scholarly journals Structure and transcriptional regulation of the Nat2 gene encoding for the drug-metabolizing enzyme arylamine N-acetyltransferase type 2 in mice

2003 ◽  
Vol 375 (3) ◽  
pp. 593-602 ◽  
Author(s):  
Sotiria BOUKOUVALA ◽  
Naomi PRICE ◽  
Kathryn E. PLANT ◽  
Edith SIM

Arylamine N-acetyltransferases (NATs) are polymorphic enzymes, well-known for their role in the metabolism of drugs and carcinogens. Mice have three NAT isoenzymes, of which NAT2 is postulated to be involved in endogenous, as well as xenobiotic, metabolism. To understand expression of the murine Nat2 gene, we have analysed its structure and transcriptional regulation. We have accurately mapped the transcription initiation site 6.5 kb upstream of the coding region of the gene, adjacent to a recently described non-coding exon. Transcription was demonstrated to start from this region in embryonic and adult liver, spleen, submaxillary gland, kidney, brain, thymus, lung and placenta, but not in the heart. Database searches and analyses of cDNA by PCR suggested alternative splicing of the single 6.2 kb intron of Nat2, and determined the position of the polyadenylation signal at 0.44 kb downstream of the coding region of the gene. Examination of the 13 kb sequence flanking the coding and non-coding exons of Nat2 revealed a single promoter, located close to the transcription-initiation site, and indicated regions likely to harbour control elements. The Nat2 promoter consists of an atypical TATA box and a Sp1 [SV40 (simian virus 40) protein 1] box identical with that found in many housekeeping gene promoters. Activity of the Nat2 promoter was severely reduced by deletion or mutation of either of these two elements, whereas the region of the Sp1 box bound cellular protein and resisted DNase I digestion. Finally, the ability of the promoter region to bind cellular protein was reduced by competition with oligonucleotides bearing the Sp1 consensus sequence.

1989 ◽  
Vol 9 (8) ◽  
pp. 3244-3252 ◽  
Author(s):  
J M Huibregtse ◽  
D R Engelke

We have shown by genomic footprinting that the 5'-flanking region of the Saccharomyces cerevisiae tRNASUP53 gene is protected from DNase I digestion. The protected region has a 5' boundary at -40 (relative to the transcription initiation site) and extends into the coding region of the gene, with a 3' boundary at approximately +15. Although the DNase I protection over this region was much greater than at the A- and B-box internal promoters, point mutations within the A or B box that reduced transcription in vitro eliminated the upstream DNase I protection. This implies that formation of a stable complex over the 5'-flanking region is dependent on interaction of the gene with transcription factor IIIC but that stability of the complex may not require continued interaction with this factor. The DNase I protection under varied growth conditions further suggested that the upstream complex is composed of two or more components. The region over the transcription initiation site (approximately +15 to -10) was less protected in stationary-phase cultures, whereas the more upstream region (approximately -10 to -40) was protected in both exponential- and stationary-phase cultures.


1990 ◽  
Vol 10 (4) ◽  
pp. 1390-1398
Author(s):  
P J Farnham ◽  
A L Means

The murine dihydrofolate reductase gene is regulated by a bidirectional promoter that lacks a TATA box. To identify the DNA sequences required for dihydrofolate reductase transcription, the activities of various templates were determined by in vitro transcription analysis. Our data indicate that sequences both upstream and downstream of the transcription initiation site modulate the activity of the dihydrofolate reductase promoter. We have focused on two regions downstream of the transcription initiation site that are important in determining the overall efficiency of the promoter. Region 1, which included exon 1 and part of intron 1, could stimulate transcription when placed in either orientation in the normal downstream position and when inserted upstream of the transcription start site. This region could also stimulate transcription in trans when the enhancer was physically separate from the promoter. Deletion of region 2, spanning 46 nucleotides of the 5' untranslated region, reduced transcriptional activity by fivefold. DNase I footprinting reactions identified protein-binding sites in both downstream stimulatory regions. Protein bound to two sites in region 1, both of which contain an inverted CCAAT box. The protein-binding site in the 5' untranslated region has extensive homology to binding sites in promoters that both lack (simian virus 40 late) and contain (adenovirus type 2 major late promoter and c-myc) TATA boxes.


