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Y Edwards

Publications and source records attributed to Y Edwards.

At least 19 recordsLinked to original sources
PubMed1995

A novel cDNA with homology to an RNA polymerase II elongation factor maps to human chromosome 5q31 (TCEB1L) and to mouse chromosome 11 (Tceb1l).

Few of the auxiliary factors that assist RNA polymerase II in the process of mRNA chain elongation have been identified. We have isolated a novel cDNA, Tceb1l, from mouse and human sources that encodes a 163-amino-acid protein and shows a significant level of identity with a recently identified RNA polymerase II transcription elongation factor, p15. Tceb1l is highly conserved throughout vertebrates and maps to mouse chromosome 11 and to the syntenic region of human chromosome 5q31. Tceb1l shows a restricted pattern of expression in the early mouse embryo, where it is absent from the neurectoderm; later Tceb1l is expressed in the caudal region of the neural tube, followed by widespread expression in many tissues, including the brain and spinal cord. These observations are consistent with Tceb1l being an RNA polymerase II elongation factor and suggest that Tceb1l/p15-like peptides may be a new family of proteins that influence RNA elongation.

Amino Acid Sequence↗
PubMed1995

The embryonic RNA helicase gene (ERH): a new member of the DEAD box family of RNA helicases.

DEAD box proteins share several highly conserved motifs including the characteristic Asp-Glu-Ala-Asp (D-E-A-D in the amino acid single-letter code) motif and have established or putative ATP-dependent RNA helicase activity. These proteins are implicated in a range of cellular processes that involve regulation of RNA function, including translation initiation, RNA splicing and ribosome assembly. Here we describe the isolation and characterization of an embryonic RNA helicase gene, ERH, which maps to mouse chromosome 1 and encodes a new member of the DEAD box family of proteins. The predicted ERH protein shows high sequence similarity to the testes-specific mouse PL10 and to the maternally acting Xenopus An3 helicase proteins. The ERH expression profile is similar, to that of An3, which localizes to the animal hemisphere of oocytes and is abundantly expressed in the embryo. ERH is expressed in oocytes and is a ubiquitous mRNA in the 9 days-post-conception embryo, and at later stages of development shows a more restricted pattern of expression in brain and kidney. The similarities in sequence and in expression profile suggest that ERH is the murine equivalent of the Xenopus An3 gene, and we propose that ERH plays a role in translational activation of mRNA in the oocyte and early embryo.

Amino Acid Sequence↗
PubMed1994

Evaluation of a transgenic mouse model for alpha-1-antitrypsin (AAT) related liver disease.

We have attempted to produce a transgenic mouse model of the neonatal liver disease associated with the human PIZ allele. Analysis of a number of transgenic mouse lines carrying either a normal human PIM gene construct or the mutant Z is reported. Using isoelectric focusing analysis of plasma from transgenic mice, we have shown that the human AAT proteins produced in mice are processed in a similar way to their counterparts in humans. By comparing the level of M and Z mRNA in liver with the levels of M and Z proteins in plasma we have inferred that, as in humans, the mutant protein tends to accumulate within the hepatocyte. Accumulation of Z protein has also been demonstrated by immunocytochemistry. Two of the M transgenic lines produce such high levels of the human protein that it, like the Z protein, accumulates as globules. Histological features of livers from 116 mice of different ages and genotypes were examined: 37 non-transgenic, 62 Z transgenic (23 low expressing and 39 high expressing) and 17 M transgenic mice, all high expressing. Cirrhosis or fibrosis was not seen in any animal and we were unable to find any evidence for neonatal liver disease. Some necrosis was seen in all genotypes and this increased significantly with age with one Z line showing significantly more frequent necrosis than any other group. This line, the highest expressing Z line, was back crossed onto 7 different genetic backgrounds but no major differences between the back crosses with respect to liver disease were observed. The mouse model we have developed is compared with other transgenic Z mouse models; none of these is representative of human neonatal liver disease. Our view is that the transgenic animals generated in these experiments may be most useful for investigating the liver manifestations that almost invariably occur in ZZ adults. Alteration of additional factors other than accumulation of Z protein, for example inactivation of the endogenous mouse genes or some environmental challenge, might produce a mouse model with more relevance to neonatal liver disease.

