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:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The fibre type distribution has been mapped in the latissimus dorsi muscle of the Dutch rabbit. Using the myosin ATPase stain, a distinct border was found to run in a cranial to caudal direction, which effectively divided the muscle into 2 segments of different fibre type proportions. Although both segments contained mostly fast twitch fibres, the medial areas were found to contain approximately 10-20% slow (i.e. type I) fibres while the lateral portions contained very few, if any, slow fibres. Significantly fewer type IIa fibres were also found in the lateral areas of the muscle. These histochemical findings were confirmed by the use of the reverse transcriptase polymerase chain reaction, which demonstrated that more messenger RNA of the slow myosin heavy chain was found in the medial regions compared with the lateral segment. These results demonstrate the importance of choosing well defined sampling sites when evaluating regimes designed to transform this heterogeneous muscle for use in subsequent myoplasty procedures.
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PMID:The fibre type composition of the rabbit latissimus dorsi muscle. 755 11

A method was established for measuring molecule numbers of three different myosin heavy chain (MHC) mRNA isoforms in total RNA preparations. The quantification was based on a combination of primer-directed reverse transcriptase and polymerase chain reactions with 5'-digoxigenin-labeled oligonucleotides, using external standards. The sensitivity of the method allowed the quantitation of mRNA amounts down to the range of 1,000 molecules (detection limit 50 molecules). The numbers determined for eight different rabbit muscles are in the range of 10(3)-10(9)/micrograms total RNA. In soleus muscle, the value of 1.11 x 10(9) MHCI mRNA molecules corresponds to approximately 8% of the total mRNA. With reference to myonuclei, this amount corresponds to 1-2 x 10(4) molecules/nucleus. A quantitative comparison of the two fast MHC mRNA isoforms with the distribution of different MHC isoforms at the protein level indicates that one of these two fast sequences is specific to MHCIIb and the other to MHCIId. However, our data point to the existence of additional MHCIId mRNA subtypes.
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PMID:Non-radioactive reverse transcriptase/polymerase chain reaction for quantification of myosin heavy chain mRNA isoforms in various rabbit muscles. 768 10

As acute nonlymphocytic leukemia (ANLL) with inv(16) (p13q22) or t(16;16)(p13;q22) has been shown to result from the fusion of transcription factor subunit core binding factor (CBFB) to a myosin heavy chain (MYH11), we sought to design methods to detect this rearrangement using reverse transcriptase-polymerase chain reaction (RT-PCR). In all of 27 inv(16)(p13q22) and four t(16;16)(p13;q22) cases tested, a chimeric CBFB-MYH11 transcript coding for an in-frame fusion protein was detected. In a more extensive RT-PCR analysis with different primer pairs, we detected a second new chimeric CBFB-MYH11 transcript in 10 of 11 patients tested. The CBFB-MYH11 reading frame of the second transcript was maintained in one patient but not in the others. We show that the different CBFB-MYH11 transcripts in one patient arise from alternative splicing. Translation of the transcript in which the CBFB-MYH11 reading frame is not maintained leads to a slightly truncated CBFB protein.
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PMID:RT-PCR diagnosis of patients with acute nonlymphocytic leukemia and inv(16)(p13q22) and identification of new alternative splicing in CBFB-MYH11 transcripts. 779 33

We examined the transcriptional activity profile of the gene for atrial natriuretic factor (ANF) in mouse embryonal carcinoma P19 cells which had been induced for in vitro cardiac myogenesis. Differentiation was assessed visually, by the degree of spontaneous beating activity, and by the appearance of striated muscle structures detected by immunofluorescence with a myosin heavy chain antibody. Northern blot analysis of RNA isolated at regular intervals throughout the differentiation program revealed abundant cardiac alpha-actin transcripts beginning at Day 6, reaching maximum levels during Days 7 to 8 and declining to low levels by Days 12 to 15. Throughout this period, the transcriptional profile of the ANF gene was similar to that of alpha-actin but at lower levels; thus, in vivo stages of abundant ANF and structural muscle gene transcription were not reached and these gene expression states appear to be uncoupled. Using the more sensitive assay of reverse transcriptase-mediated polymerase chain reactions, we observed the presence of ANF transcripts even in small samples of muscle-induced P19 cells and not in neuron-induced or undifferentiated P19 cells. Induced ANF transcript levels reached about 5-10% that found in adult atrium muscle tissue. ANF gene activity was further corroborated by nuclear transcriptional run-on assays. The P19 stem cell model system will be of value in the study of early events during cardiac muscle commitment and differentiation.
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PMID:Activation of the gene for atrial natriuretic factor during in vitro cardiac myogenesis by P19 embryonal carcinoma cells. 834 90

