Search PubMed⌕ Search

Biomedical subjects

T Russo

Publications and source records attributed to T Russo.

At least 55 records · Page 3Linked to original sources
PubMed1994

The DNA sequence encompassing the transcription start site of a TATA-less promoter contains enough information to drive neuron-specific transcription.

The FE65 gene encodes a nuclear protein of unknown function that is expressed in several areas of the rat nervous system during development and in the adult animal, particularly in somatic and visceral ganglia. FE65 mRNA is abundant in neuronal cell lines, whereas it is barely detectable in non-neuronal cells. We identified the two transcription start sites of the FE65 gene and we isolated the rat genomic fragment containing one of these two transcriptional start sites. We demonstrate that this fragment contains a promoter able to direct an efficient transcription of a reporter gene in PC12 cells and in NTERA2 cells upon their differentiation with retinoic acid, whereas it functions poorly in non-neuronal cells, such as Rat2 fibroblasts and BRL hepatocytes. This promoter is composed of two regions. The first includes a cis-element whose removal greatly decreases the transcriptional efficiency in all cells examined and which forms similar complexes with proteins from PC12 and Rat2 cells. This cis-element binds Sp1 or another GC-binding factor. The second cis-element encompasses the transcription start site and is still able to direct transcription only in neuronal cells. The DNA-protein complexes formed by this cis-element in neuronal cells differ from those formed in non-neuronal cells. The analysis of point mutations in this region indicates that the proteins that bind to this cis-element interact with both overlapping and distinct nucleotide sequences.

Amino Acid Sequence↗
PubMed1994

The DNA-binding efficiency of Sp1 is affected by redox changes.

We have previously demonstrated that the DNA-binding efficiency of Sp1 is greatly decreased in nuclear extracts from 30-month-old rat tissues compared to those from young ones, although its gene appears to be normally expressed. As reactive oxygen intermediates are known to accumulate in aged animals, we investigated the effect of oxidation on the Sp1 DNA-binding activity. Electrophoretic mobility shift assays and DNase I footprintings showed that high concentrations of dithiothreitol, added to the aged tissue extracts, fully restore the Sp1 DNA-binding efficiency. However, in young nuclear extracts hydrogen peroxide treatment strongly decreases the Sp1 DNA-binding activity that is restored by the treatment with high dithiothreitol concentrations. To ascertain whether the oxidative stress is directed toward the Sp1 molecule alone, or whether it acts on unknown Sp1 cofactor(s) necessary for DNA binding, we purified Sp1 from young rat liver and demonstrated that when the purified protein is added to aged nuclear extracts, it efficiently binds to its DNA cis-element. Moreover, purified Sp1 treated with hydrogen peroxide lost its ability to bind its cis-element and the DNA-binding efficiency was fully restored after incubation with dithiothreitol.

Aging↗
PubMed1994

Inhibition of the differentiation of human myeloid cell lines by redox changes induced through glutathione depletion.

We have investigated the effect of redox changes in vivo on the differentiation of two human myeloid cell lines, HL-60 and KG-1. The glutathione-depleting agent diethyl maleate (DEM) prevented the development of differentiated features in response to phorbol esters, including adherence of the cells to plastic surfaces and repression of the myeloperoxidase and CD34 genes. Moreover, DEM abolished phorbol 12-myristate 13-acetate-induced activation of the transcription factors AP-1 and Egr-1, suggesting that inhibition of differentiation may be due, at least in part, to redox modifications of these proteins.

Antigens, CD↗
PubMed1994

Prognostic value of early postoperative calcitonin level in medullary thyroid carcinoma.

AIMS: Serum calcitonin (CT) assay is commonly used in the diagnosis and follow-up of medullary thyroid carcinoma (MTC). The aim of this study was to ascertain whether serum CT levels, measured in the first few days after surgery, could be used to evaluate the efficacy of treatment. METHODS: A group of 33 patients was studied. In all patients the follow-up was more than 20 months. RESULTS: Preoperatively basal CT serum levels were high in all patients. Twenty-four hours after surgery CT serum levels dropped to within the normal range in 8 patients and 72 hours after operation in 7 others. In this group 1 patient was at stage I, 11 at stage II and 3 at stage III. Basal and pentagastrin stimulated CT levels continued to be in the normal range in these 15 patients 6 and 12 months after surgery and at the subsequent year by follow-up visits. No clinical or radiological evidence of disease was found during the follow-up in this group. In the other 18 patients CT was reduced but still high 72 hours after surgery; 6 months later basal serum CT levels continued to be elevated or responsive to pentagastrin stimulation. In this group restaging showed tumor relapse in the thyroid bed in 2 patients, cervical lymphadenopathy in 11, and distant metastases (bone, liver) in 3. CONCLUSIONS: Immediate postoperative CT serum levels seem to be the most useful index to evaluate the efficacy of surgical treatment and the presence of residual neoplastic tissue.

