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N Hayward

Publications and source records attributed to N Hayward.

36 records · Page 2Linked to original sources
PubMed1997

Analysis of the promoter region of the human VEGF-related factor gene.

We have characterised the promoters of the human and murine VRF (vascular endothelial growth factor (VEGF) related factor) gene. A series of deletions were made of a 553-bp region 5' of the VRF initiation codon and were used in a luciferase reporter gene assay to determine the minimal promoter of the VRF gene. The region between base pairs -443 and -195 was sufficient to mediate transcription in lymphocytes and the region between -550 and -443 enhanced this promoter activity. Primer extension studies identified two regions of transcription initiation, both of which are preceded by Sp1, AP-2 and Egr-1 transcription factor binding sites. The VRF promoter is similar to VEGF in that it is associated with a CpG island, contains sites for Sp1 and AP-2, and lacks a TATA box. However, it has marked differences in that the promoter contains Egr-1 sites and lacks both hypoxia-inducible factor-1 and AP-1 sites. These data may indicate that expression of these two growth factors is regulated by different physiological stimuli.

Animals↗
PubMed1997

Localization of frontotemporal dementia with parkinsonism in an Australian kindred to chromosome 17q21-22.

An Australian family with autosomal dominant presenile nonspecific dementia was recently described. The disease results in behavioral changes, usually disinhibition, followed by the onset of dementia accompanied occasionally by parkinsonism. Twenty-eight affected individuals were identified with an age of onset of 39 to 66 years (mean, 53 +/- 8.9 years). We mapped the disease locus to an approximately 26-cM region of chromosome 17q21-22 with a maximum two-point LOD score of 2.87. Affected individuals share a common haplotype between markers D17S783 and D17S808. This region of chromosome 17 contains the loci for several neurodegenerative diseases that lack distinctive pathological features, suggesting that these dementias, collectively referred to as frontotemporal dementia with parkinsonism linked to chromosome 17 (FTDP-17), are caused by mutations in the same gene. The entire coding region of five genes, mapped to the FTDP-17 candidate region, were also sequenced. This analysis included the microtubule-associated protein tau that is the major component of the paired helical filaments observed in Alzheimer's disease. No pathogenic mutations were identified in either the tau gene or in any of the other genes analyzed.

Adult↗
PubMed1997

Exclusion of the phosphoinositide-specific phospholipase C beta 3 (PLCB3) gene as a candidate for multiple endocrine neoplasia type 1.

The predisposing genetic defect in multiple endocrine neoplasia type 1 has been assigned to chromosomal region 11q13. Our previous attempts to identify the MEN1 gene have resulted in the isolation of the phospholipase C beta 3 gene from the actual region. PLCB3 plays an important role in signal transduction and, moreover, shows loss of expression in some endocrine tumors, in accordance with a putative tumor suppressor gene function, and thus appears to be an excellent candidate for MEN1. We have therefore undertaken screening for constitutional mutations in individuals from MEN1 families. Several sequence alterations have been discovered, none of them however fulfilling the criteria for a disease-related mutation. We can now exclude PLCB3 from candidacy as the MEN1 gene.

Chromosome Mapping↗
PubMed1997

Genomic regions regulating imprinting and insulin-like growth factor-II promoter 3 activity in transgenics: novel enhancer and silencer elements.

Transgenic lines (89) were made with constructs containing eight different combinations of candidate regulatory elements from the insulin-like growth factor-II (Igf2)-H19 region of mouse chromosome 7. In all constructs, promoter 3 of Igf2 was attached to a firefly luciferase reporter gene. Promoter 3 was the common element that imposed a decrease in reporter activity similar to that of endogenous Igf2 after birth. The specific activity of the reporter was measured on the day of birth in the liver and the brain, after each transgene had been transmitted by either the father or the mother. This procedure demonstrated that the quantity and organ distribution of expression from this promoter can be regulated by each element. The following new information was obtained. (a) The 5' differentially methylated region of Igf2 inhibits promoter 3 in the liver. (b) The conserved DNase I-hypersensitive Middle region between Igf2 and H19 is an enhancer of promoter 3 in the brain. (c) The H19 promoter inhibits Igf2 promoter 3 in the brain. The results confirmed that the H19 enhancer is a strong enhancer of promoter 3 in the liver. A new finding was that one genomic region regularly imposed imprinted gene expression. This was the H19 enhancer, and this region was sufficient to give higher expression on maternal transmission in the majority of transgenic lines. The full data are reported in Supplementary Publication SUP 50180 (8 pages), which has been deposited at the British Library Document Supply Centre, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1997) 21, 8-10.

