Multiple cis- and trans-acting elements involved in regulation of the neu gene

1990 ◽  
Vol 10 (12) ◽  
pp. 6306-6315
Author(s):  
T C Suen ◽  
M C Hung

A 2.4-kb rat neu genomic DNA fragment that hybridized to the 5'-most coding sequence of the rat neu cDNA was cloned. S1 nuclease mapping identified multiple transcriptional initiation sites. DNA sequence analysis revealed that this fragment contained 64 bp of the first intron, 81 bp of the first exon, and the upstream noncoding sequence of the neu gene. The sequence immediately upstream of the translation start site was G + C rich (greater than 75%) and contained a consensus CCAAT sequence despite the absence of a TATA box. An Sp1-binding site was found, in addition to various sequence motifs common to the promoters of the human neu gene (erbB2), the epidermal growth factor receptor gene, and the simian virus 40 enhancer. A 2.2-kb EcoRI-Narl fragment containing sequences upstream from the 3'-most transcriptional start site was fused to the bacterial chloramphenicol acetyltransferase reporter gene and shown to promote transcription efficiently. A series of promoter deletion constructs was made, and results from transfection and subsequent chloramphenicol acetyltransferase assays suggested the presence of multiple cis-acting elements that contributed either positively or negatively to the transcription activity. Cotransfection competition experiments using subcloned cis-acting elements confirmed the existence of trans-acting factors interacting with these DNA fragments. In addition, a gel retardation assay was performed to demonstrate the physical binding of nuclear factors to certain fragments. The results complemented those of the deletion studies and led us to conclude that transcriptional regulation of the neu proto-oncogene involves at least one negative and three positive trans-acting factors interacting with different cis-acting elements along the neu gene promoter.

1990 ◽  
Vol 10 (12) ◽  
pp. 6306-6315 ◽  
Author(s):  
T C Suen ◽  
M C Hung

A 2.4-kb rat neu genomic DNA fragment that hybridized to the 5'-most coding sequence of the rat neu cDNA was cloned. S1 nuclease mapping identified multiple transcriptional initiation sites. DNA sequence analysis revealed that this fragment contained 64 bp of the first intron, 81 bp of the first exon, and the upstream noncoding sequence of the neu gene. The sequence immediately upstream of the translation start site was G + C rich (greater than 75%) and contained a consensus CCAAT sequence despite the absence of a TATA box. An Sp1-binding site was found, in addition to various sequence motifs common to the promoters of the human neu gene (erbB2), the epidermal growth factor receptor gene, and the simian virus 40 enhancer. A 2.2-kb EcoRI-Narl fragment containing sequences upstream from the 3'-most transcriptional start site was fused to the bacterial chloramphenicol acetyltransferase reporter gene and shown to promote transcription efficiently. A series of promoter deletion constructs was made, and results from transfection and subsequent chloramphenicol acetyltransferase assays suggested the presence of multiple cis-acting elements that contributed either positively or negatively to the transcription activity. Cotransfection competition experiments using subcloned cis-acting elements confirmed the existence of trans-acting factors interacting with these DNA fragments. In addition, a gel retardation assay was performed to demonstrate the physical binding of nuclear factors to certain fragments. The results complemented those of the deletion studies and led us to conclude that transcriptional regulation of the neu proto-oncogene involves at least one negative and three positive trans-acting factors interacting with different cis-acting elements along the neu gene promoter.


1986 ◽  
Vol 6 (4) ◽  
pp. 1032-1043
Author(s):  
K Sato ◽  
R Ito ◽  
K H Baek ◽  
K Agarwal

We located and characterized a downstream transcriptional regulatory element in the human gastrin gene by transferring the gastrin gene 3' fragment, from which the polyadenylation signal sequence was deleted, into the shuttle vector pSCAT10 at a site located immediately downstream from the chloramphenicol acetyltransferase (CAT) gene and upstream from the simian virus 40 polyadenylation region. Study of CAT RNA derived from the hybrid plasmids, indicated regulation of transcription on the gastrin gene fragment. Analysis of deletion mutants generated from the 5' region of the fragment by CAT assay and by S1 nuclease mapping of mRNAs indicated the possible involvement of an oligothymidylate-rich sequence in transcription regulation. Mapping of gastrin gene RNA 3' ends to the 5' side proximal to the oligothymidylate-rich sequence clearly demonstrated that this sequence is a transcriptional terminator element. This unique sequence, interspersed with one or two adenines, which also functions in an orientation-dependent manner, is located 192 nucleotides downstream from the gastrin gene polyadenylation site, and serves as a transcriptional termination signal.


