Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.30.1 (S1 nuclease)
 3,660 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have identified and functionally characterized DNA sequences that regulate the expression of the human ventricular/slow twitch isoform of myosin alkali light chain (VLC1) gene. By using primer extension and S1 nuclease mapping techniques, we have shown that the VLC1 gene is transcribed from the identical site in the ventricular and slow twitch skeletal muscles. Comparison of the VLC1 sequences from +1 to -1296 in the genes for human and mouse showed that the 5'-proximal flanking region, up to about 220 nucleotides, was highly conserved (83% homology). To determine the location of sites that may be important for the function of the VLC1 promoter, a series of transient expression vectors containing progressive deletions of the VLC1 gene 5'-flanking sequence fused to the bacterial chloramphenicol acetyltransferase (CAT) gene was introduced into myogenic and nonmyogenic cells. Deletion mutagenesis of sequences between -357 and +40 revealed the presence of positive and negative activity in all the cells tested. We demonstrated that the minimal promoter sequence required to generate muscle cell-specific expression is the region between -94 to -64 upstream from the cap site and a sequence element located between -107 and -94 was found to have a positive effect in both myogenic cells and nonmyogenic cells. These two proximal regions located between -107 and -64 appear to act together to determine the cell type-specific high level expression of the VLC1 gene in muscle cells. Competition gel retardation assays revealed that the CArG sequence located between -96 and -87 interacts specifically with nuclear extracts from myogenic and nonmyogenic cells and compete for binding with the CArG sequence present in the human cardiac alpha-actin gene and with the serum response element of the c-fos gene. These results strongly suggested that similar, if not identical, the CArG box binding proteins interact with the functionally different promoter element in the VLC1, cardiac alpha-actin, and c-fos genes.
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PMID:Functional identification of the transcriptional regulatory elements within the promoter region of the human ventricular myosin alkali light chain gene. 169 44

Cardiac hypertrophy is associated with qualitative as well as quantitative changes in myocardial cells. To analyze the molecular basis of isozymic transitions of cardiac myosins in response to pressure overload, we have constructed and characterized two types of myosin heavy chain (MHC) cDNA clones, specifying alpha- and beta-MHCs, and two types of myosin alkali light chain cDNA clones, complementary to atrial type (ALC1) and ventricular type (VLC1) mRNAs from a human fetal heart cDNA library. Using the S1 nuclease mapping procedure, we showed that the MCH isozymic transitions from alpha- to beta-MHC in the pressure overloaded atria are produced by changes in the relative level of alpha- and beta-MHC gene expression. In addition, we observed that the expression of VLC1 gene is also induced in the atria subjected to severe pressure overload. Thus, it appears that the increased expression of VLC1 gene, together with the isogene switch from alpha- to beta-MHC gene, may participate in the adaptation of myocardium to new functional requirement. Then, to get a better understanding of the genetic mechanisms involved in the regulation of isogene expression, we have isolated and sequenced genomic clone for VLC1 isoform. Sequence analysis has identified multiple potential cis regulatory elements within a 686-bp upstream region. This region includes 28-bp alternating purine/pyrimidine sequences and two segment exhibiting homology to consensus sequence proposed for viral and cellular enhancer elements. In particular, a comparison of the VLC1 upstream gene sequence with those available for several muscle-specific genes revealed that CC(A + T-rich)6GG elements and CATTCCT sequence are conserved. These results suggested that CArG box (-96 to -87) has an important role in the positive regulation of the VLC1 gene and this element may be involved in the co-regulation of VLC1 and cardiac alpha-actin genes.
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PMID:The myosin gene switching in human cardiac hypertrophy. 214 55

We have introduced the chicken genes for cytoplasmic beta-actin, cardiac alpha-actin, and skeletal alpha-actin into C2 cells, a murine myogenic cell line, and into L cells by using the simian virus 40-derived vector PSV2 -gpt. In each selection, the entire population of transformed cells was analyzed for the expression and regulation of the actin genes by nuclease S1 assay and primer extension. This was compared to the expression of the vector marker Eco-gpt. The beta-actin gene is transcribed accurately and efficiently both in L-cells and in undifferentiated C2 cells. In fused C2 cells, beta-actin transcripts decrease significantly in parallel with the endogenous level of mouse beta-actin mRNA. Eco-gpt RNA levels remain essentially constant during myogenesis. The alpha-actin genes are correctly expressed at low levels in L cells but at significantly higher levels in the C2 cell background. Unlike the endogenous mouse alpha-actin gene, this level of expression does not change measurably with myogenesis. The skeletal alpha-actin gene is expressed poorly in pre- and post-fusion C2 cells, displaying no induction with differentiation. These results suggest that the tissue specificity of expression is maintained but the pattern of gene regulation for the sarcomeric actins is not. Factors in addition to the sequences flanking these genes are important for modulating gene expression during development. The decrease in the levels of beta-actin RNA during C2 cell differentiation provides a model system in which to study gene repression during development.
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PMID:Expression and regulation of chicken actin genes introduced into mouse myogenic and nonmyogenic cells. 632 84

Recent studies have documented the presence of a complete renin-angiotensin system in the proximal tubule of the kidney: however, little is known about the regulation of renin in this proximal tubular system. Therefore, we performed the present studies to learn whether the behavior of the renin system in cultured proximal tubule is similar to that of the juxtaglomerular renin system. Basal renin secretion from rabbit proximal tubular cells in primary culture was low and not affected by isoproterenol (10(-5) mol/L), diltiazem (10(-5) mol/L), or a zero-calcium bath (O nmol/L). Only the calcium ionophore A23187 (10(-4) mol/L) significantly reduced renin secretion in these cells (from 2.44 +/- 0.37 to 1.14 +/- O.08 ng angiotensin I/mg protein per hour, P<.05). When the proximal tubular cells were lysed so the effects of the test agents on intracellular renin content could be assessed, isoproterenol caused a significant twofold (107 percent) increase (from 2.02 +/- 0.56 to 4.18 +/- 0.81 ng angiotensin I/mg protein per hour, P<.05), whereas diltiazem, A23187, and zero- and high-calcium baths did not produce a significant change. The effects of these agents on renin mRNA were examined in rabbit and rat proximal tubular cells in primary culture with the use of an S1 nuclease protection assay. Densitometry analysis of renin mRNA and either GAPDH mRNA (rat) or alpha-actin (rabbit) showed no significant alterations in renin mRNA abundance. In summary, these results confirm the presence of renin mRNA in cultured proximal tubular cells and suggest that a low-level, constitutive secretion of renin occurs in this system that is decreased by A23187. Moreover, the results also suggest that proximal tubular renin is regulated, albeit differently from the juxtaglomerular renin system. Finally, short-term increments in proximal tubular renin occur without a change in renin mRNA.
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PMID:Renin regulation in cultured proximal tubular cells. 864 45