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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The type I element (CCACGTCANCGATCCGCG) is a cis-acting element that is essential for the transcriptional regulation of the wheat histone H3 (TH012) gene. The sequence CCACGTCA in the type I element resembles various plant regulatory elements that share an ACGT core sequence, which can be recognized by different basic/leucine zipper (bZIP) proteins. Here we describe the isolation and characterization of wheat cDNA clones encoding three novel bZIP proteins, designated HBP (histone promoter-binding protein)-1a(1), HBP-1a(c14), and HBP-1b(c1). These proteins specifically bind to the ACGT core sequence and, together with previously identified HBP-1a(17) and HBP-1b(c38), constitute a protein family, named the HBP-1 family. Based on their structural characteristics and DNA binding specificities, members of the HBP-1 family can be grouped into HBP-1a and HBP-1b subfamilies. The HBP-1a isoforms are characterized by their N-terminal proline-rich domain and a C-terminal bZIP domain, which binds to the CCACGT motif. In contrast, the HBP-1b isoforms have a bZIP domain at the N terminus, which binds to the ACGTCA motif, and a glutamine-rich domain at the C terminus. All members of both subfamilies interact with the CCACGTCA sequence, but their DNA binding specificities and affinities differ. Since HBP-1a isoforms form heterodimers in all pairwise combinations, heterodimer formation among these bZIP proteins may generate an expanded repertoire of regulatory potential for gene expression in plants.
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PMID:The HBP-1 family of wheat basic/leucine zipper proteins interacts with overlapping cis-acting hexamer motifs of plant histone genes. 814 92

The expression of genes encoding five histones (H1, H2A, H2B, H3 and H4) and the putative transcription factors HBP-1a (17) and HBP-1b (c38) was examined during early germination and in various tissues of young wheat seedlings. The steady-state levels of core histone (H2A, H2B, H3 and H4) mRNAs were coordinately cell cycle-dependent and paralleled the rate of DNA synthesis during early germination, whereas the expression pattern of the linker histone (H1) genes differed. The five subclass histone genes were actively expressed in the meristematic tissues of young seedlings. Moreover, H1 genes were expressed in leaves that consist mostly of non-proliferating cells, in which core histone genes showed little expression. Quantitative alterations to the mRNAs of the putative transcription factors HBP-1a (17) and HBP-1b (c38) of wheat histone genes were similar to those of the core histone mRNAs, suggesting that both factors function in the cell cycle-dependent expression of wheat core histone genes.
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PMID:Coordinate gene expression of five subclass histones and the putative transcription factors, HBP-1a and HBP-1b, of histone genes in wheat. 821 77

Protein-DNA interactions in the promoter regions of two maize histone genes have been analyzed by DNase I and DMS in vivo footprinting combined with LMPCR amplification. Both promoters present a bimodular structure characterized by a proximal cell division-specific set of interactions and a distal region which displays constitutive footprints but enhancement of these footprints upon cell proliferation. The inducible region contains two cis-elements common to all replication-dependent plant histone genes, one of them having previously been shown to be a target for the wheat nuclear protein HBP-2. In the constitutive region, the first demonstration for the existence of a transcription factor binding to the highly conserved plant histone-specific octamer CGCGGATC is provided. Exchange of cell-type-specific factors is postulated to occur at that site. Additional immediate upstream constitutive elements binding regulatory proteins include a degenerate octameric sequence, a CCAAT-box, a CACCC sequence and composite ACGTCA/ACGTGG hexameric sequences binding HBP-1-related trans-acting factors. The close proximity of these elements within the constitutive region and the redundancy of some of them suggest complex cooperation and competition mechanisms contributing to achieve the final expression level and likely also to mediate the interplay between constitutive and inducible factors.
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PMID:Constitutive and cell-division-inducible protein-DNA interactions in two maize histone gene promoters. 822 Apr 90

A nonamer motif (CATCCAACG) that is one of the cis-acting elements identified in the proximal promoter region of some wheat histone genes is included in the region that interacts with the wheat DNA-binding protein, HBP (histone gene-binding protein)-2. To obtain structural and functional information about this DNA-binding protein, we attempted to isolate a cDNA clone encoding HBP-2 on the basis of its ability to bind to a nonamer-containing 38-bp DNA fragment. Southwestern screening of a wheat cDNA library with concatenated 38-residue oligonucleotides as the probe produced one candidate clone. Nucleotide sequence analyses of this cDNA clone and the corresponding genomic clone showed that the protein deduced from the nucleotide sequence consisted of 261 amino acids and contained a set of zinc-finger motifs similar to those found in many eukaryotic transcription factors. The protein, named WZF1 (wheat zinc-finger protein 1), which was expressed from the cDNA in Escherichia coli cells, bound specifically and metal-ion-dependently to the nonamer-containing oligonucleotide. The WZF1 mRNA was highly expressed in the root apexes of wheat seedlings, but less so in the proximal portion of young leaves; whereas, histone H3 mRNA was highly expressed in both tissues. The expression patterns of the WZF1 and histone H3 genes in the early stages of germination differed, expression of the WZF1 gene being almost constant but not that of the H3 gene. The relationship of WZF1 and HBP-2 and the possible role of WZF1 in the histone gene expression were discussed.
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PMID:The putative zinc-finger protein WZF1 interacts with a cis-acting element of wheat histone genes. 822 28

