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Biomedical subjects

A Seth

Publications and source records attributed to A Seth.

At least 127 records · Page 7Linked to original sources
PubMed1996

ETS1 and ETS2 in p53 regulation: spatial separation of ETS binding sites (EBS) modulate protein: DNA interaction.

p53 is an extensively studied tumor suppressor gene implicated in the genesis of a large number of varied tumors. However, the pathways of regulation for the wild-type p53 gene and its product are as yet unknown. In situ hybridization analyses of ETS1 and ETS2 expression during mouse embryogenesis, have shown a pattern similar to that of p53 gene expression. Significantly, we have identified several ETS-binding sites (EBS) in the promoter regions of the human and mouse p53 genes. In the human promoter two of these EBS are present in the form of a palindrome, with the two EBS cores being separated by four nucleotides. This report shows that the EBS palindrome of the human p53 promoter has a high affinity for ETS1 and ETS2 and that such binding interaction intracellularly is able to activate the transcription of a CAT reporter gene by 5-10-fold using COS cells. To investigate whether the spacing between the two EBS cores influences the DNA binding activity, we synthesized oligonucleotides with increasing distances (4,12,16, and 20 bases respectively) between the two EBS cores of the palindrome. We observed an inverse correlation between an increasing distance in the two EBS cores of the palindrome and the ETS1 and ETS2 DNA binding activity respectively. Interestingly, optimal DNA binding activity was observed when the distance between the two EBS cores was four bases, identical to that which occurs in the natural promoter. Furthermore we show that the p53 mRNA is expressed at higher levels in NIH3T3 cells overexpressing ETS2 gene product, suggesting that the ETS2 transcription factor is a likely candidate for regulating the expression of p53 in vivo.

3T3 Cells↗
PubMed1996

Down's syndrome-like skeletal abnormalities in Ets2 transgenic mice.

Expression of Ets2, a proto-oncogene and transcription factor, occurs in a variety of cell types. During murine development it is highly expressed in newly forming cartilage, including in the skull precursor cells and vertebral primordia. Ets2 is located on human chromosome 21 (ref. 8) and is overexpressed in Down's syndrome (trisomy 21). Here we generate transgenic mice to investigate the consequences of overexpression of Ets2. We find that mice with less than 2-fold Ets2 overexpression in particular organs develop neurocranial, viscerocranial and cervical skeletal abnormalities. These abnormalities have similarities with the skeletal anomalies found in trisomy-16 mice and humans with Down's syndrome, in which the gene dosage of Ets2 is increased. Our results indicate that Ets2 has a role in skeletal development and implicate the overexpression of Ets2 in the genesis of some skeletal abnormalities that occur in Down's syndrome.

Abnormalities, Multiple↗
PubMed1996

Interaction of ETS-1 and ERGB/FLI-1 proteins with DNA is modulated by spacing between multiple binding sites as well as phosphorylation.

ETS is a family of transcription factors that contain a highly conserved ETS DNA binding domain. Various members of the ETS family are expressed in cells of hematopoietic lineage. ETS-1, ETS-2 and ERGB/FLI-1 are expressed at high levels in T-lymphocytes. HIV-1 infects T-cells and it has been shown that its LTR contains binding sites for various transcription factors. In this study we show that the HIV-1 core enhancer is directly regulated by ERGB/FLI-1 protein positively, as well as, negatively, depending upon the presence or absence of accessory factors in different cell types. In addition, we show that the ETS-1 transactivation activity is enhanced upon dephosphorylation of the Calmodulin-dependent Protein Kinase II phosphorylation site located in exon VII. Finally, we demonstrate that the spacing between the two EBS cores in palindromic or direct repeat sites play a crucial role in binding of ETS proteins to DNA.

Animals↗
PubMed1996

Utility of Pilot wire in angioplasty of tortuous and highly angulated coronary arteries.

We present a case of severe proximal circumflex artery tortuosity with two 90 degrees bends and then a tight stenosis in the mid part of first obtuse marginal branch. Conventional method used to cross the lesion by wire failed. However, a commercially available new wire with ability to change the degree of tip angulation (Pilot wire, USCI Bard) was then used successfully to cross the stenosis. In addition, the wire straightened the tortuosities and provided good trackability to the balloon. Thus, this new wire is a valuable addition to the angioplasty armamentarium.

