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N D Hastie

Publications and source records attributed to N D Hastie.

At least 19 recordsLinked to original sources
PubMed1992

Modulation of DNA binding specificity by alternative splicing of the Wilms tumor wt1 gene transcript.

The technique of whole-genome polymerase chain reaction was used to study the DNA binding properties of the product of the wt1 gene. The zinc finger region of this gene is alternatively spliced such that the major transcript encodes a protein with three extra amino acids between the third and fourth fingers. The minor form of the protein binds specifically to DNA. It is now shown that the major form of wt1 messenger RNA encodes a protein that binds to DNA with a specificity that differs from that of the minor form. Therefore, alternative splicing within the DNA binding domain of a transcription factor can generate proteins with distinct DNA binding specificities and probably different physiological targets.

Amino Acid Sequence↗
PubMed1992

Zinc finger point mutations within the WT1 gene in Wilms tumor patients.

A proposed Wilms tumor gene, WT1, which encodes a zinc finger protein, has previously been isolated from human chromosome 11p13. Chemical mismatch cleavage analysis was used to identify point mutations in the zinc finger region of this gene in a series of 32 Wilms tumors. Two exonic single base changes were detected. In zinc finger 3 of a bilateral Wilms tumor patient, a constitutional de novo C----T base change was found changing an arginine to a stop codon. One tumor from this patient showed allele loss leading to 11p hemizygosity of the abnormal allele. In zinc finger 2 of a sporadic Wilms tumor patient, a C----T base change resulted in an arginine to cysteine amino acid change. To our knowledge, a WT1 gene missense mutation has not been detected previously in a Wilms tumor. By comparison with a recent NMR and x-ray crystallographic analysis of an analogous zinc finger gene, early growth response gene 1 (EGR1), this amino acid change in WT1 occurs at a residue predicted to be critical for DNA binding capacity and site specificity. The detection of one nonsense point mutation and one missense WT1 gene point mutation adds to the accumulating evidence implicating this gene in a proportion of Wilms tumor patients.

Amino Acid Sequence↗
PubMed1992

Wilms' tumour: reconciling genetics and biology.

Wilms' tumour, a paediatric malignancy of the kidney, is a striking example of the relationship between aberrant development and cancer. Several different genetic loci have been implicated in the aetiology of the tumour; genomic imprinting also plays a role. One Wilms' tumour predisposition gene (WT1), encoding a zinc finger protein, is expressed in a limited set of tissues, including developing nephrons and gonads. The biology and genetics of Wilms' tumour underline the developmental relationship between kidneys and gonads.

Abnormalities, Multiple↗
PubMed1992

Equivalent expression of paternally and maternally inherited WT1 alleles in normal fetal tissue and Wilms' tumours.

Observations of non-random maternal 11p allele loss in Wilms' tumour (WT) have implied the possible involvement of an imprinted 11p locus in WT aetiology. A proposed 11p13 Wilms' tumour gene, WT1, has recently been isolated and encodes a zinc finger DNA-binding protein, the 3' untranslated region of which contains a polymorphic dinucleotide repeat (CA repeat) motif. We have exploited this transcribed CA repeat to examine the allelic expression pattern of WT1 and thereby determine whether transcriptional imprinting of this gene occurs. DNA and reverse-transcribed RNA from tumours and normal tissue were subjected to the polymerase chain reaction (PCR) using radiolabelled primers flanking the CA repeat. The gene was seen to be expressed from both of the constitutive alleles in 9-week human fetal kidney, all informative Wilm's tumours and neonatal kidney tissue adjacent to the tumours. In one tumour, known to be heterozygous for a point mutation in zinc finger 2, direct sequencing confirmed that both mutant and wild-type transcripts were being expressed. These results demonstrate that this gene is not subject to transcriptional imprinting in tumours or normal fetal kidney.

Alleles↗
PubMed1991

Positional cloning and characterization of a paired box- and homeobox-containing gene from the aniridia region.

Based on the map location of the aniridia (AN) locus in human chromosomal band 11p13, we have cloned a candidate AN cDNA (D11S812E) that is completely or partially deleted in two patients with AN. The less than 70 kb smallest region of overlap between the two deletions encompasses the 3' coding region of the cDNA. This cDNA, which spans over 50 kb of genomic DNA, detects a 2.7 kb message specifically within all tissues affected in AN. The predicted polypeptide product possesses a paired domain, a homeodomain, and a serine/threonine-rich carboxy-terminal domain, structural motifs characteristic of certain transcription factors. The concordance between expression and pathology, map location, structure, and predicted function argues that the cDNA corresponds to the AN gene.

