title: A myosin-Va tail fragment sequesters dynein light chains leading to apoptosis in melanoma cells.
abstract: Previous studies proposed that myosin-Va regulates apoptosis by sequestering pro-apoptotic Bmf to the actin cytoskeleton through dynein light chain-2 (DLC2). Adhesion loss or other cytoskeletal perturbations would unleash Bmf, allowing it to bind and inhibit pro-survival Bcl2 proteins. Here, we demonstrated that overexpression of a myosin-Va medial tail fragment (MVaf) harboring the binding site for DLC2 dramatically decreased melanoma cell viability. Morphological and molecular changes, including surface blebbing, mitochondrial outer membrane permeabilization, cytochrome-c and Smac release, as well as caspase-9/-3 activation and DNA fragmentation indicated that melanoma cells died of apoptosis. Immobilized MVaf interacted directly with DLCs, but complexed MVaf/DLCs did not interact with Bmf. Overexpression of DLC2 attenuated MVaf-induced apoptosis. Thus, we suggest that, MVaf induces apoptosis by sequestering DLC2 and DLC1, thereby unleashing the pair of sensitizer and activator BH3-only proteins Bmf and Bim. Murine embryonic fibroblasts (MEFs) lacking Bim and Bmf or Bax and Bak were less sensitive to apoptosis caused by MVaf expression than wild-type MEFs, strengthening the putative role of the intrinsic apoptotic pathway in this response. Finally, MVaf expression attenuated B16-F10 solid tumor growth in mice, suggesting that this peptide may be useful as an apoptosis-inducing tool for basic and translational studies.
authors.affiliation: Department of Cellular and Molecular Biology and Pathogenic Bioagents, Faculty of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil.
authors.forename: T C
authors.initials: TC
authors.lastname: Izidoro-Toledo
authors.forename: A C
authors.initials: AC
authors.lastname: Borges
authors.forename: D D
authors.initials: DD
authors.lastname: Araújo
authors.forename: D P S Leitão
authors.initials: DP
authors.lastname: Mazzi
authors.forename: F O
authors.initials: FO
authors.lastname: Nascimento Júnior
authors.forename: J F
authors.initials: JF
authors.lastname: Sousa
authors.forename: C P
authors.initials: CP
authors.lastname: Alves
authors.forename: A P B
authors.initials: AP
authors.lastname: Paiva
authors.forename: D M
authors.initials: DM
authors.lastname: Trindade
authors.forename: E V
authors.initials: EV
authors.lastname: Patussi
authors.forename: P M
authors.initials: PM
authors.lastname: Peixoto
authors.forename: K W
authors.initials: KW
authors.lastname: Kinnally
authors.forename: E M
authors.initials: EM
authors.lastname: Espreafico
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins / Q000172:deficiency / Q000235:genetics; D000072224:Bcl-2-Like Protein 11; D045744:Cell Line, Tumor; D056445:Cytoplasmic Dyneins / Q000235:genetics* / Q000378:metabolism; D053938:DNA Fragmentation / Q000187:drug effects; D005347:Fibroblasts / Q000378:metabolism / Q000473:pathology; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D008545:Melanoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D008565:Membrane Proteins / Q000172:deficiency / Q000235:genetics; D051379:Mice; D018345:Mice, Knockout; D018995:Myosin Heavy Chains / Q000235:genetics* / Q000378:metabolism; D024701:Myosin Type V / Q000235:genetics* / Q000378:metabolism; D009368:Neoplasm Transplantation; D010446:Peptide Fragments / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology; D011485:Protein Binding; D011518:Proto-Oncogene Proteins / Q000172:deficiency / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects; D012878:Skin Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D050998:bcl-2 Homologous Antagonist-Killer Protein / Q000172:deficiency / Q000235:genetics
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D051017:Apoptosis Regulatory Proteins; C000606775:BCL2L11 protein, human; C486655:BMF protein, human; C494773:Bak1 protein, mouse; D000072224:Bcl-2-Like Protein 11; C000606776:Bcl2l11 protein, mouse; D008565:Membrane Proteins; D010446:Peptide Fragments; D011518:Proto-Oncogene Proteins; D050998:bcl-2 Homologous Antagonist-Killer Protein; C077511:MYO5A protein, human; C427758:DYNLL1 protein, human; D024701:Myosin Type V; D018995:Myosin Heavy Chains; D056445:Cytoplasmic Dyneins; C501531:DYNLL2 protein, human