Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have used the program FOLD, which employs the Zuker folding algorithm, to identify regions of stable secondary structure in three chicken proto-oncogene mRNAs: c-src, c-myc, and c-fos. We have found that use of reverse transcriptase to synthesize a cDNA template for amplification by the polymerase chain reaction is successful only if the region chosen for amplification does not contain stem structures with calculated free energies less than -14 kcal/mol.
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PMID:Use of an RNA folding algorithm to choose regions for amplification by the polymerase chain reaction. 169 49

The relative abundance of primary transcript and mature mRNA of the c-myc, calcyclin, S14 ribosomal protein, and rRNA genes was determined densitometrically after reverse transcriptase-polymerase chain reaction and Northern blotting analysis in resting and mitogen-stimulated lymphocytes, proliferating and terminally differentiated HL-60 cells, and leukemic blast cells. Transcription and processing of c-myc and rRNA gene transcripts increased proportionally after mitogen stimulation, whereas these processes were independent of cell cycling status in the case of the S14 gene. Normal lymphocytes showed an unexpectedly large amount of primary transcript of the calcyclin gene, whereas the corresponding mRNA was undetectable. The abundance of c-myc, calcyclin, and S14 mRNA in terminally differentiated HL-60 cells decreased sharply, compared to their proliferating counterparts. This decrease reflected post-transcriptional modulation, since the abundance of precursor remained essentially unchanged. After HL-60 differentiation, the 32S rRNA levels remained relatively high, whereas the 45S primary transcript almost disappeared. Leukemic blast cells displayed highly variable precursor/mRNA ratios of c-myc, calcyclin, and S14 genes but consistently high ratios of 32S to 45S RNA, suggesting that the cleavage rate of the 32S rRNA was sharply reduced in these cells, resulting in an accumulation of this molecule. These results suggest the importance of efficient processing of primary transcript to generate adequate functional mRNA, thus regulating gene expression. Furthermore, in terminally differentiated cells and leukemic blast cells a stabilization of the primary transcript without efficient processing can be observed. The role of the stabilization of the primary transcript in terminal differentiation is further supported by the results of run-off transcription, indicating a sharp decrease of c-myc and calcyclin transcription rate in retinoic acid/dimethyl sulfoxide-treated HL-60 cells.
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PMID:Abundance of the primary transcript and its processed product of growth-related genes in normal and leukemic cells during proliferation and differentiation. 172 70

Total mRNA was extracted from activated T lymphocytes and Jurkat cells with and without heat shock, and then used for alpha-32P-labeled 1st strand cDNA synthesis with reverse transcriptase. DNA restriction fragments or cloned vectors of five oncogenes (abl, myc, myb, fos, Ki-ras) and of IL-2, IL-2 receptor, T-cell receptor beta-chain and transferrin receptor were dotted onto nitrocellulose filters. Hybridization results showed that the expression of c-myc and TfR mRNA was much lower in heat-shocked cells than in their normal counterparts. However IL-2 and Ki-ras mRNA increased after heat shock. Possible explanations for the results are discussed.
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PMID:[The effect of heat shock on mRNA expression in human T lymphocytes]. 215 Dec 59

Four Epstein-Barr virus-positive lymphoblastoid cell lines (LCL) were successfully infected in vitro with immunodeficiency virus type 1 (HIV-1) as demonstrated by reverse transcriptase activity and p24 HIV antigen in culture supernatants, positive cell staining for gag-encoded HIV proteins, presence of viral HIV genome by Southern blot analysis and ulstrastructural observations. In addition, both HIV-1-infected B cells and their supernatants efficiently transactivated the chloramphenicol acetyl transferase reporter gene which is under the control of the HIV-1 long terminal repeat. The LCL cells displayed long-term HIV-1 infection and production, but no cytopathic effects were observed. Cytofluorimetric analysis did not detect membrane CD4 presence in the LCL cells before and after HIV-1 infection; moreover, a minute amount of CD4 mRNA was observed only in one of the LCL. A monoclonal antibody specific for the viral binding site of the CD4 molecule delayed, but did not block, HIV-1 infection of the LCL cells. Following HIV-1 infection, changes in LCL phenotype were observed, consisting of a decrease in CD23- and CD39-positive cells, and a concomitant increase of cells with surface CD10 and Bac-1. Furthermore, HIV-1-infected LCL cells did not grow in tight clumps, as usually observed in uninfected LCL, but as disperse suspensions, and formed more agar colonies than control LCL. However, despite this apparent acquisition of a malignant-like phenotype, c-myc proto-oncogene rearrangement was not detected. The appearance of cells with new characteristics did not seem due to clone selection by HIV-1 infection, since all the LCL conserved their clonotypic pattern of IgH chain rearrangement. The acquisition of malignant-like features by HIV-infected B cells might be clinically significant in terms of the pathogenesis of non-Hodgkin's B cell lymphomas, which occur frequently in AIDS patients.
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PMID:Infection of Epstein-Barr virus-transformed lymphoblastoid B cells by the human immunodeficiency virus: evidence for a persistent and productive infection leading to B cell phenotypic changes. 217 Jan 47

