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Alzheimer’s disease (AD), like other multifactorial diseases, is the result of a systemic breakdown of different physiological networks. As result, several lines of evidence suggest that it could be more efficiently tackled by molecules directed toward different dysregulated biochemical targets or pathways. In this context, the selection of targets to which the new molecules will be directed is crucial. For years, the design of such multitarget-directed ligands (MTDLs) has been based on the selection of main targets involved in the “cholinergic” and the “β-amyloid” hypothesis. Recently, there have been some reports on MTDLs targeting the glycogen synthase kinase 3β (GSK-3β) enzyme, due to its appealing properties. Indeed, this enzyme is involved in tau hyperphosphorylation, controls a multitude of CNS-specific signaling pathways, and establishes strict connections with several factors implicated in AD pathogenesis. In the present Miniperspective, we will discuss the reasons behind the development of GSK-3β-directed MTDLs and highlight some of the recent efforts to obtain these new classes of MTDLs as potential disease-modifying agents.

A full-length cDNA of the rat liver Nuclear Factor 1 (NF1L21) has been cloned and expressed in S. cerevisiae to analyse the architecture of its activation domain. NF1L21 displays a specific DNA-binding activity, as well as the ability to activate transcription from an artificial NF 1-responsive promoter in yeast. Interaction of two or more NF1L21 molecules with multiple sites on the same promoter activated transcription in a synergistic fashion. Functional analysis of the activation domain of NF1L21 reveals a tripartite structure. Two distinct positive elements are required for NF1L21 -mediated transcription activation. A proline-rich element sandwiched between these two positive domains attenuates their transactivation potential. A shorter NF1L variant (NFlL4) in which the distal positive element is replaced by a different sequence was also isolated. NF1L4 displays the same DNA-binding activity and dimerisation properties as NF1L21, but is unable to activate transcription in yeast.

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.

Hereditary haemochromatosis is an autosomal recessive disorder of iron regulation that results in abnormal intestinal iron absorption with progressive iron overloading of parenchymal cells. Two specific, single point mutations of the HFE gene (C282Y and H63D) have been described in haemochromatosis patients. Epidemiological studies have revealed a strict association between hereditary haemochromatosis and C282Y homozygosis or C282Y/H63D compound heterozygosis, suggesting that these mutations may provide a useful tool for diagnosis. However, recent investigations from southern Europe have reported lower allelic frequencies of the C282Y mutation among haemochromatosis patients, apparently depending on the geographical area of the population analysed. To assess the predictive value of the detection of the C282Y and H63D HFE mutations in our geographical area, we have evaluated their occurrence in 46 haemochromatosis patients from southern Italy. We found that only 19.6% of our patients were homozygous for the C282Y mutation and 21.7% were compound C282Y/H63D heterozygotes. Among the remaining 59%, approximately 40% did not display any of the known HFE mutations. We conclude that, in southern Italy, another genetic determinant/s must be responsible for many haemochromatosis cases and that a genetic screening for the C282Y and H63D HFE mutations is not sufficient for hereditary hae- mochromatosis diagnosis.

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.

We screened a group of patients from southern Italy with clinically diagnosed familial hypercholesterolemia (FH) for mutations of the LDL receptor (LDLR) gene. RNA from each proband was analysed by RT-PCR followed by complete cDNA sequencing. Among 51 unrelated FH families we detected 17 mutations affecting the coding region of the LDLR gene. Five of these mutations, designated R395P, L783fsinsG, IVS15-3C>A, IVS3+5G>A, and 1698-1704delCACCCTAinsGCCCAAT (ITL545MPN), have not yet been reported in the literature. Interestingly, the novel IVS15-3C>A splicing mutation was detected in 20% of our unrelated FH families, suggesting an unusually high prevalence in our local population. Hum Mutat 17:433, 2001. © 2001 Wiley-Liss, Inc.

A human clone corresponding to the gene for the DNA-binding factor LFB3, a protein highly homologous to the liver-specific transcription factor LFB1, has been isolated and partially sequenced. This gene is designated TCF2. Oligonucleotide primers have been designed for LFB3 and used to amplify specifically the human gene in human/rodent somatic cell hybrids using the polymerase chain reaction. By this means, the human LFB3 gene has been mapped to the long arm of chromosome 17, between the centromere and the APL breakpoint.

The transcription start site and promoter of the rat gene coding for the transcription factor NF-1 have been identified. The NF-1 promoter was fused to the chloramphenicol acetyltransferase-coding sequence, and the resulting plasmid was transcriptionally active in the HepG2 cell line. Footprinting and gel retardation analysis indicated that the transcription factor Sp1 binds to the NF-1 promoter. Mutants in the Sp1-binding site displayed a strong reduction in transcriptional activity.

The 5' flanking region of the human alpha 1-antitrypsin (alpha 1-AT) gene contains cis-acting signals for liver-specific expression and, when fused to a reporter gene, is able to drive the expression of this gene specifically in liver cells. Here we report the results of a functional dissection of the alpha 1-AT regulatory region. The expression of the bacterial chloramphenicol-transacetylase (CAT) gene, fused to a set of alpha 1-AT 5' flanking regions shortened by progressive deletions or mutated by base pair substitutions, has been compared by transfection in HepG2 (hepatocyte) and HeLa (non-hepatocyte) human cell lines. A minimal tissue-specific element has been identified between the nucleotides -137 and -37 (from the transcriptional start site). This DNA segment activates the heterologous SV40 promoter in hepatoma cell lines but not in HeLa cells. This element contains at least two regions referred to as the A (-125/-100) and B (-84/-70) domains, both essential for transcription. There are at least two other regulatory domains located upstream of the 'minimal element'; the most active of these is located between positions -261 and -210 from the cap site. These upstream elements activate the heterologous SV40 early promoter both in hepatoma cell lines and in HeLa cells. Upon fractionation of rat liver nuclear extracts two proteins have been identified, alpha 1TF-A and alpha 1TF-B, which bind specifically to the A and B domains respectively. Transcriptionally inactive A and B domain mutants are not able to bind these proteins.