Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.7.48 (transcriptase)
9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The fibronectin receptor, alpha 5 beta 1, may be involved in many aspects of early development, including migration of endodermal and mesodermal cells during formation of the placenta, trophoblastic outgrowth in culture, and development of an invasive phenotype by fetal cytotrophoblasts. In contrast to the human blastocyst, the bovine blastocyst elongates in the uterine lumen for several days until it begins attachment, and the fetal trophoblast limits its invasion to the maternal epithelium. Fibronectin receptor expression was characterized in bovine embryos before and after their attachment to the uterus. Initially, the polymerase chain reaction (PCR) was conducted with degenerate oligonucleotide primers to isolate bovine cDNAs for the alpha 5 and beta 1 subunits. Bovine-specific primers were then constructed to assay for alpha 5 and beta 1 mRNA expression in embryo RNA during the morula through the attachment stages using reverse-transcriptase PCR. Northern blot analysis was used to quantify mRNA levels from Days 15 to 21. Integrin and fibronectin protein expression was assessed by immunohistochemical examination of embryo sections. Both alpha 5 and beta 1 subunit mRNAs were expressed throughout the stages examined. Expression of both subunit proteins was found in the endoderm at Day 14 but not at Day 18 or later. Fibronectin reactivity was not present at any of the stages examined. Between Days 18 and 21, beta 1-reactivity appeared on the lateral surfaces of the trophoblast cells. Day 24 trophoblast binucleate cells showed intense staining with the beta 1 antibody, suggesting that a beta 1-integrin is involved in binucleate cell migration.
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PMID:Fibronectin receptors in preimplantation development: cloning, expression, and localization of the alpha 5 and beta 1 integrin subunits in bovine trophoblast. 754 39

Very late antigen-4 (VLA-4) composed of alpha 4 and beta 1, a member of the beta 1-integrin subfamily, facilitates cell-to-cell interaction with vascular cell-adhesion molecule-1 (VCAM-1) on endothelial cells (EC). Attachment of blood-borne tumor cells to EC is a crucial step for hematogenous metastasis, and VLA-4-positive tumor cells can attach to EC by binding to VCAM-1. Renal-cell cancer (RCC) reveals proportionally greater percentages of metastases than other carcinomas at initial diagnosis. We investigated whether VLA-4 is expressed on RCC, and how such expression on RCC correlates with the metastatic potential of RCC. Immunohistochemical staining on 66 primary and 4 metastatic RCC showed that 4 out of 4 metastatic and 5 out of 8 primary RCC from patients with lung and/or brain metastases expressed alpha 4 and beta 1 chains. On the other hand, 13 of 58 RCC without metastases expressed alpha 4 chain, alpha 4 and beta 1 expressions were also detected on 5 out of 5 human RCC cell lines, ACHN, KRC/Y, A498, Caki1 and Caki2, by flow-cytometric analysis. Reverse-transcriptase-polymerase-chain-reaction (RT-PCR), followed by Southern-blot hybridization with cDNA probe for a alpha 4 chain, also confirmed mRNA production in 4 out of 5 RCC cell lines. Furthermore, adhesion of alpha 4-positive RCC cell lines to human umbilical-vein endothelial cells (HUVEC) was augmented by treatment of HUVEC with tumor necrosis factor-alpha (TNF-alpha). This adhesion was inhibited by anti-alpha 4 or anti-VCAM-1 antibodies, suggesting that VLA-4-VCAM-1 interaction was involved in the adhesion between RCC cells and HUVEC. Taken together, VLA-4 on RCC cells might play a crucial role in their hematogenous metastasis.
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PMID:Possible significance of VLA-4 (alpha 4 beta 1) for hematogenous metastasis of renal-cell cancer. 789 40

