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Identification and characterization of upstream open reading frames (uORF) in the 5' untranslated regions (UTR) of genes in Saccharomyces cerevisiae.

We have taken advantage of recently sequenced hemiascomycete fungal genomes to computationally identify additional genes potentially regulated by upstream open reading frames (uORFs). Our approach is based on the observation that the structure, including the uORFs, of the post-transcriptionally uORF regulated Saccharomyces cerevisiae genes GCN4 and CPA1 is conserved in related species. Thirty-eight candidate genes for which uORFs were found in multiple species were identified and tested. We determined by 5' RACE that 15 of these 38 genes are transcribed. Most of these 15 genes have only a single uORF in their 5' UTR, and the length of these uORFs range from 3 to 24 codons. We cloned seven full-length UTR sequences into a luciferase (LUC) reporter system. Luciferase activity and mRNA level were compared between the wild-type UTR construct and a construct where the uORF start codon was mutated. The translational efficiency index (TEI) of each construct was calculated to test the possible regulatory function on translational level. We hypothesize that uORFs in the UTR of RPC11, TPK1, FOL1, WSC3, and MKK1 may have translational regulatory roles while uORFs in the 5' UTR of ECM7 and IMD4 have little effect on translation under the conditions tested.

5' Untranslated Regions↗

Processing of alpha-globin and ICP0 mRNA in cells infected with herpes simplex virus type 1 ICP27 mutants.

Herpes simplex virus (HSV) ICP27 is an essential and multifunctional regulator of viral gene expression that modulates RNA splicing, polyadenylation, and nuclear export. We have previously reported that ICP27 causes the cytoplasmic accumulation of unspliced alpha-globin pre-mRNA. Here we examined the effects of a series of ICP27 mutations that alter important functional regions of the protein on the processing and nuclear transport of alpha-globin and HSV ICP0 RNA. The results demonstrate that ICP27 mutants that are impaired for growth in noncomplementing cells, including mutants in the N- and C-terminal regions, are defective in the accumulation of alpha-globin pre-mRNA. Unexpectedly, several mutants that are competent to repress the expression of reporter genes in transient transfection assays failed to accumulate unspliced RNA, implying that different mechanisms are responsible for transrepression and pre-mRNA accumulation. Several mutants caused a marked increase in the length and heterogeneity of the alpha-globin mRNA poly(A) tail, suggesting that ICP27 may directly or indirectly affect the regulation of poly(A) polymerase. ICP27 was also required for the accumulation of multiple ICP0 intron-bearing transcripts, but this effect displayed a mutational sensitivity profile different from that of accumulation of unspliced alpha-globin RNA. Moreover, unlike spliced and unspliced alpha-globin RNAs, which were efficiently exported to the cytoplasm, spliced and intron-containing ICP0 transcripts were predominantly nuclear in localization, and ICP27 was not required for nuclear retention of the spliced message. We propose that these transcript- and ICP27 allele-specific differences may be explained by the presence of a strong cis-acting ICP27 response element in the alpha-globin transcript.

Globins↗

Impairment of the DNA binding activity of the TATA-binding protein renders the transcriptional function of Rvb2p/Tih2p, the yeast RuvB-like protein, essential for cell growth.

In Saccharomyces cerevisiae, two highly conserved proteins, Rvb1p/Tih1p and Rvb2p/Tih2p, have been demonstrated to be major components of the chromatin-remodeling INO80 complex. The mammalian orthologues of these two proteins have been shown to physically associate with the TATA-binding protein (TBP) in vitro but not clearly in vivo. Here we show that yeast proteins interact with TBP under both conditions. To assess the functional importance of these interactions, we examined the effect of mutating both TIH2/RVB2 and SPT15, which encodes TBP, on yeast cell growth. Intriguingly, only those spt15 mutations that affected the ability of TBP to bind to the TATA box caused synthetic growth defects in a tih2-ts160 background. This suggests that Tih2p might be important in recruiting TBP to the promoter. A DNA microarray technique was used to identify genes differentially expressed in the tih2-ts160 strain grown at the restrictive temperature. Only 34 genes were significantly and reproducibly affected; some up-regulated and others down-regulated. We compared the transcription of several of these Tih2p target genes in both wild type and various mutant backgrounds. We found that the transcription of some genes depends on functions possessed by both Tih2p and TBP and that these functions are substantially impaired in the spt15/tih2-ts160 double mutants that confer synthetic growth defects.

