scholarly journals Multiple silencer elements are involved in regulating the chicken vimentin gene.

1994 ◽  
Vol 14 (2) ◽  
pp. 934-943 ◽  
Author(s):  
R J Garzon ◽  
Z E Zehner

Vimentin, a member of the intermediate filament protein family, exhibits tissue- as well as development-specific expression. Transcription factors that are involved in expression of the chicken vimentin gene have been described and include a cis-acting silencer element (SE3) that is involved in the down-regulation of this gene (F. X. Farrell, C. M. Sax, and Z. E. Zehner, Mol. Cell. Biol. 10:2349-2358, 1990). In this study, we report the identification of two additional silencer elements (SE1 and SE2). We show by transfection analysis that all three silencer elements are functionally active and that optimal silencing occurs when multiple (at least two) silencer elements are present. In addition, the previously identified SE3 can be divided into three subregions, each of which is moderately active alone. By gel mobility shift assays, all three silencer elements plus SE3 subregions bind a protein which by Southwestern (DNA-protein) blot analysis is identical in molecular mass (approximately 95 kDa). DNase I footprinting experiments indicate that this protein binds to purine-rich sites. Therefore, multiple elements appear to be involved in the negative regulation of the chicken vimentin gene, which may be important in the regulation of other genes as well.

1994 ◽  
Vol 14 (2) ◽  
pp. 934-943
Author(s):  
R J Garzon ◽  
Z E Zehner

Vimentin, a member of the intermediate filament protein family, exhibits tissue- as well as development-specific expression. Transcription factors that are involved in expression of the chicken vimentin gene have been described and include a cis-acting silencer element (SE3) that is involved in the down-regulation of this gene (F. X. Farrell, C. M. Sax, and Z. E. Zehner, Mol. Cell. Biol. 10:2349-2358, 1990). In this study, we report the identification of two additional silencer elements (SE1 and SE2). We show by transfection analysis that all three silencer elements are functionally active and that optimal silencing occurs when multiple (at least two) silencer elements are present. In addition, the previously identified SE3 can be divided into three subregions, each of which is moderately active alone. By gel mobility shift assays, all three silencer elements plus SE3 subregions bind a protein which by Southwestern (DNA-protein) blot analysis is identical in molecular mass (approximately 95 kDa). DNase I footprinting experiments indicate that this protein binds to purine-rich sites. Therefore, multiple elements appear to be involved in the negative regulation of the chicken vimentin gene, which may be important in the regulation of other genes as well.


1992 ◽  
Vol 12 (5) ◽  
pp. 2230-2240
Author(s):  
D M Stover ◽  
Z E Zehner

Vimentin is a tissue-specific, developmentally regulated member of the intermediate filament protein family normally expressed in cells of mesenchymal origin. Transcription factors which recognize specific cis-acting elements of the chicken gene include Sp-1 and the 95-kDa silencer protein which binds to a 40-bp silencer element at -608 (F. X. Farrell, C. M. Sax, and Z. E. Zehner, Mol. Cell. Biol. 10:2349-2358, 1990). In this study, we have identified a region upstream of the silencer element which restores gene activity. This region has been further delineated into two functional subelements of 75 and 260 bp. In transient transfection assays, the 75-bp element overrides the silencer effect of pStkCAT by 100%, while the 260-bp element is about half as active. Neither element affects gene activity when the silencer element is absent. Therefore, these elements do not function as enhancers, but they may serve only to override the silencer element and therefore can be viewed as antisilencers. In addition, the 75-bp element binds a specific 140-kDa protein, as determined by gel mobility shift assays and Southwestern (DNA-protein) blots, the binding site of which has been delineated to a 10- to 17-bp element by DNase I protection experiments. During myogenesis, a direct correlation can be made between the binding efficiency of the 140-kDa protein, the silencer protein, and gene activity in vivo. Genes known to contain a functional silencer element also contain at least one antisilencer element, as determined by sequence identity. Therefore, we have identified an antisilencer element and protein important in the developmental regulation of vimentin gene expression which may be involved in the regulation of other genes.


