RESUMEN
Hemoglobin (Hb) variants involving alpha-chains are less common in the global population than Hb variants resulting from beta-chain alterations. Generally, alpha-chain Hb variants are caused by point mutations affecting alpha-1 and/or alpha-2 genes of the alpha-globin cluster (HBA1 and HBA2). In Brazil, the most prevalent alpha-chain Hb variant is Hb Hasharon. In this study, we present the first case of an Hb Val de Marne variant in the Americas, specifically in Brazil.
Asunto(s)
Hemoglobinas Anormales/genética , Adulto , Sustitución de Aminoácidos , Brasil , Femenino , Genética de Población , Genotipo , Hemoglobinas Anormales/metabolismo , Humanos , Mutación , Mutación PuntualRESUMEN
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.