A novel t(6;7)(p24;q21) in a chronic myelocytic leukemia in complete cytogenetic remission after therapy with imatinib mesylate.

Emergence of additional cytogenetic clones in chronic myelocytic leukemia (CML) patients who become Philadelphia chromosome-negative (Ph-) after alpha-interferon therapy (or more recently with imatinib mesylate) have been described. We report here a case of a novel t(6;7)(p21;q23) that developed in a CML patient in complete cytogenetic remission during imatinib therapy. In this case, fluorescence in situ hybridization and reverse transcriptase polymerase chain reaction showed a normal pattern for BCR and ABL genes, suggesting that a different and unrelated clone developed after the disappearance of the Ph chromosome.

MCT1 and its accessory protein CD147 are differentially regulated by TSH in rat thyroid cells.

In thyroid cells, basal and TSH-stimulated glycolysis is associated with lactic acid efflux. In this report, we address whether monocarboxylate transporters (MCTs) are present in thyroid tissue for exporting excess lactic acid generated by aerobic glycolysis. Using immunostaining techniques, we show that MCT4 localizes with its accessory protein CD147 in the basolateral membrane of rat thyroid follicular cells. In cultured rat thyroid (FRTL-5) cells, MCT1 rather than MCT4 is expressed. CD147 colocalizes and coimmunoprecipitates with MCT1. TSH upregulates MCT1/CD147 expression as a function of time through a cAMP-dependent mechanism as forskolin reproduces the effect of TSH. TSH enhances protein expression of both MCT1 and CD147 in FRTL-5 cells. Whereas MCT1 protein expression is controlled at the level of transcription, CD147 protein expression is regulated by a posttranscriptional mechanism. Results of these studies suggest that hormone stimulation of lactate transport is mediated by regulating MCT1 transcription.

Interplay of negative and positive signals controls endoderm-specific expression of the ascidian Cititf1 gene promoter.

Cititf1 is an early and specific marker of endoderm development in Ciona intestinalis [ Development 126, 5149]. Here, we examine Cititf1 transcriptional regulation focusing in particular on its endodermal restricted expression. Through the analysis of Ciona embryos, electroporated with different portions of Cititf1 5'-flanking region fused to lacZ, we characterized a minimal 300-bp cis-regulatory sequence able to closely reproduce the spatial and temporal expression pattern of the endogenous gene. This enhancer contains at least three distinct regulatory regions, two of which are responsible for activation of transcription in the endoderm and in the mesenchyme, respectively, while the third is a negative control element that represses mesenchyme transcription. We have further defined the sequences responsible for transcriptional activation in the endoderm by clustered point mutations and DNA-binding assays.

Ci-GATAa, a GATA-class gene from the ascidian Ciona intestinalis: isolation and developmental expression.

Members of the GATA family of zinc finger transcription factors have been shown to play important roles in controlling gene expression in a variety of cell types in many metazoan. Here, we describe the identification of Ci-GATAa, a member of this gene family, in the ascidian Ciona intestinalis. Whole-mount in situ hybridization showed that Ci-GATAa was expressed in a highly dynamic manner. The maternal transcript was evenly distributed in the embryo during early stages of development; however, the signal gradually decreased until it disappeared at the 64-cell stage. A zygotic transcript was detected at the 110-cell stage in the blastomeres precursors of three different tissues (brain vesicle, mesenchyme, and trunk lateral cells) and the signal was conserved in these territories up to the larval stage, indicating an important role for Ci-GATAa during ascidian differentiation.