RESUMEN
We have identified the Drosophila uba2 protein (dUba2). Analysis of the amino acid composition reveals similarity with both the mammalian (47% identity) and yeast (31% identity) homologues. dUba2 is present throughout the Drosophila life cycle but is most abundant during stages of proliferation. The protein is nucleoplasmic throughout much of the cell cycle, however it is lost from the nucleus during mitosis. The DUba2 localisation in the nucleoplasm is not uniform but is observed as concentrated patches reminiscent of the staining patterns seen for other proteins from this group. The nature of these sites is not clear, however the failure of dUba2 to localise to the sites of chorion amplification in ovaries suggests that they are not sites of ongoing DNA replication.
Asunto(s)
Proteínas de Drosophila , Drosophila melanogaster/genética , Proteínas de Insectos/genética , Proteínas Nucleares/genética , Enzimas Activadoras de Ubiquitina , Secuencia de Aminoácidos , Animales , Femenino , Genes de Insecto , Humanos , Datos de Secuencia Molecular , Proteínas Nucleares/metabolismoRESUMEN
Three promoters have been identified for the human estrogen receptor-alpha gene. The positions of promoters A and B are known whereas that of the recently identified promoter C is not. Cloning and hybridization experiments demonstrated that promoter C is located more than 21 kb upstream of promoter A. The use of the three promoters was examined in estrogen receptor-positive breast cancer cell lines, cell lines derived from other malignancies, and some normal tissues by RT-PCR and transient transfection. All estrogen-responsive breast cancer cell lines used all three promoters, apart from ZR-75 cells, which did not use promoter B in one of two sublines examined. Cell lines derived from other malignancies and other normal tissues that express lower levels of estrogen receptor-alpha showed more selective promoter usage. This suggests that the level of expression of estrogen receptor-alpha is determined by the number of promoters used, rather than the selective use of specific promoters. We also show that promoter C is used more widely than suggested by others. Analysis of a series of estrogen receptor-positive primary breast tumors showed that all three promoters were used in all the tumors. All three promoters were modulated by estrogen in estrogen-responsive breast cancer cell lines: all three promoters were down-regulated by estrogen in MCF-7 cells in which estrogens reduce receptor expression whereas all promoters used were upregulated in T47D, ZR-75, and EFM-19 cells in which estrogens increase receptor expression. This suggests that it is the repertoire of transcription factors present within a cell rather than the selective use of a specific promoter that determines whether estrogen receptor-alpha expression is increased or decreased by estrogen.
Asunto(s)
Estrógenos/metabolismo , Regiones Promotoras Genéticas , Receptores de Estrógenos/genética , Receptores de Estrógenos/metabolismo , Neoplasias de la Mama/genética , Carcinoma/genética , Clonación Molecular , Receptor alfa de Estrógeno , Regulación de la Expresión Génica , Genes Reporteros , Células HeLa , Humanos , Elementos de Respuesta/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Análisis de Secuencia de ADN , Células Tumorales CultivadasRESUMEN
BACKGROUND: There is growing enthusiasm for doing carotid endarterectomy based on duplex examination alone, avoiding the risks of arteriography. Duplex cannot directly visualize proximal carotid or arch lesions. This study evaluates the prevalence of such lesions and the ability of duplex to predict their presence. METHODS: A retrospective review was conducted of 650 consecutive carotid duplex examinations followed by arteriography. RESULTS: Twenty-seven proximal lesions (10 occlusions and 17 stenoses) were predicted by duplex and confirmed by arteriography. One lesion was missed by duplex, for a sensitivity and specificity of 96% and 100%, respectively. The accuracy was 99%, and the negative predictive value was 99%. Prevalence of proximal lesions was 4% overall, but only 3% for stenotic lesions. CONCLUSIONS: Proximal carotid and intrathoracic lesions are rare and can be predicted by duplex scan, thus avoiding arteriography. The absence of such lesions can be inferred with confidence from a negative duplex examination.