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


A myosin-Va tail fragment sequesters dynein light chains leading to apoptosis in melanoma cellsTC Izidoro-Toledo1,8, AC Borges1,8, DD Araujo1,2,3, DPS Leitao Mazzi1, FO Nascimento Junior1, JF Sousa1,4, CP Alves1, APB Paiva1, DM Trindade1,5, EV Patussi1,6, PM Peixoto7, KW Kinnally7 and EM Espreafico*,1Previous studies proposed that myosin-Va regulates apoptosis by sequestering pro-apoptotic Bmf to the actin cytoskeletonthrough dynein light chain-2 (DLC2). Adhesion loss or other cytoskeletal perturbations would unleash Bmf, allowing it to bindand 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 ascaspase-9/-3 activation and DNA fragmentation indicated that melanoma cells died of apoptosis. Immobilized MVaf interacteddirectly with DLCs, but complexed MVaf/DLCs did not interact with Bmf. Overexpression of DLC2 attenuated MVaf-inducedapoptosis. Thus, we suggest that MVaf induces apoptosis by sequestering DLC2 and DLC1, thereby unleashing the pair ofsensitizer and activator of apoptosis, the 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.Cell Death and Disease (2013) 4, e547; doi:10.1038/cddis.2013.45; published online 21 March 2013Subject Category: Cancer (AU)

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