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At least 199 records · Page 11Linked to original sources

PubMed1996

The glial glutamate transporter complementary DNA in patients with amyotrophic lateral sclerosis.

Here, we report a mutation screening by single-stranded conformational analysis of the astroglial human brain glutamate transporter (HBGT) II complementary DNA in patients with amyotrophic lateral sclerosis. The conformational analysis data indicate a lack of sequence variations in the HBGT II coding region in 6 patients with amyotrophic lateral sclerosis and the same number of nonneurological control subjects. In both groups, three variants of the HBGT II 5' untranslated region were isolated. We have no evidence that the reported complementary DNA variants are disease specific.

ATP-Binding Cassette Transporters↗

PubMed1993

Expression of a rat glutathione-S-transferase complementary DNA in rat mammary carcinoma cells: impact upon alkylator-induced toxicity.

The role of glutathione-S-transferase (GST) in alkylator drug resistance has been studied in MatB rat mammary carcinoma cells. A series of GST transfectant cell lines was established by using an expression vector containing the complementary DNA for the rat GST Yc gene under regulation of the SV40 early region promoter and the antibiotic resistance plasmid pSV2neo. Transfectant cell lines expressing up to 4-fold higher total GST activity than in the parental wild type cell line were identified. Southern blot analysis confirmed a DNA fragment corresponding in size to the transfected GST Yc complementary DNA. Wild type MatB cells contain very low levels of Yc protein, whereas the Yc+ clones showed greatly increased amounts of the Yc subunit. The effect of increased GST Yc activity on the sensitivity of the transfected clones to various cytotoxic agents was assessed by using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide cell survival assay. The clones expressing recombinant GST Yc were more resistant to melphalan (6- to 12-fold), mechlorethamine (10- to 16-fold), and chlorambucil (7- to 30-fold). In late passage populations of the GST Yc+ clones that had been grown over a period of 14 months under continuous selection in G418, GST activity was decreased and it was paralleled by a decrease in Yc protein. These late passage clones with diminished GST Yc content also demonstrate a partial reversion toward the wild type phenotype as determined by cytotoxicity assays using melphalan, mustargen, and chlorambucil. Interstrand DNA cross-links induced by mechlorethamine were significantly lower at 0, 2, and 20 h posttreatment in one of the GST Yc+ clones when compared to wild type MatB cells. These studies indicate that GST Yc overexpression can confer resistance to alkylating agents and that this correlates with inhibition of DNA cross-link formation.

Alkylating Agents↗

PubMed1991

Isolation of a complementary DNA fragment of hepatitis C virus in Taiwan revealed significant sequence variations compared with other isolates.

To clone and characterize hepatitis C virus strains present in Taiwan, RNA was extracted from liver tissue collected from a patient during the acute phase of posttransfusion non-A, non-B hepatitis. RNA was then subjected to complementary DNA synthesis and the polymerase chain reaction, using primers derived from the original nucleotide sequence of the United States hepatitis C virus strain. A complementary DNA clone, HCV-T3, containing 552 base pairs of hepatitis C virus complementary DNA sequences was isolated and characterized. The homologies in nucleotide sequence between the Taiwan isolate and either the United States or Japan isolate were 80.1% and 91.5%, respectively. However, most of the nucleotide changes occurred in the third base positions, resulting in much higher homologies in amino acid sequence of 91.8% and 97.3%, respectively. Amplification of the less conserved region of hepatitis C virus genome with the polymerase chain reaction was improved by use of primers with nucleotides matched to the local strain. Finally, in addition to the liver and serum, the viral genome was also demonstrated in the spleen tissue by similar methods, suggesting another possible target for hepatitis C viral infection. These findings indicate that there is considerable heterogeneity in hepatitis C virus genomes isolated from different areas of the world.

Adult↗

PubMed1994

Functional expression of a stably transfected parathyroid hormone/parathyroid hormone related protein receptor complementary DNA in CHO cells.