Adenosine Triphosphatases↗

Three non-allelic epistatically interacting methyltransferase mutations produce novel tocopherol (vitamin E) profiles in sunflower.

Wildtype sunflower (Helianthus annuus L.) seeds are a rich source of alpha-tocopherol (vitamin E). The g = Tph(2) mutation disrupts the synthesis of alpha-tocopherol, enhances the synthesis of gamma-tocopherol, and was predicted to knock out a gamma-tocopherol methyltransferase (gamma-TMT) necessary for the synthesis of alpha-tocopherol in sunflower seeds--wildtype (g(+) g(+)) lines accumulated > 90% alpha-tocopherol, whereas mutant (g g) lines accumulated > 90% gamma-tocopherol. We identified and isolated two gamma-TMT paralogs (gamma-TMT-1 and gamma-TMT-2). Both mapped to linkage group 8, cosegregated with the g locus, and were transcribed in developing seeds of wildtype lines. The g mutation greatly decreased gamma-TMT-1 transcription, caused alternative splicing of gamma-TMT-1, disrupted gamma-TMT-2 transcription, and knocked out one of two transcription initiation sites identified in the wildtype; gamma-TMT transcription was 36 to 51-fold greater in developing seeds of wildtype (g(+) g(+)) than mutant (g g) lines. F(2) populations (B109 x LG24 and R112 x LG24) developed for mapping the g locus segregated for a previously unidentified locus (d). B109, R112, and LG24 were homozygous for a null mutation (m = Tph(1)) in MT-1, one of two 2-methyl-6-phytyl-1,4-benzoquinone/2-methyl-6-solanyl-1,4-benzoquinone methyltransferase (MPBQ/MSBQ-MT) paralogs identified in sunflower. The d mutations segregating in B109 x LG24 and R112 x LG24 were allelic to a cryptic mutation identified in the other MPBQ/MSBQ-MT paralog (MT-2) and disrupted the synthesis of alpha- and gamma-tocopherol in F(2) progeny carrying m or g mutations--m m g(+) g(+) d d homozygotes accumulated 41.5% alpha- and 58.5% beta-T, whereas m m g g d d homozygotes accumulated 58.1% gamma- and 41.9% delta-T. MT-2 cosegregated with d and mapped to linkage group 4. Hence, novel tocopherol profiles are produced in sunflower seed oil by three non-allelic epistatically interacting methyltransferase mutations.

Alleles↗

Undifferentiated carcinoma of the pancreas: analysis of intermediate filament profile and Ki-ras mutations provides evidence of a ductal origin.

Undifferentiated carcinomas and osteoclast-like giant cell tumours of the pancreas commonly contain foci of neoplastic ductal glands. To test the hypothesis that undifferentiated carcinomas and osteoclast-like giant cell tumours have a ductal origin, the immunocytochemical cytokeratin pattern and the frequency and type of Ki-ras mutations at colon 12 were studied in a series of 17 undifferentiated carcinomas and two osteoclast-like giant cell tumours. The cytokeratin features of undifferentiated carcinomas and osteoclast-like giant cell tumours were compared with those found in 10 ductal adenocarcinomas, 20 acinar cell carcinomas, 25 neuroendocrine tumours, and 15 solid-pseudopapillary tumours. All undifferentiated carcinomas and osteoclast-like giant cell tumours stained with at least one cytokeratin antibody, and 13/19 of them with antibodies against cytokeratins 7, 8, 18, and 19. The latter cytokeratins were expressed in all ductal adenocarcinomas, but only in 15/20 acinar cell carcinomas, 2/25 neuroendocrine tumours, and 1/15 solid-pseudopapillary tumours. In addition to cytokeratin, 15/19 undifferentiated carcinomas/osteoclast-like giant cell tumours were positive for vimentin. Ki-ras mutations at codon 12 were found in 10 undifferentiated carcinomas and one osteoclast-like giant cell tumour from which DNA could be successfully amplified. The Ki-ras mutation patterns were analysed in six tumours and corresponded to those typical of ductal adenocarcinomas. In tumours with ductal and anaplastic components, both components revealed identical mutation patterns. From these findings, it is concluded that both undifferentiated carcinomas and osteoclast-like giant cell tumours belong to the pancreatic tumours that show a ductal phenotype. Since undifferentiated carcinomas and osteoclast-like giant cell tumours share the same cytokeratin and Ki-ras features, they are probably derived from the same cell lineage.

