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)

To study the mechanisms by which the influenza A virus RNA-dependent RNA polymerase switches from transcription to replication we have devised a riboprobe protection technique with which we analyzed the 3' end sequence of (+)-strand RNA products of an in vitro transcription reaction containing purified virion-RNP complexes in the presence and the absence of the putative regulatory proteins NP and NS1. We found that the addition of these proteins did not result in the synthesis of full-length (+)-strand RNA products resulting from read-through of the polyadenylation signal or replication. Because NS1 and NP are both phosphoproteins we searched for protein kinase activity that might play a role in regulating RNA synthesis. We showed that virion RNP complexes phosphorylated NS1 but possessed no autophosphorylating activity. Soluble NP protein derived from RNP complexes did not phosphorylate NS1, but did phosphorylate casein. When NP protein was dephosphorylated, however, it no longer phosphorylated casein. We also showed that NS1 was an ssRNA-binding protein which binds nonspecifically to all ssRNA, and that this activity is not dependent on its state of phosphorylation.
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PMID:Influenza A virus in vitro transcription: roles of NS1 and NP proteins in regulating RNA synthesis. 182 5

The genes for the long form of the human and the short form of the mouse PRL receptors were transfected independently into NIH 3T3 cells. Reverse transcriptase-polymerase chain reaction indicated that the transfectant designated LFH contained message for only the long form and the transfectant designated SFM had message for only the short form of the receptor. Both transfectant cell lines specifically bound lactogenic hormones with high affinity and responded to PRL in culture with a 2- to 3-fold increase in cell number preceded by transient activation of mitogen-activated protein kinase. After a PRL-responsive casein-chloramphenicol acetyl transferase (CAT) construct was introduced into both LFH and SFM cells, CAT activity was induced by PRL only in the LFH-CAT cells. Thus, while the long form of the receptor can transduce the differentiation signal, both the long and the short forms of the receptor can signal the cells to grow.
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PMID:Transduction of prolactin's (PRL) growth signal through both long and short forms of the PRL receptor. 861 11

Nonsegmented negative strand RNA viruses package an RNA-dependent RNA polymerase composed of two subunits, a large protein L and a phosphoprotein P, for transcription and replication of their genome RNAs. The RNA polymerase activity resides within the L protein, while the P protein acts as a transcription factor or transactivator of the polymerase. Since P protein is heavily phosphorylated and phosphorylation is known to regulate function of many viral as well as cellular proteins, the role of phosphorylation of P protein in the gene expression of this group of RNA viruses has recently been investigated. Through expression in bacteria the P protein was produced in large quantity in the nonphosphorylated form and involvement of cellular kinase(s) in its phosphorylation was studied. Casein kinase II and/or protein kinase C have been shown to play a critical role in the activation of P protein in transcription. These findings have opened up a new avenue for studying an important regulatory step in virus gene expression that may lead to the development of an effective antiviral agent.
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PMID:Role of cellular kinases in the gene expression of nonsegmented negative strand RNA viruses. 922 28

