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Antisense transcripts with FANTOM2 clone set and their implications for gene regulation.

We have used the FANTOM2 mouse cDNA set (60,770 clones), public mRNA data, and mouse genome sequence data to identify 2481 pairs of sense-antisense transcripts and 899 further pairs of nonantisense bidirectional transcription based upon genomic mapping. The analysis greatly expands the number of known examples of sense-antisense transcript and nonantisense bidirectional transcription pairs in mammals. The FANTOM2 cDNA set appears to contain substantially large numbers of noncoding transcripts suitable for antisense transcript analysis. The average proportion of loci encoding sense-antisense transcript and nonantisense bidirectional transcription pairs on autosomes was 15.1 and 5.4%, respectively. Those on the X chromosome were 6.3 and 4.2%, respectively. Sense-antisense transcript pairs, rather than nonantisense bidirectional transcription pairs, may be less prevalent on the X chromosome, possibly due to X chromosome inactivation. Sense and antisense transcripts tended to be isolated from the same libraries, where nonantisense bidirectional transcription pairs were not apparently coregulated. The existence of large numbers of natural antisense transcripts implies that the regulation of gene expression by antisense transcripts is more common that previously recognized. The viewer showing mapping patterns of sense-antisense transcript pairs and nonantisense bidirectional transcription pairs on the genome and other related statistical data is available on our Web site.

Animals↗

Comparative genomic analyses of frog virus 3, type species of the genus Ranavirus (family Iridoviridae).

Frog virus 3 (FV3) is the type species member of the genus Ranavirus (family Iridoviridae). To better understand the molecular mechanisms involved in the replication of FV3, including transcription of its highly methylated DNA genome, we have determined the complete nucleotide sequence of the FV3 genome. The FV3 genome is 105903 bp long excluding the terminal redundancy. The G + C content of FV3 genome is 55% and it encodes 98 nonoverlapping potential open reading frames (ORFs) containing 50-1293 amino acids. Eighty-four ORFs have significant homology to known proteins of other iridoviruses, whereas twelve of these unique FV3 proteins do not share homology to any known protein. A microsatellite containing a stretch of 34 tandemly repeated CA dinucleotide in a noncoding region was detected. To date, no such sequence has been reported in any animal virus.

Animals↗

Expression profile of long noncoding RNAs and comprehensive analysis of lncRNA-cisTF-DGE regulation in condyloma acuminatum.

OBJECTIVE: To identify differentially expressed long noncoding RNAs (lncRNAs) in condyloma acuminatum (CA) and to explore their probable regulatory mechanisms by establishing coexpression networks. METHODS: High-throughput RNA sequencing was performed to assess genome-wide lncRNA expression in CA and paired adjacent mucosal tissue. The expression of candidate lncRNAs and their target genes in larger CA specimens was validated using real-time quantitative reverse transcriptase polymerase chain reaction (RT‒qPCR). Furthermore, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were used for the functional enrichment analysis of these candidate lncRNAs and differential mRNAs. The coexpressed mRNAs of the candidate lncRNAs, calculated by Pearson's correlation coefficient, were also analysed using GO and KEGG analysis. In addition, the interactions among differentially expressed lncRNAs (DElncRNAs)-cis-regulatory transcription factors (cisTFs)-differentially expressed genes (DEGs) were analysed and their network was constructed. RESULTS: A total of 546 lncRNAs and 2553 mRNAs were found to be differentially expressed in CA compared to the paired control. Functional enrichment analysis revealed that the DEGs coexpressed with DElncRNAs were enriched in the terms of cell adhesion and keratinocyte differentiation, and the pathways of ECM-receptor interaction, local adhesion, PI3K/AKT and TGF-ß signaling. We further constructed the network among DElncRNAs-cisTFs-DEGs and found that these 95 DEGs were mainly enriched in GO terms of epithelial development, regulation of transcription or gene expression. Furthermore, the expression of 3 pairs of DElncRNAs and cisTFs, EVX1-AS and HOXA13, HOXA11-AS and EVX1, and DLX6-AS and DLX5, was validated with a larger number of specimens using RT‒qPCR. CONCLUSION: CA has a specific lncRNA profile, and the differentially expressed lncRNAs play regulatory roles in mRNA expression through cis-acting TFs, which provides insight into their regulatory networks. It will be useful to understand the pathogenesis of CA to provide new directions for the prevention, clinical treatment and efficacy evaluation of CA.