1986 ◽  
Vol 6 (1) ◽  
pp. 302-314 ◽  
Author(s):  
R D Andersen ◽  
B W Birren ◽  
S J Taplitz ◽  
H R Herschman

As shown by Southern blot analysis, the metallothionein-1 (MT-1) genes in rats comprise a multigene family. We present the sequence of the MT-1 structural gene and compare its features with other metallothionein genes. Three MT-1 pseudogenes which we sequenced apparently arose by reverse transcription of processed mRNA transcripts. Two of these, MT-1 psi a and MT-1 psi c, are retrogenes which derive from the MT-1 mRNA, having diverged from the MT-1 gene 6.9 and 2.6 million years ago, respectively. The third, MT-1 psi b, differs from the MT-1 cDNA by only three nucleotide alterations. Surprisingly, MT-1 psi b also preserves sequence homology for 142 base pairs 5' to the transcription initiation site of the parent gene; it contains a promoter sequence sufficient for specifying metal ion induction. We identified, by S1 nuclease mapping, an RNA polymerase II initiation site 432 base pairs 5' of the MT-1 transcription initiation site of the MT-1 structural gene which could explain the formation of the mRNA precursor to this pseudogene. We were unable to detect MT-1 psi b transcripts, either in liver tissue or after transfection. We conclude that the absence of detectable transcripts from this pseudogene is due to either a reduced level of transcription or the formation of unstable transcripts as a consequence of the lack of a consensus sequence normally found 3' of transcription termination in the MT-1 structural gene.


1989 ◽  
Vol 9 (8) ◽  
pp. 3244-3252
Author(s):  
J M Huibregtse ◽  
D R Engelke

We have shown by genomic footprinting that the 5'-flanking region of the Saccharomyces cerevisiae tRNASUP53 gene is protected from DNase I digestion. The protected region has a 5' boundary at -40 (relative to the transcription initiation site) and extends into the coding region of the gene, with a 3' boundary at approximately +15. Although the DNase I protection over this region was much greater than at the A- and B-box internal promoters, point mutations within the A or B box that reduced transcription in vitro eliminated the upstream DNase I protection. This implies that formation of a stable complex over the 5'-flanking region is dependent on interaction of the gene with transcription factor IIIC but that stability of the complex may not require continued interaction with this factor. The DNase I protection under varied growth conditions further suggested that the upstream complex is composed of two or more components. The region over the transcription initiation site (approximately +15 to -10) was less protected in stationary-phase cultures, whereas the more upstream region (approximately -10 to -40) was protected in both exponential- and stationary-phase cultures.


1986 ◽  
Vol 6 (1) ◽  
pp. 302-314
Author(s):  
R D Andersen ◽  
B W Birren ◽  
S J Taplitz ◽  
H R Herschman

As shown by Southern blot analysis, the metallothionein-1 (MT-1) genes in rats comprise a multigene family. We present the sequence of the MT-1 structural gene and compare its features with other metallothionein genes. Three MT-1 pseudogenes which we sequenced apparently arose by reverse transcription of processed mRNA transcripts. Two of these, MT-1 psi a and MT-1 psi c, are retrogenes which derive from the MT-1 mRNA, having diverged from the MT-1 gene 6.9 and 2.6 million years ago, respectively. The third, MT-1 psi b, differs from the MT-1 cDNA by only three nucleotide alterations. Surprisingly, MT-1 psi b also preserves sequence homology for 142 base pairs 5' to the transcription initiation site of the parent gene; it contains a promoter sequence sufficient for specifying metal ion induction. We identified, by S1 nuclease mapping, an RNA polymerase II initiation site 432 base pairs 5' of the MT-1 transcription initiation site of the MT-1 structural gene which could explain the formation of the mRNA precursor to this pseudogene. We were unable to detect MT-1 psi b transcripts, either in liver tissue or after transfection. We conclude that the absence of detectable transcripts from this pseudogene is due to either a reduced level of transcription or the formation of unstable transcripts as a consequence of the lack of a consensus sequence normally found 3' of transcription termination in the MT-1 structural gene.


