Biomedical subjects

L Chiariotti

Publications and source records attributed to L Chiariotti.

30 records · Page 2Linked to original sources

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

Activation of the galectin-1 (L-14-I) gene from nonexpressing differentiated cells by fusion with undifferentiated and tumorigenic cells.

Expression of the galectin-1 (L-14-I) gene, elevated in most differentiated and transformed cell lines, has been studied in cell hybrid systems. Fusion of L-14-I nonproducing rat liver differentiated FAO cells with dedifferentiated rat liver BRL3A cells leads to extinction of liver-specific gene expression while L-14-I mRNA levels remain high. Interspecific hybrids produced by fusion of tumorigenic human osteosarcoma 143TK- with FAO cells show loss of both differentiated functions and tumorigenic phenotype and activation of the FAO L-14-I alleles. Increased expression of rat L-14-I alleles was also observed in human osteosarcoma x rat thyroid cells transient heterokaryons. The data presented here show that expression of the L-14-I gene is subject to dominant positive control and that it correlates with loss of differentiation-specific functions, but it is independent from tumorigenicity. L-14-I activation in FAO cells is achieved by treatment with 5-azacytidine. This result suggests that DNA demethylation is responsible or a prerequisite for L-14-I activation in hybrids.

Alleles↗

PubMed1993

Mapping on human and mouse chromosomes of the gene for the beta-galactoside-binding protein, an autocrine-negative growth factor.

The structural gene for beta-galactoside-binding protein (Lgals-1), a cell growth regulatory molecule and cystostatic factor, is assigned to the E-region of mouse chromosome 15 and to the region q12-q13.1 of human chromosome 22. The evolutionary conservation of these two regions has been previously suggested from comparative mapping of several loci. These include the murine SIS oncogene (Pdgfb) and its human homolog, the platelet-derived growth factor-beta polypeptide, PDGFB. The findings presented here extend the genetic homology of the two regions.

Animals↗

PubMed1992

Increased expression of the negative growth factor, galactoside-binding protein, gene in transformed thyroid cells and in human thyroid carcinomas.

Murine beta-galactoside-binding protein has been shown to be a cell growth regulatory molecule and a cytostatic factor. We analysed the beta-galactoside-binding protein gene expression in a thyroid cell system including two normal cell lines (FRTL-5 and PC Cl 3) and the same cells transfected by several oncogenes that induce different degrees of malignancy and differentiation. We show that beta-galactoside-binding protein mRNA levels correlate with the expression of the malignant phenotype. Run-on experiments suggest that a transcriptional effect accounts at least in part for such a difference. We also show that the beta-galactoside-binding protein gene expression is increased in most human papillary thyroid carcinomas compared with normal thyroid.

Adenovirus E1A Proteins↗

PubMed1991

Structure and expression of the negative growth factor mouse beta-galactoside binding protein gene.

Following the identification of murine beta-galactoside binding protein (mGBP) as an autocrine negative growth factor we have now isolated and characterized the genomic region spanning the mGBP gene and have determined the 5' end of the transcript by primer extension, S1 mapping and mRNA sequence. The gene is found to be contained within 4 kilobases and composed of four exons of 79, 80, 171 and 197 nucleotides separated by three introns of 1200, 1600 and 193 nucleotides. The DNA region upstream of the 5' end of the transcript contains canonical sequences for eukaryotic promoter elements including CAT and TATA boxes and several DNA motifs for potential transcription regulation. The gene is differentially expressed in a variety of normal tissues.

Amino Acid Sequence↗

PubMed1989

Nucleotide sequence and expression of a cDNA clone encoding a fetal rat binding protein for insulin-like growth factors.

The insulin-like growth factors (IGFs), IGF-I and IGF-II, occur in plasma and tissue fluids complexed to specific binding proteins. Although the role of the binding proteins is not completely defined, they are capable of modulating the biological activity of the IGFs. In order to better understand the function of these proteins, we have isolated a clone from the BRL-3A rat liver cell line that encodes a protein corresponding to the IGF binding protein in fetal rat serum. The cDNA clone encodes a precursor protein of 304 amino acids (32,886 daltons), comprised of a 34-residue hydrophobic prepeptide and a 270-residue mature protein (29,564 daltons). The deduced amino acid sequence agrees with the sequence of 173 amino acid residues determined by Edman degradation. The mature protein contains 18 cysteines and no N-glycosylation sites. It contains an Arg-Gly-Asp (RGD) sequence near the carboxyl terminus. A similar sequence is present on many extracellular matrix proteins and contributes to their recognition by cellular adhesion receptors. The cloned cDNA has been transcribed in vitro and the resulting RNA expressed in Xenopus oocytes. Injected oocytes secrete a 33-kDa protein that is immunoprecipitated by polyclonal antibodies to the BRL-3A binding protein and binds IGF-I and IGF-II with the same affinity and specificity as does purified BRL-3A binding protein. The binding protein cDNA probe hybridizes to an approximately 2-kilobase mRNA in BRL-3A cells and in multiple fetal rat tissues including liver, kidney, intestine, and lung. Levels of this mRNA are greatly reduced in the corresponding adult tissues. The rat IGF binding protein is closely related to the partial amino acid sequences reported for a bovine IGF binding protein and more distantly related to a human IGF binding protein that recently has been cloned. No significant homologies were identified to other proteins. Thus, the rat IGF binding protein that we have cloned appears to be a distinct member of a family of related IGF binding proteins. We postulate that the structurally distinct IGF binding proteins may have different biological functions.

Aging↗

PubMed1988

A new member of the ras gene superfamily identified in a rat liver cell line.