The chromosomal locations of the genes in common wheat that encode the five histones and five members of the HBP (histone gene-binding protein)-1 family were determined by hybridizing their cloned DNAs to genomic DNAs of nullitetrasomic and telosomic lines of common wheat, Triticum aestivum cv. Chinese Spring. The H1 and H2a genes are located on different sets of homoeologous chromosomes or chromosome arms, namely, 5A, 5B and 5D, and 2AS, 2BS and 2DS, respectively. Genes for the other histones, H2b, H3 and H4, are found in high copy number and are dispersed among a large number of chromosomes. The genes for all members of the HBP-1 family are present in small copy numbers. Those for HBP-1a(1) are located on six chromosome arms, 3BL, 5AL, 5DL, 6AL, 6BS and 7DL, whereas those for each HBP-1a(c14), 1a(17), 1b(c1), and 1b(c38) are on a single set of homoeologous chromosome arms; 4AS, 4BL, 4DL; 6AS, 6BS, 6DS; 3AL, 3BL, 3DL; and 3AS, 3BS, 3DS, respectively. The genes for histones H1 and H2a, and for all members of the HBP-1 family except HBP-1a(1) are assumed to have different phylogenetic origins. The genes for histone 2a and HBP-1a(17) are located in the RFLP maps of chromosomes 2B and 6A, respectively. Gene symbols are proposed for all genes whose chromosomal locations have been determined.
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PMID:Chromosomal locations of the genes for histones and a histone gene-binding protein family HBP-1 in common wheat. 834 98

The S phase-specific expression of histone genes provides an interesting model for studying activation of gene transcription during the cell cycle. In plants, however, trans-acting factors responsible for histone gene transcription are poorly documented. Using combined gel shift, UV cross-linking and competition analysis, we carried out a systematic study to identify and characterize proteins binding with the previously established cis elements of the plant histone gene promoters. Nuclear extracts prepared from the highly synchronizable tobacco BY2 cells were used. We confirmed the presence of proteins binding to the hexamer (ACGTCA) motif which has been previously identified as the binding site of wheat HBP-1 proteins. Interestingly, multiple proteins were found to bind specifically with the nonamer (CAATCCAAC) element and their DNA-binding activity was abolished upon in vitro protein phosphatase treatment. This later result imply phosphorylation/dephosphorylation as a potential post-translational control for DNA-binding activity of nonamer-binding proteins. In addition, the DNA-binding activity of these nonamer-binding proteins was found to be positively correlated with the S phase-specific expression of the histone genes in the synchronized cells, suggesting their function in the activation of transcription during the G1/S transition. Finally, several proteins were observed to bind specifically with an A/T-rich hexamer (TAATAT) motif. Their DNA-binding activity, however, was insensitive to phosphatase activity in vitro and relatively constitutive during the cell cycle. This A/T-rich hexamer as a new cis-acting element of plant histone genes is discussed.
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PMID:Protein complexes binding to cis elements of the plant histone gene promoters: multiplicity, phosphorylation and cell cycle alteration. 904 59

The wheat bZIP protein HBP-1a(17) is a putative transcription factor regulating histone gene expression. To delineate the functional domain(s) of this factor, we made a series of effector constructs expressing fusion proteins, in which various portions of HBP-1a(17) are fused to the DNA-binding domain of the yeast transcriptional activator GAL4, in plant cells. When the beta-glucuronidase (GUS) reporter gene, driven by the wheat histone H3 core promoter harboring the GAL4-binding sequence, was co-transfected with such effector genes into tobacco protoplasts, several portions of HBP-1a(17) influenced reporter gene expression. The N-terminal one-third of HBP-1a(17), termed the P region (residues 1-118) due to its Pro content, did not activate the reporter gene, in contrast to the corresponding Pro-rich region of Arabidopsis GBF1 (residues 1-110), which functions as an activation domain. When the P region was divided into two, however, both its N-terminal (1-56; termed NP) and C-terminal (58-118; termed PC) halves were able to enhance expression of the reporter gene. When the NP region was further divided into NP(5-30) and NP(30-56), both regions still retained activating ability. These results suggest that the P region of HBP-1a(17) is composed of several modules each having activating function, and modification and/or conformational changes of the P region might influence its function.
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PMID:Dissection of the wheat transcription factor HBP-1a(17) reveals a modular structure for the activation domain. 906 88