RNA, Long Noncoding↗

Quantitated transcript haplotypes (QTH) of AGTR1, reduced abundance of mRNA haplotypes containing 1166C (rs5186:A>C), and relevance to metabolic syndrome traits.

The angiotensin II type 1 receptor (AGTR1) is the main target through which angiotensin II influences cardiovascular tone, cell growth, and fluid and electrolyte balance. AGTR1 polymorphism has been reported to associate with hypertension, myocardial infarction (MI), and metabolic traits. Here we describe a novel approach to quantitation of transcript haplotypes (QTH) of AGTR1. To determine relative allelic expression from haplotypes, within-individual-between-allele ratiometric analyses in placental cDNA were developed for the transcribed SNPs rs5182:C>T (encoding p.L191) and rs5186:A>C (3'-noncoding "A1166C"). Additionally, between-individual comparisons were made using TaqMan assays applied to both homozygous and heterozygous genotypes and haplotypes. In conjunction, linkage disequilibrium (LD) and genomic haplotype associations with metabolic syndrome were examined. There was no significant difference of mRNA level for alleles of rs5182:C>T, but allele and mRNA haplotypes carrying 1166C exhibited reduced abundance. The effect was much greater in CC homozygotes than in heterozygotes. The promoter region was confirmed to be in a separate haplotype block from the AGTR1 3' region containing rs5182:C>T and rs5186:A>C. Metabolic syndrome trait associations were strongest for the 3' block generally and for the C allele of rs5186:A>C specifically. All effects were much more prominent in homozygotes, possibly reflecting interallelic interaction through feedback loops of mRNA regulation. Differential abundance of AGTR1 mRNA haplotypes may mediate clinical phenotypic observations of the AGTR1 genotype.

Aged↗

Expression of the actin gene family in embryos of the sea urchin Lytechinus pictus.

The genome of the sea urchin Lytechinus pictus includes genes encoding four cytoskeletal actins LpC1-4 and the muscle actin LpM. Gene-specific probes corresponding to 3' noncoding termini have been used to characterize their patterns of expression by in situ hybridization. The gene encoding LpC1 actin, which is most similar in sequence to the Strongylocentrotus purpuratus CyI actin, has a complex developmental profile of expression. LpC1 transcripts become prominent in the archenteron and secondary mesenchyme cells of embryos, as well as in adult testis and ovary. The LpC2 actin gene is predominantly expressed in aboral ectoderm of embryos, similarly to the pattern of expression of its closest relatives in S. purpuratus, the SpCyIIIa and SpCyIIIb actin genes. The LpC3 actin gene is expressed at low levels in secondary mesenchyme cells. The LpC4 actin gene is expressed in a subset of primary mesenchyme cells which may be actively engaged in skeletogenesis. Transcripts of the LpM gene accumulate in esophageal muscle cells beginning during gastrulation before overt differentiation. Each of the L. pictus actin genes has a distinct pattern of expression, none of which is identical to that of any S. purpuratus actin gene. These results indicate that the regulation of expression of members of the actin gene family, even those likely to have common ancestors, has diverged as these sea urchin species diverged.

Actins↗

Mapping of host range restriction of the rakkyo strain of tobacco mosaic virus in Nicotiana tabacum cv. bright yellow.

The rakkyo strain (TMV-R) and the common strain (TMV-U1) of tobacco mosaic virus exhibit distinct host range differences. TMV-R infects rakkyo plants, a monocot host that TMV-U1 is unable to infect. However, TMV-R causes only latent infection in Nicotiana tabacum cv. Bright Yellow (BY) in inoculated leaves, whereas TMV-U1 infects BY systemically and induces mosaic symptoms. Complete nucleotide sequencing of the TMV-R genomic RNA revealed amino acid changes in the 130K/ 180K replicase proteins, the 30K protein, and the coat protein and nucleotide changes in the 5' and 3' noncoding regions compared to TMV-U1. To identify viral components involved in determination of differences in host range, we have mapped determinants for the differential infection phenotype in BY plants by constructing chimeric viruses between the two strains in the present study. Examination of the infection phenotypes of the 14 constructed chimeric viruses in BY showed that determinants defining the differential infection phenotype in BY reside in the 130K/180K replicase proteins and the 3' noncoding region. Cognate combination of the 130K/180K replicase proteins and the 3' noncoding region of TMV-U1 origin is required to produce systemic infection in BY plants.

