RESUMEN
Tumor necrosis factor (TNF) superfamily members BAFF, or B-cell activation factor of the TNF family, and APRIL, a proliferation-inducing ligand, are involved in normal B-cell survival and differentiation. They interact with 3 receptors: BAFF-R, specific to BAFF; and TACI and BCMA, which are shared by BAFF and APRIL. We tested the potential role of these proteins in B-cell chronic lymphocytic leukemia (B-CLL) resistance to apoptosis. TACI and BAFF-R mRNAs were found in leukemic B cells. BAFF and APRIL mRNAs and proteins were detected in B-CLL leukemic cells and normal blood or tonsil-derived B lymphocytes. Yet, in contrast to normal B lymphocytes, BAFF and APRIL were expressed at the membranes of leukemic cells. Adding soluble BAFF or APRIL protected B-CLL cells against spontaneous and drug-induced apoptosis and stimulated NF-kappaB activation. Conversely, adding soluble BCMA-Fc or anti-BAFF and anti-APRIL antibodies enhanced B-CLL apoptosis. Moreover, a soluble form of BAFF was detected using surface-enhanced laser desorption/ionization-time-of-flight mass spectrometry (SELDI-TOF MS) in the sera of B-CLL patients but not of healthy donors. Taken together, our results indicate that B-CLL cells can be rescued from apoptosis through an autocrine process involving BAFF, APRIL, and their receptors. Inhibiting BAFF and APRIL pathways may be of therapeutic value for B-CLL treatment.
Asunto(s)
Regulación Neoplásica de la Expresión Génica/genética , Leucemia Linfocítica Crónica de Células B/sangre , Leucemia Linfocítica Crónica de Células B/patología , Proteínas de la Membrana/genética , Neuropéptidos/genética , Factor de Necrosis Tumoral alfa/genética , Anciano , Anticuerpos , Apoptosis , Factor Activador de Células B , Secuencia de Bases , Cartilla de ADN , Femenino , Citometría de Flujo , Humanos , Leucemia Linfocítica Crónica de Células B/genética , Masculino , Espectrometría de Masas , Proteínas de la Membrana/sangre , Proteínas de la Membrana/inmunología , Persona de Mediana Edad , FN-kappa B/metabolismo , Estadificación de Neoplasias , Neuropéptidos/sangre , Neuropéptidos/inmunología , Proteínas Nucleares , Nucleosomas/genética , ARN Mensajero/genética , Receptores del Factor de Necrosis Tumoral/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Miembro 13 de la Superfamilia de Ligandos de Factores de Necrosis Tumoral , Factor de Necrosis Tumoral alfa/inmunologíaRESUMEN
Centrosomes provide docking sites for regulatory molecules involved in the control of the cell division cycle. The centrosomal matrix contains several proteins, which anchor kinases and phosphatases. The large A-Kinase Anchoring Protein AKAP450 is acting as a scaffolding protein for other components of the cell signaling machinery. We selectively perturbed the centrosome by modifying the cellular localization of AKAP450. We report that the expression in HeLa cells of the C terminus of AKAP450, which contains the centrosome-targeting domain of AKAP450 but not its coiled-coil domains or binding sites for signaling molecules, leads to the displacement of the endogenous centrosomal AKAP450 without removing centriolar or pericentrosomal components such as centrin, gamma-tubulin, or pericentrin. The centrosomal protein kinase A type II alpha was delocalized. We further show that this expression impairs cytokinesis and increases ploidy in HeLa cells, whereas it arrests diploid RPE1 fibroblasts in G1, thus further establishing a role of the centrosome in the regulation of the cell division cycle. Moreover, centriole duplication is interrupted. Our data show that the association between centrioles and the centrosomal matrix protein AKAP450 is critical for the integrity of the centrosome and for its reproduction.