1985 ◽  
Vol 5 (9) ◽  
pp. 2443-2453 ◽  
Author(s):  
A Israel ◽  
S N Cohen

We report results indicating that expression and hormonally controlled negative regulation of the human pro-opiomelanocortin (POMC) gene in mouse fibroblasts can be accomplished by the placement nearby of a simian virus 40 enhancer sequence. Expression resulting from correctly initiated transcription required the enhancer in cis both in cells stably transfected with the POMC gene and in a transient expression assay with constructs that fused that POMC promoter region to the protein-coding region of the herpes simplex virus thymidine kinase (TK) gene. Negative regulation of POMC transcription by glucocorticoids was demonstrated in transiently infected cells by assaying for TK activity encoded by the POMC-TK fusion constructs and by quantitative S1 nuclease mapping. The sequences responsible for such regulation were shown to be contained within a DNA segment that extends 670 base pairs upstream from the cap site for POMC mRNA.


1985 ◽  
Vol 5 (9) ◽  
pp. 2433-2442
Author(s):  
E D Lewis ◽  
J L Manley

We investigated the nucleotide sequence requirements of the adenovirus 2 late promoter when activated by either a trans-acting regulatory protein or a cis-acting enhancer element. Using deletion mutants in transient expression assays, we determined that the 5' limit of the region required for activation by a trans-acting regulatory protein, the adenovirus early region 1a gene product, and the simian virus 40 enhancer is the same in both 293 and HeLa cells. Surprisingly, the 3' limit of required sequences varied, depending on the mechanism of activation. Activation mediated by the early region 1a protein endogenous in 293 cells or produced after cotransfection of HeLa cells requires the region around the transcriptional start site, whereas activation brought about by an enhancer element in HeLa cells has no requirement for these sequences. Under no conditions tested did the simian virus 40 enhancer activate the late promoter in 293 cells, even when sequences sufficient for enhancer-mediated activation in HeLa cells, but not for early region 1a activation, were present. These results suggest the existence of at least two different mechanisms for positive regulation of promoter activity.


1986 ◽  
Vol 6 (4) ◽  
pp. 1032-1043 ◽  
Author(s):  
K Sato ◽  
R Ito ◽  
K H Baek ◽  
K Agarwal

We located and characterized a downstream transcriptional regulatory element in the human gastrin gene by transferring the gastrin gene 3' fragment, from which the polyadenylation signal sequence was deleted, into the shuttle vector pSCAT10 at a site located immediately downstream from the chloramphenicol acetyltransferase (CAT) gene and upstream from the simian virus 40 polyadenylation region. Study of CAT RNA derived from the hybrid plasmids, indicated regulation of transcription on the gastrin gene fragment. Analysis of deletion mutants generated from the 5' region of the fragment by CAT assay and by S1 nuclease mapping of mRNAs indicated the possible involvement of an oligothymidylate-rich sequence in transcription regulation. Mapping of gastrin gene RNA 3' ends to the 5' side proximal to the oligothymidylate-rich sequence clearly demonstrated that this sequence is a transcriptional terminator element. This unique sequence, interspersed with one or two adenines, which also functions in an orientation-dependent manner, is located 192 nucleotides downstream from the gastrin gene polyadenylation site, and serves as a transcriptional termination signal.


1985 ◽  
Vol 5 (9) ◽  
pp. 2433-2442 ◽  
Author(s):  
E D Lewis ◽  
J L Manley

We investigated the nucleotide sequence requirements of the adenovirus 2 late promoter when activated by either a trans-acting regulatory protein or a cis-acting enhancer element. Using deletion mutants in transient expression assays, we determined that the 5' limit of the region required for activation by a trans-acting regulatory protein, the adenovirus early region 1a gene product, and the simian virus 40 enhancer is the same in both 293 and HeLa cells. Surprisingly, the 3' limit of required sequences varied, depending on the mechanism of activation. Activation mediated by the early region 1a protein endogenous in 293 cells or produced after cotransfection of HeLa cells requires the region around the transcriptional start site, whereas activation brought about by an enhancer element in HeLa cells has no requirement for these sequences. Under no conditions tested did the simian virus 40 enhancer activate the late promoter in 293 cells, even when sequences sufficient for enhancer-mediated activation in HeLa cells, but not for early region 1a activation, were present. These results suggest the existence of at least two different mechanisms for positive regulation of promoter activity.


1985 ◽  
Vol 5 (9) ◽  
pp. 2443-2453
Author(s):  
A Israel ◽  
S N Cohen

We report results indicating that expression and hormonally controlled negative regulation of the human pro-opiomelanocortin (POMC) gene in mouse fibroblasts can be accomplished by the placement nearby of a simian virus 40 enhancer sequence. Expression resulting from correctly initiated transcription required the enhancer in cis both in cells stably transfected with the POMC gene and in a transient expression assay with constructs that fused that POMC promoter region to the protein-coding region of the herpes simplex virus thymidine kinase (TK) gene. Negative regulation of POMC transcription by glucocorticoids was demonstrated in transiently infected cells by assaying for TK activity encoded by the POMC-TK fusion constructs and by quantitative S1 nuclease mapping. The sequences responsible for such regulation were shown to be contained within a DNA segment that extends 670 base pairs upstream from the cap site for POMC mRNA.