Adult↗
PubMed1995

ETS1 transactivates the human GM-CSF promoter in Jurkat T cells stimulated with PMA and ionomycin.

Activation of T helper cells results in coordinate expression of a number of cytokines involved in differentiation, proliferation and activation of the haematopoietic system. Granulocyte-macrophage colony-stimulating factor (GM-CSF) is one such cytokine whose increased expression results partly from increases in transcription. Cis-acting elements with NF kappa B, AP-1 and ETS-like motifs have been identified in the promoter region of the GM-CSF gene, which are important for transcriptional activity following PMA and ionomycin stimulation. A number of the ETS family of transcription factors are expressed in T cells, including ETS1 and ELF1. Here we describe the ability of these factors to interact with a site (GM5), located within the CLE0 element, -47 to -40 upstream of the GM-CSF transcription initiation site. Exogenous ETS1, but not ELF1, can transactivate GM-CSF, through the GM5 site, in a PMA/ionomycin dependent manner. Other unidentified ETS-like factors present in Jurkat cells are also capable of binding GM5. Mutation of the core ETS binding site from -GGAA- to -GGAT- prevents the binding of ETS-like factors with the exception of ETS1. The GM-CSF promoter, modified in this way to be ETS1 specific, is fully responsive to PMA/ionomycin induction, in addition to ETS1 transactivation in the presence of PMA and ionomycin. Together these data suggest that ETS1 may be involved in mediating the increased GM-CSF production associated with T cell activation.

Base Sequence↗
PubMed1995

Identification of novel genes from stomach cancer cell lines by differential display.

Gastric cancer is a leading cause of cancer death in many parts of the world. None of the tumor markers available to date provide for a reliable screening/diagnostic test. By using differential display technology on gastric cancer nonmetastatic (RF1) and metastatic (RF48) cell lines, we have isolated six novel cDNA clones. Five of them have not been previously identified. However, one of them appears to be the human homolog of the bovine oligomycin sensitivity conferral protein (oscp). Northern blot analysis showed that this clone is expressed at a much higher level in the metastatic (RF48) than the nonmetastatic (RF1) cancer cell line from the same patient. High level expression of the same gene is also observed in the breast cancer cell lines BT20 and T47D. The other five novel clones isolated showed either low or no expression in the RF1 and RF48 gastric cell lines, but variable levels of expression were detectable in breast cancers cell lines and normal tissues.

Adenosine Triphosphatases↗
PubMed1995

Characterization of factors regulating successful immunotherapy using a tumor-specific cytotoxic T lymphocyte clone: role of interleukin-2, cycling pattern of lytic activity and adhesion molecules.

Adoptive immunotherapy against cancer has met with varying degrees of success, the reasons for which remain unclear. The present study characterizes factors that regulate successful immunotherapy of mice bearing a syngeneic T-cell lymphoma, designated LSA, using a tumor-specific cytotoxic T lymphocyte (CTL) clone, PE-9. Adoptive transfer of PE-9 cells afforded significant protection in normal but not in nude mice against LSA tumor. However, the PE-9 cells could protect the nude mice when injected along with normal CD4+ T cells. Administration of IL-2 along with PE-9 cells failed to enhance tumor immunotherapy. IL-2 therapy was toxic inasmuch as injection of the CTL clone PE-9 + IL-2, but not PE-9 or IL-2 alone, for 5 days into irradiated mice caused vascular leak syndrome (VLS). PE-9 cells cultured with high doses of rIL-2 in vitro also caused TCR-independent and MHC-unrestricted lysis of SV40-transformed endothelial cells. Furthermore, PE-9 cells cultured in vitro for 24-96 hr with IL-2 exhibited cycling pattern of tumor-specific cytotoxicity with maximum cytotoxicity demonstrable at 48 hr and virtually no cytolytic activity at 96 hr of culture or thereafter. The loss of cytotoxicity correlated with down-regulation of several adhesion molecule expressions on PE-9 cells, particularly the alpha beta-TCR, as well as the mRNA for TNF-alpha, IFN-gamma and perforin, although the levels of granzyme A were not altered. Interestingly, the outcome of immunotherapy by PE-9 cells depended on the cycling pattern of cytotoxicity. Our data suggest that successful immunotherapy against cancer using a CTL clone depends on several factors, such as the cycling pattern of lytic activity, density of adhesion molecules, levels of cytokines expressed and the ability of IL-2 and CTL to trigger VLS.