Animals↗
PubMed1996

Characterization of the murine VEGF-related factor gene.

We describe here the molecular cloning and characterization of the murine homolog of the human vascular endothelial growth factor-related factor (VRF) gene. cDNAs for two alternatively spliced forms of the murine vrf gene have been isolated, the putative translation products of which differ at their carboxyl termini due to a shift in reading frame caused by insertion, or lack thereof, of exon 6, in a similar fashion to human VRF (hVRF). The message lacking exon 6 encodes a protein (mvrf167) with 86% identity and 92% conservation of amino acid residues with hVRF. The protein coding region of the gene spans approximately 5kb of genomic DNA and is composed of 8 exons ranging in size from 36 to 398bp. The genomic structure of murine vrf is highly conserved with the human homolog in relation to position of splice junctions and the presence of contiguous exons 6 and 7. A short polymorphic AC repeat is present in the 3' untranslated region of murine vrf. A major band of approximately 1.3kb was expressed in all adult mouse tissues examined.

Amino Acid Sequence↗
PubMed1996

Permeability of the blood brain barrier by the bradykinin agonist, RMP-7: evidence for a sensitive, auto-regulated, receptor-mediated system.

The novel bradykinin (BK) analog, RMP-7, was characterized in a series of in vitro tests to establish its selectivity as a B2 agonist. It was then used to study bradykinin's role in permeabilizing the blood brain barrier (BBB) and blood brain-tumor barrier (BTB), using an RG2 rat glioma model. These studies demonstrated that: (1) B2 receptor stimulation permeabilizes both the BBB and BTB in a dose-related fashion with greater effects observed in brain tumor-associated tissue, (2) the increased permeability is sensitive, rapid and transient, and (3) tachyphylaxis occurs with continuous agonist administration, suggesting autoregulation of the system's effects. These data therefore support the existence of a sophisticated, responsive and tightly regulated BK system whose activity modulates the permeability of the BBB.

Animals↗
PubMed1996

Cloning and characterization of a novel human gene related to vascular endothelial growth factor.

This paper describes the cloning and characterization of a new member of the vascular endothelial growth factor (VEGF) gene family, which we have designated VRF for VEGF-related-factor. Sequencing of cDNAs from a human fetal brain library and RT-PCR products from normal and tumor tissue cDNA pools indicate two alternatively spliced messages with open reading frames of 621 and 564 bp, respectively. The predicted proteins differ at their carboxyl ends resulting from a shift in the open reading frame. Both isoforms show strong homology to VEGF at their amino termini, but only the shorter isoform maintains homology to VEGF at its carboxyl terminus and conserves all 16 cysteine residues of VEGF165. Similarity comparisons of this isoform revealed overall protein identity of 48% and conservative substitution of 69% with VEGF189. VRF is predicted to contain a signal peptide, suggesting that it may be a secreted factor. The VRF gene maps to the D11S750 locus at chromosome band 11q13, and the protein coding region, spanning approximately 5 kb, is comprised of 8 exons that range in size from 36 to 431 bp. Exons 6 and 7 are contiguous and the two isoforms of VRF arise through alternate splicing of exon 6. VRF appears to be ubiquitously expressed as two transcripts of 2.0 and 5.5 kb; the level of expression is similar among normal and malignant tissues.

Amino Acid Sequence↗
PubMed1996

Clustered inactivating mutations and benign polymorphisms of the calcium receptor gene in familial benign hypocalciuric hypercalcemia suggest receptor functional domains.

