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M R Eccles

Publications and source records attributed to M R Eccles.

At least 37 records · Page 2Linked to original sources
PubMed1995

Mutation of the PAX2 gene in a family with optic nerve colobomas, renal anomalies and vesicoureteral reflux.

Paired box (PAX) genes play a critical role in human development and disease. The PAX2 gene is expressed in primitive cells of the kidney, ureter, eye, ear and central nervous system. We have conducted a mutational analysis of PAX2 in a family with optic nerve colobomas, renal hypoplasia, mild proteinuria and vesicoureteral reflux. We report a single nucleotide deletion in exon five, causing a frame-shift of the PAX2 coding region in the octapeptide domain. The phenotype resulting from the PAX2 mutation in this family was very similar to abnormalities that have been reported in Krd mutant mice. These data suggest that PAX2 is required for normal kidney and eye development.

Abnormalities, Multiple↗
PubMed1995

Comparative in situ hybridization analysis of PAX2, PAX8, and WT1 gene transcription in human fetal kidney and Wilms' tumors.

Wilms' tumor (WT) is a childhood renal neoplasm with histological features resembling fetal kidney development. Two members of the paired box family of genes, PAX2 and PAX8, are expressed in WT and are potentially involved in its induction. A zinc finger gene, WT1, which is involved in WT induction, encodes a DNA binding protein, and like PAX2 and PAX8 proteins is a transcription factor with an important role in kidney development. We have compared the expression patterns of PAX2, PAX8, and WT1 in fetal kidney and WTs by in situ hybridization. The PAX2, PAX8, and WT1 genes were transcribed in the condensed mesenchyme and early stages of epithelial differentiation in fetal kidney. WT1 gene transcription was observed in the glomeruli of fetal kidney until a later stage in development than PAX genes. In WTs all three genes were expressed in the condensed blastema, but WT1 expression was not detectable in the epithelial structures in two WTs. No evidence of attenuation of PAX gene expression was found in WT. These results suggest that in some WTs the expression of WT1 is attenuated in structures that continued to express PAX genes. It is unlikely that both PAX2 and PAX8 genes would be mutated in WT. However, failure of PAX gene expression to attenuate in WTs may result from mutations involved in the onset of the tumor.

DNA-Binding Proteins↗
PubMed1994

Alternative messenger RNA forms and open reading frames within an additional conserved region of the human PAX-2 gene.

PAX-2 is a member of a family of genes containing a highly conserved paired box domain. The paired box domain encodes a DNA binding motif, indicating that PAX proteins may function as transcriptional regulators, participating in a hierarchical network of gene regulation during embryogenesis. In this report, we provide evidence that there is an additional conserved region near the predicted COOH-terminus of PAX-2, PAX-5, and PAX-8. We also describe alternative splicing of a conserved 83-nucleotide segment in the 3' coding sequence of the PAX-2 gene. PAX-2 transcripts that contain the 83-nucleotide insertion encode a putative protein with an alternative COOH-terminus. The presence of an additional conserved region and alternative splicing within the predicted COOH-terminal region of several PAX genes has implications for the evolutionary origins and for the DNA binding site specificity of PAX-2, PAX-5, and PAX-8.

Alternative Splicing↗
PubMed1994

Expression of WT1 protein in fetal kidneys and Wilms tumors.

