An antisense promoter of the murine c-myc gene is localized within intron 2

1992 ◽  
Vol 12 (3) ◽  
pp. 1324-1329
Author(s):  
D B Spicer ◽  
G E Sonenshein

Previously we have demonstrated the existence of stable transcripts from the noncoding strand of a rearranged c-myc gene in murine plasmacytomas in which the oncogene has translocated to an immunoglobulin constant-region gene element (M. Dean, R. B. Kent, and G. E. Sonenshein, Nature [London] 305:443-446, 1983). The resulting RNAs are chimeric, containing c-myc antisense and immunoglobulin sense sequences. A normal unrearranged murine c-myc gene is transcribed in the antisense orientation throughout much of the gene; however, stable transcripts have not been detected. In this study, using Northern (RNA) blot, S1 nuclease, and primer extension analyses, we have mapped the 5' end of the stable chimeric transcripts to a site 175 bp from the start of exon 3, within intron 2 of the c-myc gene. In vitro transcription assays with constructs containing this site and 400 bp upstream, in the antisense orientation, and nuclear extracts from plasmacytoma cells, as well as a number of cell lines with normal unrearranged c-myc genes, indicated that this promoter was functional. This finding was confirmed in transient transfection assays using the antisense promoter linked to the chloramphenicol acetyltransferase reporter gene. These results suggest that a normal promoter of antisense transcription is used following c-myc gene translocation.

1992 ◽  
Vol 12 (3) ◽  
pp. 1324-1329 ◽  
Author(s):  
D B Spicer ◽  
G E Sonenshein

Previously we have demonstrated the existence of stable transcripts from the noncoding strand of a rearranged c-myc gene in murine plasmacytomas in which the oncogene has translocated to an immunoglobulin constant-region gene element (M. Dean, R. B. Kent, and G. E. Sonenshein, Nature [London] 305:443-446, 1983). The resulting RNAs are chimeric, containing c-myc antisense and immunoglobulin sense sequences. A normal unrearranged murine c-myc gene is transcribed in the antisense orientation throughout much of the gene; however, stable transcripts have not been detected. In this study, using Northern (RNA) blot, S1 nuclease, and primer extension analyses, we have mapped the 5' end of the stable chimeric transcripts to a site 175 bp from the start of exon 3, within intron 2 of the c-myc gene. In vitro transcription assays with constructs containing this site and 400 bp upstream, in the antisense orientation, and nuclear extracts from plasmacytoma cells, as well as a number of cell lines with normal unrearranged c-myc genes, indicated that this promoter was functional. This finding was confirmed in transient transfection assays using the antisense promoter linked to the chloramphenicol acetyltransferase reporter gene. These results suggest that a normal promoter of antisense transcription is used following c-myc gene translocation.


1988 ◽  
Vol 8 (11) ◽  
pp. 4799-4807 ◽  
Author(s):  
L J Brunet ◽  
A J Berk

The adenovirus E1A proteins are essential for the normal temporal activation of transcription from every other adenoviral early promoter. High-level E1A expression in the absence of viral infection would facilitate biochemical studies of E1A-mediated transactivation. Toward this end, we introduced the adenovirus type 2 E1A gene under the control of the murine mammary tumor virus promoter into HeLa cells. Uninduced cells expressed little or no detectable E1A mRNA. Upon induction, mRNA levels accumulated to about 50% of the level observed in 293 cells. The level of E1A expression in these cells could be controlled by varying the concentration of the inducing glucocorticoid. Under these conditions of varying E1A concentrations, it was observed that activation of the E2, E3, and E4 promoters of H5dl312 initiated at the same E1A concentration and that transcription from each promoter increased as the E1A concentration increased. These results indicate that E1A-mediated transactivation is proportional to the concentration of E1A protein. E1A-dependent transcriptional stimulation of the E4 promoter was reproduced in an in vitro transcription system, demonstrating that expression of only the E1A proteins was sufficient to increase the transcriptional activity of nuclear extracts.


1991 ◽  
Vol 11 (5) ◽  
pp. 2832-2841
Author(s):  
N Mechti ◽  
M Piechaczyk ◽  
J M Blanchard ◽  
P Jeanteur ◽  
B Lebleu

A strong block to the elongation of nascent RNA transcripts by RNA polymerase II occurs in the 5' part of the mammalian c-fos proto-oncogene. In addition to the control of initiation, this mechanism contributes to transcriptional regulation of the gene. In vitro transcription experiments using nuclear extracts and purified transcription templates allowed us to map a unique arrest site within the mouse first intron 385 nucleotides downstream from the promoter. This position is in keeping with that estimated from nuclear run-on assays performed with short DNA probes and thus suggests that it corresponds to the actual block in vivo. Moreover, we have shown that neither the c-fos promoter nor upstream sequences are absolute requirements for an efficient transcription arrest both in vivo and in vitro. Finally, we have characterized a 103-nucleotide-long intron 1 motif comprising the arrest site and sufficient for obtaining the block in a cell-free transcription assay.