1992 ◽  
Vol 12 (5) ◽  
pp. 2230-2240 ◽  
Author(s):  
D M Stover ◽  
Z E Zehner

Vimentin is a tissue-specific, developmentally regulated member of the intermediate filament protein family normally expressed in cells of mesenchymal origin. Transcription factors which recognize specific cis-acting elements of the chicken gene include Sp-1 and the 95-kDa silencer protein which binds to a 40-bp silencer element at -608 (F. X. Farrell, C. M. Sax, and Z. E. Zehner, Mol. Cell. Biol. 10:2349-2358, 1990). In this study, we have identified a region upstream of the silencer element which restores gene activity. This region has been further delineated into two functional subelements of 75 and 260 bp. In transient transfection assays, the 75-bp element overrides the silencer effect of pStkCAT by 100%, while the 260-bp element is about half as active. Neither element affects gene activity when the silencer element is absent. Therefore, these elements do not function as enhancers, but they may serve only to override the silencer element and therefore can be viewed as antisilencers. In addition, the 75-bp element binds a specific 140-kDa protein, as determined by gel mobility shift assays and Southwestern (DNA-protein) blots, the binding site of which has been delineated to a 10- to 17-bp element by DNase I protection experiments. During myogenesis, a direct correlation can be made between the binding efficiency of the 140-kDa protein, the silencer protein, and gene activity in vivo. Genes known to contain a functional silencer element also contain at least one antisilencer element, as determined by sequence identity. Therefore, we have identified an antisilencer element and protein important in the developmental regulation of vimentin gene expression which may be involved in the regulation of other genes.


1990 ◽  
Vol 10 (12) ◽  
pp. 6524-6532
Author(s):  
S M Frisch ◽  
J H Morisaki

Proteolysis by type IV collagenase (T4) has been implicated in the process of tumor metastasis. The T4 gene is expressed in fibroblasts, but not in normal epithelial cells, and its expression is specifically repressed by the E1A oncogene of adenovirus. We present an investigation of the transcriptional elements responsible for basal, E1A-repressible, and tissue-specific expression. 5'-Deletion analysis, DNase I footprinting, and gel mobility shift assays revealed a strong, E1A-repressible enhancer element, r2, located about 1,650 bp upstream of the start site. This enhancer bound a protein with binding specificity very similar to that of the transcription factor AP-2. A potent silencer sequence was found 2 to 5 bp downstream of this enhancer. The silencer repressed transcription from either r2 or AP-1 enhancer elements and in the context of either type IV collagenase or thymidine kinase (tk) gene core promoters; enhancerless transcription from the latter core promoter was also repressed. Comprising the silencer were two contiguous, autonomously functioning silencer elements. Negative regulation of T4 transcription by at least two factors was demonstrated. mcf-7 proteins specifically binding both elements were detected by gel mobility shift assays; a protein of approximately 185 kDa that bound to one of these elements was detected by DNA-protein cross-linking. The silencer repressed transcription, in an r2 enhancer-tk promoter context, much more efficiently in T4-nonproducing cells (mcf-7 or HeLa) than in T4-producing cells (HT1080), suggesting that cell type-specific silencing may contribute to the regulation of this gene.


1994 ◽  
Vol 14 (11) ◽  
pp. 7363-7376 ◽  
Author(s):  
A Cvekl ◽  
C M Sax ◽  
E H Bresnick ◽  
J Piatigorsky

The abundance of crystallins (> 80% of the soluble protein) in the ocular lens provides advantageous markers for selective gene expression during cellular differentiation. Here we show by functional and protein-DNA binding experiments that the chicken alpha A-crystallin gene is regulated by at least five control elements located at sites A (-148 to -139), B (-138 to -132), C (-128 to -101), D (-102 to -93), and E (-56 to -41). Factors interacting with these sites were characterized immunologically and by gel mobility shift experiments. The results are interpreted with the following model. Site A binds USF and is part of a composite element with site B. Site B binds CREB and/or CREM to enhance expression in the lens and binds an AP-1 complex including CREB, Fra2 and/or JunD which interacts with USF on site A to repress expression in fibroblasts. Sites C and E (which is conserved across species) bind Pax-6 in the lens to stimulate alpha A-crystallin promoter activity. These experiments provide the first direct data that Pax-6 contributes to the lens-specific expression of a crystallin gene. Site D (-104 to -93) binds USF and is a negative element. Thus, the data indicate that USF, CREB and/or CREM (or AP-1 factors), and Pax-6 bind a complex array of positive and negative cis-acting elements of the chicken alpha A-crystallin gene to control high expression in the lens and repression in fibroblasts.


1990 ◽  
Vol 10 (12) ◽  
pp. 6524-6532 ◽  
Author(s):  
S M Frisch ◽  
J H Morisaki

Proteolysis by type IV collagenase (T4) has been implicated in the process of tumor metastasis. The T4 gene is expressed in fibroblasts, but not in normal epithelial cells, and its expression is specifically repressed by the E1A oncogene of adenovirus. We present an investigation of the transcriptional elements responsible for basal, E1A-repressible, and tissue-specific expression. 5'-Deletion analysis, DNase I footprinting, and gel mobility shift assays revealed a strong, E1A-repressible enhancer element, r2, located about 1,650 bp upstream of the start site. This enhancer bound a protein with binding specificity very similar to that of the transcription factor AP-2. A potent silencer sequence was found 2 to 5 bp downstream of this enhancer. The silencer repressed transcription from either r2 or AP-1 enhancer elements and in the context of either type IV collagenase or thymidine kinase (tk) gene core promoters; enhancerless transcription from the latter core promoter was also repressed. Comprising the silencer were two contiguous, autonomously functioning silencer elements. Negative regulation of T4 transcription by at least two factors was demonstrated. mcf-7 proteins specifically binding both elements were detected by gel mobility shift assays; a protein of approximately 185 kDa that bound to one of these elements was detected by DNA-protein cross-linking. The silencer repressed transcription, in an r2 enhancer-tk promoter context, much more efficiently in T4-nonproducing cells (mcf-7 or HeLa) than in T4-producing cells (HT1080), suggesting that cell type-specific silencing may contribute to the regulation of this gene.


