The vitamin K–dependent γ-glutamyl carboxylase gene contains a TATA-less promoter with a novel upstream regulatory element

Blood ◽  
2003 ◽  
Vol 102 (4) ◽  
pp. 1333-1339 ◽  
Author(s):  
Elizabeth E. Romero ◽  
Umaima Marvi ◽  
Zachary E. Niman ◽  
David A. Roth

Abstract The expression of the vitamin K–dependent γ-glutamyl carboxylase gene in liver is developmentally regulated. Since the gene product catalyzes an essential post-translational modification of the vitamin K–dependent blood coagulation proteins, the regulation of carboxylase expression is critical for hemostasis. We analyzed the activity of the rat carboxylase gene 5′-regulatory DNA sequences in rat hepatoma cell lines at different states of differentiation. These studies demonstrated that the 2.6-kb 5′-flanking sequence has differentiation-dependent transcriptional activity. Transient gene expression assays, examining the effects of nested deletions and site-directed mutagenesis of putative regulatory sequences, together with electrophoretic mobility shift assays (EMSAs) were used to identify sequences critical for the developmentally regulated transcription of the rat carboxylase gene. We identified a DNA sequence (–76 to –65; GTTCCGGCCTTC) not known to bind to transcription factors, yet which functions as an upstream promoter element. In vivo genomic DNA footprinting confirms the presence of nuclear protein–DNA interactions at this site in the endogenous carboxylase gene in differentiated hepatoma cells. Therefore, this DNA sequence has specific nuclear protein–binding activity and functional properties consistent with a regulatory element that plays a critical role in the developmental expression of the carboxylase gene, and hence the regulation of vitamin K–dependent blood coagulation protein synthesis.

1981 ◽  
Vol 90 (5) ◽  
pp. 1387-1395 ◽  
Author(s):  
Yasuo OHNO ◽  
Hisao KATO ◽  
Takashi MORITA ◽  
Sadaaki IWANAGA ◽  
Katsumi TAKADA ◽  
...  

Genetics ◽  
2003 ◽  
Vol 165 (2) ◽  
pp. 457-466 ◽  
Author(s):  
M García-Rubio ◽  
P Huertas ◽  
S González-Barrera ◽  
A Aguilera

AbstractHomologous recombination of a particular DNA sequence is strongly stimulated by transcription, a phenomenon observed from bacteria to mammals, which we refer to as transcription-associated recombination (TAR). TAR might be an accidental feature of DNA chemistry with important consequences for genetic stability. However, it is also essential for developmentally regulated processes such as class switching of immunoglobulin genes. Consequently, it is likely that TAR embraces more than one mechanism. In this study we tested the possibility that transcription induces recombination by making DNA more susceptible to recombinogenic DNA damage. Using different plasmid-chromosome and direct-repeat recombination constructs in which transcription is driven from either the PGAL1- or the Ptet-regulated promoters, we haveshown that either 4-nitroquinoline-N-oxide (4-NQO) or methyl methanesulfonate (MMS) produces a synergistic increase of recombination when combined with transcription. 4-NQO and MMS stimulated recombination of a transcriptionally active DNA sequence up to 12,800- and 130-fold above the spontaneous levels observed in the absence of transcription, whereas 4-NQO and MMS alone increased recombination 193- and 4.5-fold, respectively. Our results provide evidence that TAR is due, at least in part, to the ability of transcription to enhance the accessibility of DNA to exogenous chemicals and internal metabolites responsible for recombinogenic lesions. We discuss possible parallelisms between the mechanisms of induction of recombination and mutation by transcription.


2021 ◽  
Vol 129 (Suppl_1) ◽  
Author(s):  
Cristine J Reitz ◽  
Marjan Tavassoli ◽  
Da Hye Kim ◽  
Sina Hadipour-Lakmehsari ◽  
Saumya Shah ◽  
...  