The predominant variety of familial benign hypocalciuric hypercalcemia (FBHH) is FBHH(3q), which is associated with presumed inactivating mutations of the cell surface calcium receptor (CaR) gene on chromosome 3q13.3-q21. We sought mutations of the CaR gene in FBHH by direct sequencing of PCR-amplified genomic DNA from 14 affected families: 8 mapped to 3q13, 1 mapped to chromosome 19p, and 5 unmapped. We sequenced the entire coding region of the gene (exons 2-7) in one or two affected members of each family and found six point mutations that altered one amino acid, cosegregated with hypercalcemia, and were absent in more than 100 unaffected persons. Four mutations were unique (S53P, D215G, S657Y, and P748R), and two had been reported previously (P55L and R185Q). Of four mutant CaR proteins expressed in Xenopus oocytes, three were deficient in extracellular Ca2+-induced signaling. No CaR mutations were found in eight families, including the one mapped to chromosome 19p. Three benign polymorphisms occurred in the COOH-terminal region of the CaR protein in 10%, 15%, and 30% of more than 100 unaffected persons. Thus, FBHH-causing CaR mutations were clustered in the NH2-terminal extracellular and membrane-spanning regions of the receptor protein. We suggest that these are important functional domains, probably for calcium binding and signal transduction, respectively. Finally, mutations in regulatory or intronic regions of the CaR gene may also underlie many cases of FBHH.

Amino Acid Sequence↗
PubMed1995

Allelic losses on chromosome band 11q13 in aldosterone-producing adrenal tumors.

We examined loss of heterozygosity (LOH) in 14 aldosterone-producing adrenal tumors, with six linearly ordered restriction fragment length polymorphism (RFLP) markers that map within a 12-cM region containing the MEN1 locus on 11q13. Among 11 tumors that were informative for at least one marker, five showed LOH at one or more loci, and two distinct regions of deletion were identified. The proximal region overlapped with the location of the MEN1 locus previously predicted by linkage analyses in MEN1 families and the commonly deleted region in hyperparathyroid tumors. This suggests that one of the genes associated with development of aldosterone-producing adrenal tumors may coincide with the MEN1 locus, and that a second gene, distal to the MEN1 locus, may also play a role in the development of this type of tumor.

Adrenal Gland Neoplasms↗
PubMed1995

Exclusion of the 13-kDa rapamycin binding protein gene (FKBP2) as a candidate gene for multiple endocrine neoplasia type 1.

The MEN1 gene is considered to be a tumour suppressor gene and has been localised to a 1-Mb region of 11q13.1. In this study, we report the physical localisation of the 13-kDa FK506 and rapamycin binding protein gene (FKBP2) to the cosmid marker D11S750, which is located inside the MEN1 region of non-recombination. The product of this gene is involved in signal transduction and is thus a candidate cell growth regulator or tumour suppressor gene. Northern studies have revealed that FKBP2 is expressed in those tissues predisposed to hyperplasia in MEN1; however, single-strand conformation polymorphism analysis and direct sequencing of DNAs from affected members of MEN1 kindreds and sporadic tumour DNAs have been performed and no mutations have been found. These studies exclude FKBP2 as a candidate gene for MEN1.

Base Sequence↗
PubMed1995

Glutathione S-transferase GSTM1 null genotype is not overrepresented in Australian patients with nevoid basal cell carcinoma syndrome or sporadic melanoma.

The GSTM1 gene on chromosome 1p encodes the carcinogen-detoxification enzyme, glutathione S-transferase (mu subclass). The homozygous null genotype at this locus has been associated with increased susceptibility to malignancy, including some skin cancers. One hundred and twenty-four Australian patients with sporadic melanoma and 62 with familial basal cell carcinomas (a feature of nevoid basal cell carcinoma syndrome, NBCCS) were examined for germline homozygous deletions of GSTM1 using multiplex polymerase chain reactions. The homozygous null genotype was not overrepresented in either those with a single melanoma or in the NBCCS cases. Nor did it significantly accelerate tumorigenesis in either group. Analyses of much larger sample sizes will be required to investigate the representation of the null genotype in patients with multiple melanoma primaries and in those with melanoma co-existing with other non-cutaneous malignancies.