BACKGROUND: Wilms' tumors are embryonic kidney neoplasms believed to result from a perturbation in the development of the metanephric blastema. A candidate gene (WT1) has been cloned that has been found to be mutated in a number of Wilms' tumors, consistent with its suggested role as a tumor suppressor gene. This gene has been shown to be essential to the normal development of the embryonic kidney. EXPERIMENTAL DESIGN: The aim of the present study was to provide information on the level at which the WT1 gene is regulated. Immunohistochemistry, immunofluorescence, and in situ hybridization was used to examine the localization of WT1 protein and mRNA, respectively. We further used immunofluorescence to examine the WT1 expression in seven Wilms' tumors. RESULTS: In fetal kidneys, WT1 transcripts were detected with increasing levels of hybridization signal in induced blastemal cells, renal vesicles, pre-podocytes of comma- and S-shaped bodies, and podocytes of glomeruli. WT1 protein, detected by an antibody raised against recombinant WT1 fusion protein, was seen in the nuclei of the same cell types mentioned above, and the staining intensity was comparable to the levels of WT1 transcripts. Immunostaining of seven Wilms tumors demonstrated that WT1 protein was expressed only in neoplastic structures whose normal counterparts also expressed WT1 protein. Neither stromal cells nor rhabdomyoblasts contained WT1 protein. CONCLUSIONS: The results show that in fetal kidney, WT1 transcripts and protein are coordinately expressed, and strongly associated with differentiation of metanephric blastemal cells into epithelial cells. Furthermore, the finding that WT1 transcripts and protein are coordinately expressed, suggests that WT1 gene expression is primarily regulated at the level of transcription.

Blotting, Western↗
PubMed1994

Cloning of novel Wilms tumor gene (WT1) cDNAs; evidence for antisense transcription of WT1.

WT1 is a tumor suppressor gene that has been implicated in Wilms tumor, and is expressed in cells of mesodermal origin. The Wit-1 gene is located approximately 2 kb from the WT1 gene, and is expressed coordinately with WT1. WT1 and Wit-1 are bi-directionally transcribed from the same promoter region. We have screened a human fetal kidney cDNA library to identify novel WT1 cDNA clones. Here we report the cloning of cDNA clones which span part of intron 1 of WT1, exon 1, upstream sequences between WT1 and Wit-1 and part of the Wit-1 gene. Northern blot and RNAase protection analysis using subcloned fragments of the cDNAs corresponding to regions from within intron 1 of WT1 suggest that a 7-10 Kb RNA is expressed in human fetal kidney, which overlaps with WT1 and is transcribed in the same direction as Wit-1.

Base Sequence↗
PubMed1993

Insulin-like growth factor II and WT1 transcript localization in human fetal kidney and Wilms' tumor.

In situ hybridization was used to examine, in parallel, the localization of insulin-like growth factor II (Igf2) and WT1 transcripts in normal fetal kidney and Wilms' tumor. The expression of Igf2 and WT1 transcripts in the fetal kidney is almost complementary in both the epithelial and stromal cell lineages derived from the undifferentiated metanephrogenic blastema. The patterns of transcription of Igf2 in three Wilms' tumors appeared to be perturbed as compared to the normal fetal kidney. In these tumors Igf2 transcripts were detected in structures that are developmentally equivalent to the renal vesicle, which in the normal kidney do not contain Igf2 transcripts. These results suggest that Wilms' tumors arise from an alteration in the regulation of Igf2 mRNA synthesis.

Base Sequence↗
PubMed1993

Relaxation of insulin-like growth factor II gene imprinting implicated in Wilms' tumour.

Genomic imprinting has been implicated in the onset of several embryonal tumours but the mechanism is not well understood. Maternal chromosome 11p15 loss of heterozygosity and paternal chromosome 11 isodisomy suggest that imprinted genes are involved in the onset of Wilms' tumour and the Beckwith-Wiedemann syndrome. The insulin-like growth factor II (IGF2) gene located at 11p15.5 has been put forward as a candidate gene as it is maternally imprinted (paternally expressed) in the mouse, and is expressed at high levels in Wilms' tumours. We report here that the IGF2 gene is expressed from the paternal allele in human fetal tissue, but that in Wilms' tumour expression can occur biallelically. These results provide, to our knowledge, the first evidence that relaxation of imprinting may play a role in the onset of disease and suggest a new genetic mechanism involved in the development of cancer.

Alleles↗
PubMed1993

Structural analysis of the human insulin-like growth factor-II P3 promoter.