1988 ◽  
Vol 8 (11) ◽  
pp. 4799-4807
Author(s):  
L J Brunet ◽  
A J Berk

The adenovirus E1A proteins are essential for the normal temporal activation of transcription from every other adenoviral early promoter. High-level E1A expression in the absence of viral infection would facilitate biochemical studies of E1A-mediated transactivation. Toward this end, we introduced the adenovirus type 2 E1A gene under the control of the murine mammary tumor virus promoter into HeLa cells. Uninduced cells expressed little or no detectable E1A mRNA. Upon induction, mRNA levels accumulated to about 50% of the level observed in 293 cells. The level of E1A expression in these cells could be controlled by varying the concentration of the inducing glucocorticoid. Under these conditions of varying E1A concentrations, it was observed that activation of the E2, E3, and E4 promoters of H5dl312 initiated at the same E1A concentration and that transcription from each promoter increased as the E1A concentration increased. These results indicate that E1A-mediated transactivation is proportional to the concentration of E1A protein. E1A-dependent transcriptional stimulation of the E4 promoter was reproduced in an in vitro transcription system, demonstrating that expression of only the E1A proteins was sufficient to increase the transcriptional activity of nuclear extracts.


1988 ◽  
Vol 8 (10) ◽  
pp. 4362-4369
Author(s):  
Y Li ◽  
R F Shen ◽  
S Y Tsai ◽  
S L Woo

The human alpha-1-antitrypsin (AAT) gene is expressed in the liver, and its deficiency causes pulmonary emphysema. We have demonstrated that its 5'-flanking region contains cis-acting elements capable of directing proper transcription in the presence of rat liver nuclear extract. The in vitro transcription system is tissue-specific in that the AAT promoter is functional in nuclear extracts prepared from the liver but not from HeLa cells. Experiments in which rat liver and HeLa nuclear extracts were mixed suggested the presence of a specific activator(s) in hepatocytes rather than a repressor(s) in nonproducing cells. Two protected regions were detected in the promoter by DNase I footprinting analysis with rat liver nuclear extracts. Region one spanned -78 to -52 and region two spanned -125 to -100 in the 5'-flanking sequence of the gene. By gel retardation assays with synthetic oligonucleotides, at least two distinct liver nuclear factors were identified, HNF-1 and HNF-2 (hepatocyte nuclear factors), which bound specifically to the first and second region, respectively. We present evidence that HNF-1 and HNF-2 are positively acting, tissue-specific transcription factors that regulate hepatic expression of the human AAT gene.


Blood ◽  
1994 ◽  
Vol 84 (9) ◽  
pp. 2992-3000 ◽  
Author(s):  
DJ Picketts ◽  
CR Mueller ◽  
D Lillicrap

Abstract Hemophilia B Leyden is a rare form of inherited factor IX deficiency in which patients experience spontaneous postpubertal recovery of factor IX levels. The mutations resulting in this disorder are localized in a 40-nucleotide region encompassing the major transcriptional start site for factor IX. Here we report the further characterization of five cis- acting elements in the factor IX promoter and the effects on protein binding and transcriptional activation of five Leyden mutations (at nucleotides +13, -5, -6, -20, and -26) that occur within the proximal three elements (sites 1 through 3). Bandshift studies using nuclear extracts from four different rat tissues have shown that at least some of the proteins binding to each of the five sites are ubiquitous in nature. The pattern of DNA binding at site 1 suggests that this element plays an important role in mediating the liver-specific expression of factor IX. Additional studies with liver nuclear extracts obtained at several different points in development have shown an increase in DNA binding at sites 1, 4, and 5 between 1 day and 1 week. Using DNase I footprint analysis and competition bandshift studies, we have shown that the binding of nuclear proteins to each of the mutant sites is disrupted to a variable extent. There appears to be some, although reduced, protein binding to all of the mutant oligonucleotides apart from the -26 mutant. In vitro transcription assays have shown that each of the mutations reduces the global proximal promoter activity by approximately 40%. Two double mutant promoters did not show any additional downregulation in the in vitro transcription assay. In experiments designed to assess the relative transcriptional activity mediated from each of the five sites independently, we have tested artificial homopolymer promoters of each site in the in vitro transcription assay. These studies show that sites 4 and 5 are the strongest activators and that transactivation from site 5 is further enhanced by the albumin D site-binding protein. In summary, these investigations show deleterious effects of each of the Leyden mutations tested on the binding of trans-acting factors and also show disruption of transcriptional activation in a functional in vitro transcription assay. Our results also show that cis-acting elements 4 and 5 are the principal activators of this locus.