Basal Cell Carcinoma↗
PubMed1994

Incidence of familial melanoma and MLM2 gene.

The overall incidence of melanoma is increasing world wide. We investigated whether there has been an increase in familial melanoma by studying age at onset among different birth cohorts in 18 melanoma kindreds linked to a predisposition gene (MLM2) on chromosome 9. The cumulative incidence of melanoma was 21-fold higher (95% CI 5.2-84.6) among subjects born after 1959 than in those born before 1900. The expected age of onset of the group born after 1959 was 24 years earlier (21.0 vs 45.0 years). These data support the notion that phenotypic penetrance of the MLM2 gene is increasing, presumably as a result of the interaction of sunlight exposure and mutation at this locus.

Adolescent↗
PubMed1992

Predictive testing for multiple endocrine neoplasia type 1 using DNA polymorphisms.

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominantly inherited predisposition to neoplastic lesions of the parathyroids, pancreas, and the pituitary. We have previously located the predisposing genetic defect to the long arm of chromosome 11 by genetic linkage. In this study, 124 members of six MEN1 families, including 59 affected individuals, were genotyped for restriction fragment length polymorphisms with different DNA probes, and the genetic linkage between these marker systems and MEN1 was determined. 13 marker systems (17 DNA probes) were found to be linked to MEN1. These markers are located within a region on chromosome 11 spanning 14% meiotic recombinations, with the MEN1 locus in the middle. Four of the marker systems are on the centromeric side of MEN1, and four on the telomeric side, based on meiotic crossovers. The remaining five DNA probes are closely linked to MEN1, with no crossovers in our set of families. The 13 marker systems can be used for an accurate and reliable premorbid test for MEN1. In most clinical situations it is possible to identify a haplotype of this part of chromosome 11 with the mutant MEN1 allele in the middle. The calculated predictive accuracy is greater than 99.5% if three such marker systems are informative. Therefore, genetic linkage testing can be used for informed genetic counseling in MEN1 families, and to avoid unnecessary biochemical screening programs.

Chromosome Mapping↗
PubMed1990

Detection of somatic mutations in tumours of diverse types by DNA fingerprinting with M13 phage DNA.

Hybridization of M13 phage DNA to Southern blots of human DNA produces an individual-specific DNA fingerprint. In this study, tumour and lymphocyte DNA from a series of patients with melanoma, Merkel-cell carcinoma, Burkitt's lymphoma and Wilms' tumour was probed with M13 DNA to detect somatic mutations in the DNA of the tumours. Somatic changes were observed in tumour DNA of 16 out of the 28 cases examined. This frequency compared favourably with the frequency with which tumour-specific changes have been found when using the Jeffreys DNA fingerprinting probe 33.15, and demonstrates that M13 DNA provides a useful additional probe for the study of somatic changes in tumours. The finding that multiple DNA fragments were lost or gained in DNA fingerprints from individual tumours indicates a marked degree of complexity in the genetic changes involved in the evolution of certain human cancers.

Bacteriophages↗
PubMed1988

A Taqi RFLP of the human TGF alpha gene is significantly associated with cutaneous malignant melanoma.

A TaqI restriction fragment length polymorphism (RFLP) of the human transforming growth factor alpha (hTGF alpha) locus was analyzed in DNA from 63 normal individuals, 34 malignant melanoma (MM) cell lines, and 18 melanoma biopsy specimens. The frequency of a 2.7-kb allele (0.18) in MM cell lines was significantly higher (p less than 0.01) than in lymphoblastoid cell lines (LCLs) derived from unaffected controls (0.05). The frequency (0.14) in MM biopsies was similar to that in MM cell lines although, owing to the small numbers investigated, it was not significantly higher than in controls. In the case of 5 MM patients who were constitutionally heterozygous for alleles at the TGF alpha locus, no apparent losses of heterozygosity were observed in the corresponding tumour DNA. Thus, the constitutional presence of the 2.7-kb allele may be a risk factor for melanoma.

Alleles↗