Adenocarcinoma↗

Nuclear factor kappa B activation is a potential target for preventing pancreatic carcinoma by aspirin.

BACKGROUND: Pancreatic carcinoma exhibits a unique genetic profile of mutations that may play key roles in its progression to malignant phenotypes. Constitutive activation of transcription factor nuclear factor kappa B (NF-kappaB) is a frequent molecular alteration in pancreatic carcinoma, suggesting a possible link between inflammation and cancer. The aims of the current study were to determine the effects of aspirin on pancreatic carcinoma prevention and to reveal a possible mechanism of aspirin-mediated cancer chemoprevention. METHODS: An orthotopic mouse model with human pancreatic carcinoma cell lines PANC-1, PANC-1/Puro, and PANC-1/IkappaBalphaM was used to study the inhibitory effects of aspirin on pancreatic tumor formation. RESULTS: Aspirin inhibited constitutive NF-kappaB activity in culture and, in turn, decreased the expression of the NF-kappaB downstream target gene, Cox-2, in PANC-1 or PANC-1/Puro cells, without significantly inhibiting the in vitro growth of PANC-1/Puro cells. All animals inoculated with either PANC-1 or PANC-1/Puro cells, and not given aspirin, developed pancreatic tumors, whereas none of the mice injected with PANC-1/IkappaBalphaM cells showed any evidence of pancreatic tumor formation. Animals given aspirin for 6 days before, or at the time of, orthotopic tumor cell injection showed a significantly lower incidence of tumor formation compared with those receiving aspirin 2 weeks after inoculation and controls receiving no aspirin. CONCLUSIONS: Aspirin repressed tumor formation by PANC-1 cells in vivo in a prophylactic setting, suggesting a possible mechanism for aspirin's preventive effect in pancreatic carcinoma through inhibition of NF-kappaB activation and a mechanistic link between inflammation and tumorigenesis. Aspirin-mediated antiinflammatory approaches might be an effective strategy to prevent pancreatic carcinoma.

Adenocarcinoma↗

Mutagenic activity of cisplatin in the lacZ plasmid-based transgenic mouse model.

Cis-diamminedichloroplatinum (II) (cisplatin) is a well characterized antitumor drug used for the treatment of a variety of human cancers. The cytotoxicity of cisplatin is mainly mediated through the formation of DNA adducts, which are also believed to be responsible for the secondary malignancies produced by the drug. The aim of this study was to determine the in vivo mutagenic activity of cisplatin in the lacZ plasmid-based transgenic mouse model. The mutant frequency (MF) and the spectrum of mutations induced by cisplatin in the mouse liver were analyzed and compared to controls. The mean MF in the lacZ gene was increased 2-fold in mice treated with a single 6 mg/kg body weight dose of cisplatin and sacrificed after 17 and 28 days (P = 0.001 and P < 0.0001). Restriction analysis and sequencing of mutant DNA showed that cisplatin was able to induce both large deletions and point mutations. A specific profile of base substitution and frameshift mutations was identified in treated mice, consisting primarily of G:C-->A:T transitions at GpG and ApG sites, the preferential DNA binding sites of cisplatin, and single basepair deletions/insertions. The present results provide the first evidence that cisplatin has mutagenic activity in vivo and induces a characteristic pattern of mutations in the mouse liver. This mutagenicity may be responsible for its tumorigenic activity.

Animals↗

Tagging target genes of the MAT1-2-1 transcription factor in Fusarium verticillioides (Gibberella fujikuroi MP-A).