DNA-Directed DNA Polymerase↗

Transcriptional analysis of two endoinulinase genes inuA and inuB in Aspergillus niger and nucleotide sequences of their promoter regions.

Aspergillus niger 12 contained two copies of endoinulinase genes (inuA and inuB) in the genome (K. Ohta et al., Biosci. Biotechnol. Biochem., 62, 1731-1738, 1998). The inuA- and inuB-specific DNA probes were constructed according to the respective 3'-noncoding sequences that diverged from each other. Poly(A)+ RNA was prepared from mycelia grown on inulin, fructose, or glucose in submerged culture. Three endoinulinase cDNA sequences that corresponded to the coding regions and their 5'- and 3'-flanking regions were obtained by reverse transcription and subsequent polymerase chain reaction. Southern blot analysis revealed that the amplified cDNA 3'-noncoding sequences hybridized to the inuB probe but not to the inuA probe, regardless of the carbon source. The data suggest that only the inuB gene was transcribed constitutively. Four distinct 5' ends of the transcripts were observed at positions -80(A), -72(G), -69(A), and -65(A) from the start codon. The inuB mRNAs were polyadenylated at various sites between 94 and 297 bp downstream of the stop codon. We have determined the nucleotide sequences of the 1201- and 1017-bp 5'-noncoding regions of the inuA and inuB genes, respectively. The inuB promoter region included a putative TATA box at -116 (TATATA).

Journal Article↗

Asymmetric methylation in the hypermethylated CpG promoter region of the human L1 retrotransposon.

We have investigated the function and sequence specificity of DNA methylation in the hypermethylated CpG island promoter region of the endogenous human LINE-1 (L1) retrotransposon family. In nontransformed human embryonic fibroblasts, inhibition of DNA methylation with 5-azadeoxycytidine induced a greater than 4-fold increase in transcription from potentially functional L1 elements without increasing the transcription level of the majority of degenerate elements, implicating hypermethylation in the repression of L1 activity. Using bisulfite genomic sequencing to assess the pattern of methylation in a subset of nondegenerate L1 elements, we found 29 sites within a 460-base pair region of the noncoding (top) DNA strand of the L1 promoter in which cytosine methylation was maintained with high efficiency. Of these, 25 were at CG dinucleotides and four were in non-CG sites. When the methylation sites were analyzed for the complementary (bottom) strand, the only highly conserved sites of methylation were in CG dinucleotides. Several of these sites of CG methylation in the bottom (coding) strand were at positions where top (noncoding) strand-derived sequences were unmethylated, suggesting that these sites might be maintained in a hemi-methylated state. Hence, there is a subset of human L1 elements in which methylation is efficiently maintained in asymmetric non-CG sites and further that this non-CG methylation may be part of a wider phenomenon involving hemi-methylation at CG dinucleotides. Maintenance of asymmetric methylation at non-CG sites (and possibly at hemi-methylated CG dinucleotides) could be through a novel DNA methyltransferase activity. Alternatively, the promoter region of L1 elements may be induced by factor binding to form some type of secondary structure that presents as a highly efficient substrate for de novo methylation.

Amino Acid Sequence↗

Family-based analysis using a dense single-nucleotide polymorphism-based map defines genetic variation at PSORS1, the major psoriasis-susceptibility locus.