Animals↗
PubMed1993

Expression from the proximal promoter of the carbonic anhydrase 1 gene as a marker for differentiation in colon epithelia.

Carbonic anhydrase 1 (CA1) catalyses the reversible hydration of CO2 and is important for cellular diffusion of CO2, ion transport and pH regulation. The gene encoding CA1 (CA1) has two promoters. In adult colon epithelia the proximal promoter determines high levels of expression and the distal erythroid promoter is repressed. RNA in situ hybridisation shows that CA1 mRNA is abundant in differentiating cells of the colonic crypt as they migrate to the luminal surface, but is not present at the base of the crypts and levels are low on the luminal surface. It is likely that CA1 gene expression in these cells is regulated by differential transcription and/or mRNA stability. In contrast CA1 protein is localised predominantly on the luminal surface. Since CA1 mRNA and protein do not exactly co-localise it can be inferred that CA1 expression is also subject to post-transcriptional control. CA1 mRNA is significantly reduced in colon carcinoma and in adenomas from familial adenomatous polyposis patients. Loss of CA1 expression is associated with the disappearance of differentiated epithelial cells. Out of twelve colon carcinoma cell lines three, LIM1215, LIM1899 and HT115, expressed CA1 and nine did not. This variation in expression may also be associated with cell type differentiation.

Base Sequence↗
PubMed1992

Sequence of the complete cDNA and the 5' structure of the human sucrase-isomaltase gene. Possible homology with a yeast glucoamylase.

The complete sequence of the 6 kb cDNA and the 5' genomic structure are reported for the gene coding for the human intestinal brush border hydrolase sucrase-isomaltase. The human sucrase-isomaltase cDNA shows a high level of identity (83%) with that of the rabbit enzyme, indicating that the protein shares the same structural domains in both species. In addition to the previously reported homology with lysosomal alpha-glucosidase, the sucrase and isomaltase subunits also appear to be homologous to a yeast glucoamylase. A 14 kb human genomic clone has been isolated which includes the first three exons and the first two introns of the gene, as well as 9.5 kb 5' to the major start site of transcription. The first exon comprises 62 bp of untranslated sequence and the second starts exactly at the initiation ATG codon. Typical CAAT and TATA boxes are seen upstream of the first exon. A genetic polymorphism is described which involves a PstI site in the second intron. Southern blotting, sequencing and mRNA studies indicate that the structures of the sucrase-isomaltase gene and its mRNA are unaltered in the two human colon cancer cell lines Caco-2 and HT-29 in comparison with normal human small intestine.

Amino Acid Sequence↗
PubMed1992

Nucleotide sequence and chromosomal assignment of a cDNA encoding the large isoform of human glutamate decarboxylase.

Glutamic acid decarboxylase (GAD) catalyses the conversion of L-glutamic acid to the inhibitory neurotransmitter gamma-aminobutyric acid (GABA). Two forms of human GAD, GAD65 and GAD67, are encoded by two separate genes. A full length human GAD67 cDNA has been isolated from a human frontal cortex cDNA library and the nucleotide sequence determined. The GAD67 gene has been mapped to chromosome 2 using the polymerase chain reaction to amplify specifically the human sequence in rodent/human somatic cell hybrid DNA. This confirms that human GAD67 is not syntenic with the smaller GAD isoform GAD65 which has been assigned to chromosome 10. Production of polyclonal antiserum to a baculovirus-expressed GAD67 enabled immunocytological detection of GAD in the rat brain.

Amino Acid Sequence↗
PubMed1991

Usefulness of blood tests carried out during screening of the elderly population in one practice.

A screening programme for elderly patients in a six partner rural practice in west Wales had been found to be unhelpful. When screening became mandatory in April 1990 it was decided to make the programme more medical. The 773 patients aged 75 years or over in the practice were therefore offered a blood test as part of the mandatory screening programme. A total of 631 blood samples were taken. On checking haemoglobin concentrations, 39 patients (6.2%) were found to have levels below 11.5 g dl-1 (30 women, nine men). Forty two patients (7.1%) were found to have a blood urea concentration of more than 10.0 mmol l-1 and only three patients were found to be deficient in potassium, none of whom were receiving long term diuretic medication. Of the 16 patients (2.8%) discovered to have a lower than normal serum thyroxine concentration, 12 were not known to the practice. A raised mean corpuscular volume (greater than 100.0 fl) was found in 35 patients (5.9%) (24 women, 11 men), but only one of these was anaemic. However, among the patients with a low mean corpuscular volume (less than 80.0 fl), seven had a haemoglobin concentration of less than 11.5 g dl-1. Although this exercise has produced clinical benefit for a few patients, and has been interesting and academically stimulating, it cannot be concluded that the benefits obtained are worth the effort that has been involved.

