RESUMEN
Huntington disease is caused by the expansion of a polyglutamine repeat in the Huntingtin protein (Htt) that leads to degeneration of neurons in the central nervous system and the appearance of visible aggregates within neurons. We have developed and tested suppressor polypeptides that bind mutant Htt and interfere with the process of aggregation in cell culture. In a Drosophila model, the most potent suppressor inhibits both adult lethality and photoreceptor neuron degeneration. The appearance of aggregates in photoreceptor neurons correlates strongly with the occurrence of pathology, and expression of suppressor polypeptides delays and limits the appearance of aggregates and protects photoreceptor neurons. These results suggest that targeting the protein interactions leading to aggregate formation may be beneficial for the design and development of therapeutic agents for Huntington disease.
Asunto(s)
Proteínas del Tejido Nervioso/química , Proteínas del Tejido Nervioso/genética , Proteínas Nucleares/química , Proteínas Nucleares/genética , Péptidos/química , Animales , Western Blotting , Células COS , Línea Celular , Células Cultivadas , ADN Complementario/metabolismo , Drosophila , Epítopos , Glutatión Transferasa/metabolismo , Proteínas Fluorescentes Verdes , Cinética , Proteínas Luminiscentes/metabolismo , Microscopía Fluorescente , Microscopía por Video , Datos de Secuencia Molecular , Mutación , Neuronas/metabolismo , Células Fotorreceptoras de Invertebrados/metabolismo , Plásmidos , Unión Proteica , Estructura Terciaria de Proteína , Proteínas Recombinantes de Fusión/metabolismo , Secuencias Repetitivas de Aminoácido , Supresión Genética , Factores de Tiempo , TransfecciónRESUMEN
The transmembrane proto-oncogene receptor tyrosine kinase (RTK) ROS is an orphan receptor that is aberrantly expressed in neoplasms of the central nervous system. Here, we report the fusion of its carboxy-terminal kinase domain to the amino-terminal portion of a protein called FIG (Fused in Glioblastoma) in a human glioblastoma multiforme (GBM). By characterizing both FIG and ROS genes in normal and in U118MG GBM cells, we determined that an intra-chromosomal homozygous deletion of 240 kilobases on 6q21 is responsible for the formation of the FIG-ROS locus. The FIG-ROS transcript is encoded by 7 FIG exons and 9 ROS-derived exons. We also demonstrate that the FIG-ROS locus encodes for an in-frame fusion protein with a constitutively active kinase activity, suggesting that FIG-ROS may act as an oncogene. This is the first example of a fusion RTK protein that results from an intra-chromosomal deletion, and it represents the first fusion RTK protein isolated from a human astrocytoma.