The murine transformed cell line YC-8 and beta-adrenergic receptor agonist (isoproternol) treated rat and mouse parotid gland acinar cells ectopically express cell surface beta 1-4 galactosyltransferase during active proliferation. This activity is dependent upon the expression of the GTA-kinase (p58) in these cells. Using total RNA, cDNA clones for the protein coding region of the kinase were isolated by reverse transcriptase-PCR cloning. DNA sequence analysis failed to show sequence differences with the normal homolog from mouse cells although Southern blot analysis of YC-8, and a second cell line KI81, indicated changes in the restriction enzyme digestion profile relative to murine cell lines which do not express cell surface galactosyltransferase. The rat cDNA clone from isoproterenol-treated salivary glands showed a high degree of protein and nucleic acid sequence homology to the GTA-kinase from both murine and human sources. Northern blot analysis of YC-8 and a control cell line LSTRA revealed the synthesis of a major 3.0 kb mRNA from both cell lines plus the unique expression of a 4.5 kb mRNA in the YC-8 cells. Reverse transcriptase-PCR of LSTRA and YC-8 confirmed the increased steady state levels of the GTA-kinase mRNA in YC-8. In the mouse, induction of cell proliferation by isoproterenol resulted in a 50-fold increase in steady state mRNA levels for the kinase over the low level of expression in quiescent cells. Expression of the rat 3' untranslated region in rat parotid cells in vitro led to an increased rate of DNA synthesis, cell number an ectopic expression of cell surface galactosyltransferase in the sense orientation. Antisense expression or vector alone did not alter growth characteristics of acinar cells. A polyclonal antibody monospecific to a murine amino terminal peptide sequence revealed a uniform distribution of GTA-kinase over the cytoplasm of acinar and duct cells of control mouse parotid glands. However, upon growth stimulation, kinase was detected primarily in a perinuclear and nuclear immunostaining pattern. Western blot analysis confirmed a translocation from a cytoplasmic localization in both LSTRA and quiescent salivary cells to a membrane-associated localization in YC-8 and proliferating salivary cells.
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PMID:Characterization of the synthesis and expression of the GTA-kinase from transformed and normal rodent cells. 804 64

Modulation of the three beta-adrenergic receptor subtypes (beta-ARs) by insulin was investigated in mouse 3T3-F442A adipocytes. Saturation and competition experiments measuring binding of 125I-labeled (-)-cyanopindolol to adipocyte membranes demonstrated that cell exposure to insulin for 4 days caused a 3.5-fold decrease in the density of the major beta-AR component of the adipocyte, the beta 3-AR, while beta 1-AR sites remained unchanged and beta 2-ARs were undetectable. This correlated with a lower potency of the beta 3-AR-selective agonists CGP12177, ICI201651, and BRL37344 in stimulating adenylate cyclase. Northern blotting analysis indicated that insulin induced a rapid and sharp decrease in beta 3-AR mRNA levels. This effect was detectable at low insulin concentrations (EC50 = 3 nM) and was not observed in the presence of insulin-like growth factor I, suggesting an insulin receptor-mediated phenomenon. Reverse transcriptase-PCR analysis showed that, in contrast to its dramatic down-regulatory effect on beta 3-AR mRNA, insulin did not modify the levels of beta 1- and beta 2-AR transcripts. As assessed by nuclear run-on assays, insulin inhibited the beta 3-AR gene transcription rate by 90% within 30 min. mRNA turnover experiments showed that the half-life of beta 3-AR mRNA was short (90 min) and remained unaffected by insulin. These findings demonstrate the genetic control of a beta-AR subtype expression by insulin and reveal a mechanism for the regulation by this hormone of cAMP-dependent biological processes in adipocytes.
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PMID:Transcriptional down-regulation by insulin of the beta 3-adrenergic receptor expression in 3T3-F442A adipocytes: a mechanism for repressing the cAMP signaling pathway. 820 47

Angiotensin II (Ang II), a vasoactive octapeptide, has been implicated in cardiac growth and the development of hypertrophy and fibrosis secondary in hypertensive disease. These consequences of Ang II imply an effect on the function and morphology of cardiac interstitial cells (fibroblasts). The present investigation was designed to (1) determine whether neonatal heart fibroblasts (NHFs) possess functional Ang II receptors on their plasma membrane and (2) examine the effects of Ang II on NHFs in vitro using three- and two-dimensional (3D and 2D, respectively) cultures. Several analytic techniques were used to test the specific questions of the present study. Since cardiac fibroblast phenotype can be influenced by culture conditions, both 2D and 3D cultures were used in the present investigations. Reverse-transcriptase polymerase chain reaction and radioligand binding analysis were used to test for the presence of Ang II receptors on NHFs. Both revealed that NHFs in 2D culture possess Ang II receptor mRNA and Ang II receptors. When isolated NHFs were cultured in 3D collagen gels and treated with Ang II, gel contraction was stimulated by NHFs. This effect was attenuated by the specific Ang II receptor antagonist [Sar1,Ala8]Ang II. Ang II-stimulated gel contraction was completely inhibited by extracellular matrix receptor (beta 1-integrin) antibodies (P < .05), supporting previous studies indicating that collagen gel contraction is mediated via the integrins. Immunofluorescent staining was used to test the localization of cell-surface integrins. A more intense staining pattern for beta 1-integrin in Ang II-treated versus control cells was observed.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Integrin-mediated collagen gel contraction by cardiac fibroblasts. Effects of angiotensin II. 829 68

