The t(3;9)(q11-q12;q22) translocation associated with human extraskeletal myxoid chondrosarcomas results in a chimeric molecule in which the N-terminal domain (NTD) of the TFG (TRK-fused gene) is fused to the TEC (Translocated in Extraskeletal Chondrosarcoma) gene. Little is known about the biological function of TFG-TEC. Because the NTDs of TFG-TEC and TEC are structurally different, and the TFG itself is a cytoplasmic protein, the functional consequences of this fusion in extraskeletal myxoid chondrosarcomas were examined. The results showed that the chimeric gene encoded a nuclear protein that bound DNA with the same sequence specificity as the parental TEC protein. Comparison of the transactivation properties of TFG-TEC and TEC indicated that the former has higher transactivation activity for a known target reporter containing TEC-binding sites. Additional reporter assays for TFG (NTD) showed that the TGF (NTD) of TFG-TEC induced a 12-fold increase in the activation of luciferase from a reporter plasmid containing GAL4 binding sites when fused to the DNA-binding domain of GAL4, indicating that the TFG (NTD) of the TFG-TEC protein has intrinsic transcriptional activation properties. Finally, deletion analysis of the functional domains of TFG (NTD) indicated that the PB1 (Phox and Bem1p) and SPYGQ-rich region of TFG (NTD) were capable of activating transcription and that full integrity of TFG (NTD) was necessary for full transactivation. These results suggest that the oncogenic effect of the t(3;9) translocation may be due to the TFG-TEC chimeric protein and that fusion of the TFG (NTD) to the TEC protein produces a gain-of-function chimeric product.
Long QT syndrome (LQTS) is characterized by the prolongation of the QT interval in ECG and manifests predisposition to life threatening arrhythmia which often leads to sudden cardiac death. We encountered a 3-generation family with 5 affected family members in which LQTS was inherited in autosomal dominant manner. The LQTS is considered an ion channel disorder in which the type and location of the genetic mutation determines to a large extent the expression of the clinical syndrome. Upon screening of the genomic sequences of cardiac potassium ion channel genes, we found a single nucleotide C deletion mutation in the exon 3 of KCNH2 gene that co-segregates with the LQTS in this family. This mutation presumably resulted in a frameshift mutation, P151fs+15X. This study added a new genetic cause to the pool of mutations that lead to defected potassium ion channels in the heart.
Hairless (HR), a transcriptional cofactor, is highly expressed in the skin and brain. To characterize the effects of HR expression in the skin, we examined its capacity for transcriptional regulation of its target genes in mouse skin and keratinocytes. We found that Foxe1 mRNA expression was suppressed in HR-overexpressing skin, as well as in HR-expressing keratinocytes. In turn, Msx1 expression was downregulated contingent on Foxe1 downregulation in skin and keratinocytes. We also found that expression of Sfrp1 was also correlated with that of Foxe1. Further investigation of the mechanisms involved in the transcriptional regulation of these genes will facilitate our understanding of the relationship among genes involved in hair follicle morphogenesis and cycling. [BMB reports 2011; 44(7): 478-483]
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