Amino Acid Sequence↗
PubMed1990

Extensive telomere repeat arrays in mouse are hypervariable.

In this study we have analysed mouse telomeres by Pulsed Field Gel Electrophoresis (PFGE). A number of specific restriction fragments hybridising to a (TTA-GGG)4 probe in the size range 50-150kb can be detected. These fragments are devoid of sites for most restriction enzymes suggesting that they comprise simple repeats; we argue that most of these are likely to be (TTAGGG)n. Each discrete fragment corresponds to the telomere of an individual chromosome and segregates as a Mendelian character. However, new size variants are being generated in the germ line at very high rates such that inbred mice are heterozygous at all telomeres analysable. In addition we show that specific small (approximately 4-12kb) fragments can be cleaved within some terminal arrays by the restriction enzyme MnII which recognises 5'(N7)GAGG3'. Like the complete telomere-repeat arrays (TRA's) these fragments form new variants at high rates and possibly by the same process. We speculate on the mechanisms that may be involved.

Animals↗
PubMed1990

Telomere reduction in human colorectal carcinoma and with ageing.

We have hypothesized that end-to-end chromosome fusions observed in some tumours could play a part in genetic instability associated with tumorigenesis and that fusion may result from the loss of the long stretches of G-rich repeats found at the ends of all linear chromosomes. We therefore asked whether there is telomere loss or reduction in common tumours. Here we show that in most of the colorectal carcinomas that we analysed, there is a reduction in the length of telomere repeat arrays relative to the normal colonic mucosa from the same patient. We speculate on the consequences of this loss for tumorigenesis. We also show that the telomere arrays are much smaller in colonic mucosa and blood than in fetal tissue and sperm, and that there is a reduction in average telomere length with age in blood and colon mucosa. We propose that the telomerase is inactive in somatic tissues, and that telomere length is an indicator of the number of cell divisions that it has taken to form a particular tissue and possibly to generate tumours.

Adenoma↗
PubMed1990

A molecular genetic linkage map of mouse chromosome 2.

Interspecific backcross mice were used to create a molecular genetic linkage map of chromosome 2. Genomic DNAs from N2 progeny were subjected to Southern blot analysis using molecular probes that identified the Abl, Acra, Ass, C5, Cas-1, Fshb, Gcg, Hox-5.1, Jgf-1, Kras-3, Ltk, Pax-1, Prn-p, and Spna-2 loci; these loci were added to the 11 loci previously mapped to the distal region of chromosome 2 in the same interspecific backcross to generate a composite multilocus linkage map. Several loci mapped near, and may be the same as, known mutations. Comparisons between the mouse and the human genomes indicate that mouse chromosome 2 contains regions homologous to at least six human chromosomes. Mouse models for human diseases are discussed.

Animals↗
PubMed1990

Wilms' tumour as a paradigm for the relationship of cancer to development.

Wilms' tumour or nephroblastoma is one of the commonest solid paediatric malignant diseases, accounting for 8% of childhood cancers. The tumour arises through aberrant differentiation of metanephric mesenchyme and thus represents a paradigm for the relationship of cancer and development. There is considerable heterogeneity in the pathology of Wilms' tumour and several genes have been implicated in its aetiology. One of these genes, located at chromosome 11p13, is categorised as a 'tumour suppressor' gene since loss of function can lead to malignancy. It has not been possible as yet to correlate the involvement of a particular locus with a subset of tumour pathology. The recently cloned Wilms' tumour gene encodes a putative transcription factor which is likely to activate or repress the expression of other genes in kidney development. We have shown by in situ hybridization that expression of this gene is restricted to specific cell types within the developing kidney. It is also expressed in a limited range of embryonic tissues, including the gonad, spleen and mesothelium. With the benefit of this new information, we speculate on the part played by this gene in normal kidney development, in tumorigenesis and in other aspects of Wilms' tumour; these include associated congenital abnormalities, genetic predisposition to second tumours and inheritance of Wilms' tumour.

Abnormalities, Multiple↗
PubMed1989

Human telomeres contain at least three types of G-rich repeat distributed non-randomly.