Dilated cardiomyopathy (DCM) is one of the most common causes of heart failure, yet the majority of the underlying signaling mechanisms remain poorly characterized. Protein phosphorylation is a key regulatory element with profound effects on the activity and function of signaling networks; however, there is a lack of comprehensive phosphoproteomic studies in human DCM patients. We assessed the hypothesis that an integrative phosphoproteomics analysis of human DCM would reveal novel phosphoprotein candidates involved in disease pathophysiology. Combined proteomic and phosphoproteomic analysis of explanted left ventricular tissue samples from DCM patients ( n =4) and non-failing controls ( n =4) identified 5,570 unique proteins with 13,624 corresponding phosphorylation sites. From these analyses, we identified αT-catenin as a unique candidate protein with a cluster of 4 significantly hyperphosphorylated sites in DCM hearts ( P <0.0001), with no change in total αT-catenin expression at the protein level. Bioinformatics analyses of human datasets and confocal imaging of human and mouse cardiac tissue show highly cardiac-enriched expression of αT-catenin, localized to the cardiomyocyte intercalated disc. High resolution 3-dimensional reconstruction shows elongated intercalated disc morphology in DCM hearts (10.07±0.76 μm in controls vs. 17.20±1.87 μm in DCM, P <0.05, n =3/group), with significantly increased colocalization of αT-catenin with the intercalated disc membrane protein N-cadherin (Pearson’s coefficient 0.55±0.04 in controls vs. 0.71±0.02 in DCM, P <0.05, n =3/group). To investigate the functional role of cardiac αT-catenin phosphorylation, we overexpressed WT protein vs. non-phosphorylatable forms based on the loci identified in DCM hearts, in adult mouse cardiomyocytes using lentiviral transduction. Confocal imaging revealed significant internalization of the phospho-null form, as compared to the prominent intercalated disc staining of the WT protein (17.78±0.79% of WT vs. 9.25±0.49% of 4A mutant, P <0.0001, n =50 cells/group). Together, these findings suggest a critical role for αT-catenin phosphorylation in maintaining cardiac intercalated disc organization in human DCM.


1991 ◽  
Vol 11 (2) ◽  
pp. 641-654
Author(s):  
C Hinkley ◽  
M Perry

Xenopus oocytes, arrested in G2 before the first meiotic division, accumulate histone mRNA and protein in the absence of chromosomal DNA replication and therefore represent an attractive biological system in which to examine histone gene expression uncoupled from the cell cycle. Previous studies have shown that sequences necessary for maximal levels of transcription in oocytes are present within 200 bp at the 5' end of the transcription initiation site for genes encoding each of the five major Xenopus histone classes. We have defined by site-directed mutagenesis individual regulatory sequences and characterized DNA-binding proteins required for histone H2B gene transcription in injected oocytes. The Xenopus H2B gene has a relatively simple promoter containing several transcriptional regulatory elements, including TFIID, CBP, and ATF/CREB binding sites, required for maximal transcription. A sequence (CTTTACAT) in the H2B promoter resembling the conserved octamer motif (ATTTGCAT), the target for cell-cycle regulation of a human H2B gene, is not required for transcription in oocytes. Nonetheless, substitution of a consensus octamer motif for the variant octamer element activates H2B transcription. Oocyte factors, presumably including the ubiquitous Oct-1 factor, specifically bind to the consensus octamer motif but not to the variant sequence. Our results demonstrate that a transcriptional regulatory element involved in lymphoid-specific expression of immunoglobulin genes and in S-phase-specific activation of mammalian H2B histone genes can activate transcription in nondividing amphibian oocytes.


1986 ◽  
Vol 6 (12) ◽  
pp. 4548-4557
Author(s):  
J Hirsh ◽  
B A Morgan ◽  
S B Scholnick

We delimited sequences necessary for in vivo expression of the Drosophila melanogaster dopa decarboxylase gene Ddc. The expression of in vitro-altered genes was assayed following germ line integration via P-element vectors. Sequences between -209 and -24 were necessary for normally regulated expression, although genes lacking these sequences could be expressed at 10 to 50% of wild-type levels at specific developmental times. These genes showed components of normal developmental expression, which suggests that they retain some regulatory elements. All Ddc genes lacking the normal immediate 5'-flanking sequences were grossly deficient in larval central nervous system expression. Thus, this upstream region must contain at least one element necessary for this expression. A mutated Ddc gene without a normal TATA boxlike sequence used the normal RNA start points, indicating that this sequences is not required for start point specificity.