1994 ◽  
Vol 14 (11) ◽  
pp. 7363-7376
Author(s):  
A Cvekl ◽  
C M Sax ◽  
E H Bresnick ◽  
J Piatigorsky

The abundance of crystallins (> 80% of the soluble protein) in the ocular lens provides advantageous markers for selective gene expression during cellular differentiation. Here we show by functional and protein-DNA binding experiments that the chicken alpha A-crystallin gene is regulated by at least five control elements located at sites A (-148 to -139), B (-138 to -132), C (-128 to -101), D (-102 to -93), and E (-56 to -41). Factors interacting with these sites were characterized immunologically and by gel mobility shift experiments. The results are interpreted with the following model. Site A binds USF and is part of a composite element with site B. Site B binds CREB and/or CREM to enhance expression in the lens and binds an AP-1 complex including CREB, Fra2 and/or JunD which interacts with USF on site A to repress expression in fibroblasts. Sites C and E (which is conserved across species) bind Pax-6 in the lens to stimulate alpha A-crystallin promoter activity. These experiments provide the first direct data that Pax-6 contributes to the lens-specific expression of a crystallin gene. Site D (-104 to -93) binds USF and is a negative element. Thus, the data indicate that USF, CREB and/or CREM (or AP-1 factors), and Pax-6 bind a complex array of positive and negative cis-acting elements of the chicken alpha A-crystallin gene to control high expression in the lens and repression in fibroblasts.


1994 ◽  
Vol 14 (4) ◽  
pp. 2503-2515
Author(s):  
A Andrianopoulos ◽  
W E Timberlake

The Aspergillus nidulans abaA gene encodes a protein containing an ATTS DNA-binding motif and is required for the terminal stages of conidiophore development. Results from gel mobility shift and protection, missing-contact, and interference footprint assays showed that AbaA binds to the sequence 5'-CATTCY-3', where Y is a pyrimidine, making both major- and minor-groove contacts. Multiple AbaA binding sites are present in the cis-acting regulatory regions of several developmentally controlled structural genes as well as those of the upstream regulatory gene brlA, the downstream regulatory gene wetA, and abaA itself. These cis-acting regulatory regions confer AbaA-dependent transcriptional activation in a heterologous Saccharomyces cerevisiae gene expression system. From these observations, we propose that the AbaA transcription factor establishes a novel set of feedback regulatory loops responsible for determination of conidiophore development.


1989 ◽  
Vol 9 (10) ◽  
pp. 4204-4212
Author(s):  
M H Feuerman ◽  
R Godbout ◽  
R S Ingram ◽  
S M Tilghman

Previous work identified four upstream cis-acting elements required for tissue-specific expression of the alpha-fetoprotein (AFP) gene: three distal enhancers and a promoter. To further define the role of the promoter in regulating AFP gene expression, segments of the region were tested for the ability to direct transcription of a reporter gene in transient expression assay. Experiments showed that the region within 250 base pairs of the start of transcription was sufficient to confer liver-specific transcription. DNase I footprinting and band shift assays indicated that the region between -130 and -100 was recognized by two factors, one of which was highly sequence specific and found only in hepatoma cells. Competition assays suggested that the liver-specific binding activity was HNF-1, previously identified by its binding to other liver-specific promoters. Mutation of the HNF-1 recognition site at -120 resulted in a significant reduction in transcription in transfection assays, suggesting a biological role for HNF-1 in the regulation of AFP expression.


2007 ◽  
Vol 189 (9) ◽  
pp. 3660-3664 ◽  
Author(s):  
Suvit Loprasert ◽  
Wirongrong Whangsuk ◽  
James M. Dubbs ◽  
Ratiboot Sallabhan ◽  
Kumpanart Somsongkul ◽  
...  

ABSTRACT Sinorhizobium meliloti hpdA, which encodes the herbicide target 4-hydroxyphenylpyruvate dioxygenase, is positively regulated by HpdR. Gel mobility shift and DNase I footprinting analyses revealed that HpdR binds to a region that spans two conserved direct-repeat sequences within the hpdR-hpdA intergenic space. HpdR-dependent hpdA transcription occurs in the presence of 4-hydroxyphenylpyruvate, tyrosine, and phenylalanine, as well as during starvation.


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