The expression of insulin-like growth factor-II (IGF-II) has been observed previously in many human cancers. The human IGF-II P3 promoter has been shown by others to give rise to abundant 6.0 kb and 2.2 kb fetal transcripts which are expressed in a variety of both paediatric and adult tumours. In order to determine the mechanism by which the P3 promoter is controlled, the promoter was analysed in cell lines using chloramphenicol acetyltransferase (CAT) assay and DNAase I footprinting techniques. The data indicated that P3 is a complex promoter involving at least nine transcription factor binding sites. Furthermore, high levels of 5-methylcytosine detected in the P3 promoter of HeLa genomic DNA suggest that IGF-II gene expression may also be influenced by DNA methylation.

Base Sequence↗
PubMed1993

Constitutional relaxation of insulin-like growth factor II gene imprinting associated with Wilms' tumour and gigantism.

We have examined the imprinting of the insulin-like growth factor II gene (IGF2) in ten normal kidney samples from children with renal embryonal neoplasms. In kidney samples from nine children with normal growth profiles, IGF2 mRNA was transcribed monoallelically, consistent with normal imprinting of the gene. But in one child who had generalized somatic overgrowth, IGF2 was transcribed from both alleles in her kidney, peripheral blood leukocytes and Wilms' tumour. These findings suggest that a defect in genomic imprinting can occur constitutionally, leading to growth abnormalities and predisposition to Wilms' tumour.

Alleles↗
PubMed1993

Human insulin-like growth factor type I and type II receptors are not imprinted.

We have shown that the insulin-like growth factor type I and II receptors are expressed equally from the maternal and paternal alleles in human tissues. The imprinting status of the type I insulin-like growth factor receptor has not been reported while the type II receptor has previously been shown to be maternally expressed in the mouse. That the imprinting of the insulin-like growth factor type II receptor is not conserved between mouse and humans suggests that the physiological role of the IGF2 receptor may differ between these two species.

Alleles↗
PubMed1993

Insulin-like growth factor II messenger ribonucleic acid expression in Wilms tumor, nephrogenic rest, and kidney.

BACKGROUND: Wilms tumors (WTs) are embryonic neoplasms of the kidney that are believed to arise from primitive metanephrogenic blastema. Our previous reports and those of others indicate that WTs show an increased expression of insulin-like growth factor II (IGF-II) mRNA. However, the precise role of IGF-II on Wilms tumorigenesis is not known. A central question is to determine whether the increased IGF-II expression in WTs simply reflects the fetal nature of WTs (effect), or is induced by specific changes in gene expression (cause). EXPERIMENTAL DESIGN: This study included 31 sporadic WTs, 7 fetal and 3 adult kidneys and 1 yolk sac tumor. Clinical and histologic summaries of WT cases are shown in Table 1. In WTs, the relative area of blastemal, epithelial, poorly differentiated spindle cell and heterologous cell components were assessed. Dot and Northern blot hybridization, using cDNA probes, were done to assess the level of IGF-II mRNA expression. In situ RNA hybridization was employed to localize IGF-II transcripts. Immunohistochemistry was applied to frozen sections to demonstrate cytokeratin and type-IV collagen. These results were then correlated with the histology of WTs and their precursor lesions, i.e., nephrogenic rests (NRs). RESULTS: Dot blot hybridization indicated that IGF-II transcripts were 32- to 64-fold more abundant in WTs than in the adjacent uninvolved kidneys. In situ hybridization showed that WTs, NRs, and fetal kidney shared a common feature in which IGF-II transcripts were predominantly associated with blastema. However, WTs and NRs differed from fetal kidney in that occasional epithelial structures and dense blastema showed aberrant, sustained IGF-II expression. CONCLUSIONS: The data indicate two points. 1) There is an inverse correlation between nephroblastic differentiation and IGF-II expression in developing fetal kidney. 2) The IGF-II expression in WTs and NRs does not simply reflect the embryonal nature of the tumor but is rather significantly altered, suggesting a role as a transforming growth factor in Wilms tumorigenesis.