Animals↗
PubMed1995

Coronary angioplasty for the control of intractable ventricular arrhythmia.

Ventricular arrhythmias (VAs) that occur following an acute extensive anterior myocardial infarction (MI) usually respond to conventional antiarrhythmic regimes of treatment. Rarely, the VA may prove intractable to therapy. This report is of three patients who presented at varying time frames (3 h to 10 weeks) following an anterior MI. They exhibited sustained monomorphic ventricular tachycardia and hemodynamic instability despite multiple antiarrhythmic drug therapy, intravenous magnesium, direct-current cardioversion (DCCV), overdrive pacing (in one case), and intra-aortic balloon counterpulsation (IABP). Although there was no clinical evidence of continuing ischemia and although coronary angiography that was done in each case showed the infarct-related artery (IRA) to subtend akinetic areas on left ventricular (LV) angiogram, percutaneous transluminal coronary angioplasty (PTCA) of the IRA was done in all three cases. Reestablishing patency of the IRA helped in controlling the VA dramatically with average therapeutic doses of antiarrhythmic drugs. All three patients showed this control to have been maintained over a follow-up period of more than 1 year, with partial improvement in LV function and signal-averaged electrocardiogram negative for late potentials. Thus, in patients with extensive infarction and intractable VA, PTCA of the IRA may provide control of VA even in the absence of clinical signs of active ischemia or viable muscle mass.

Angioplasty, Balloon, Coronary↗
PubMed1995

Multivessel coronary angioplasty with anomalous origin of the left main coronary artery.

We report a case of coronary angioplasty to the right coronary artery, the circumflex, and the left anterior descending artery in a patient with anomalous left main coronary artery arising from the right aortic sinus of Valsalva. At angiographically documented follow-up of more than 2 years, the patient remains well without restenosis. This case represents the only such report in the literature. Angioplasty hardware was an important factor in successful crossing and dilatation of multiple severe and distal stenoses in the anomalous left system; appropriate technical details are discussed.

Angioplasty, Balloon, Coronary↗
PubMed1995

Sarcoidosis.

Explore the source record for details and available documents.

Child↗
PubMed1994

Constitutive activation of the interleukin 2 gene in the induction of spontaneous in vitro transformation and tumorigenicity of T cells.

There is growing evidence to suggest that tumorigenic transformation of cells may result from aberrant regulation of autocrine growth factor production. In the current study we describe the spontaneous in vitro transformation of T-lymphocyte cell lines during routine cell culture as evidenced by autonomous growth without any requirement for stimulation or exogenous interleukin 2 (IL-2). These cells constitutively expressed the IL-2 gene and were inhibited from proliferating by addition of antibodies against IL-2, the IL-2 receptor, or IL-2 antisense oligonucleotides, thereby suggesting that the cell transformation resulted from IL-2-mediated autocrine growth. The transformed cells when injected into nude but not normal mice induced tumors that were inhibited by antibodies against IL-2 and the IL-2 receptor as well as by immunosuppressive drugs such as cyclosporin A. These studies demonstrate that aberrant regulation of IL-2 production can lead to spontaneous transformation of T cells in vitro, capable of inducing tumors in vivo. Our studies not only provide evidence for the important role played by autocrine growth factors in tumorigenicity but also stress the need to use caution while performing immunotherapy using in vitro-cultured T cells against cancer and viral infections, particularly in an immunodeficient host, to exclude any possible transfer of transformed mutant cells.

Animals↗
PubMed1994

Isolation and sequence analysis of the human syntaxin-encoding gene.

STX-related genes (encoding syntaxin) have been identified in rat and yeast; however, no human STX gene has been isolated thus far. Here, we describe the nucleotide sequence of the first human STX gene isolated from a placental library. It encodes a 297-amino-acid (aa) protein and is 89% identical to the aa sequence of rat STX 4a.

Amino Acid Sequence↗
PubMed1994

Binary and ternary complexes between T-cell receptor, class II MHC and superantigen in vitro.