The molecular mechanisms underlying the heterogeneity in contractile properties observed among smooth muscle tissues are unknown. We examined whether part of this diversity might be intrinsic to myosin by comparing structural and enzymatic properties of myosins from two physiologically diverse tissues. Using the reverse transcriptase polymerase chain reaction, we compared avian intestinal smooth muscle and vascular smooth muscle myosin heavy chain (MHC) mRNA. We found that intestinal, but not vascular, MHC mRNA contains an insert of 21 nucleotides, encoding 7 amino acids, in a region near the ATP binding site in the myosin head. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of purified myosin revealed that the relative mobilities of the previously described intestinal MHC isoforms SM1 (204 kDa) and SM2 (200 kDa) were slower than the corresponding vascular SM1 and SM2 isoforms. Furthermore, antibodies raised against a synthetic peptide corresponding to the deduced amino acid sequence of the intestinal insert strongly recognized intestinal SM1 and SM2 but only weakly recognized the vascular isoforms. The presence of the insert in intestinal myosin correlated with a higher velocity of movement of actin filaments in vitro and a higher actin-activated Mg(2+)-ATPase activity, compared with vascular myosin. Other than the MHC insert, one other structural difference distinguished intestinal and vascular myosins: two isoforms of the 17-kDa myosin light chain were found in vascular myosin, whereas a single isoform was found in intestinal myosin. Exchange of the intestinal myosin light chains onto the vascular MHC did not alter its activity in the in vitro motility assay, suggesting that the 7-amino acid MHC insert is responsible for the different enzymatic activities of vascular and intestinal myosins.
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PMID:An insert of seven amino acids confers functional differences between smooth muscle myosins from the intestines and vasculature. 850 18

We demonstrate, using reverse transcriptase-polymerase chain reaction, that, whereas abdominal aorta from rabbit consists almost entirely of myosin heavy chain (MHC) mRNA with no insert at the 5'-terminal coding region, the distributing arteries (femoral and saphenous) begin to show MHC mRNA with the 21-nucleotide insert that encodes seven amino acids in the ATP-binding region located in the myosin head. The femoral/iliac artery contains > 50% inserted mRNA, whereas the more distal saphenous artery contains > 80% inserted mRNA. This insert is also present in the smooth muscle from rat tail artery but is absent in the smooth muscle from rat aorta. The actin-activated ATPase activity of myosin from the rabbit femoral/saphenous artery is 1.7-fold higher than that of the myosin from the aorta. A concomitant increase (about twofold) in the maximum shortening velocity of the saphenous artery, compared with that of the aorta, indicates that the preponderance of the inserted myosin is associated with both an increase in the actin-activated ATPase activity and a larger maximum velocity of shortening. Furthermore, analysis of the 17-kDa essential light chain from the aorta reveals near equal quantities of the 17-kDa light chain isoforms a and b, whereas the myosin from the femoral/ saphenous artery contains predominantly the 17-kDa light chain a isoform. Together, these data indicate that the smooth muscle cells from the small distributing arteries are similar to those of visceral smooth muscle with respect to the expression of myosin isoforms, actin-activated myosin ATPase activity and contractility.
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PMID:NH2-terminal-inserted myosin II heavy chain is expressed in smooth muscle of small muscular arteries. 917 44

We review the current understanding of the myosin heavy chain (MHC) isoforms and show that the mRNA levels of smooth muscle (SM)1 and SM2 mimic the expressed levels of SM1 and SM2 protein. The reverse transcriptase-polymerase chain reaction technique has been shown to be sufficiently sensitive to examine SM-MHC expression at the single cell level. Most single smooth muscle cells isolated from adult rabbit carotid express both SM1 and SM2. However, expression of these SM-MHC isoforms at the cellular level is nonuniform and highly variable. This work provides a foundation for future investigations as to the possible unique functional characteristics of the SM-MHC isoforms, SM1 and SM2. This methodology may also prove useful when used with mechanical studies to determine the physiological significance of the alternatively spliced myosin isoforms, including the SM-MHC-head and LC17 isoforms.
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PMID:Myosin isoform heterogeneity in single smooth muscle cells. 918 12