A new member of the ras genes superfamily was isolated from a cDNA library derived from a rat liver cell line (BRL-3A). The predicted 201 amino acids ras-like protein shows 30-35% homology with other members of the ras and ras-related gene products so far described. Conserved features include the GTP-binding and hydrolysis domains and the carboxyl terminal cysteine residues. A protein of the expected size (Mr 23,000) was synthesized in an in vitro transcription-translation system. The BRL-ras gene is present in single copy in the rat genome and is ubiquitously expressed at high levels in all tissues and cell lines examined.

Amino Acid Sequence↗

PubMed1988

Structure and function of the Salmonella typhimurium and Escherichia coli K-12 histidine operons.

We have determined the complete nucleotide sequence of the histidine operons of Escherichia coli and of Salmonella typhimurium. This structural information enabled us to investigate the expression and organization of the histidine operon. The proteins coded by each of the putative histidine cistrons were identified by subcloning appropriate DNA fragments and by analyzing the polypeptides synthesized in minicells. A structural comparison of the gene products was performed. The histidine messenger RNA molecules produced in vivo and the internal transcription initiation sites were identified by Northern blot analysis and S1 nuclease mapping. A comparative analysis of the different transcriptional and translational control elements within the two operons reveals a remarkable preservation for most of them except for the intercistronic region between the first (hisG) and second (hisD) structural genes and for the rho-independent terminator of transcription at the end of the operon. Overall, the operon structure is very compact and its expression appears to be regulated at several levels.

Amino Acid Sequence↗

PubMed1988

Structure of the rat insulin-like growth factor II transcriptional unit: heterogeneous transcripts are generated from two promoters by use of multiple polyadenylation sites and differential ribonucleic acid splicing.

The rat insulin-like growth factor II (rIGF-II) gene, which exists as a single copy in the genome, is expressed as a multitranscript family of mRNA molecules ranging in size from 4.6 to 1 kilobases. Part of this heterogeneity can be ascribed to the presence of two different promoters, each transcribing alternative 5'-noncoding regions which are spliced to common coding exons. In the present study we use a combination of DNA sequence analysis of the gene, mapping of the mRNA molecules by Northern analysis and ribonuclease protection experiments, and DNA sequence analysis of cDNA clones complementary to different regions of the genome to establish the structure of several rIGF-II mRNA species. These results indicate that RNA heterogeneity also arises from the use of different polyadenylation sites. In addition, a variant 2 kilobases RNA was observed that was colinear with the distal 1700 base pairs of the 3147 base pair long exon 3, and may arise by alternative RNA splicing. These posttranscriptional modifications of RNAs arising from the rIGF-II transcription unit may generate molecules with different functional potential.

Animals↗

PubMed1986

Structure and expression of the rat insulin-like growth factor II (rIGF-II) gene. rIGF-II RNAs are transcribed from two promoters.

Insulin-like growth factor II (IGF-II) is a mitogenic polypeptide present in rat plasma at high levels during fetal and early postnatal life and is believed to play an important, although as yet undefined, role in fetal development. Both in humans and rats, expression of the IGF-II gene results in the appearance of several mRNA species. In the present study, cDNA and synthetic oligonucleotide probes were used to isolate and characterize the rat IGF-II gene from genomic libraries. The rat IGF-II gene extends over 12 kilobase pairs and contains two 5'-noncoding exons and three protein-coding exons. The two 5' exons represent alternative 5' regions of different mRNA molecules and are expressed from two distinct promoters. The two promoters are transcribed with different efficiencies but exhibit similar tissue-specific expression and regulation with developmental age.

Amino Acid Sequence↗

PubMed1986

Gene structure in the histidine operon of Escherichia coli. Identification and nucleotide sequence of the hisB gene.

The bifunctional enzyme imidazoleglycerolphosphate dehydratase and histidinolphosphate phosphatase is encoded by the hisB gene. The fourth gene of the histidine operon, hisB, was cloned and mapped on a 2,300 base pair DNA fragment. In the present study we report the complete nucleotide sequence of the hisB gene of Escherichia coli. The gene is 1,068 nucleotides long and codes for a protein of 355 amino acids with an apparent molecular weight of 39,998 daltons. The protein product(s) of the hisB region of both Salmonella typhimurium and E. coli were identified by subcloning and expression in an in vitro translation system. In both organisms the hisB gene directed the synthesis of a single protein with an apparent molecular weight of 40,500 daltons, consistent with the data derived from the nucleotide sequence analysis.

Amino Acid Sequence↗

PubMed1986

Nucleotide sequence of the Escherichia coli hisD gene and of the Escherichia coli and Salmonella typhimurium hisIE region.

In this paper we report the nucleotide sequence of the hisD gene of Escherichia coli and of the his IE region of both E. coli and Salmonella typhimurium. The hisD gene codes for a bifunctional enzyme, L-histidinol:NAD+ oxidoreductase, of 434 amino acids with a molecular mass of 46,199 daltons. We established that the hisIE region of both S. typhimurium and E. coli is composed of a single gene and not, as previously believed, of two separate genes. The derived amino acid sequence indicates that the hisIE gene codes for a bifunctional protein of 203 amino acids with an approximate molecular mass of 22,700 daltons. We also determined the nucleotide sequence of a deletion mutant in S. typhimurium which abolishes the hisF and hisI functions but retains the hisE function. We deduced that the mutant produces a chimeric protein fusing the aminoterminal region of the upstream hisF gene to the carboxyl-terminal domain of the hisIE gene which encodes for the hisE function. In view of these results the structural and functional organization of the histidine operon in enteric bacteria needs to be revised. The operon is composed of only 8 genes and the pathway leading to the biosynthesis of the amino acid requires 11 enzymatic steps.

Amino Acid Sequence↗