Aged↗
PubMed1990

Mapping of mouse carbonic anhydrase-3, Car-3: another locus in the homologous region of mouse chromosome 3 and human chromosome 8.

At least six separate genes determining tissue- and organelle-specific isoforms of carbonic anhydrase are known. We have determined the chromosome location of one of these genes, carbonic anhydrase-3 (Car-3), in the mouse and carried out a linkage analysis of Car-1, Car-2, and Car-3. Car-3 has been assigned to band 3A2 by in situ hybridization. We identified a PstI restriction fragment length polymorphism between Mus spretus and Mus mus domesticus and, by using an interspecific backcross, showed that Car-3 is 2.4 +/- 1.7% SE from both Car-1 and Car-2, calculating genetic distance as percentage recombination. No recombinants were found between Car-1 and Car-2 in 100 backcross offspring, and when these data are combined with earlier results, these two loci are estimated to be 1.2 cM from each other at the 95% confidence interval. The three homologous carbonic anhydrase loci in man had earlier been assigned to 8q22, and the finding of linkage of Car-3 to Car-1 and Car-2 in the mouse adds another locus to the conserved segments on mouse chromosome 3 and human chromosome 8.

Animals↗
PubMed1990

The polymorphic human DNA sequence D8S8 assigned to 8q13-21.1, close to the carbonic anhydrase gene cluster, by isotopic and nonisotopic in situ hybridization and by linkage analysis.

Restriction fragment length polymorphism at the D8S8 locus is explained by the occurrence of at least two alternative alleles at two separate TaqI sites; TaqI-A allele frequencies 0.73 and 0.27 and TaqI-B allele frequencies 0.94 and 0.06. The D8S8 locus has been assigned to 8q13-21.1, near to the carbonic anhydrase (CA) gene cluster, by in situ hybridization to metaphase chromosomes using both tritium and immunofluorescently labelled probes. Linkage analysis using the CEPH family DNA panel indicates a close genetic linkage between D8S8 and CA3, with a lod score of +7.80 at theta = 0.05 in males.

Alleles↗
PubMed1989

Cloning and characterization of the major insulin-responsive glucose transporter expressed in human skeletal muscle and other insulin-responsive tissues.

Complementary DNA clones encoding a facilitative glucose transporter-like protein have been isolated from human small intestine and muscle cDNA libraries. This 509-amino acid protein has 65.3, 54.3, and 57.5% identity with the previously described human erythrocyte/HepG2, liver, and fetal muscle glucose transporter/transporter-like proteins, respectively. RNA blotting studies indicate that transcripts encoding this protein are very abundant in adult human skeletal muscle and subcutaneous fat. The adult skeletal muscle glucose transporter-like protein was expressed in vitro by cDNA-directed transcription and cell-free translation of the synthetic mRNA. The in vitro-synthesized protein reacted with a monoclonal antibody, 1F8, which recognizes the insulin-regulatable glucose transporter expressed in rat skeletal muscle, heart, and adipocytes. In contrast, in vitro-synthesized erythrocyte/HepG2 and fetal muscle glucose transporters did not react with 1F8. The high levels in adult skeletal muscle and subcutaneous fat of mRNA encoding the adult skeletal muscle glucose transporter and its specific reactivity with monoclonal antibody 1F8 suggest that this protein is the major insulin-regulatable glucose transporter expressed in skeletal muscle and other insulin-responsive tissues.

Adipose Tissue↗
PubMed1989

Soluble bovine galactose-binding lectin. cDNA cloning reveals the complete amino acid sequence and an antigenic relationship with the major encephalitogenic domain of myelin basic protein.