An assay was developed for rapid and sensitive analysis of myosin heavy chain (MHC) mRNA expression in rodent skeletal muscle. Only 2 microg of total RNA were necessary for the simultaneous analysis of relative mRNA expression of six different MHC genes. We designed synthetic DNA fragments as internal standards, which contained the relevant primer sequences for the adult MHC mRNAs type I, IIa, IIx, IIb as well as the embryonic and neonatal MHC mRNAs. A known amount of the synthetic fragment was added to each polymerase chain reaction (PCR) and yielded a product of different size than the amplified MHC mRNA fragment. The ratio of amplified MHC fragment to synthetic fragment allowed us to calculate percentages of the gene expression of the different MHC genes in a given muscle sample. Comparison with the traditional Northern blot analysis demonstrated that our reverse transcriptase-PCR-based assay was reliable, fast, and quantitative over a wide range of relative MHC mRNA expression in a spectrum of adult and neonatal rat skeletal muscles. Furthermore, the high sensitivity of the assay made it very useful when only small quantities of tissue were available. Statistical analysis of the signals for each MHC isoform across the analyzed samples showed a highly significant correlation between the PCR and the Northern signals as Pearson correlation coefficients ranged between 0.77 and 0.96 (P < 0.005). This assay has potential use in analyzing small muscle samples such as biopsies and samples from pre- and/or neonatal stages of development.
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PMID:Analysis of myosin heavy chain mRNA expression by RT-PCR. 933 50

Combined methodologies of histochemistry, immunohistochemistry, sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE), reverse transcriptase polymerase chain reaction (RT-PCR) and a histochemical method specific for myofibrillar ATPase (mATPase) of the type IIX myosin heavy chain (MyHC) isoform were used to study human and rat single fibres to examine the homology between type II MyHC isoform-based fibres of both species. We demonstrate that human type II fibres exhibit antigenic mATPase and 3'-untranslated region (3'-UTR) sequence determinants homologous to the IIA and IIX but not the IIB MyHC isoforms of the rat. Both immunolabelling with anti-MyHC monoclonal antibodies and the mATPase method used with frozen sections confirmed that all human type II fibres express type IIA and/or type IIX MyHC. Quantitative immunohistochemistry failed to recognize human fibres with antigenic characteristics corresponding to hybrid IIXB MyHC-based fibres. Ca2+-stimulated maximum myosin ATPase activity, determined by quantitative histochemistry, revealed that human IIX fibres (with an optical density or OD = 0.707) display enzyme activity which is comparable to that of the rat type IIX (OD = 0.687) but lower than that of the rat type IIB fibres (OD = 0.836). The results do not support the notion that MyHC IIB is expressed in human limb muscles, even in hybrid fibres. We conclude that human type II fibres have been misclassified in numerous previous publications and that this has important implications in attempts to compare the physiological characteristics of fibre types, particularly when animal models are used.
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PMID:Comparison of the molecular, antigenic and ATPase determinants of fast myosin heavy chains in rat and human: a single-fibre study. 935 15

Growth hormone (GH) increases the amount of insulin-like growth factor-I (IGF-I) mRNA in rat skeletal muscle, but this effect has not been demonstrated in human muscle. An autocrine effect of IGF-I produced in muscle may be an important determinant of the increased muscle mass associated with GH therapy. Thus, we examined IGF-I mRNA abundance in skeletal muscle biopsy samples taken 10 h after a subcutaneous injection of GH (0.03 mg/kg, n = 6) or placebo (normal saline, n = 5) in men and women over 60 years of age. Relative tissue concentrations of IGF-I mRNA were evaluated with a competitive reverse transcriptase-polymerase chain reaction assay. Mean plasma IGF-I concentrations rose steadily after the GH injection, and were 74% higher in the GH group than in the control group at the time of the muscle biopsies. There was no consistent difference between the GH and control groups in muscle IGF-I mRNA abundance when expressed in relation to total RNA or polyadenylated RNA. However, one GH-treated subject had three times more IGF-I mRNA, relative to polyadenylated RNA, than the average control subject. There was no effect of GH on levels of mRNAs encoding the most abundant myofibrillar proteins, actin and myosin heavy chain. These data do not support the hypothesis that increased IGF-I mRNA abundance in skeletal muscle is required for the anabolic effect of GH in people over 60 years of age.
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PMID:Insulin-like growth factor-I, actin, and myosin heavy chain messenger RNAs in skeletal muscle after an injection of growth hormone in subjects over 60 years old. 939 11


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