Psoriasis is a common skin disorder of multifactorial origin. Genomewide scans for disease susceptibility have repeatedly demonstrated the existence of a major locus, PSORS1 (psoriasis susceptibility 1), contained within the major histocompatibility complex (MHC), on chromosome 6p21. Subsequent refinement studies have highlighted linkage disequilibrium (LD) with psoriasis, along a 150-kb segment that includes at least three candidate genes (encoding human leukocyte antigen-C [HLA-C], alpha-helix-coiled-coil-rod homologue, and corneodesmosin), each of which has been shown to harbor disease-associated alleles. However, the boundaries of the minimal PSORS1 region remain poorly defined. Moreover, interpretations of allelic association with psoriasis are compounded by limited insight of LD conservation within MHC class I interval. To address these issues, we have pursued a high-resolution genetic characterization of the PSORS1 locus. We resequenced genomic segments along a 220-kb region at chromosome 6p21 and identified a total of 119 high-frequency SNPs. Using 59 SNPs (18 coding and 41 noncoding SNPs) whose position was representative of the overall marker distribution, we genotyped a data set of 171 independently ascertained parent-affected offspring trios. Family-based association analysis of this cohort highlighted two SNPs (n.7 and n.9) respectively lying 7 and 4 kb proximal to HLA-C. These markers generated highly significant evidence of disease association (P<10-9), several orders of magnitude greater than the observed significance displayed by any other SNP that has previously been associated with disease susceptibility. This observation was replicated in a Gujarati Indian case/control data set. Haplotype-based analysis detected overtransmission of a cluster of chromosomes, which probably originated by ancestral mutation of a common disease-bearing haplotype. The only markers exclusive to the overtransmitted chromosomes are SNPs n.7 and n.9, which define a 10-kb PSORS1 core risk haplotype. These data demonstrate the power of SNP haplotype-based association analyses and provide high-resolution dissection of genetic variation across the PSORS1 interval, the major susceptibility locus for psoriasis.

Case-Control Studies↗

Denaturing high-performance liquid chromatography for the detection of mutations and polymorphisms in UBE3A.

Angelman syndrome (AS) is caused by maternal deficiency of UBE3A, the gene encoding E6-AP ubiquitin-protein ligase. Our objectives were to develop conditions for denaturing high-performance liquid chromatography (dHPLC) analysis of UBE3A and to compare the sensitivity to direct genomic sequencing. Genomic DNA was obtained from 17 Angelman patients with known mutations and from 120 normal controls. DNA was amplified for the 10 coding exons and 6 upstream noncoding exons of UBE3A. Using dHPLC, the mutations previously identified in 17 Angelman patients were all easily detected using a single dHPLC condition for most exon-containing fragments. An analysis of all 16 exons in 120 normal controls identified 15 other DNA alterations of varying frequency, all of which are assumed to be benign. We conclude that dHPLC is a reliable and convenient method for detecting mutations in UBE3A causing Angelman syndrome. No disease-causing mutations were found in the noncoding exons.

5' Untranslated Regions↗

Structure and expression of the bovine oxytocin receptor gene.

The gene for the bovine oxytocin receptor has been sequenced using a combination of clones derived from a bovine endometrial cDNA library from estrus and a bovine genomic DNA library, with confirmation of structure using reverse transcription PCR programmed by term myometrial RNA. The receptor belongs to the seven transmembrane domain family and predicts a protein of 391 amino acids. A comparison of the genomic sequence with the cDNA structure, as well as reverse transcription polymerase chain reaction (RT-PCR) analysis, shows there are two introns, one in the 5'noncoding region that appears to be differentially spliced in the bovine uterus and a conserved intron within the open reading frame between the regions encoding the transmembrane domains VI and VII. Northern blot analysis indicated three major transcripts in myometrium and endometrium in vivo at approximately 6.5 kb, 3.5 kb, and 2.0 kb. In situ hybridization analysis of uterine tissue at term showed highest mRNA concentrations in the endometrial epithelium, particularly in the deep glands, a pattern confirmed also at the immunohistochemical level by monoclonal antibodies raised against a human amino-terminal peptide. Further confirmation of the identity of the receptor was obtained by transient transfection of a reconstituted receptor construct into COS-7 cells. The expressed receptor was shown to have identical pharmacological properties in respect to various oxytocin analogs to the natural bovine endometrial receptor.

Amino Acid Sequence↗

Characterization of Borrelia lusitaniae isolates collected in Tunisia and Morocco.