Muscle cell migration plays an important role in the incorporation of transplanted myoblasts in muscle fibers. Understanding the mechanisms underlying the high migration capacity of the C(2)C(12) myoblast cell line may help to develop approaches to improve the migration of normal myoblasts and consequently to increase their participation to the host myofiber regeneration. We have previously shown that matrix metalloproteinases are implicated in the in vivo migration of C(2)C(12). Here, we studied the role of urokinase plasminogen activator (uPA) in this process. The expression of uPA mRNA and the enzymatic activity of uPA were studied in both normal myoblasts and the C(2)C(12) myoblast cell line. Reverse transcriptase polymerase chain reaction analysis showed that uPA mRNA was more strongly expressed in C(2)C(12) cells than in normal myoblasts. The enzymatic activity of secreted uPA analyzed by casein zymography is higher in medium conditioned by C(2)C(12) cells than in medium conditioned by normal myoblasts. Using our previously described microtube technique to assess in vivo cell migration, we showed that uPA is implicated in the in vivo migration of C(2)C(12) cells since this migration was abrogated in the presence of aprotinin (a general serine protease inhibitor) or amiloride (a uPA-specific inhibitor). We, therefore, hypothesized that increasing endogenous uPA expression by normal myoblasts may improve their migration capacity. Since an accumulating body of evidence has shown that growth factors regulate expression of uPA in a wide range of cells, we treated normal myoblasts with several growth factors alone or in combination with components of the extracellular matrix (ECM). All stimulants tested showed a minimal to strong effect on uPA enzymatic activity as assayed by zymography analysis. The positive effect of basic fibroblast growth factor (bFGF) on uPA enzymatic activity was slightly potentiated in the presence of fibronectin. Moreover, the pretreatment and coinjection of mouse myoblasts with bFGF alone or in combination with fibronectin improved significantly their in vivo migration throughout the tibialis anterior muscle of mdx mice. These results suggest that increasing uPA expression by an appropriate combination of growth factors and ECM components constitutes a possible approach to improving the migration of myogenic cells after transplantation.
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PMID:The urokinase plasminogen activator: an interesting way to improve myoblast migration following their transplantation. 1241 83

A bush-type plant was selected from tropical pumpkin 'cga' (Cucurbita moschata Duchesne) in order to study the vine development in C. moschata. In this study, a novel gene encoding NADH dehydrogenase was isolated from the vine line (cgaV) of C. moschata, that was not expressed in the near isogenic bush line (cgaBu). This gene, designated as CmV1 (C. moschata vine 1), was 545 bp in length and was composed of a 477 bp open reading frame, which had 99% nucleotide similarity to the chloroplast ndhJ gene for NADH dehydrogenase subunit J from Brassica oleracea. The deduced amino acid sequence of CmV1 had 99% similarity to NADH dehydrogenase subunit J from Arabidopsis and had 98% similarity to NADH dehydrogenase subunit from Barbarea verna. Analysis of the basic characteristics of the CmV1 protein revealed that it has one Respiratory chain NADH dehydrogenase 30 kD subunit signature, three N-myristoylation sites, one Casein kinase II phosphorylation site, and one Protein kinase C phosphorylation site. Reverse transcriptase-PCR analysis showed that CmV1 was expressed at a high level in the internodes and hypocotyls and was expressed stronger in elongating internodes than in fully expanded internodes. In conclusion, results obtained in the present study suggest that CmV1 gene might play important roles in vine elongation of tropical pumpkin.
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PMID:Molecular cloning and expression of a bush related CmV1 gene in tropical pumpkin. 1930 73

The process of placental separation is not completely understood. In domestic animals, especially cattle, it is important that expulsion of the fetal membranes takes place in a timely manner in order to achieve maximal reproductive efficiency. The activity of the matrix-metalloprotease (MMP) family of proteases is known to be reduced in placentomes from cases of retained placenta. Members of the MMP family are known to be activated by the plasminogen activator (PA) family of proteases. We hypothesized that the expression and activity of the PA family increase in the cotyledon and/or caruncle as parturition approaches, with maximal expression and activity at parturition. To test this hypothesis, we performed reverse-transcriptase quantitative PCR and plasminogen-casein zymography to detect the presence and activity of PA family members in the placentome leading up to and during parturition in spontaneous and dexamethasone-induced parturient ewes. The results from our experiments indicated that serine proteases inhibitor E1 (SERPINE1) mRNA abundance in the cotyledon was different between treatment groups (P = 0.0002). In the caruncle, gene expression for plasminogen activator urokinase-type (PLAU) was different (P = 0.0154), and there was a strong trend for differences in SERPINE1 expression (P = 0.0565). These results demonstrate that expression of the PA system in the placentome changes from late pregnancy to parturition, and the presence or activity of these enzymes may occur after fetal expulsion.
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PMID:The plasminogen activator system in the ovine placentome during late gestation and stage-two of parturition. 2358 21