1989 ◽  
Vol 108 (2) ◽  
pp. 579-593 ◽  
Author(s):  
M J Monteiro ◽  
D W Cleveland

We have used transient and stable DNA transfection to force synthesis of the mouse NF-L and NF-M genes in nonneuronal cultured animal cells. When the authentic NF-L gene (containing 1.7 kb of sequences 5' to the transcription initiation site) was transfected into L cells, correctly initiated NF-L mRNA was produced from the transfected gene but not the endogenous NF-L genes. Therefore, the normal restriction of NF-L expression to neurons cannot derive exclusively from absence in nonneuronal cells of neuron-specific transcription factors. When the NF-L coding region was linked to the strong promoter from Moloney Murine Sarcoma virus, we obtained high levels of synthesis of NF-L subunits (accumulating to as much as 9% of cell protein in stable cell lines). Although NF-L and NF-M polypeptides are normally expressed exclusively in postmitotic neurons, NF-L or NF-M polypeptides expressed in fibroblasts were efficiently assembled into intermediate filament arrays, thus demonstrating the competence of both NF-L and NF-M to assemble in vivo in the absence of additional neuron-specific factors. As judged by immunofluorescence localization and by the alteration in the solubility of the endogenous vimentin filaments, filaments containing NF-L appeared to be copolymers with vimentin. Neither the alteration in the properties of the vimentin array nor the accumulation of NF-L to a level that made it the second most abundant cellular protein (after actin) had any observable effect on cell viability or growth rate.


1991 ◽  
Vol 11 (10) ◽  
pp. 5190-5196
Author(s):  
S K Pal ◽  
S S Zinkel ◽  
A A Kiessling ◽  
G M Cooper

We have employed transient expression assays to analyze the sequences that direct c-mos transcription in mouse oocytes. Plasmids containing the chloramphenicol acetyltransferase (CAT) gene fused to either a 2.4-kb or a 731-bp fragment from the 5'-flanking region of c-mos produced similar levels of CAT activity when injected into nuclei of growing oocytes. BAL 31 deletions revealed that sequences up to 20 bp upstream of the major transcription start site could be removed without any significant loss of CAT activity. Promoter activity only decreased when these deletions closely approached the transcription start site, which was mapped at 53 nucleotides upstream of the first ATG in the c-mos open reading frame. On the other hand, deletion of sequences within 20 nucleotides downstream of the transcription initiation site resulted in a 10-fold reduction in CAT expression. A similar decrease in promoter activity was observed as a result of point mutations in these 5' untranslated sequences. Thus, sequences immediately downstream of the transcription start site, including a consensus sequence (PyPyCAPyPyPyPyPy) present in the initiator elements of several genes, appear to regulate c-mos expression in mouse oocytes. Reverse transcription-polymerase chain reaction analysis of RNA from injected oocytes showed that this regulation is manifest at the transcriptional level. Expression of c-mos in mouse oocytes thus appears to be directed by a simple promoter consisting only of sequences immediately surrounding the transcription start site, including an initiator element in the untranslated leader.