Adolescent↗
PubMed1992

A third Wilms' tumor locus on chromosome 16q.

Loss of heterozygosity studies have been used to identify chromosomal regions which are frequently deleted and thus indicate areas which may harbor tumor suppressor genes. As a result, both the WT1 gene located in chromosome 11p13 and an unidentified gene(s) within chromosome 11p15 have been implicated in Wilms' tumorigenesis. Cytogenetic and linkage studies suggest that additional non-chromosome 11 sites are involved in Wilms' tumor. Because these sites may also involve loss of heterozygosity, loci on 33 autosomal arms were screened for allele loss in a series of Wilms' tumors. We found that in addition to loss on chromosome 11p (11 of 25 informative tumors) there was significant loss on chromosome 16q (9 of 45 informative tumors), while the total frequency of allele loss excluding these loci was low (9 of 426 total informative loci). These data indicate that losses of both chromosome 11p and 16q alleles are nonrandom events and suggest that 16q is the location of a third tumor suppressor gene underlying Wilms' tumorigenesis. The parental origin of the lost chromosome 16q allele was determined in eight sporadic tumors. Alleles of paternal and of maternal origin were each lost in four sporadic tumors indicating that, unlike chromosome 11p, alleles of either parental origin are lost on 16q.

Alleles↗
PubMed1992

A colony-stimulating factor 1 (CSF-1) receptor/platelet-derived growth factor-beta receptor gene fusion confers CSF-1 independence and tumorigenicity on a c-myc-immortalized monocyte cell line.

Monocytes and macrophages express the receptor for the hematopoietic growth factor colony-stimulating factor 1 (CSF-1) and require this factor for growth in culture. A murine monocyte tumor cell line that lacks the usual requirement for CSF-1 was isolated. On the basis of the similarity of the structures of the CSF-1 and platelet-derived growth factor (PDGF) receptors and because monocytes normally secrete PDGF, we analyzed the tumor cell line for anomalous expression of the PDGF-R beta gene. Two different cDNAs that each contain sequences corresponding to the complete coding sequence of PDGF-R beta fused (in frame) to the amino-terminal half of the CSF-1 receptor were isolated. Introduction of these PDGF-R beta-related cDNAs into two partially transformed, CSF-1-dependent monocyte cell lines resulted in autonomous growth and cell transformation. These monocyte cell lines exhibit a novel form of growth factor receptor activation that can lead to oncogenic growth in collaboration with the c-myc oncogene.

Amino Acid Sequence↗
PubMed1992

Expression of the PAX2 gene in human fetal kidney and Wilms' tumor.

We have examined the pattern of expression of the human PAX2 gene in Wilms' tumors and human fetal kidney by Northern blot and in situ hybridization. Human PAX2 encodes a paired box-containing protein and has a high degree of homology with mouse and Drosophila paired box genes. In situ hybridization analysis reveals that PAX2 is expressed in nephrogenic structures in fetal kidney and also in Wilms' tumors. This pattern of expression suggests that PAX2 may have a role in differentiation of tissues in the kidney. In fetal kidney, PAX2 expression rapidly attenuates following the initial differentiation, but no evidence of attenuation was found in Wilms' tumors. The timing of PAX2 expression is restricted to fetal development, although high levels of expression were also observed in nephrogenic rests of residual normal juvenile kidney tissue adjacent to a Wilms' tumor. Nephrogenic rests are the presumptive precursors of Wilms' tumor but are not necessarily neoplastic. The failure of PAX2 expression to attenuate in Wilms' tumors and nephrogenic rests may be associated with events leading to the onset of Wilms' tumor. By somatic cell hybrid mapping, the PAX2 gene was localized to chromosome 10q22.1-q24.3, although this region has not previously been implicated in Wilms' tumor.

Amino Acid Sequence↗