We report the cloning of two full-length cDNAs coding for the human beta 1-integrin which diverge from each other for their 5'-untranslated sequences. Characterization of a genomic clone containing these two sequences showed that they are contiguous, spaced by 261 nucleotides, and both followed by donor splice sites. Analysis by primer extension and transient transfection in a human osteogenic sarcoma cell line (MG-63) demonstrated the existence of two independent promoters for transcription initiation. The two promoter regions are very G+C-rich, and lack both a TATA box and a CAAT box. Northern blot analysis showed that transcripts starting from the distal promoter (with respect to the first coding exon) are at least 20-fold more abundant than transcripts originating from the proximal one. The levels of both transcripts increase after transforming growth factor-beta 1 induction, however, mRNAs originating from the proximal promoter increase at an higher extent. Reverse transcriptase/polymerase chain reaction analysis performed on different human tissues and cell lines revealed that, while the distal promoter is ubiquitously active, the proximal promoter is not. These findings suggest a possible complex pattern for regulation of the human beta 1-integrin gene expression.
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PMID:Human beta 1-integrin gene expression is regulated by two promoter regions. 844 90

The purpose of this study was to characterize the phenotype and clonality of the T cell population in patients who experience acute rejection (AR) following bone marrow transplantation (BMT) from a partially mismatched related donor (PMRD). Phenotypic analysis was performed using flow cytometry, assignment of donor/host lineage by cytogenetics or HLA-specific flow cytometry, and analysis of the T cell receptor (TCR) by reverse-transcriptase polymerase chain reaction (RT-PCR). We have previously reported the initial appearance in the blood of AR patients of host CD8+brightCD3low T cells that progressively express increasing amounts of CD3+ cells. We now report that this cell population can differentiate into either a cytotoxic T cell phenotype (CD3+CD8+HLA-DR+CD57-) usually associated with AR of grafts from matched unrelated donors or a suppressor T cell phenotype (CD3+CD8+CD57+HLA-DR-) usually associated with AR of grafts from matched sibling donors. Analysis of the TCR V beta subsets from two patients revealed sorted host CD3+CD8+ cells (purity 90-95%) from the first patient to express V beta 18 almost exclusively. In a second patient with late rejection (55 days post-BMT), the CD3+CD8+ cells were predominantly restricted to V beta 1, 5.1, 7, 9, and 18. Although CD3+CD8+ T cells are known to be associated with AR, cytotoxic and suppressor lineages in AR from the same type of BMT and clonal distribution of T cells in AR have not been reported. Preliminary results suggest that V beta expression in AR of PMRD grafts is restricted and host T cell phenotype may vary. Further studies will investigate whether specific mismatches correlate with specific V beta usage and/or host T cell phenotype.
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PMID:Characterization of acute bone marrow graft rejection in T cell-depleted, partially mismatched related donor bone marrow transplantation. 854 52

This study was undertaken to determine whether receptor and non-receptor components of the adenylate cyclase (AC) cascade were altered in brown adipose tissue (BAT) of 14-day-old pre-obese (fa/fa) rats, before endocrine status is strongly modified by fa gene expression. Activity of the AC catalytic subunit did not differ between the two genotypes. In fa/fa rats compared with control Fa/fa rats, there was a 50% decrease in the activity of alpha Gs (stimulated by NaF or guanosine 5'-[gamma-thio]triphosphate) but no change in protein content (Western blotting). alpha Gi function, assessed by the inhibitory action of low concentrations of guanosine 5'-[beta gamma-imido]triphosphate upon 10(-4) M forskolin-stimulated AC activity, was equally low in both genotypes. Analysis of dose-response curves for different beta-agonists revealed that (i) both the basal and the maximally stimulated activity of AC were 2-fold lower in fa/fa rats than in Fa/fa rats; (ii) BRL37344 and CGP12177 (beta 3 agonists) were less potent in fa/fa than in Fa/fa rats (Kact. multiplied by 2); (iii) noradrenaline and isoprenaline (Iso), at the low-affinity site (beta 3-AR), were less potent in fa/fa than in Fa/fa pups (Kact. increased by 30 and 20% respectively). At the high-affinity site (mainly beta 1) these two agonists were more potent in fa/fa than in Fa/fa rats (Kact. decreased by 40 and 80% respectively). In good agreement with the latter result, the beta 1-adrenergic receptor (beta 1-AR)-selective antagonist CGP20712A had more effect on the Iso-stimulated AC activity in pre-obese than in lean pups (2-fold decreased in IC50). Binding experiments with [3H]CGP12177 show that in BAT of suckling rats, beta 3-ARs represent 80% of the total beta-ARs. Bmax values for the two sites were not affected by the genotype, although the beta 3-AR mRNA concentration in BAT (quantitative reverse-transcriptase PCR) was 3-fold lower in fa/fa rats than in Fa/fa pups. In conclusion, these results provide evidence for alterations in beta 1- and beta 3-AR signalling in BAT of 14-day-old suckling pre-obese Zucker rats with a decreased activity of alpha Gs. The impaired AC responsiveness to catecholamines might be a primary contributor to the development of this genetic obesity.
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PMID:Early alterations in the brown adipose tissue adenylate cyclase system of pre-obese Zucker rat fa/fa pups: decreased G-proteins and beta 3-adrenoceptor activities. 855 20