2008 ◽  
Vol 28 (24) ◽  
pp. 7504-7513 ◽  
Author(s):  
Maxime Tremblay ◽  
Yumin Teng ◽  
Michel Paquette ◽  
Raymond Waters ◽  
Antonio Conconi

ABSTRACT Nucleotide excision repair (NER) removes a plethora of DNA lesions. It is performed by a large multisubunit protein complex that finds and repairs damaged DNA in different chromatin contexts and nuclear domains. The nucleolus is the most transcriptionally active domain, and in yeast, transcription-coupled NER occurs in RNA polymerase I-transcribed genes (rDNA). Here we have analyzed the roles of two members of the xeroderma pigmentosum group C family of proteins, Rad4p and Rad34p, during NER in the active and inactive rDNA. We report that Rad4p is essential for repair in the intergenic spacer, the inactive rDNA coding region, and for strand-specific repair at the transcription initiation site, whereas Rad34p is not. Rad34p is necessary for transcription-coupled NER that starts about 40 nucleotides downstream of the transcription initiation site of the active rDNA, whereas Rad4p is not. Thus, although Rad4p and Rad34p share sequence homology, their roles in NER in the rDNA locus are almost entirely distinct and complementary. These results provide evidences that transcription-coupled NER and global genome NER participate in the removal of UV-induced DNA lesions from the transcribed strand of active rDNA. Furthermore, nonnucleosome rDNA is repaired faster than nucleosome rDNA, indicating that an open chromatin structure facilitates NER in vivo.


1990 ◽  
Vol 10 (4) ◽  
pp. 1390-1398 ◽  
Author(s):  
P J Farnham ◽  
A L Means

The murine dihydrofolate reductase gene is regulated by a bidirectional promoter that lacks a TATA box. To identify the DNA sequences required for dihydrofolate reductase transcription, the activities of various templates were determined by in vitro transcription analysis. Our data indicate that sequences both upstream and downstream of the transcription initiation site modulate the activity of the dihydrofolate reductase promoter. We have focused on two regions downstream of the transcription initiation site that are important in determining the overall efficiency of the promoter. Region 1, which included exon 1 and part of intron 1, could stimulate transcription when placed in either orientation in the normal downstream position and when inserted upstream of the transcription start site. This region could also stimulate transcription in trans when the enhancer was physically separate from the promoter. Deletion of region 2, spanning 46 nucleotides of the 5' untranslated region, reduced transcriptional activity by fivefold. DNase I footprinting reactions identified protein-binding sites in both downstream stimulatory regions. Protein bound to two sites in region 1, both of which contain an inverted CCAAT box. The protein-binding site in the 5' untranslated region has extensive homology to binding sites in promoters that both lack (simian virus 40 late) and contain (adenovirus type 2 major late promoter and c-myc) TATA boxes.


1991 ◽  
Vol 11 (10) ◽  
pp. 5190-5196 ◽  
Author(s):  
S K Pal ◽  
S S Zinkel ◽  
A A Kiessling ◽  
G M Cooper

We have employed transient expression assays to analyze the sequences that direct c-mos transcription in mouse oocytes. Plasmids containing the chloramphenicol acetyltransferase (CAT) gene fused to either a 2.4-kb or a 731-bp fragment from the 5'-flanking region of c-mos produced similar levels of CAT activity when injected into nuclei of growing oocytes. BAL 31 deletions revealed that sequences up to 20 bp upstream of the major transcription start site could be removed without any significant loss of CAT activity. Promoter activity only decreased when these deletions closely approached the transcription start site, which was mapped at 53 nucleotides upstream of the first ATG in the c-mos open reading frame. On the other hand, deletion of sequences within 20 nucleotides downstream of the transcription initiation site resulted in a 10-fold reduction in CAT expression. A similar decrease in promoter activity was observed as a result of point mutations in these 5' untranslated sequences. Thus, sequences immediately downstream of the transcription start site, including a consensus sequence (PyPyCAPyPyPyPyPy) present in the initiator elements of several genes, appear to regulate c-mos expression in mouse oocytes. Reverse transcription-polymerase chain reaction analysis of RNA from injected oocytes showed that this regulation is manifest at the transcriptional level. Expression of c-mos in mouse oocytes thus appears to be directed by a simple promoter consisting only of sequences immediately surrounding the transcription start site, including an initiator element in the untranslated leader.


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