Chinese hamster ovary (CHO) cells were stably transfected with OK-O complementary DNA encoding the parathyroid hormone/parathyroid hormone related protein (PTH/PTHrP) receptor derived from opossum kidney (OK) cells (Jüppner et al., 1991). A subclone of transfected CHO cells, CHO-E2, presented high affinity binding of 125I-labeled [Tyr36]chickenPTHrP(1-36)amide ([125I]chPTHrP(1-36)) (Kd 1.28 +/- 0.10 nM) similar to that of wildtype OK cells (Kd 2.23 +/- 0.16 nM) (P < 0.01). Photoaffinity labeling of the PTH/PTHrP receptors using N-hydroxysuccinimidyl-4-azidobenzoate modified [125I]chPTHrP(1-36) revealed the same specifically labeled 90 kDa protein in CHO-E2 and OK cells. In CHO-cells, chPTHrP(1-36) stimulated cyclic AMP accumulation in dose-dependent fashion (EC50 0.15 +/- 0.04 nM) and raised peak cytosolic free calcium concentration (EC50 2.90 +/- 0.36 nM) independent of extracellular calcium, and stimulated phosphate uptake (EC50 0.21 +/- 0.07 nM). Both, chPTHrP(1-36) and 12-O-tetradecanoylphorbol-13-acetate stimulated phosphate uptake were suppressed by staurosporine. But, Sp-cyclic adenosine-3',5'-monophosphothioate did not affect phosphate uptake in CHO-E2 cells. In conclusion, a PTH/PTHrP receptor stably expressed in CHO cells is linked to stimulation of phosphate uptake. Receptor coupling presumably occurred through the protein kinase C rather than the protein kinase A pathway.

Alkaloids↗

PubMed1994

Adenovirus-mediated transfer of human lipase complementary DNA to the gallbladder.

BACKGROUND/AIMS: Despite many improvements in current therapy, exocrine pancreatic insufficiency remains a significant problem in cystic fibrosis. To establish a new therapy for exocrine pancreatic insufficiency, the feasibility of transferring the human pancreatic lipase complementary DNA to the gallbladder as a possible target using a recombinant adenovirus vector was evaluated. METHODS: The adenovirus vector AdCMV. Lip was constructed using the cytomegalovirus immediate early promoter to drive the human pancreatic lipase complementary DNA. In vitro infection of the human gallbladder epithelial cell line HS-181 and ex vivo infection of the sheep gallbladder with AdRSV. beta-gal (an adenovirus vector containing the Escherichia coli lacZ [(beta-galactosidase] gene) or AdCMV. Lip were evaluated. RESULTS: The supernatant from AdCMV. Lip-infected HS-181 showed the secretion of active lipase for at least 2 weeks in vitro. The epithelium of gallbladder infected with AdRSV.beta-gal ex vivo showed the expression of the beta-galactosidase. The fluid from the gallbladder lumen infected with AdCMV. Lip showed the increased lipase activity. CONCLUSIONS: These observations show that an adenovirus vector can transfer a human pancreatic enzyme in vitro and ex vivo, suggesting the feasibility of in vivo gene therapy for exocrine pancreatic insufficiency in cystic fibrosis.

Adenoviridae↗

PubMed1993

Binding and phasing of Escherichia coli single-stranded DNA-binding protein by the secondary structure of phage G4 origin of complementary DNA strand synthesis (G4oric).