Inhaled nitric oxide (NO) is an important new therapeutic agent used to treat pulmonary arterial hypertension in a variety of disease states. However, the effects of NO on cells in the lung are uncertain. Previously, we have shown that NO gas depresses neutrophil oxidative cell function and increases neutrophil cell death. The purpose of this in vitro study was to determine the mechanism of neutrophil death. We hypothesized that NO hastened cell death by inducing apoptosis. To mimic the clinical environment of patients with respiratory failure, we also studied the effects of hyperoxia on neutrophil cell viability and apoptosis. Isolated human neutrophils were exposed to 80% O2 (O2), NO at 20 ppm in room air (NO/RA), 20 ppm NO blended with 80% O2 (NO/O2), or RA alone (control) for 2 to 24 h. Experiments were repeated with NO concentrations of 5 and 50 ppm and with 20 ppm in the presence of superoxide dismutase (SOD). Neutrophils were also incubated in the absence or presence of neutrophil stimulant fMLP (10 nM). Neutrophil cell viability was measured by fluorescence viability/cytotoxicity assay. Neutrophil apoptosis was assessed by cell death detection ELISA for histone-associated DNA fragments, TdT transferase-mediated fluorescence-labeled dUTP nick end labeling (TUNEL) assay, and DNA fragmentation gel electrophoresis. NO/O2-exposed neutrophils showed decreased viability at 2 h (31.7 +/- 3.7%, mean % viability +/- SD) compared with control (94.7 +/- 4.7%), O2 (75.6 +/- 9.3%), and NO/RA (62.8 +/- 14.9%; P < 0.05 by ANOVA; n = 9). Although control neutrophils demonstrated marked apoptosis at 24 h, there was no significant apoptosis at 2, 4, or 6 h (P < 0.001 by Kruskal-Wallis, n = 20) as assessed by ELISA and TUNEL assays. When compared with RA controls at 2 h, neutrophils exposed to NO/O2 showed significantly more apoptosis (292% of control, range: 106 to 2,488%, P < 0.001 by ANOVA and Kruskal-Wallis) but not with exposure to NO/RA or O2 alone. These findings were confirmed by TUNEL assay (n = 4, P < 0.05). NO/ RA and NO/O2-exposed neutrophils demonstrated both evidence of necrosis and enhanced DNA fragmentation at 2 h by gel electrophoresis (n = 2). Fifty parts per million NO produced similar findings, but exposure to 5 ppm NO did not induce significant DNA fragmentation. Coincubation with SOD inhibited NO/ O2-associated apoptosis, suggesting peroxynitrite contributed to cell death. Stimulation with fMLP did not alter apoptosis induced in neutrophils exposed to NO/RA or NO/O2. We conclude that exogenous NO gas, at clinically relevant concentrations under hyperoxic conditions, induces cell death in neutrophils in part by enhancing DNA fragmentation.
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PMID:Exogenous nitric oxide enhances neutrophil cell death and DNA fragmentation. 949 Jun 60

The type I element (CCACGTCANCGATCCGCG), consisting of the Hex motif (CCACGTCA) and the reverse-oriented Oct motif (GATCCGCG), is necessary and sufficient to confer the S phase-specific transcription of the wheat histone H3 (TH012) gene. The transcriptional regulation via the type I element is thought to occur through interactions between transcription factors which bind specifically to the Hex and Oct motifs. Here we report S phase-specific DNA-binding proteins interacting with the type I element in partially synchronized wheat cultured cells. Hex motif-binding proteins found here resembled HBP-1a, as reported previously in terms of DNA-binding specificity. DNA-binding activities of the HBP-1a-like proteins were modulated by phosphorylation/dephosphorylation. In the electrophoretic mobility shift assay of the wheat nuclear extract, we also found three Oct motif-specific binding proteins, named OBRF (octamer-binding regulatory factor)-1, -2 and -3. One of the HBP-1a-like proteins and OBRF-1 appeared predominantly at the S phase. Thus, it was supposed that these two factors play a crucial role in the S phase-specific regulation of wheat histone gene expression.
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PMID:S phase-specific DNA-binding proteins interacting with the Hex and Oct motifs in type I element of the wheat histone H3 promoter. 1067 46

Vascular remodeling is a key feature of many pathologic states, including atherosclerosis, or hypertension. Vascular smooth muscle cells participate in determining the vessel structure by several mechanisms such as cell migration, cell growth, or cell death (necrosis or apoptosis). Here we report that thapsigargin, an inhibitor of endoplasmic reticulum Ca2+ -adenosine triphosphatase (ATPase), is able to induce apoptosis in human vascular smooth muscle cells (HVSMCs). Apoptosis was assessed by three different methods: differential chromatin binding dye staining. cytoplasmic histone-associated DNA fragments detection by enzyme-linked immunosorbent assay (ELISA) and terminal deoxyribonucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL). When HVSMCs were treated for 1 h with thapsigargin (100 nM-10 microM), there was a concentration-dependent increase in both parameters 24 h after the thapsigargin pulse. When a time-course experiment was performed, both parameters were significantly enhanced from 3 to 6 h after the exposure to thapsigargin. We conclude that thapsigargin promotes apoptosis in HVSMCs, providing a useful tool for the study of programmed cell death in human vascular smooth muscle.
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PMID:Thapsigargin induces apoptosis in cultured human aortic smooth muscle cells. 1106 29


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