1991 ◽  
Vol 11 (2) ◽  
pp. 1023-1029
Author(s):  
Y Li ◽  
D Li ◽  
K Osborn ◽  
L F Johnson

The thymidylate synthase (TS) gene is a housekeeping gene that is expressed at much higher levels in proliferating cells than in quiescent cells. We have studied the role of the TS 5'-flanking sequences in regulating the level of expression of the mouse TS gene. A variety of chimeric TS minigenes that contain different promoters linked either to the TS coding region (with or without introns) or to the chloramphenicol acetyltransferase (CAT) coding region were constructed. The activities of the minigenes were determined by transfecting them into cultured cells and measuring the levels of mRNA or enzyme derived from the chimeric genes. We found that the mouse TS promoter had about the same strength as the simian virus 40 early promoter but was significantly stronger than the herpes simplex virus thymidine kinase promoter. Stable transfection studies revealed that minigenes consisting of the normal TS promoter (extending to -1 kb), coding region, and polyadenylation signal were regulated normally in response to growth stimulation. When the TS promoter was replaced by the simian virus 40 early promoter or by a TS promoter that retained only 60 nucleotides upstream of the first transcriptional start site, the minigene was expressed constitutively. A minigene consisting of the TS promoter (extending to -1 kb) linked to the CAT coding region was also expressed constitutively. These observations indicate that sequences upstream of the transcriptional start sites of the TS gene are necessary, although not sufficient, for normal growth-regulated expression of the mouse TS gene.


1989 ◽  
Vol 9 (6) ◽  
pp. 2378-2386
Author(s):  
L A Neuhold ◽  
Y Shirayoshi ◽  
K Ozato ◽  
J E Jones ◽  
D W Nebert

The mouse cytochrome P1450 (CYP1A1) gene is responsible for the metabolism of numerous carcinogens and toxic chemicals. Induction by the environmental contaminant tetrachlorodibenzo-p-dioxin (TCDD) requires a functional aromatic hydrocarbon (Ah) receptor. We examined the 5'-flanking region of the CYP1A1 gene in mouse hepatoma Hepa-1 wild-type cells and a mutant line having a defect in chromatin binding of the TCDD-receptor complex. We identified two cis-acting elements (distal, -1071 to -901 region; proximal, -245 to -50 region) required for constitutive and TCDD-inducible CYP1A1 gene expression. Three classes of DNA-protein complexes binding to the distal element were identified: class I, found only in the presence of TCDD and a functional Ah receptor, that was heat labile and not competed against by simian virus 40 (SV40) early promoter DNA; class II, consisting of at least three constitutive complexes that were heat stable and bound to SV40 DNA; and class III, composed of at least three constitutive complexes that were thermolabile and were not competed against by SV40 DNA. Essential contacts for these proteins were centered at -993 to -990 for the class I complex, -987, -986, or both for the class II complexes, and -938 to -927 for the class III complexes. The proximal element was absolutely essential for both constitutive and TCDD-inducible CYP1A1 gene expression, and at least two constitutive complexes bound to this region. These data are consistent with the proximal element that binds proteins being necessary but not sufficient for inducible gene expression; interaction of these proteins with those at the distal element was found to be required for full CYP1A1 induction by TCDD.


1982 ◽  
Vol 2 (9) ◽  
pp. 1044-1051 ◽  
Author(s):  
C M Gorman ◽  
L F Moffat ◽  
B H Howard

We constructed a series of recombinant genomes which directed expression of the enzyme chloramphenicol acetyltransferase (CAT) in mammalian cells. The prototype recombinant in this series, pSV2-cat, consisted of the beta-lactamase gene and origin of replication from pBR322 coupled to a simian virus 40 (SV40) early transcription region into which CAT coding sequences were inserted. Readily measured levels of CAT accumulated within 48 h after the introduction of pSV2-cat DNA into African green monkey kidney CV-1 cells. Because endogenous CAT activity is not present in CV-1 or other mammalian cells, and because rapid, sensitive assays for CAT activity are available, these recombinants provided a uniquely convenient system for monitoring the expression of foreign DNAs in tissue culture cells. To demonstrate the usefulness of this system, we constructed derivatives of pSV2-cat from which part or all of the SV40 promoter region was removed. Deletion of one copy of the 72-base-pair repeat sequence in the SV40 promoter caused no significant decrease in CAT synthesis in monkey kidney CV-1 cells; however, an additional deletion of 50 base pairs from the second copy of the repeats reduced CAT synthesis to 11% of its level in the wild type. We also constructed a recombinant, pSV0-cat, in which the entire SV40 promoter region was removed and a unique HindIII site was substituted for the insertion of other promoter sequences.


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