1989 ◽  
Vol 9 (7) ◽  
pp. 2928-2933 ◽  
Author(s):  
B W Howell ◽  
M Lagacé ◽  
G C Shore

We have identified an essential cis element in the proximal promoter region of the rat carbamyl phosphate synthetase I (CPSI) gene that is requisite for promoter activity in liver nuclear extracts. Excess synthetic oligonucleotides specifying this region abolished promoter-dependent in vitro transcription. We show that C/EBP, a nuclear factor enriched in liver but found as well in other tissues, such as gut, fat, and lung, interacts with an inverted repeat, GTTGCAAC, at the core of the essential cis element. In brain, a tissue that did not express CPSI or contain significant levels of C/EBP, a different factor was capable of binding at or near the C/EBP recognition element. Activity of the CPSI promoter in liver nuclear extracts was also dependent on sequences 5' to the C/EBP motif; presumably, factors binding to elements within this upstream region are instrumental in restricting CPSI gene expression to liver and intestinal mucosa.


1989 ◽  
Vol 9 (7) ◽  
pp. 3122-3126 ◽  
Author(s):  
T Tamura ◽  
A Aoyama ◽  
T Inoue ◽  
M Miura ◽  
H Okano ◽  
...  

The mouse myelin basic protein promoter was transcribed in brain nuclear extracts. The distal promoter region from -253 to -54 directed preferential transcription in brain extracts, whereas the same region repressed transcription activity in liver extracts. Stimulation of transcription was observed when the distal region was located only in a native orientation. The proximal region downstream from -53 alone still directed preferential transcription. It is suggested that cooperative function by the two promoter regions may be required for higher specificity.


1986 ◽  
Vol 6 (7) ◽  
pp. 2392-2401 ◽  
Author(s):  
P J Farnham ◽  
R T Schimke

We have developed an in vitro transcription system for the murine dihydrofolate reductase gene. Although transcription in vitro from a linearized template was initiated at the same start sites as in vivo, the correct ratios were more closely approximated when a supercoiled template was used. In addition, whereas the dihydrofolate reductase promoter functions bidirectionally in vivo, the initiation signals directed unidirectional transcription in this in vitro system. The dihydrofolate reductase gene does not have a typical TATA box, but has four GGGCGG hexanucleotides within 300 base pairs 5' of the AUG codon. Deletion analysis suggested that, although sequences surrounding each of the GC boxes could specify initiation approximately 40 to 50 nucleotides downstream, three of the four GC boxes could be removed without changing the accuracy or efficiency of initiation at the major in vivo site. The dihydrofolate reductase promoter initiated transcription very rapidly in vitro, with transcripts visible by 1 min and almost maximal by 2 min at 30 degrees C with no preincubation. Nuclear extracts prepared from cells blocked in the S phase by aphidicolin or from adenovirus-infected cells at 16 h postinfection had enhanced dihydrofolate reductase transcriptional activity. This increased in vitro transcription mimicked the increase in dihydrofolate reductase mRNA seen in S-phase cells and suggested the presence of a cell-cycle-specific factor(s) which stimulated transcription from the dihydrofolate reductase gene.


1988 ◽  
Vol 8 (3) ◽  
pp. 1290-1300
Author(s):  
H Watanabe ◽  
T Imai ◽  
P A Sharp ◽  
H Handa

Two kinds of trans-acting factors that regulate transcription from the promoter of the adenovirus early-region 4 (E4) have been identified by reconstituting nuclear extracts of HeLa cells. They were designated E4TF1 and E4TF3 for E4 transcription factors. These factors were responsible for efficient and accurate transcription in vitro from the E4 promoter, as were another transcription factor, designated E4TF2, and a crude fraction containing endogenous RNA polymerase II. E4TF1 stimulated transcription from the E4 promoter but not from the major late promoter or the E4 mutant promoter lacking the E4TF1-binding site. Footprint analysis of E4TF1 revealed that it binds to a specific region, residing between 132 and 152 base pairs upstream from the initiation site of the E4 mRNA. E4TF3 also regulated transcription from the E4 promoter. E4TF3 protected four ca. 20-base-pair regions in a DNase I footprinting assay. They were located around 40, 160, 230, and 260 base pairs upstream from the initiation site of E4 mRNA. Specific inhibition of E4 transcription was observed by addition of DNA fragments covering one of the E4TF1- and E4TF3-binding sites to in vitro transcription assays. These results suggest that both E4TF1 and E4TF3 regulate E4 transcription by binding to the specific upstream elements in the E4 promoter. These factors may be involved in the E1A transactivation of E4 transcription.


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