RESUMO
BCL-2 family proteins regulate the mitochondrial apoptotic pathway. BOK, a multidomain BCL-2 family protein, is generally believed to be an adaptor protein similar to BAK and BAX, regulating the mitochondrial permeability transition during apoptosis. Here we report that BOK is a positive regulator of a key enzyme involved in uridine biosynthesis; namely, uridine monophosphate synthetase (UMPS). Our data suggest that BOK expression enhances UMPS activity, cell proliferation, and chemosensitivity. Genetic deletion of Bok results in chemoresistance to 5-fluorouracil (5-FU) in different cell lines and in mice. Conversely, cancer cells and primary tissues that acquire resistance to 5-FU down-regulate BOK expression. Furthermore, we also provide evidence for a role for BOK in nucleotide metabolism and cell cycle regulation. Our results have implications in developing BOK as a biomarker for 5-FU resistance and have the potential for the development of BOK-mimetics for sensitizing 5-FU-resistant cancers.
Assuntos
Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Uridina/metabolismo , Animais , Apoptose/efeitos dos fármacos , Biomarcadores Tumorais/metabolismo , Proliferação de Células/efeitos dos fármacos , Dano ao DNA , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Fluoruracila/farmacologia , Mamíferos , Camundongos , Complexos Multienzimáticos/metabolismo , Orotato Fosforribosiltransferase/metabolismo , Orotidina-5'-Fosfato Descarboxilase/metabolismo , Ligação Proteica/efeitos dos fármacos , Domínios Proteicos , Proteínas Proto-Oncogênicas c-bcl-2/química , Proteína Supressora de Tumor p53/metabolismoRESUMO
Here, we review recent studies aimed at defining the importance of quaternary structure to a model oligomeric enzyme, dihydrodipicolinate synthase. This will illustrate the complementary and synergistic outcomes of coupling the techniques of analytical ultracentrifugation with enzyme kinetics, in vitro mutagenesis, macromolecular crystallography, small angle X-ray scattering, and molecular dynamics simulations, to demonstrate the role of subunit self-association in facilitating protein dynamics and enzyme function. This multitechnique approach has yielded new insights into the molecular evolution of protein quaternary structure.