The Experts below are selected from a list of 1215 Experts worldwide ranked by ideXlab platform
Jerry Pelletier - One of the best experts on this subject based on the ideXlab platform.
-
Regulation of renal EGF receptor expression is normal in Denys-Drash Syndrome
Kidney international, 1997Co-Authors: Caroline Vicanek, Emanuela Ferretti, Cynthia G. Goodyer, Elena Torban, Peter Moffett, Jerry Pelletier, Paul GoodyerAbstract:Regulation of renal EGF receptor expression is normal in Denys-Drash Syndrome. In patients with Denys-Drash Syndrome, mutations of the Wilms' tumor suppressor gene are associated with nephroblastomas and developmental abnormalities of the genital tract and renal glomerulus. Normally, the Wilms' tumor gene product (WT1) is expressed at high levels in visceral glomerular epithelial cells (VGEC) of the emerging fetal glomerulus. We demonstrate that WT1 could normally serve to suppress EGF receptor expression in VGEC, since immunoreactive EGF receptor is strikingly absent compared to epithelial cells of the emerging proximal and distal tubule, which lack WT1. When HEK293 cells were co-transfected with plasmids containing EGFR enhancer/promoter elements linked to a CAT reporter and plasmids containing WTl cDNA, EGFR enhancer/promoter activity was suppressed by all wild-type WT1 isoforms, but not by deletion mutants of WT1 lacking normal zinc-finger or N-terminal domains. Surprisingly, plasmids expressing a Denys-Drash WT1 mutant (R394W) retained the ability to suppress EGFR promoter activity in this system. Furthermore, we found that immunoreactive EGFR was appropriately undetectable in glomeruli from a three-year-old girl with Denys-Drash Syndrome and in sections of her Wilm's tumor. These data suggest that faulty suppression of EGFR cannot account for the abnormalities of glomerulogenesis seen in Denys-Drash patients.
-
Nephropathy with Wilms tumour or gonadal dysgenesis: incomplete Denys-Drash Syndrome or separate diseases?
European journal of pediatrics, 1995Co-Authors: Klaus Schmitt, Bernhard Zabel, Gerald Tulzer, Franz Eitelberger, Jerry PelletierAbstract:We report three children, one presenting with nephropathy, bilateral Wilms tumour (WT) and cryptorchism, one with combined nephropathy and gonadal dysgenesis and one with nephropathy which developed 13 years after a WT. The first case was recognized as typical Denys-Drash Syndrome (DDS) which is characterized by the combination of nephropathy, intersex disorders and WT. The two other patients, who did not express the full spectrum of the Syndrome, were older than 10 years, when they reached and stage renal failure. The fact that nephropathy in childhood is combined with such rare diseases like gonadal dysgenesis and/or WT, supports the concept of a common aetiology with DDS. Therefore, the patients were analysed for possible Wilms tumour suppressor gene (WT1) mutations. In all three individuals mutations in the heterozygous configuration could be demonstrated. These results provide evidence that incomplete and complete DDS are diseases of the same spectru. WT1 analysis of more children with two symptoms of the triad of DDS should be helpful in establishing genotype-phenotype correlations and in understanding differences in the clinical picture of DDS.
-
Denys-Drash Syndrome: a role for the WT1 tumour suppressor gene in urogenital development
Seminars in Developmental Biology, 1994Co-Authors: Wendy Bruening, Jerry PelletierAbstract:Abstract The study of inherited disease provides unique insight into basic developmental and biochemical processes. By linking the pathogenesis of complex malformations to mutations of specific genes, the function of those genes in normal developmental biology can be inferred. One such disorder is the Denys-Drash Syndrome, where identification of genetic lesions within the WT1 tumour suppressor gene has provided astonishing insight into events regulating development of the urogenital system.