Adolescent↗
PubMed1994

Transcriptional regulation of the human H ferritin-encoding gene (FERH) in G418-treated cells: role of the B-box-binding factor.

We have analysed the molecular basis underlying the increase in ferritin heavy-chain mRNA (FERH) levels in cells exposed to the antibiotic Geneticin (G418). Transient transfection experiments demonstrate that this increase is paralleled by an enhanced transcription driven by the promoter (pFERH) for the human FERH gene, in which the most proximal promoter element (B-box) appears to play a key role. This region is conserved in human and rat, and binds an unknown factor. The DNA-protein complex composed of B-box-binding factor and its cis-element becomes more abundant in the G418-treated cells, as compared with the untreated ones.

Animals↗
PubMed1994

Expression of the soluble lectin L-14 gene is induced by TSH in thyroid cells and suppressed by retinoic acid in transformed neural cells.

Expression of the soluble lectin L-14 is low in normal and very high in transformed thyroid cells. We show that L-14 gene expression is transiently induced upon thyrotropin stimulation of normal quiescent FRTL-5 rat thyroid cells. Permanent activation of L-14 gene expression is obtained in the same cells infected with a wild-type and a temperature sensitive mutant of Kirsten murine sarcoma virus, both at the permissive and non permissive temperature for transformation. We also find that L-14 mRNA is undetectable in rat brain but is abundant in rat oligodendrocytes precursors transformed by polyoma middle T oncogene. Retinoic acid treatment of these transformed cells leads to acquisition of a differentiated phenotype accompanied by a 30-fold decrease of L-14 mRNA levels. Removal of retinoic acid restores both the transformed undifferentiated phenotype and high L-14 expression. Taken together these results indicate that growth stimulation and induction of cell differentiation are accompanied by strong modulation of L-14 gene expression.

Animals↗
PubMed1994

Growth-arrested dependence of aldolase A L-type mRNA expression in rodent cell lines.

Two ubiquitous (L- and F-type) and one muscle-specific (M-type) mRNA species are generated by the human aldolase A gene. Despite the high degree of sequence similarities in the promoter region between human and rodents, no L-type mRNA expression has yet been found in the latter. Here we demonstrate that L-type aldolase A mRNA is expressed during the differentiation of mouse myogenic C2.7 and rat oligodendrocyte precursor CEINGE C13 cells. The L-type mRNA expression is increased during differentiation and is associated with cell-growth arrest caused by nocodazole treatment or serum deprivation in C2.7 and CEINGE C13 cells, respectively. The L-type aldolase A mRNA is correctly processed at the L1-L2 junction.

Animals↗
PubMed1994

Expression of the neuron-specific FE65 gene marks the development of embryo ganglionic derivatives.

The major transcript of the FE65 gene is a neuron-specific mRNA that encodes a nuclear protein whose aminoterminal domain strongly activates the transcription of a reporter gene when fused to a heterologous DNA-binding domain. FE65 gene expression is regulated during neuronal differentiation of the NTERA-2 cell line, and it is temporally and spatially restricted during mouse embryo development. It is first detected around day 10 of gestation in the basal plate of the neural tube, and then, at the subsequent stages of development and in the newborn animals, it is found solely in neural structures. Its expression is most abundant in the neural crest derivatives (e.g. spinal and encephalic ganglia), ganglionic structures of sense organs (ganglionic layer of the retina and olfactory epithelium), as well as the ganglionic structures of the autonomic nervous system. Thus FE65 gene expression can be considered a marker of the development of embryo ganglionic derivatives.

Animals↗
PubMed1993

Immortalization of a cell line showing some characteristics of the oligodendrocyte phenotype.