A full-length cDNA clone for the 13-14 kDa soluble beta-galactoside-binding lectin was isolated from a bovine fibroblast cDNA library. The derived amino acid sequence shows eight differences from a preliminary partial amino acid sequence given previously for the bovine heart lectin. This observation led to a re-examination of the data and correction of the heart lectin protein sequence. Except for a possible polymorphism of the heart lectin at position 57, the fibroblast and heart lectin sequences are considered identical. The epitope recognized by two monoclonal anti-(bovine lectin) antibodies, 36/8 and 9/5, was identified as the tetrapeptide sequence W-G-A/S-E/D by the isolation of several different cDNA clones from a human intestine cDNA library. A similar tetrapeptide is present in all of the soluble beta-galactoside-binding animal lectins sequenced thus far. It is also found in myelin basic protein, which we show is antigenically cross-reactive with the lectin. In myelin basic protein the tetrapeptide is a part of the major domain previously shown to be responsible for the induction of experimental allergic encephalomyelitis.

Amino Acid Sequence↗
PubMed1989

Mouse carbonic anhydrase III: nucleotide sequence and expression studies.

A cDNA for the mouse carbonic anhydrase, CAIII, has been isolated from a lambda gt11 expression library. The cloned cDNA contains all of the coding region (777 bp) and both 5' untranslated (86-bp) and 3' untranslated (217-bp) sequences. The coding sequence shows 87% homology at the nucleotide level and 91% homology, when amino acid residues are compared, with human CAIII. Protein and mRNA analyses show that CAIII is present at low levels in cultured myoblasts and is abundant in adult skeletal muscle and in liver. The marked sex-related differences in CAIII distribution, described for rat liver, are not seen in the mouse. Restriction fragment length polymorphisms using TaqI and PstI are described which distinguish between Mus spretus and Mus musculus domesticus.

Amino Acid Sequence↗
PubMed1988

Induction of carbonic anhydrase III mRNA and protein by denervation of rat muscle.

Carbonic anhydrase III (CAIII) protein and mRNA amounts in fast- and slow-twitch rat muscles were examined after resection of the sciatic nerve. Striking changes occur in the fast-twitch anterior tibialis (AT) and extensor digitorum longus (EDL) muscles, where CAIII protein and mRNA are increased several-fold 16 days after denervation. The data suggest that these changes are regulated in part by changes in gene transcription and that they perhaps signal a fast-to-slow fibre type transition in these denervated muscles. AT and EDL show some differences in the effects of denervation, which are suggestive of variation in the timing of denervation-induced responses and/or the CAIII protein/mRNA turnover rates in the two muscles.

Actins↗
PubMed1988

Changes in skeletal muscle gene transcription induced by chronic stimulation.

The mRNA products of four genes, carbonic anhydrase III (CAIII), fast myosin heavy chain (MHCf), actin and glyceraldehyde-3-phosphate dehydrogenase (GAPDH), were assayed by Northern and slot-blot analysis in rabbit tibialis anterior and extensor digitorum longus muscles that were subjected to electrical stimulation for periods of up to 21 days. Marked changes in mRNA levels were seen for all four genes. The mRNA for CAIII, which is specific for type 1 fibers, rose significantly, whereas the MHCf mRNA fell markedly in the stimulated muscles. Changes in GAPDH mRNA were consistent with a reduced dependence on anaerobic glycolysis as an energy source. Actin mRNA levels were noticeably depressed in the early stages of stimulation. Thus for several classes of muscle protein, the response to chronic low-frequency stimulation appears to involve changes at the level of gene transcription.

Actins↗
PubMed1987

Deletions of fetal and adult muscle cDNA in Duchenne and Becker muscular dystrophy patients.

We have isolated a cDNA molecule from a human adult muscle cDNA library which is deleted in several Duchenne muscular dystrophy patients. Patient deletions have been used to map the exons across the Xp21 region of the short arm of the X chromosome. We demonstrate that a very mildly affected 61 year old patient is deleted for at least nine exons of the adult cDNA. We find no evidence for differential exon usage between adult and fetal muscle in this region of the gene. There must therefore be less essential domains of the protein structure which can be removed without complete loss of function. The sequence of 2.0 kb of the adult cDNA shows no homology to any previously described protein listed in the data banks although sequence comparison at the amino acid level suggests that the protein has a structure not dissimilar to rod structures of cytoskeletal proteins such as lamin and myosin. There are single nucleotide differences in the DNA sequence between the adult and fetal cDNAs which result in amino acid changes but none that would be predicted to change the structure of the protein dramatically.

Amino Acid Sequence↗