-
germline mutations in the wilms tumor suppressor gene are associated with abnormal urogenital development in Denys Drash Syndrome
Cell, 1991Co-Authors: Jerry Pelletier, Wendy Bruening, Clifford E Kashtan, Michael S Mauer, Carlos J Manivel, Jane E Striegel, Donald C Houghton, C Junien, R HabibAbstract:Denys-Drash Syndrome is a rare human condition in which severe urogenital aberrations result in renal failure, pseudohermaphroditism, and Wilms' tumor (nephroblastoma). To investigate its possible role, we have analyzed the coding exons of the Wilms' tumor suppressor gene (WT1) for germline mutations. In ten independent cases of Denys-Drash Syndrome, point mutations in the zinc finger domains of one WT1 gene copy were found. Nine of these mutations are found within exon 9 (zinc finger III); the remaining mutation is in exon 8 (zinc finger II). These mutations directly affect DNA sequence recognition. In two families analyzed, the mutations were shown to arise de novo. Wilms' tumors from three individuals and one juvenile granulosa cell tumor demonstrate reduction to homozygosity for the mutated WT1 allele. Our results provide evidence of a direct role for WT1 in Denys-Drash Syndrome and thus urogenital system development.
Jun-ichi Hata - One of the best experts on this subject based on the ideXlab platform.
-
A necropsy case of Denys-Drash Syndrome with a WT1 mutation in exon 7.
Journal of medical genetics, 2002Co-Authors: Ryuji Fukuzawa, Sakamoto J, Jun-ichi HataAbstract:The Wilms tumour suppressor gene 1 ( WT1 ) is located on chromosome 11p13, encodes zinc finger domains, and its product plays a role in the regulation of gene transcription.1 Since expression of WT1 is observed in the glomerular epithelium of the kidneys and the genital ridge during the embryonic period, WT1 is thought to have a functional role in renal and gonadal organogenesis.2,3 Denys-Drash Syndrome (DDS) is characterised by WT1 mutations, early onset renal failure, abnormal sex differentiation, and a predisposition to Wilms tumour.4,5 It is thought that presence of a constitutional point mutation in the zinc finger domain of WT1 in one allele causes diffuse mesangial sclerosis (DMS) and abnormal sex differentiation by a dominant negative effect, that is, loss of normal function of both alleles may result from a dysfunctional mutation in only one allele, while deletion of the normal WT1 gene usually gives rise to Wilms tumour in children with DDS. Most DDS patients carrying WT1 mutations have missense changes in exon 8 or 9 affecting zinc finger 2 or 3.6 Thus, zinc fingers 2 and 3 in particular are thought to have an important DNA binding capacity. Whether missense mutations in exon 7 altering WT1 zinc finger 1 structure are responsible for DDS is not well understood. Although this patient has previously been reported,7 we describe here the pathological findings together with the clinical and biological significance of an altered WT1 zinc finger 1. The child was delivered vaginally at 42 weeks of gestation. The birth weight was 2620 g. There was no parental consanguinity or family history of renal disease. The patient initially presented at 11 months of age with rapidly progressive …
-
Isolated diffuse mesangial sclerosis and Wilms tumor suppressor gene.
The Journal of pediatrics, 2001Co-Authors: Shu Ichi Ito, Haruhito Kikuchi, Ayako Takata, Jun-ichi Hata, Hiroshi Hataya, Masahiro Ikeda, Masataka HondaAbstract:Diffuse mesangial sclerosis is a rare renal disease, occurring either in isolation or as part of Denys-Drash Syndrome. Denys-Drash Syndrome originates from mutations of the Wilms tumor suppressor gene (WT1 ). We describe the presence of WT1 mutations in 7 Japanese children with isolated diffuse mesangial sclerosis.
-
Constitutional WT1 correlate with clinical features in children with progressive nephropathy.