Superantigens are proteins that in association with class II major histocompatibility complex (MHC)-bearing cells can stimulate virtually all T cells that express particular classes of the variable beta-domains of the T-cell receptor (TCR). This mechanism of T-cell activation circumvents the usual requirement for peptide-specific MHC recognition. Staphylococcus aureus enterotoxin B (SEB) is a bacterial superantigen that causes food poisoning and shock. We have characterized the tertiary complex of SEB, a soluble T-cell receptor, and a soluble class II MHC molecule DR1, and the three binary complexes TCR-SEB, SEB-DR1, and the peptide-specific complex DR1-TCR. We report here that in each case the specificity of the interaction among the soluble molecules is the same as observed in biological assays. Native gel electrophoresis and plasmon resonance affinity measurements indicate that SEB-TCR complex can form in the absence of class II MHC and that SEB-TCR interaction increases the binding of DR1. The observation that a superantigen can form complexes with TCR in both the absence and presence of class II MHC may provide a mechanism for its ability to induce anergy in some circumstances and activation in others (reviewed in ref. 8).

Amino Acid Sequence↗
PubMed1994

P53 gene mutations in women with breast cancer and a previous history of benign breast disease.

Mutations of the p53 tumour suppressor gene are the most common genetic lesions in human cancers and have been reported in breast cancer as part of the Li-Fraumeni syndrome. In the present study, we determined frequencies and types of the p53 mutations in breast cancer tissues in women with a history of benign breast disease (BBD) identified in Florence, Italy, with (n = 6) or without (n = 10) a family history of breast cancer. Among the cases with a family history of breast cancer and BBD, 2 out of 6 had p53 gene mutations in cancer samples. 1 patient had a mutation at codon 248 and the other had double mutations at codons 243 and 241. In these cases, the p53 gene was also analysed in the tissue samples from previous BBD lesions; however, no mutations were observed (0 out of 6). These results suggest that the p53 mutations occur during advanced stages of tumour progression. In sporadic breast cancer cases with a history of BBD, p53 point mutations were observed of tumour progression. In sporadic breast cancer cases with a history of BBD, p53 point mutations were observed in four samples (4 out of 10). Two of these mutations turned out to be silent changes and one of the samples showed triple mutations at amino acid positions 267, 277 and 296. No p53 gene mutations were found in the breast tumour tissues of 10 additional women from the same area with a family history of breast cancer, but no previous BBD (0 out of 10). Family history of breast cancer does not appear to affect the frequency of p53 mutations in women with a previous history of BBD.

Base Sequence↗
PubMed1994

The EndoA enhancer contains multiple ETS binding site repeats and is regulated by ETS proteins.

EndoA is a type II keratin and with EndoB (type I keratin), constitutes intermediate filaments in various simple epithelial tissues. EndoA is developmentally regulated and has an enhancer that is located at the 3'- end of the gene. This enhancer contains two single and five dual Ets binding sites. Thus far, no other promoter or enhancer has been shown to contain as many potential clustered Ets binding sites. To study the transcriptional regulation of EndoA by the ETS family proteins, we amplified the EndoA enhancer fragment from mouse genomic DNA by PCR, and cloned it into the pBLCAT2 vector upstream from the CAT reporter gene. Several pBLCAT-ENDOA clones were sequenced to verify the presence of all the ETS binding sites. Clones that did not show any point mutations in the ETS binding sites were chosen to study the transcription regulation by ETS1, ETS2 and ERGB/FLI-1 gene products. EMSA results indicated that the ETS1, ETS2 and ERGB/FLI-1 proteins bind to the enhancer sequence, and DNase I protection data demonstrated that the ETS proteins protect all seven EBS core sequences. Cotransfection of the COS cells with the pBLCAT-ENDOA construct, along with increasing amounts of different ETS expression vectors, resulted in a significant induction of CAT reporter gene expression. Previously, we have shown that the overexpression of the ETS1 gene transforms NIH3T3, and these transformed cells (7AQS2.1) produce high levels of ETS1 protein (Seth & Papas, 1990). In this report, we show that the undifferentiated P19 EC cells do not express detectable levels of ETS1; however, an elevated level of ETS1 is expressed in differentiated derivatives of these cells. We therefore used these two cell lines to examine the activity of the EndoA enhancer with the ETS1 product. Transfection of the pBLCAT-ENDOA construct alone in undifferentiated P19 EC cells results in very low CAT gene expression; however, upon differentiation with retinoic acid the level of CAT gene activity increases dramatically. Similarly, an increase in CAT expression from the same construct (pBLCAT-ENDOA) was also observed in 7AQS2.1 cells. Our results therefore indicate that the EndoA enhancer is regulated by ETS proteins via interaction with multiple ETS-binding site sequences.

Animals↗