Mating type in filamentous ascomycetes is controlled by idiomorphic alleles, named MAT1-1 and MAT1-2, which contain 1-3 genes. Of these genes MAT1-1-1 and MAT1-2-1 encode putative transcription factors and are thus considered to be the major regulators of sexual communication and mating. Fungi with no known sexual stage may also have fully functional mating type genes and therefore it was plausible to hypothesize that the MAT products may also regulate other types of genes not involved directly in the mating process. To identify putative target genes of these transcription factors in Fusarium verticillioides, DeltaMAT1-2-1 knock out mutants were produced and transcript profiles of mutant and wild type were compared by means of differential cDNA hybridization. Clones, either up- or down-regulated in the DeltaMAT1-2-1 mutant were sequenced and a total of 248 sequences were blasted against the NCBI database as well as the Gibberella zeae and Gibberella moniliformis genomes. Fifty-five percent of the clones were down-regulated in the mutant, indicating that the MAT1-2-1 product positively affected these tagged sequences. On the other hand, 45% were found to be up-regulated in the mutant, suggesting that the MAT1-2-1 product also exerted a negative regulatory function on this set of genes. Sequences involved in protein synthesis and metabolism occurred more frequently among the clones up-regulated in the mutant, whereas genes belonging to cell signalling and communication were especially frequently tagged among the sequences down-regulated in the mutant.

DNA, Complementary↗

Denaturing HPLC-based approach for detection of COL7A1 gene mutations causing dystrophic epidermolysis bullosa.

Dystrophic epidermolysis bullosa (DEB) is a rare clinically heterogeneous genodermatosis due to genetic defects in type VII collagen gene (COL7A1). Identification of COL7A1 mutations is a challenge since this gene comprises 118 exons and more than 300 mutations scattered over the gene have been reported. Here, we describe for the first time the use of denaturing high performance liquid chromatography (DHPLC) for COL7A1 mutation detection. To validate the method, exon-specific DHPLC conditions were applied to screen DNA samples from patients carrying known COL7A1 mutations. Abnormal DHPLC profiles were obtained for all known mutations. Subsequent DHPLC analysis of 17 DEB families of unknown genotype allowed the identification of 21 distinct mutations, 9 of which were novel. The DHPLC mutation detection rate was significantly higher compared with our mutation scanning rate with conventional techniques (97% vs 86%), indicating DHPLC as the method of choice for COL7A1 molecular characterization in DEB patients.

Base Sequence↗

High DNA damage by benzo[a]pyrene 7,8-diol-9,10-epoxide in bronchial epithelial cells from patients with lung cancer: comparison with lung parenchyma.

In the present study, the level of benzo[a]pyrene 7,8-diol-9,10-epoxide-N(2)-deoxyguanosine (BPDE-N(2)-dG) in normal bronchial epithelial cells from non-cancerous bronchus of 22 lung cancer subjects was evaluated and compared to the lung parenchyma. We found very high formation of BPDE-N(2)-dG adduct in samples corresponding to a pure preparation of bronchial epithelial cells with 4-fold interindividual differences in the DNA adduct levels in the range of 36.5-175.4 BPDE-N(2)-dG adducts/10(8) nucleotides in smokers (mean: 84.7+/-38.4; n = 13) and 3-fold differences in the range of 19.7-62.4 in non-smokers (mean: 37.6+/-22.2; n = 3). DNA isolated from the bronchial tissue consisting of bronchial lining epithelium with adjacent lamina propria showed significantly lower BPDE-N(2)-dG formation (P < 0.001) in the range of 0.4-4.2 BPDE-N(2)-dG adducts/10(8) nucleotides (mean: 1.8+/-0.56; n = 6). This difference is clearly related to the procedure used to prepare the bronchial tissue samples leading to the presence of different types of cells. Eight samples from the normal parenchyma did not show measurable adducts, the other 14 samples showed 50-fold variation (mean: 1.7+/-1.5; range 0.1-5.2 adducts/10(8) nucleotides; n = 14). There were considerably higher adduct levels in pure bronchial epithelial cells than in parenchymal tissue (75.8+/-38.8 vs 0.9+/-1.5 adducts/10(8) nucleotides) (P < 0.0002) BPDE-N(2)-dG adduct concentrate almost exclusively in bronchial epithelial cells. The adduct values obtained in bronchial epithelial cells could be considered as 'critical' for the initiation of human lung cancer. The high formation of BPDE-N(2)-dG adducts in bronchial epithelial cells and investigations showing that the profile of mutations induced by BPDE in these cells is similar to that seen in the p53 gene isolated from human lung tumors implicates benzo[a]pyrene as important carcinogen in tobacco-induced lung cancer in human beings.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗

New developments in microarray technology.