The origin of phage G4 DNA complementary strand synthesis (G4oric) consists of three stem-loop structures (stem loops I, II, and III) that have been proposed as a recognition site for primase during primer RNA (pRNA) synthesis (Godson, G. N., Barrell, B. G., Staden, R., and Fiddes, J. C. (1978) Nat. New Biol. 276, 236-247; Fiddes, J. C., Barrell, B. G., and Godson, G. N. (1978) Proc. Natl. Acad. Sci. U.S.A. 75, 1081-1085; Sims, J., Capon, D., and Dressler, D. (1979) J. Biol. Chem. 254, 12615-12628). It is generally considered that the double-stranded DNA stem-loop structure is not coated with Escherichia coli single-stranded DNA-binding protein (SSB), but is recognized by primase as naked DNA (Kornberg, A., and Baker, J. (1992) DNA Replication, 2nd Ed., p. 280, W. H. Freeman & Co., New York). Using small G4oric single-stranded DNA fragments of various sizes (302, 278, 149, and 100 nucleotides) consisting of the core 100-nucleotide stem-loop region plus differing lengths of 3'- and 5'-flanking sequence as substrates for gel retardation and DNase I and micrococcal nuclease digestion, we show that under conditions of pRNA synthesis, two SSB tetramers bind to the stem-loop structure. With increasing lengths of 5'- and 3'-flanking sequence, more SSB tetramers are added. Regardless of the number of SSB tetramers bound, however, the region of DNA containing the pRNA initiation site is always left accessible to nuclease digestion. In situ copper-phenanthroline footprinting of individual gel shift assembly intermediates shows that on the 302-nucleotide G4oric, the first two SSB tetramers assemble at random, but the addition of more SSB tetramers results in formation of a unique structure. In this structure, SSB tetramers protect both sides of stem loop III plus the intervening region between stem loops III and I, but leave most of stem loop I and the CTG pRNA initiation site accessible to copper-phenanthroline. Primase can only synthesize pRNA when the stem-loop structure is saturated with SSB and presumably in the unique configuration. The G4oric stem-loop structure therefore appears to dictate the phasing of SSB to leave a primase recognition site as free DNA.

Base Sequence↗

PubMedDate not supplied

[Functional value of 980-1061 sequences of human 18S ribosomal RNA using complementary DNA probes].

Region 980-1061 in human 18S rRNA was chosen on the basis of our previous results indicating, that the cross-linking sites of alkylating mRNA analogs are located within this region. In the present study, we have used 10 DNA 15-mers complementary to various overlapping sequences within the 18S rRNA positions 980-1061. Their ability to bind selectively at the desired rRNA sequences was proved by hydrolysis of 18S rRNA within heteroduplexes with the corresponding probes by RNase H. Only four of the probes were able to bind to 40S subunits indicating, that the corresponding 18S rRNA sequences 980-994, 987-1001, 1025-1039 and 1032-1046 are exposed within the subunits. None of the probes inhibited tRNA-dependent binding of oligo(U) messengers to 40S subunits. Nevertheless, two probes (complementary to 18S rRNA sequences 987-1001 and 1025-1039) being covalently attached to 40S subunits, inhibited translation of poly(U) by human 80S ribosomes in a cell-free system. The binding of messenger trinucleotide in the complex pAUG.40S.Met-tRNA.eIF-2.GTP was strongly affected by the same oligomers. Thus 987-1001 and 1025-1039 18S rRNA sequences are supposed to be involved in interaction with mRNA in the course of translation.

Base Sequence↗

PubMed1997

Studying functional significance of the sequence 980-1061 in the central domain of human 18S rRNA using complementary DNA probes.

Region 980-1061 in human 18S rRNA has been chosen on the basis of our previous results, indicating that cross-linking sites of the alkylating mRNA analogs are located within this region. In the present study, we have used 10 DNA 15-mers complementary to various overlapping sequences within the 18S rRNA positions 980-1061. Their abilities to bind selectively to the target rRNA sequences were proved by hydrolysis of 18S rRNA within heteroduplexes with the corresponding probes by RNase H. Four sequences (980-994, 987-1001, 1025-1039 and 1032-1046) were found to be well accessible for binding of the respective cDNA probes within 40S subunits. None of the oligomers inhibited tRNA(Phe)-dependent binding of oligo(U) messenger to 40S subunits and binding of Met-tRNA(imet) to 40S subunits in the presence of eIF-2 and nonhydrolysable GTP analog. Nevertheless, two probes (complementary to the 18S rRNA sequences 987-1001 and 1025-1039) being covalently attached to 40S subunits, inhibited translation of poly(U) by human 80S ribosomes in a cell-free system. The same oligomers revealed the most pronounced inhibitory action on the binding of messenger trinucleotide in the complex pAUG.40S.Met-tRNA(imet).eIF-2.GTP. Results of these functional assays demonstrate the importance of the 18S rRNA sequences 987-1001 and 1025-1039 for translation process on human ribosomes, most probably at the initiation step.