We have used the polyoma middle T oncogene to immortalize cells from rat embryo encephalon. Immunostaining experiments with monoclonal antibodies demonstrated that the cells of one of the obtained lines, named CEINGE CL3, are stained by anti-vimentin and anti-S100 antibodies, are not stained by anti-neurofilaments (NF) or anti-glial fibrillary acidic-protein (GFAP) antibodies. Only a subset of the CEINGE CL3 cells (20-30%) is stained by an anti-galactocerebroside antibody. Northern blot analysis demonstrated that these cells express low levels of proteolipid protein mRNA, whereas polymerase chain reaction (PCR) amplification failed to evidentiate the presence of both NF and GFAP mRNAs. Either retinoic acid or forskolin treatments or a combination of them are able to induce morphological changes that are accompanied by a complete growth arrest.

Animals↗
PubMed1993

Isolation and structural characterization of the rat gene encoding the brain specific snRNP-associated polypeptide "N".

We isolated the gene encoding the brain specific snRNP-associated polypeptide "N" from a rat genomic library. Some intronless genes have previously been reported for this polypeptide in the rat. In contrast, our gene consists of at least nine exons (the last exon(s) encoding the 3'-end of the mRNA has not been isolated). The second intron of the gene is probably so long as to hamper the cloning of the complete gene into a single phage vector. Therefore, we used polymerase chain reaction amplification of the rat genome with oligonucleotides designed on the basis of known cDNA sequences that allowed us to isolate and clone the first two exons at the 5'-end of the gene. Primer extension studies revealed multiple transcription start sites, all of them contained within the first exon. The intron/exon organization coincides with the alternative splicing events suggested by the sequences of the various cDNA species isolated so far. As also reported by others, genomic Southern analysis suggests the presence of other genomic regions containing sequences strongly hybridizing to the cDNA. We isolated and characterized two of these regions. They contain sequences very similar to the cDNA, not interrupted by introns and flanked by a polyA tail at their 3'-ends; hence they are considered two different pseudogenes.

Amino Acid Sequence↗
PubMed1993

The mouse iduronate sulfatase gene: identification of a novel transcript.

Complementary DNAs, cDNAs, coding for iduronate sulfatase (IDS, E.C.3.1.6.13) have been isolated and characterized in man and mouse. The murine cDNA (MTA16) was highly homologous to the human counterpart. By screening the same mouse thymus cDNA library another cDNA (MTA13) was isolated: it is 1831 bp long and is identical to a part of the MTA16 cDNA in its 5' region, but it is completely divergent in the 3' region. Characterization of the MTA13 mRNA as well as its genomic organization are presented. The results herein reported support the hypothesis that MTA13 and MTA16 mRNAs are encoded by the same gene.

Amino Acid Sequence↗
PubMed1992

Sp1 DNA binding efficiency is highly reduced in nuclear extracts from aged rat tissues.

To explore the role of transcriptional factors in the genesis of the senescent phenotype, nuclear extracts from 4- and 30-month-old rat brains were analyzed for the presence of DNA-binding proteins able to interact with double-stranded oligonucleotides containing recognition sites for sequence-specific DNA-binding factors. Gel shift assays revealed that the DNA-binding efficiency of Sp1 is significantly reduced in aged animals compared to young ones, whereas CTF/NF1 and AP1 from young and old rat nuclear extracts bind their DNA targets with the same efficiency. The quantitative analysis of Sp1 by immunoblotting indicated that equivalent quantities and degrees of heterogeneity of Sp1 protein are present in both nuclear extracts, suggesting that the observed difference is not due to a different expression of this transcriptional factor. DNase I footprinting of the heavy chain ferritin gene promoter, which contains a Sp1 binding site, demonstrated that the nuclear extract from 30-month-old rat brain does not protect the region involved in the regulation of the H ferritin gene by Sp1. This results in a reduction of about 50% of the expression of the H ferritin mRNA in aged rat brains. Furthermore, the Sp1 binding sites present in the SV40 early promoter are not protected in a DNase I footprinting assay where a nuclear extract from 30-month-old rat brain was used as a source of DNA binding proteins. Liver nuclear extracts prepared from young and aged rats demonstrated that a decrease of Sp1 binding efficiency is similarly present in this tissue.

Aging↗
PubMed1991

A rat brain mRNA encoding a transcriptional activator homologous to the DNA binding domain of retroviral integrases.

