Vincenzo De Simone

Transcriptional regulation of liver-specific gene expression.

Abstract Liver-specific gene expression is regulated by four families of transcriptional activatory proteins that are not liver-specific, but are still restricted to a subset of tissues. The current opinion is that liver-specificity is a consequence of the combinatorial action of these factors, which could represent ‘functional compartments’ coexisting in the hepatocyte.

Direct targets of Klf5 transcription factor contribute to the maintenance of mouse embryonic stem cell undifferentiated state.

BackgroundA growing body of evidence has shown that Krüppel-like transcription factors play a crucial role in maintaining embryonic stem cell (ESC) pluripotency and in governing ESC fate decisions. Krüppel-like factor 5 (Klf5) appears to play a critical role in these processes, but detailed knowledge of the molecular mechanisms of this function is still not completely addressed.ResultsBy combining genome-wide chromatin immunoprecipitation and microarray analysis, we have identified 161 putative primary targets of Klf5 in ESCs. We address three main points: (1) the relevance of the pathways governed by Klf5, demonstrating that suppression or constitutive expression of single Klf5 targets robustly affect the ESC undifferentiated phenotype; (2) the specificity of Klf5 compared to factors belonging to the same family, demonstrating that many Klf5 targets are not regulated by Klf2 and Klf4; and (3) the specificity of Klf5 function in ESCs, demonstrated by the significant differences between Klf5 targets in ESCs compared to adult cells, such as keratinocytes.ConclusionsTaken together, these results, through the definition of a detailed list of Klf5 transcriptional targets in mouse ESCs, support the important and specific functional role of Klf5 in the maintenance of the undifferentiated ESC phenotype.See: http://www.biomedcental.com/1741-7007/8/125

Short and highly efficient synthetic promoters for melanoma-specific gene expression.

Here, we report the construction and functional analysis of synthetic promoters designed for gene therapy applications requiring strong and specific gene expression in melanoma cell lines. We have analysed the transcriptional activity of different combinations of two transcriptional regulatory modules, a melanocyte‐specific element from the human tyrosinase promoter and a cell‐cycle‐specific element from the human α‐fetoprotein promoter. Transient expression assays in different cell lines show that several of these composite synthetic promoters can drive a strong and selective expression of a reporter gene in melanoma cell, providing us with a new powerful tool for gene therapy of melanomas.

Increased carotid artery intima-media thickness is associated with a novel mutation of low-density lipoprotein receptor independently of major cardiovascular risk factors

The current study sought to investigate the role of low-density lipoprotein receptor (LDLr) mutations in assessing the risk profile of familial hypercholesterolemia (FH) patients, independently of major cardiovascular risk factors. FH due to LDLr mutations is associated with premature atherosclerosis. The variable clinical severity of the disease in heterozygotes has been related to cholesterol levels and the coexistence of other cardiovascular risk factors, but the independent role of different LDLr mutations is still unclear. cDNA of LDL gene was sequenced in 102 patients with clinical features of heterozygous FH. Carotid artery intima-media thickness (IMT) was measured by B-mode ultrasound imaging in all patients. Sixteen different mutations (5 never described) were found in 82 patients (49 families; mean age, 39 years; 53% women). One of the newly described mutations, the 2312-3 C-->A, was found in 24 patients (13 families). The mean of maximum thicknesses was significantly higher in the 2312-3 C-->A group than in patients with other LDLr mutations (P=.004 after adjustment for major cardiovascular risk factors). Similar results (P=.001) were obtained in the adjusted comparisons of probands only, and of the patients with similar baseline cholesterol (P=.002). This study indicates that the identification of an LDLr mutation can help to assess the risk profile of FH patients independently of the major cardiovascular risk factors.

Transcriptional Control of Gene Expression in Hepatic Cells

In this chapter, we review the regulation of gene expression in hepatic cells, with emphasis on the cis-acting elements located in the proximal promoter region and on the properties of the transcriptional factors active in liver.