A myosin-Va tail fragment sequesters dynein light chains leading to apoptosis in melanoma cells

• Published in: Cell death & disease 2013-03, Vol.4 (3), p.e547-e547
• Main Authors: Izidoro-Toledo, T C, Borges, A C, Araújo, D D, Leitão Mazzi, D P S, Nascimento, F O, Sousa, J F, Alves, C P, Paiva, A P B, Trindade, D M, Patussi, E V, Peixoto, P M, Kinnally, K W, Espreafico, E M
• Format: Article
• Language: English
• Subjects: 631/67/1813/1634; 631/80/82/23; Adaptor Proteins, Signal Transducing - genetics; Adaptor Proteins, Signal Transducing - metabolism; Animals; Antibodies; Apoptosis - drug effects; Apoptosis Regulatory Proteins - deficiency; Apoptosis Regulatory Proteins - genetics; bcl-2 Homologous Antagonist-Killer Protein - deficiency; bcl-2 Homologous Antagonist-Killer Protein - genetics; Bcl-2-Like Protein 11; Biochemistry; Biomedical and Life Sciences; Cell Biology; Cell Culture; Cell Line, Tumor; Cytoplasmic Dyneins - genetics; Cytoplasmic Dyneins - metabolism; DNA Fragmentation - drug effects; Fibroblasts - metabolism; Fibroblasts - pathology; Gene Expression Regulation, Neoplastic - drug effects; Humans; Immunology; Life Sciences; Melanoma - genetics; Melanoma - metabolism; Melanoma - pathology; Membrane Proteins - deficiency; Membrane Proteins - genetics; Mice; Mice, Knockout; Myosin Heavy Chains - genetics; Myosin Heavy Chains - metabolism; Myosin Type V - genetics; Myosin Type V - metabolism; Neoplasm Transplantation; Original; original-article; Peptide Fragments - genetics; Peptide Fragments - metabolism; Peptide Fragments - pharmacology; Protein Binding; Proto-Oncogene Proteins - deficiency; Proto-Oncogene Proteins - genetics; Signal Transduction - drug effects; Skin Neoplasms - genetics; Skin Neoplasms - metabolism; Skin Neoplasms - pathology
• ISSN: 2041-4889
• DOI: 10.1038/cddis.2013.45

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.