the plakin family, giant multi-modular proteins able to connect the intermediate filament, microtubule and microfilament cytoskeletal networks with each other and to distinct cell membrane sites. They also serve as scaffolds for signaling proteins that modulate cytoskeletal dynamics. To gain better insights into the functions of BPAG1a/b, we further characterized their C-terminal region important for their interaction with microtubules and assessed the role of these isoforms in the cytoskeletal organization of C2.7 myoblast cells. Our results show that alternative splicing does not only occur at the 5' end of Dst and Macf1 pre-mRNAs, as previously reported, but also at their 3' end, resulting in expression of additional four mRNA variants of BPAG1 and MACF1. These isoform-specific C-tails were able to bundle microtubules and bound to both EB1 and EB3, two microtubule plus end proteins. In the C2.7 cell line, knockdown of BPAG1a/b had no major effect on the organization of the microtubule and microfilament networks, but negatively affected endocytosis and maintenance of the Golgi apparatus structure, which became dispersed. Finally, knockdown of BPAG1a/b caused a specific decrease in the directness of cell migration, but did not impair initial cell adhesion. These data provide novel insights into the complexity of alternative splicing of Dst pre-mRNAs and into the role of BPAG1a/b in vesicular transport, Golgi apparatus structure as well as in migration in C2.7 myoblasts.
authors.affiliation: Department of Clinical Research, University of Bern, Bern, Switzerland; Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland; Department of Dermatology, Inselspital, Bern University Hospital, Bern, Switzerland.
authors.forename: Kseniia
authors.initials: K
authors.lastname: Poliakova
authors.affiliation: Department of Pathology and Cell Biology, Columbia University College of Physicians and Surgeons, New York, New York, United States of America.
authors.forename: Adijat
authors.initials: A
authors.lastname: Adebola
authors.affiliation: Department of Pathology and Cell Biology, Columbia University College of Physicians and Surgeons, New York, New York, United States of America.
authors.forename: Conrad L
authors.initials: CL
authors.lastname: Leung
authors.affiliation: Department of Clinical Research, University of Bern, Bern, Switzerland; Department of Dermatology, Inselspital, Bern University Hospital, Bern, Switzerland.
authors.forename: Bertrand
authors.initials: B
authors.lastname: Favre
authors.affiliation: Department of Pathology and Cell Biology, Columbia University College of Physicians and Surgeons, New York, New York, United States of America.
authors.forename: Ronald K H
authors.initials: RK
authors.lastname: Liem
authors.affiliation: Department of Clinical Research, University of Bern, Bern, Switzerland.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Schepens
authors.affiliation: Department of Clinical Research, University of Bern, Bern, Switzerland; Department of Dermatology, Inselspital, Bern University Hospital, Bern, Switzerland.
authors.forename: Luca
authors.initials: L
authors.lastname: Borradori
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D017398:Alternative Splicing; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D002460:Cell Line; D002465:Cell Movement / Q000502:physiology*; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism; D000071821:Dystonin; D004705:Endocytosis / Q000502:physiology*; D006056:Golgi Apparatus / Q000378:metabolism*; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism; D008969:Molecular Sequence Data; D032446:Myoblasts / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D020033:Protein Isoforms / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; C095667:Dst protein, mouse; D000071821:Dystonin; C584107:EB1 protein, mouse; C522423:EB3 protein, mouse; D008869:Microtubule-Associated Proteins; D009419:Nerve Tissue Proteins; D020033:Protein Isoforms