We determined the sequence of the 1.5-kb insert upstream to c-myc in the transmissible venereal tumor (TVT) of dogs. The sequence is highly homologous to the 3' region of the mammalian repetitive LINE element. The insert is bound by a 10-bp repeat indicating DNA transposition by a mechanism involving reverse transcriptase. We analyzed DNA of four TVT tumors from various geographical locations as well as normal canine DNA for the presence of the LINE insert. The results indicate that in all TVT tumors, but not in normal tissues, the same LINE insert was present upstream to c-myc. This result suggests that TVT tumors in various dogs may have a common cellular origin.
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PMID:Common origin of transmissible venereal tumors (TVT) in dogs. 333 Jul 87

Transformation of hematopoietic cells by the p210bcr/abl tyrosine kinase appears to require the expression of a functional MYC protein, suggesting that simultaneous targeting of BCR-ABL and c-myc might be a rational strategy for attempting treatment of Phil-adelphia leukemia. To test this hypothesis, severe combined immunodeficiency mice injected with Philadelphia leukemic cells were treated systemically with equal doses of bcr-abl or c-myc antisense oligodeoxynucleotides (ODNs) or with both ODNs in combination. Compared with the mice treated with individual agents, the disease process was much slower in the group treated with both ODNs, as revealed by flow cytometry, clonogenic assay, and reverse transcriptase-polymerase chain reaction analysis to detect leukemic cells in mouse tissue cell suspensions, and by enumeration of liver metastases. The retardation of the disease process was positively correlated with a markedly increased survival of leukemic mice treated with both ODNs. These data demonstrate the therapeutic potential of targeting multiple cooperating oncogenes.
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PMID:Leukemia treatment in severe combined immunodeficiency mice by antisense oligodeoxynucleotides targeting cooperating oncogenes. 750 9

We present a second-strand cDNA synthesis method that takes advantage of both the very high processivity and the very high 3' exonuclease activity of T7 DNA polymerase. The first strand is synthesized with reverse transcriptase using oligo(dT) as a primer. After alkaline hydrolysis of the mRNA template, a tract of dT residues is synthesized with terminal transferase at the 3' end of the first strand. The second strand is synthesized using oligo(dA) as a primer. Several oligo(dA) molecules probably anneal to the poly(dT) tract. Because the 3' exonuclease activity of T7 DNA polymerase is very high, the region of the tract annealed to these oligo(dA) molecules is digested. However, the region of the tract annealed to the very oligo(dA) molecule used as a primer for second-strand synthesis is protected. The resulting cDNA molecules could be cloned with a high efficiency. The size distribution of cloned c-myc DNAs was estimated by Southern blot analysis of phage DNA prepared from the amplified library and by analysis of isolated clones. The results indicate that this method allows to obtain full-length cDNA clones with a high efficiency.
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PMID:Efficient second-strand cDNA synthesis using T7 DNA polymerase. 752 64