Using a combination of different oligonucleotides and restriction enzymes we have examined the gross organisation of repeats within the most distal region of human chromosomes. We demonstrate here that human telomeres do not contain a pure uniform 6 base pair repeat unit but that there are at least three types of repeat. These three types of repeat are present at the ends of most or all human chromosomes. The distribution of each type of repeat appears to be non-random. Each human telomere has a similar arrangement of these repeats relative to the ends of the chromosome. This could reflect differences in the functions that they perform, or might result from the mutation and correction processes occurring at human telomeres. The number of repeat units, the repeat types and arrangement differs at mouse telomeres. Analysing the change in length of the telomeric repeat region between an individuals blood and germline DNA reveals that this is due to variable amounts of the TTAGGG repeat and not the other repeat types. This organization of repeat units at human telomeres will only be confirmed upon the isolation and sequencing of full length (10-15 kb), intact human telomeres.

Animals↗
PubMed1989

Rapid isolation of moderate and highly polymorphic DNA fragments mapping close to WT (Wilms' tumour) and AN2 (aniridia) on chromosome 11.

Genes implicated in the development of Wilms' tumour (WT) and aniridia (AN2) have been localised to a sub-region of band p13 on chromosome 11 by molecular and cytogenetic characterisation of WAGR syndrome patients carrying variable constitutional deletions. Polymorphic markers for the region would be valuable for linkage analysis in the familial forms of both Wilms' tumour and aniridia, as well as for studying somatic rearrangements of chromosome 11 in a variety of tumour types. Here we describe the isolation and characterisation of three frequently polymorphic arbitrary DNA fragments that map proximal to the AN2 and WT loci.

Chromosome Mapping↗
PubMed1989

Human telomeres: fusion and interstitial sites.

The ends of human chromosomes have been shown recently to resemble those of simple organisms. With this in mind, we discuss the nature and possible significance of rare chromosome fusion events thought to involve telomeres, particularly those fusion events found in some tumours. Also we argue that interstitial telomere-like stretches may be particularly prone to recombination, breakage and fragility.

Animals↗
PubMed1989

CpG islands surround a DNA segment located between translocation breakpoints associated with genitourinary dysplasia and aniridia.

We have isolated a DNA segment absent from all the constitutionally deleted chromosomes 11 of our patients with Wilms tumor. This marker separates two balanced translocations that break in band 11p13: the distal one associated with aniridia (AN2), and the proximal one with genitourinary dysplasia (GUD). The GUD breakpoint maps within the smallest region of overlap (SRO) for the Wilms tumor (WT) gene locus, thus strengthening the previous suggestion of an association between Wilms tumor and other abnormalities of the genitourinary system. The 11p13 translocation breakpoint associated with T-cell acute lymphatic leukemia (T-ALL) is centromeric to the SRO and separated from the WT locus by at least one known gene. This region of the human genome (11p13) is rich in CpG islands that potentially identify genes, some of which may be involved in the various phenotypes associated with the WAGR syndrome. This is consistent with the proposition that the majority of human genes are in G-negative bands.

Animals↗
PubMed1989

Aniridia, Wilms' tumor and human chromosome 11.

Aniridia-a developmental abnormality of the eye in which the iris is apparently absent-has been shown to be genetically associated with Wilms' tumor (an embryonic nephroblastoma) in the WAGR syndrome. Genetic and cytogenetic evidence points to band p13 of human chromosome 11 as the localization of the genes responsible for these defects. Deleted chromosomes 11 from WAGR patients and clinically associated translocations involving 11p13 have been used to map and order genes and anonymous DNA markers around the WAGR locus refining the localization of the aniridia and Wilms' tumor genes to within about 1 million base pairs of DNA.

Animals↗
PubMed1989

Wilms tumour: a developmental anomaly.

Wilms tumour (WT) is a developmental anomaly of the kidney which results from loss of function of at least one so called tumour suppressor gene on chromosome 11. The position of the gene at chromosome 11p13 is known through the association of WT with aniridia (lack of an iris), mental retardation and genitourinary abnormalities in the WAGR syndrome. Here we discuss the high resolution mapping studies to locate the position of the gene and conclude that the gonadal abnormalities in WAGR patients may be due to a defect in the WT gene itself. In support of this role in genitourinary development we show that a candidate WT gene is expressed in specific regions of the developing kidney and in fetal and embryonic gonads.

Abnormalities, Multiple↗