1986 ◽  
Vol 6 (12) ◽  
pp. 4353-4361
Author(s):  
S Alexander ◽  
A M Cibulsky ◽  
S D Cuneo

Mutant strains of Dictyostelium discoideum carrying dis mutations fail to transcribe specifically the family of developmentally regulated discoidin lectin genes during morphogenesis. The phenotypes of these mutants strongly suggested that the mutations reside in regulatory genes. Using these mutant strains, we showed that multiple regulatory genes are required for the expression of the lectin structural genes and that these regulatory genes (the dis+ alleles) act in trans to regulate this gene family. These regulatory genes fall into two complementation groups (disA and disB) and map to linkage groups II and III, respectively. A further regulatory locus was defined by the identification of an unlinked supressor gene, drsA (discoidin restoring), which is epistatic to disB, but not disA, and results in the restoration of lectin expression in cells carrying the disB mutation. Mutant cells carrying the drsA allele express the discoidin lectin gene family during growth and development, in contrast to wild-type cells which express it only during development. Therefore, the suppressor activity of the drsA allele appears to function by making the expression of the discoidin lectins constitutive and no longer strictly developmentally regulated. The data indicate that normal expression of the discoidin lectins is dependent on the sequential action of the disB+, drsA+, and disA+ gene products. Thus, we described an interacting network of regulatory genes which in turn controls the developmental expression of a family of genes during the morphogenesis of D. discoideum.


1992 ◽  
Vol 12 (8) ◽  
pp. 3614-3627
Author(s):  
P G Traber ◽  
G D Wu ◽  
W Wang

Sucrase-isomaltase (SI) is an enterocyte-specific gene which exhibits a complex pattern of expression during intestinal development and in the adult intestinal mucosa. In the studies described in this report, we demonstrate that enterocyte-specific transcription of the SI gene is regulated by an evolutionarily conserved promoter that extends approximately 180 bp upstream of the transcription start site. DNase I footprint analysis allowed the identification of three nuclear protein-binding sites within the SI promoter (SIF1, SIF2, and SIF3 [SI footprint]), each of which acted as a positive regulatory element for transcription in intestinal cell lines. SIF1 was shown to bind nuclear protein complexes present in primary mouse small intestinal cell and in an intestinal cell line (Caco-2). However, SIF1-binding proteins were absent in a variety of other epithelial and nonepithelial cells. In vitro mutagenesis experiments demonstrated that the SIF1 site is required for high-level promoter activity in intestinal cells. The SIF3 element formed prominent binding complexes with intestinal and liver nuclear extracts, whereas nuclear proteins from other epithelial and nonepithelial cells formed weaker complexes of different mobilities. The SIF2 element bound nuclear proteins in a pattern similar to that of SIF3, and cross-competition studies suggested that SIF2 and SIF3 may bind the same nuclear proteins. Taken together, these data have allowed the identification of novel DNA-binding proteins that play an important role in regulating intestine-specific transcription of the SI gene.


1993 ◽  
Vol 13 (8) ◽  
pp. 4494-4504
Author(s):  
D Nitsch ◽  
G Schütz

Tyrosine aminotransferase gene expression is confined to parenchymal cells of the liver, is inducible by glucocorticoids and glucagon, and is repressed by insulin. Three enhancers control this tissue-specific and hormone-dependent activity, one of which, located at -11 kb, is implicated in establishing an active expression domain. We have studied in detail this important regulatory element and have identified a 221-bp fragment containing critical enhancer sequences which stimulated the heterologous thymidine kinase promoter more than 100-fold in hepatoma cells. Within this region, we have characterized two essential liver-specific enhancer domains, one of which was bound by proteins of the hepatocyte nuclear factor 3 (HNF3) family. Analyses with the dedifferentiated hepatoma cell line HTC suggested that HNF3 alpha and/or -gamma, but not HNF3 beta, are involved in activating the tyrosine aminotransferase gene via the -11-kb enhancer. Genomic footprinting and in vitro protein-DNA binding studies documented cell-type-specific binding of ubiquitous factors to the second essential enhancer domain, which by itself stimulated the thymidine kinase promoter preferentially in hepatoma cells. These results will allow further characterization of the role of these enhancer sequences in developmental activation of the tyrosine aminotransferase gene.


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