During pregnancy, the resident stromal cells of the endometrium differentiate to become decidual cells and produce a pericellular basement membrane. We used immunofluorescence and Western blotting with a panel of monoclonal Ab specific for various laminin subunits to examine the composition of decidual laminin. The stromal cell basement membrane contained subunits alpha 2 (M), beta 1 (B1), beta 2 (S), and gamma 1 (B2). Low levels of alpha 1 could also be detected. The glandular and vascular basement membranes of decidual tissue contained subunits alpha 1 (A), beta 1, and gamma 1. An extract was produced from decidual extracellular matrix. Western blots of nonreducing gels showed the presence of high molecular weight complexes containing alpha 2, beta 1, beta 2, and gamma 1. These data indicated that laminins 2 and 4 are coexpressed by decidual cells. Laminin 1 was present in the extract as a minor component. In contrast, cultured stromal cells expressed laminin 1 as the major secreted variant. Immunolocalization was carried out using tissue from various stages of the nonpregnant cycle. The alpha 2 chain polypeptide was absent in the proliferative phase of the cycle but present in late secretory phase in perivascular areas where predecidual differentiation occurs. Reverse transcriptase-PCR experiments confirmed the presence of alpha 2 chain mRNA in decidua but showed that this transcript is detectable throughout the nonpregnant cycle. The results showed that laminins 2 and 4 are hormonally regulated products of decidual cells. The composition of the vascular and epithelial basement membranes remained constant throughout the cycle.
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PMID:Laminins 2 and 4 are expressed by human decidual cells. 856 85

The regulation of the expression of beta-adrenoceptor (beta-ARs) is not thoroughly understood. We demonstrate that the rat heart cell-line H9c2 expresses both beta 1- and beta 2-ARs. In radioligand-binding experiments, the maximal binding capacity of (-)-[125I]-iodocyanopindolol was determined as 18 +/- 0.6 fmol/mg of protein with a KD of 35.4 +/- 4.1 pM. Competitive radioligand-binding experiments with subtype-specific beta-antagonists reveal a subtype ratio of beta 1- to beta 2-ARs of 29%: 71%. With competitive reverse-transcriptase PCR we found beta 2-mRNA to be up to 1600 times more frequent than beta 1-mRNA. Treatment of the H9c2 cell-line with the beta-adrenergic agonist (-)-isoproterenol (10(-6) M), the antagonist (-)-propranolol (10(-6) M) and the glucocorticoid dexamethasone (500 nM) induces regulatory effects on both the beta-AR protein and mRNA level. Isoproterenol treatment leads to down-regulation of the total receptor number by 56 +/- 4%, due to a decrease in beta 2-ARs, while maintaining the beta 1-AR number constant. On the transcription level, both beta 1-and beta 2-mRNAs are decreased by 30% and 42% respectively. mRNA stability measurements reveal a reduced half-life of beta 2-mRNA from 9.3 h to 6.5 h after isoproterenol treatment. Incubation of cells with (-)-propranolol does not affect the amounts of beta-ARs and their mRNAs. Dexamethasone induces a 1.8 +/- 0.2-fold increase in beta-AR number over the basal level as well as a 1.9 +/- 0.2-fold increase in the amount of beta 2-mRNA. Because the half-life of beta 2-mRNA was unaffected by dexamethasone, the increased beta 2-mRNA level must be due to an enhanced transcription rate. The beta 1-mRNA levels are unchanged during dexamethasone-incubation of the cells. Our data clearly demonstrate that treatment of H9c2 rat heart cells with isoproterenol and dexamethasone induces alterations in the level of RNA stability as well as gene transcription, leading to altered receptor numbers.
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PMID:Regulation of beta-adrenoceptor density and mRNA levels in the rat heart cell-line H9c2. 876 Mar 84


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