Alkylation↗

PubMed1999

Hormone therapy failure in human prostate cancer: analysis by complementary DNA and tissue microarrays.

BACKGROUND: The molecular mechanisms underlying the progression of prostate cancer during hormonal therapy have remained poorly understood. In this study, we developed a new strategy for the identification of differentially expressed genes in hormone-refractory human prostate cancer by use of a combination of complementary DNA (cDNA) and tissue microarray technologies. METHODS: Differences in gene expression between hormone-refractory CWR22R prostate cancer xenografts (human prostate cancer transplanted into nude mice) and a xenograft of the parental, hormone-sensitive CWR22 strain were analyzed by use of cDNA microarray technology. To validate the data from cDNA microarrays on clinical prostate cancer specimens, a tissue microarray of specimens from 26 prostates with benign prostatic hyperplasia, 208 primary prostate cancers, and 30 hormone-refractory local recurrences was constructed and used for immunohistochemical detection of protein expression. RESULTS: Among 5184 genes surveyed with cDNA microarray technology, expression of 37 (0.7%) was increased more than twofold in the hormone-refractory CWR22R xenografts compared with the CWR22 xenograft; expression of 135 (2.6%) genes was reduced by more than 50%. The genes encoding insulin-like growth factor-binding protein 2 (IGFBP2) and 27-kd heat-shock protein (HSP27) were among the most consistently overexpressed genes in the CWR22R tumors. Immunohistochemical analysis of tissue microarrays demonstrated high expression of IGFBP2 protein in 100% of the hormone-refractory clinical tumors, in 36% of the primary tumors, and in 0% of the benign prostatic specimens (two-sided P =.0001). Overexpression of HSP27 protein was demonstrated in 31% of the hormone-refractory tumors, in 5% of the primary tumors, and in 0% of the benign prostatic specimens (two-sided P =.0001). CONCLUSIONS: The combination of cDNA and tissue microarray technologies enables rapid identification of genes associated with progression of prostate cancer to the hormone-refractory state and may facilitate analysis of the role of the encoded gene products in the pathogenesis of human prostate cancer.

Animals↗

PubMed1995

In vivo transfection of hepatitis C virus complementary DNA into rodent liver by asialoglycoprotein receptor mediated gene delivery.

An in vivo model of hepatitis C virus (HCV) infection is needed to enable investigation of the mechanism of the liver injury that it causes. In this study, we used asialoglycoprotein receptor mediated gene delivery to obtain expression of the complementary DNA (cDNA) coding the core and part of the envelope 1 protein of HCV because selective delivery to the hepatocytes has been reported to be attained with this method. The optimum carrier-DNA ratio was examined using in vitro transfection and found to be important for the efficiency of this method. In transfection in vivo, microautoradiographical examination showed that the transfected plasmids were delivered selectively to the liver parenchymal cells. To obtain an immunohistochemically detectable level of protein expression in rodent liver, some modifications for increasing the in vivo transfection efficiency were performed; a lysosomal enzyme inhibitor, chloroquine, was used and the administration route of the carrier-DNA complex was changed from the tail vein to the portal vein. On the bases of these results, in vivo transfection with expression vector of HCV core/E1 region was performed. In rat liver transfected by intraportal injection with chloroquine, the transcript RNA and the core protein were detected. These results indicated that the HCV core/E1 expression vector was not merely delivered but also successfully expressed in the liver using asialoglycoprotein receptor mediated gene delivery. The number of the HCV core expressing cells in the transfected liver was similar to that in patients with hepatitis C. These in vivo transfected animals should be useful for investigating the role of this region in the liver injury caused by HCV.

Animals↗

PubMed1998

Full-length complementary DNA of hepatitis C virus genome from an infectious blood sample.