We have isolated a rat cDNA, named FE65, hybridizing to an mRNA of about 2,300 nucleotides present in rat brain, undetectable in rat liver and very poorly represented in other tissues. An mRNA of the same size is present in human neuroblastoma cells and is absent from other human cell lines. The FE65 cDNA contains an open reading frame (ORF) coding for a polypeptide of 499 amino acids in which 143 residues can be aligned with the DNA binding domain of the integrases encoded by mammalian immunodeficiency viruses. The remaining part of the FE65 ORF is not homologous with the correspondent regions of the integrases; the first 206 residues of the FE65 ORF show numerous negative charges and a short sequence not dispensable for the function of the transactivating acidic domain of the jun family transcriptional factors. A plasmid which expresses FE65 amino acids 1-232 fused to the yeast GAL4 DNA binding domain was co-transfected with a plasmid containing five GAL4 binding sites upstream of a minimal Adenovirus promoter controlling the expression of the CAT gene. This experiment showed that the fused protein GAL4-FE65 is able to obtain a 30-40 fold increase of the CAT gene expression compared to the expression observed in the presence of the GAL4 DNA binding domain alone. Two types of FE65 mRNA are present in rat brain, differing only for six nucleotides. We demonstrate that this is the consequence of a neuron-specific alternative splicing of a six-nucleotide miniexon, which is also present in the human genome, in an intron/exon context very similar to that of the rat FE65 gene.

Amino Acid Sequence↗
PubMed1990

Isolation of cDNA fragments hybridizing to rat brain-specific mRNAs.

A cDNA minilibrary in pUC18 has been generated from 3-month-old rat brains. Two hundred clones were randomly selected and sequenced. Comparison with a nucleic acid and protein data bank revealed a number of cDNA fragments not homologous to any published sequence. Northern blot analyses of some of these clones yielded 5 brain-specific cDNA fragments. The full-length cDNA for one of these clones has been isolated and completely sequenced. It corresponds to an mRNA of about 1,500 nucleotides, which is present in brain and, to a lesser extent, in heart and skeletal muscle. Its expression is developmentally regulated in the rat brain from 14-day embryos to 3-month-old adults. A very recent comparison with the EMBL nucleotide sequence data bank showed that this mRNA codes for a brain-specific snRNP-associated protein.

Aging↗
PubMed1989

[Pre-, intra- and postoperative somatosensory evoked potentials in cervical vertebral and spinal cord injuries].

Somatosensory Evoked Potentials (SEPs) to upper limb nerves stimulation, are able to detect cervical medullary dysfunction in case of cervical spine trauma. We have monitored cervical spinal cord functionality in 13 subjects with severe cervical spine trauma. In most of subjects, a prolonged P11onset-P13onset interval was found. Postoperatory a reduced P11onset-P13onset interval well correlates with clinical improving of medullary function. Intraoperatory, a transitory impairment of spinal cord function was found during medullary distraction and vertebral body fusion.

Cervical Vertebrae↗
PubMed1988

Oligonucleotide-directed mutagenesis: a sequence-based screening.

A procedure to screen for mutant clones obtained by oligonucleotide-directed mutagenesis has been developed. It is based on the preparation of phage containing supernatants from a number (100 or more) of randomly chosen mutagenized M13 plaques. Aliquots from these supernatants are mixed to obtain pools, each containing 10 phages. Heterogeneous single-stranded DNA is prepared from these pools and used as template in a "single letter" sequence according to the dideoxy chain terminator method. Thus, the pool(s) containing the mutated sequence and the mutated sequence itself is identified by sequencing the single-stranded DNAs of the 10 phages present in the selected pool.

Animals↗
PubMed1988

Postfusional latency in stereoscopic slant perception and the primitives of stereopsis.

Random dot stereograms of slanted surfaces were constructed, each representing one or two slanted surfaces in different relative arrangements and with different axes. Latency to fusion and from fusion to stereoscopic resolution was measured for each stimulus. It was found that latency to fusion was always very brief but that latency to stereoscopic resolution varied markedly, depending upon the orientation and arrangement of the stereoscopic surfaces. A gradient of discontinuities at a surface boundary produced an instant slant response for that surface, whereas a gradient of absolute disparities across the surface did not, except under conditions where vertical declination (a form of orientation disparity) was present. We conclude that stereopsis is not based on the primitives used in matching the images for fusion and that it is, at least initially, a response to disparity discontinuities which play no role in the fusion process. We also conclude that vertical declination is responded to globally as a slant around a horizontal axis but that other forms of orientation disparity are ineffective. The evidence from our experiments does not support the existence of a stereoscopic ability to respond globally to differences in magnification (or spatial frequency). It is suggested that stereoscopic perception of slant around a vertical axis is slow because it results from the integration of local processes.

Attention↗