The c-myc proto-oncogene is a reliable marker of the "G0-early G1" transition, and its down-regulation is believed to be necessary to obtain cellular differentiation. In murine spermatogenesis, the level of c-myc transcripts does not correlate with the rate of cellular division. Proliferation of supposed staminal spermatogonia to reproduce themselves is induced with a local 5 Gy X-ray dose in 90-day-old C57Bl/6 mice. c-myc quantification by a newly developed competitive reverse transcriptase polymerase chain reaction (RT-PCR) was carried out to follow the expression course of this proto-oncogene. Damage and restoration of spermatogenesis were analyzed at days 3, 6, 9, 10, 13, 30, and 60 after injury by relative testes/body weight determination and histological examination. Proliferative status was determined by histone H3 Northern blot analysis. c-myc mRNA level was 10 times higher after 3 days in the irradiated animals compared to the controls. An increasing number of copies were noted up to 10 days, but promptly decreased to the base level found for irradiated mice from 13 to 60 days. Interestingly, the expression of histone H3 detected S phase only in testes at 60 days from damage.
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PMID:Course of c-myc mRNA expression in the regenerating mouse testis determined by competitive reverse transcriptase polymerase chain reaction. 753 36

The relationship between clinical and molecular characteristics of 45 treated individuals with histologically-documented human immunodeficiency virus (HIV)-associated B-cell non-Hodgkin's lymphoma was examined to determine whether differences in molecular features of lymphoma were associated with differences in clinical outcome. Tissue specimens from these tumors were evaluated for evidence of Ig heavy-chain gene rearrangements using both Southern blot analysis and reverse transcriptase polymerase chain reaction (RT-PCR). Lymphomas were also evaluated for the presence of Epstein-Barr virus (EBV) DNA sequences and c-myc gene rearrangements. Twenty-five lymphomas were characterized as polyclonal and 20 as monoclonal. PCR amplification of expressed Ig variable (V)-region genes confirmed polyclonality in three extensively studied polyclonal lymphomas. The median CD4 count was significantly higher in the group with polyclonal disease (277/microL) than in the group with monoclonal disease (123/microL), P = .04. The complete response rate to therapy was significantly higher in patients with polyclonal disease (78%) and CD4 greater than 200/microL (81%) than in those with monoclonal disease (31%) and CD4 less than 200/microL (33%). CD4 count, clonality, and presence of EBV DNA sequences were the most important predictors of survival. Both Kaplan-Meier and Cox proportional hazards analyses showed a markedly prolonged survival in those patients with both CD4 > or = 200/microL and polyclonal disease. Histologically the polyclonal lymphomas were high grade in appearance and contained prominent macrophages. All seven surviving patients were in this group. Median survival for those individuals whose tumors contained EBV sequences was only 3.2 months (range, 0.4 to 19.5), whereas those with EBV- tumors survived for a median of 9.0 months (range, 0.7 to 65.2), P = .0007. These data indicate that molecular features of HIV-associated lymphomas may be important predictors of clinical outcome. These characteristics define a distinct subset of patients with polyclonal EBV- tumors and CD4 counts greater than 200/microL that appear to have a less aggressive clinical course.
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PMID:Influence of molecular characteristics on clinical outcome in human immunodeficiency virus-associated non-Hodgkin's lymphoma: identification of a subgroup with favorable clinical outcome. 753 86

To find early and sensitive indicators of treatment response in breast cancer, we studied the mRNA levels of proliferation-related genes during growth arrest of the human breast cancer cell lines T47D and MCF7. A sensitive reverse transcriptase-PCR (RT-PCR) technique was used in order to monitor gene expression in small samples of cells. Estrogen-depletion and treatment with tamoxifen effectively induced a G1-arrest in both cell lines, accompanied by a decrease of the mRNA levels of histone H4, cyclin A, cyclin D1, and c-myc. Cyclin A expression decreased most strongly: up to 32-fold within 7 days. The expression of c-fos and WAF1 increased during growth arrest. In conclusion, significant changes of the levels of proliferation-related mRNAs, induced by growth arrest, can be measured in small samples of breast carcinoma cells using RT-PCR. Especially the decrease of the cyclin A mRNA level seems a potential early indicator of clinical response to tamoxifen therapy in breast cancer patients.
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PMID:Growth arrest associated changes of mRNA levels in breast cancer cells measured by semi-quantitative RT-PCR: potential early indicators of treatment response. 758 69


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