We constructed a full-length complementary DNA (cDNA) clone of hepatitis C virus (HCV) from a blood sample of an HCV carrier. The blood from the carrier was eventually transfused to a patient who later developed typical posttransfusion hepatitis C. It was also shown to be infectious to chimpanzees. We obtained 12 overlapping cDNA fragments altogether, covering the entire HCV genome. By subcloning and sequencing, clones considered to constitute the major population were selected. We could also detect 98 base pairs of extra sequences at the 3' end of the genome. After confirming the overlapping sequences, we combined the fragments to make a full-length cDNA. The HCV population in the donor was heterogeneous, as determined by their nucleotide sequences of the hypervariable region in envelope protein, but a few virus clones were selected in the recipient after transmission. The similar convergence of the virus population was previously observed when the same blood sample was injected into a chimpanzee. Interestingly, virus clones isolated during the acute phase in the recipient and the chimpanzee had sequences in the hypervariable region identical to that of the full-length cDNA clone. The full-length cDNA clone of HCV constructed in this study may originate from infectious virus clones.

Amino Acid Sequence↗

PubMed2000

Detecting activation of ribosomal protein S6 kinase by complementary DNA and tissue microarray analysis.

BACKGROUND: Studies by comparative genomic hybridization (CGH) have shown that chromosomal region 17q23 is amplified in up to 20% of primary breast cancers. We used microarray analyses to measure the expression levels of genes in this region and to explore their prognostic importance. METHODS: A microarray that contained 4209 complementary DNA (cDNA) clones was used to identify genes that are overexpressed in the MCF-7 breast cancer cell line as compared with normal mammary tissue. Fluorescence in situ hybridization was used to analyze the copy number of one overexpressed gene, ribosomal protein S6 kinase (S6K), and to localize it to the 17q23 region. Northern and western blot analyses were used to measure S6K gene and protein expression, and an enzymatic assay was used to measure S6K activity. Tumor tissue microarray analysis was used to study amplification of S6K and the HER-2 oncogene, another 17q-linked gene, and the relationship between amplification and prognosis was analyzed. The Kaplan-Meier method was used for data analysis, and the log-rank test was used for statistical analysis. All P values are two-sided. RESULTS: S6K was amplified and highly overexpressed in MCF-7 cells relative to normal mammary epithelium, and protein expression and enzyme activity were increased. S6K was amplified in 59 (8.8%) of 668 primary breast tumors, and a statistically significant association between amplification and poor prognosis (P =.0021) was observed. Amplification of both S6K and HER-2 implied particularly poor survival (P =.0001). CONCLUSIONS: The combination of CGH information with cDNA and tissue microarray analyses can be used to identify amplified and overexpressed genes and to evaluate the clinical implications of such genes and genomic rearrangements. S6K is likely to be one of the genes at 17q23 that is amplified during oncogenesis and may adversely affect the prognosis of patients with this amplification.

Blotting, Northern↗

PubMed1987

Complementary DNA for human T-cell cyclophilin.

Complementary DNA encoding human cyclophilin, a specific cyclosporin A-binding protein, has been isolated from the leukemic T-cell line Jurkat and sequenced. Comparison of the deduced amino acid sequence with the previously determined sequence of bovine thymus cyclophilin reveals only three differences: an additional amino acid at the carboxy terminus end and two internal changes. RNA transfer blot analysis indicates an mRNA size of approximately 1 kb for human T-cell cyclophilin. Phytohaemagglutinin and phorbol myristate acetate induction of T cells treated or not with cyclosporin A affects only marginally the level of cyclophilin mRNA. Southern blot analysis of human genomic DNA digested with different restriction enzymes strongly suggests the existence of a multigene family for cyclophilin.

Amino Acid Sequence↗

PubMed1991

Cloning and expression of complementary DNA encoding an antigen of Trichinella spiralis.

Complementary DNA (cDNA) encoding a 49-kDa antigen of Trichinella spiralis was cloned, characterized, and expressed in Escherichia coli by recombinant DNA methods. As a first step, 29 residues of N-terminal amino acid sequence were determined by direct analysis of highly purified antigen. Mixed-sequence primers based on the amino acid sequence were then synthesized and used as primers to generate a partial cDNA by the polymerase chain reaction (PCR). A nearly full-length cDNA was then obtained by PCR using a specific 5'-end primer and a non-specific 3'-end primer. Complete sequence of the 1133-bp cDNA was determined. Translation of this sequence predicts an N-glycosylated polypeptide of 322 amino acids. The cDNA was expressed as a fusion protein in bacteria which could be recognized in Western blots both by sera from mice immunized with purified native 49-kDa antigen and by sera from swine infected with the parasite. These findings suggest that recombinant P49 is a potentially valuable antigen both for vaccine development and immunodiagnosis.