Borrelia lusitaniae is a species within the complex Borrelia burgdorferi sensu lato and is infrequently isolated in Europe. In contrast, this species is by far the most predominant in North Africa and in Portugal. In this study, we analyzed the genetic diversity, at several loci, of a large population of isolates from free-living Ixodes ricinus ticks collected in Tunisia and Morocco. We found a moderate diversity of the whole genome by using pulsed-field gel electrophoresis as well as in the ospA gene sequences, compared to a high level of strain homogeneity in the small noncoding ribosomal spacer. In contrast, a high diversity of this locus has been previously reported for Portuguese isolates. We hypothesize that B. lusitaniae strains isolated in North Africa constitute a clone of Portuguese origin.

Animals↗

Torovirus non-discontinuous transcription: mutational analysis of a subgenomic mRNA promoter.

Toroviruses (order Nidovirales) are enveloped positive-strand RNA viruses of mammals. The prototype torovirus, equine torovirus strain Berne (Berne virus [BEV]), uses two different transcription strategies to produce a 3'-coterminal nested set of subgenomic (sg) mRNAs. Its mRNA 2 carries a leader sequence derived from the 5' end of the genome and is produced via discontinuous transcription. The remaining three sg mRNAs, 3 to 5, are colinear with the 3' end of the genome and are made via non-discontinuous RNA synthesis. Their synthesis is supposedly regulated by short conserved sequence motifs, 5'-ACN3-4CUUUAGA-3', within the noncoding intergenic regions that precede the M, HE, and N genes (A. L. van Vliet, S. L. Smits, P. J. Rottier, and R. J. de Groot, EMBO J. 21:6571-6580, 2002). We have now studied the--for nidoviruses unusual--non-discontinuous transcription mechanism in further detail by probing the role of the postulated transcription-regulating sequences (TRSs). To this end, we constructed a synthetic defective interfering (DI) RNA, carrying a 24-nucleotide segment of the intergenic region between the HE and N genes. We demonstrate that this DI RNA, when introduced into BEV-infected cells, directs the synthesis of a sg DI RNA species; in fact, a 16-nucleotide cassette containing the TRS already proved sufficient. Synthesis of this sg DI RNA, like that of mRNAs 3 to 5 of the standard virus, initiated at the 5'-most adenylate of the TRS. An extensive mutational analysis of the TRS is presented. Our results provide first and formal experimental evidence that the conserved motifs within the BEV intergenic sequences indeed drive sg RNA synthesis.

Animals↗

Structure of the promoter of the Dictyostelium discoideum prespore EB4 gene.

EB4 is one of several cloned cDNAs that is expressed as mRNA only after the aggregation stage of Dictyostelium discoideum differentiation and exclusively in prespore and spore cells (E. Barklis and H. F. Lodish, Cell 32:1139-1148, 1983). We have isolated the unique genome fragment corresponding to the 5' portion of the EB4 message and the EB4 promoter. The EB4 transcript has an unusually long, G + C-rich, 5' noncoding region, but initiates at several start sites within a region of DNA that is 96% A + T. The sequence GTGGTGG, along with slight variations, occurs several times in the promoter. We have used the EB4 promoter to drive the transcription of an EB4/beta-galactosidase fusion transcript in yeast cells. Although the cap sites of the fused transcript in yeast cells are located in the region where multiple EB4 transcripts are initiated in Dictyostelium, the unregulated expression of the fusion transcript in yeast does not mimic the normal regulated pattern of EB4 mRNA expression in D. discoideum.

Base Sequence↗

Isolation of cDNA and genomic clones encoding human pro-alpha 1 (III) collagen. Partial characterization of the 3' end region of the gene.

A cDNA library constructed from human fibroblast poly(A+) RNA was screened for the identification of chimeric molecules bearing collagen-specific sequences. Analysis of three of the resulting positive clones showed that they encoded for the COOH-terminal propeptide region of the human Type III collagen. In addition, three overlapping clones covering more than 21 kilobases of the Type III gene were isolated from Charon 4A libraries of human genomic fragments. Identity between these and the cDNA clones was obtained by direct DNA sequencing. Establishment of the exon/intron arrangement of the Type III gene was obtained by electron microscopic analysis in conjunction with sequencing of selected genomic regions. Sequence comparison with other collagen genes confirmed some evolutionary features of this important family of proteins. Finally, the collinearity of two mRNA transcripts with 3' noncoding region length polymorphism was established.