Microarrays have emerged as indispensable research tools for gene expression profiling and mutation analysis. New classification of cancer subtypes, dissecting the yeast metabolism and large-scale genotyping of human single nucleotide polymorphisms are important results being obtained with this technique. Realizing the microsphere-based massively parallel signature sequencing technique as fluid microarrays, building new types of protein arrays and constructing miniaturized flow-through systems, which can potentially take this technology from the research bench into industrial, clinical and other routine applications, exemplify the intense developments that are now ongoing in this field.

Biotechnology↗

A diacylglycerol kinase modulates long-term thermotactic behavioral plasticity in C. elegans.

A memory of prior thermal experience governs Caenorhabditis elegans thermotactic behavior. On a spatial thermal gradient, C. elegans tracks isotherms near a remembered temperature we call the thermotactic set-point (T(S)). The T(S) corresponds to the previous cultivation temperature and can be reset by sustained exposure to a new temperature. The mechanisms underlying this behavioral plasticity are unknown, partly because sensory and experience-dependent components of thermotactic behavior have been difficult to separate. Using newly developed quantitative behavioral analyses, we demonstrate that the T(S) represents a weighted average of a worm's temperature history. We identify the DGK-3 diacylglycerol kinase as a thermal memory molecule that regulates the rate of T(S) resetting by modulating the temperature range of synaptic output, but not temperature sensitivity, of the AFD thermosensory neurons. These results provide the first mechanistic insight into the basis of experience-dependent plasticity in this complex behavior.

Animals↗

Jun, the oncoprotein.

Cellular Jun (c-Jun) and viral Jun (v-Jun) can induce oncogenic transformation. For this activity, c-Jun requires an upstream signal, delivered by the Jun N-terminal kinase (JNK). v-Jun does not interact with JNK; it is autonomous and constitutively active. v-Jun and c-Jun address overlapping but not identical sets of genes. Whether all genes essential for transformation reside within the overlap of the v-Jun and c-Jun target spectra remains to be determined. The search for transformation-relevant targets of Jun is moving into a new stage with the application of DNA microarrays technology. Genetic screens and functional tests remain a necessity for the identification of genes that control the oncogenic phenotype.

Animals↗

Safety and efficacy of KOGENATE Bayer in previously untreated patients (PUPs) and minimally treated patients (MTPs).

Safety and efficacy of KOGENATE Bayer (Kogenate FS), a second-generation full-length recombinant factor VIII formulated with sucrose as stabilizer and produced without the addition of human albumin during purification and the final formulation, was assessed in a prospective, international clinical trial including 31 previously untreated patients (PUPs) and minimally treated patients (MTPs) with severe haemophilia A in home therapy and surgery. Factor VIII inhibitor development was monitored and mutation type profiles were analysed. As of 30 June 2000, the patients received a total of 2.729 infusions (mean 88; range 6-274) for bleeding episodes, surgery or prophylactic treatment. No unexpected drug-related adverse events were observed. Four patients developed an inhibitor after 3-12 exposure days (EDs). One patient successfully underwent immune tolerance treatment; inhibitors in two patients disappeared spontaneously with on-demand treatment, while the inhibitor titre remains low in one patient. Twenty-nine patients (93%) with more than 20 EDs can be regarded as at low risk for inhibitor development. In conclusion, KOGENATE Bayer is efficacious and well-tolerated for treatment of children with severe haemophilia A. The incidence of inhibitor formation is not different to that observed with other recombinant or plasma-derived products.

Adolescent↗

Dynamic analysis of the QT interval in long QT1 syndrome patients with a normal phenotype.