Amino Acid Sequence↗

PubMed1988

Role of the potential secondary structures in phage G4 origin of complementary DNA strand synthesis.

Phage G4 origin of complementary DNA strand synthesis (oric) consists of three stable stem-loop structures (I, II, and III). Mutant oric sequences with alterations in the structure of stem-loop II, stem-loop III, and the stem-loop II-III spacer region have been constructed and cloned into the filamentous phage vectors to assay their functional activity. Changes in the lowermost GC base pair in the stem of stem-loop III, in the 9-bp spacer region between the stems of stem-loops II and III, and in the loop of stem-loop II, impair or abolish in vivo oric function. The results suggest that recognition sequences for dnaG primase must be present in the loop of stem-loop II, and in the spacer region between the stems of stem-loops II and III.

Bacteriophages↗

PubMedDate not supplied

Amino-acid sequence of the catalytic subunit of the (Na+ + K+)ATPase deduced from a complementary DNA.

We have isolated and characterized a complementary DNA for the catalytic subunit of the sheep kidney sodium/potassium-dependent ATPase. The 1,016-amino-acid protein seems to have eight transmembrane domains. The apparent ouabain binding site is located at the extracellular junction of two transmembrane domains and is linked to the phosphorylation site by a 60-amino-acid conserved sequence that may be a major channel for energy transduction.

Amino Acid Sequence↗

PubMedDate not supplied

Amino-acid sequence of a Ca2+ + Mg2+-dependent ATPase from rabbit muscle sarcoplasmic reticulum, deduced from its complementary DNA sequence.

We have cloned and sequenced complementary DNA encoding a Ca2+-ATPase of rabbit muscle sarcoplasmic reticulum. We propose a model of the protein which has 3 cytoplasmic domains joined to a set of 10 transmembrane helices by a narrow, penta-helical stalk. In this model, ATP bound to one cytoplasmic domain would phosphorylate an aspartate in an adjoining cytoplasmic domain, inducing translocation of Ca2+ from binding sites on the stalk.

Amino Acid Sequence↗

PubMed1987

Isolation and sequence of complementary DNA encoding human extracellular superoxide dismutase.

A complementary DNA (cDNA) clone from a human placenta cDNA library encoding extracellular superoxide dismutase (EC-SOD; superoxide:superoxide oxidoreductase, EC 1.15.1.1) has been isolated and the nucleotide sequence determined. The cDNA has a very high G+C content. EC-SOD is synthesized with a putative 18-amino acid signal peptide, preceding the 222 amino acids in the mature enzyme, indicating that the enzyme is a secretory protein. The first 95 amino acids of the mature enzyme show no sequence homology with other sequenced proteins and there is one possible N-glycosylation site (Asn-89). The amino acid sequence from residues 96-193 shows strong homology (approximately 50%) with the final two-thirds of the sequences of all known eukaryotic CuZn SODs, whereas the homology with the P. leiognathi CuZn SOD is clearly lower. The ligands to Cu and Zn, the cysteines forming the intrasubunit disulfide bridge in the CuZn SODs, and the arginine found in all CuZn SODs in the entrance to the active site can all be identified in EC-SOD. A comparison with bovine CuZn SOD, the three-dimensional structure of which is known, reveals that the homologies occur in the active site and the divergences are in the part constituting the subunit contact area in CuZn SOD. Amino acid sequence 194-222 in the carboxyl-terminal end of EC-SOD is strongly hydrophilic and contains nine amino acids with a positive charge. This sequence probably confers the affinity of EC-SOD for heparin and heparan sulfate. An analysis of the amino acid sequence homologies with CuZn SODs from various species indicates that the EC-SODs may have evolved from the CuZn SODs before the evolution of fungi and plants.

Amino Acid Sequence↗