Amino Acid Sequence↗

Nucleotide sequence of the gene for human factor IX (antihemophilic factor B).

Two different human genomic DNA libraries were screened for the gene for blood coagulation factor IX by employing a cDNA for the human protein as a hybridization probe. Five overlapping lambda phages were identified that contained the gene for factor IX. The complete DNA sequence of about 38 kilobases for the gene and the adjacent 5' and 3' flanking regions was established by the dideoxy chain termination and chemical degradation methods. The gene contained about 33.5 kilobases of DNA, including seven introns and eight exons within the coding and 3' noncoding regions of the gene. The eight exons code for a prepro leader sequence and 415 amino acids that make up the mature protein circulating in plasma. The intervening sequences range in size from 188 to 9473 nucleotides and contain four Alu repetitive sequences, including one in intron A and three in intron F. A fifth Alu repetitive sequence was found immediately flanking the 3' end of the gene. A 50 base pair insert in intron A was found in a clone from one of the genomic libraries but was absent in clones from the other library. Intron A as well as the 3' noncoding region of the gene also contained alternating purine-pyrimidine sequences that provide potential left-handed helical DNA or Z-DNA structures for the gene. KpnI repetitive sequences were identified in intron D and the region flanking the 5' end of the gene. The 5' flanking region also contained a 1.9-kb HindIII subfamily repeat. The seven introns in the gene for factor IX were located in essentially the same position as the seven introns in the gene for human protein C, while the first three were found in positions identical with those in the gene for human prothrombin.

Amino Acid Sequence↗

Identification of the lytic origin of DNA replication in human cytomegalovirus by a novel approach utilizing ganciclovir-induced chain termination.

Infection with human cytomegalovirus in the presence of the antiviral nucleotide analog ganciclovir results in continuing low-level viral DNA synthesis and the accumulation of relatively small fragments of double-stranded progency DNA. These fragments consistently proved to represent amplification of sequences from only one small section of the viral genome (EcoRI-V) lying near the center of the unique L segment. Further mapping revealed that the viral sequences represented in these fragments occurred in gradients of abundance that decreased in both directions from a point near 0.35 to 0.4 map unit. The proportion of amplified sequences increased with both time after infection and dosage of ganciclovir used. We conclude that the primary lytic cycle replication origin of human cytomegalovirus lies within a 3- to 4-kb region immediately upstream and to the right of the promoter for the single-stranded DNA-binding protein (DB140). The amplified origin-containing DNA molecules appeared to arise by continuing rounds of bidirectional initiation on truncated fragments of the genome that were generated as a result of chain termination effects induced by the incorporation of ganciclovir into the viral DNA. Inspection of the DNA sequence in the vicinity of ori-Lyt revealed a large complex upstream region that may be a noncoding intergenic domain and that bears no homology to any previously described herpesvirus origin. This 2.5-kb region includes many duplicated and inverted sequences, together with consensus CRE/ATF and other transcription factor-binding sites, and an interesting set of 23 copies of an interspersed decamer consensus element AAAACACCGT that is also conserved at the equivalent locus in simian cytomegalovirus. This work represents the first identification of an origin domain in a cytomegalovirus genome and is the first demonstration of a bidirectional mechanism for any herpesvirus lytic cycle origin.

Base Sequence↗

Annotation of cis-regulatory elements by identification, subclassification, and functional assessment of multispecies conserved sequences.

An important step toward improving the annotation of the human genome is to identify cis-acting regulatory elements from primary DNA sequence. One approach is to compare sequences from multiple, divergent species. This approach distinguishes multispecies conserved sequences (MCS) in noncoding regions from more rapidly evolving neutral DNA. Here, we have analyzed a region of approximately 238kb containing the human alpha globin cluster that was sequenced and/or annotated across the syntenic region in 22 species spanning 500 million years of evolution. Using a variety of bioinformatic approaches and correlating the results with many aspects of chromosome structure and function in this region, we were able to identify and evaluate the importance of 24 individual MCSs. This approach sensitively and accurately identified previously characterized regulatory elements but also discovered unidentified promoters, exons, splicing, and transcriptional regulatory elements. Together, these studies demonstrate an integrated approach by which to identify, subclassify, and predict the potential importance of MCSs.

Animals↗