AIMS: In families with the long QT syndrome penetrance may be low: up to 70% of gene carriers may have a normal QTc interval. These patients require therapy, similar to that in those with longer QTc intervals, but identifying them, using molecular analysis, is difficult to apply on a large scale. A large French family affected by the long QT1 syndrome was followed-up over a 25-year period. In adult males but not in females, the QTc interval normalized after puberty. We aimed to find clinical criteria, based on ambulatory ECG recordings so that we could improve diagnosis in affected members with a normal QTc. METHODS AND RESULTS: Linkage analysis and direct sequencing were an indicator of the long QT1 gene in our family. Reverse transcription-polymerase chain reaction analysis demonstrated abnormal transcripts in lymphocytes from silent gene carriers. The functional profile of mutated protein isoforms was investigated using the patch-clamp technique. Dynamic analysis of ventricular depolarization was conducted using Holter recordings in patients, and in sex- and age-matched controls. Circadian variations of the QTc interval and the QT/RR relationship were assessed. Sensitivity, specificity, and predictive values were evaluated for proposed clinical criteria. We found that dynamic analysis of the QT interval permitted individual diagnosis in mutation carriers even when the QTc interval was normal (adult males). CONCLUSION: Dynamic analysis of the QT interval is of diagnostic value in the long QT1 syndrome in patients with a normal phenotype. Clinical implications include improvement in screening and patient management.

Adolescent↗

The Vibrio cholerae chitin utilization program.

Chitin, an insoluble polymer of GlcNAc, is an abundant source of carbon, nitrogen, and energy for marine microorganisms. Microarray expression profiling and mutational studies of Vibrio cholerae growing on a natural chitin surface, or with the soluble chitin oligosaccharides (GlcNAc)(2-6), GlcNAc, or the glucosamine dimer (GlcN)2 identified three sets of differentially regulated genes. We show that (i) ChiS, a sensor histidine kinase, regulates expression of the (GlcNAc)(2-6) gene set, including a (GlcNAc)2 catabolic operon, two extracellular chitinases, a chitoporin, and a PilA-containing type IV pilus, designated ChiRP (chitin-regulated pilus) that confers a significant growth advantage to V. cholerae on a chitin surface; (ii) GlcNAc causes the coordinate expression of genes involved with chitin chemotaxis and adherence and with the transport and assimilation of GlcNAc; (iii) (GlcN)2 induces genes required for the transport and catabolism of nonacetylated chitin residues; and (iv) the constitutively expressed MSHA pilus facilitates adhesion to the chitin surface independent of surface chemistry. Collectively, these results provide a global portrait of a complex, multistage V. cholerae program for the efficient utilization of chitin.

Cell Adhesion↗

Genome-wide transcriptional profiling of the Bacillus subtilis cold-shock response.

The transcriptome of Bacillus subtilis was analysed at different time points (30, 60 and 90 min) after a temperature downshift from 37 to 18 degrees C using DNA macroarrays. This approach allowed the identification of around 50 genes exhibiting an increased mRNA level and around 50 genes exhibiting a decreased mRNA level under cold-shock conditions. Many of the repressed genes encode enzymes involved in the biosynthesis of amino acids, nucleotides and coenzymes, indicating metabolic adaptation of the cells to the decreased growth rate at the lower temperature. The strongest cold-inducible gene encodes fatty acid desaturase, which forms unsaturated fatty acids from saturated phospholipid precursors, thereby increasing membrane fluidity. The cold-shock-induced increase of mRNA levels of the classical cold-shock genes cspB, cspC and cspD could be verified. Furthermore, besides many genes encoding proteins of unknown function, some genes encoding ribosomal proteins were transcriptionally up-regulated, which points to an adaptive reprogramming of the ribosomes under cold-shock conditions. Interestingly, the amount of mRNA specified by the operon ptb-bcd-buk-lpd-bkdA1-bkdA2-bkdB, which encodes enzymes involved in degradation of branched-chain amino acids, also increases after a temperature downshift. As cells utilize the isoleucine and valine degradation intermediates alpha-methylbutyryl-CoA and isobutyryl-CoA for synthesis of branched-chain fatty acids, this finding reflects the adaptation of membrane lipid composition, ensuring the maintenance of appropriate membrane fluidity at low temperatures. The results of the DNA array analyses were verified for several selected genes by RNA slot-blot analysis and compared with two-dimensional PAGE analyses.

Bacillus subtilis↗