Journal of medical genetics, 2000Co-Authors: Ayako Takata, Haruhito Kikuchi, Ryuji Fukuzawa, Masataka Honda, Shu Ichi Ito, Jun-ichi HataAbstract:Editor—The WT1 tumour suppressor gene encodes a transcriptional factor containing four zinc fingers.1 2This gene has two alternative splicing regions, one consisting of 17 amino acids which are encoded by the whole of exon 5 and the other comprising three amino acids (lysine, threonine, and serine (KTS)) situated between the third and fourth zinc fingers encoded by the 3′ end of exon 9. Four isoforms of the gene thus occur depending on the presence or absence of these regions.3 These isoforms are present in a fixed proportion in tissues where they are expressed. WT1 is expressed from the condensing mesenchyme to mature podocytes in fetal kidneys. The other sites are genital ridges and fetal gonads. Therefore, this gene is thought to play an important role in the development of the kidneys and gonads.4 5Functional impairment of this gene is considered to give rise to urogenital abnormalities and Wilms tumours. Denys-Drash Syndrome and Frasier Syndrome, both of which are characterised by nephropathy with genital abnormalities, have been recognised as disorders related to WT1 mutations. Denys-Drash Syndrome consists of the triad of progressive nephropathy characterised by diffuse mesangial sclerosis (DMS), genital abnormalities, and Wilms tumour.6 The incomplete form consists of nephropathy with genital abnormalities or Wilms tumour. In virtually all patients with Denys-Drash Syndrome, point mutations are detected in the zinc finger domain encoded by exons 7 to 10 of the WT1 gene.7 The mutations noted in Denys-Drash Syndrome patients are frequently missense changes in exons 8 and 9 that encode the second and third zinc fingers. Frasier Syndrome is a clinical entity proposed by Moorthy et al 8 to be related to but distinguished from Denys-Drash Syndrome. Frasier Syndrome is characterised by a slowly progressing nephropathy, male pseudohermaphroditism, and no Wilms tumour. …
-
A point mutation found in the WT1 gene in a sporadic Wilms' tumor without genitourinary abnormalities is identical with the most frequent point mutation in Denys-Drash Syndrome
FEBS letters, 1993Co-Authors: Yoshikiyo Akasaka, Haruhito Kikuchi, Toshihiro Nagai, Nobuyoshi Hiraoka, Shingo Kato, Jun-ichi HataAbstract:We have analyzed exon 9 of the WT1 gene of 18 non-familial/sporadic unilateral Wilms' tumors (WTs) from Japanese patients, by the polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) method. After screening these WTs, a nucleotide alternation, which was present on both alleles, was found in only one case. Furthermore, PCR-SSCP analysis of the constitutional DNA revealed that this patient carried the mutation on only one allele in the germline. Sequence analysis showed that the tumor carried a point mutation (C-1180 to T-1180) in WT1 exon 9 of both alleles, resulting in an Arg-394 to Trp-394 amino acid substitution within the third zinc finger domain of the WT1 product. Interestingly, this mutation is identical with the most frequent point mutation associated with the Denys-Drash Syndrome. However, the classical triad of Denys-Drash Syndrome does not apply to this patient. This is in the first report of the point mutation in the zinc finger domain of both WT1 alleles in a sporadic unilateral WT without genitourinary abnormalities, and the mutation suggests that some sporadic WTs carry the Denys-Drash WT1 mutations.
Melissa H. Little - One of the best experts on this subject based on the ideXlab platform.
-
A zinc finger truncation of murine WT1 results in the characteristic urogenital abnormalities of Denys–Drash Syndrome
Proceedings of the National Academy of Sciences of the United States of America, 1999Co-Authors: Charles E. Patek, Stewart Fleming, Colin G. Miles, Melissa H. Little, Jean Paul Charlieu, Alan Richard Clarke, Kiyoshi Miyagawa, Sheila Christie, Jennifer Doig, David J. HarrisonAbstract:The Wilms tumor-suppressor gene, WT1, plays a key role in urogenital development, and WT1 dysfunction is implicated in both neoplastic (Wilms tumor, mesothelioma, leukemias, and breast cancer) and nonneoplastic (glomerulosclerosis) disease. The analysis of diseases linked specifically with WT1 mutations, such as Denys–Drash Syndrome (DDS), can provide valuable insight concerning the role of WT1 in development and disease. DDS is a rare childhood disease characterized by a nephropathy involving mesangial sclerosis, XY pseudohermaphroditism, and/or Wilms tumor (WT). DDS patients are constitutionally heterozygous for exonic point mutations in WT1, which include mutations predicted to truncate the protein within the C-terminal zinc finger (ZF) region. We report that heterozygosity for a targeted murine Wt1 allele, Wt1tmT396, which truncates ZF3 at codon 396, induces mesangial sclerosis characteristic of DDS in adult heterozygous and chimeric mice. Male genital defects also were evident and there was a single case of Wilms tumor in which the transcript of the nontargeted allele showed an exon 9 skipping event, implying a causal link between Wt1 dysfunction and Wilms tumorigenesis in mice. However, the mutant WT1tmT396 protein accounted for only 5% of WT1 in both heterozygous embryonic stem cells and the WT. This has implications regarding the mechanism by which the mutant allele exerts its effect.
-
dna binding capacity of the wt1 protein is abolished by Denys Drash Syndrome wt1 point mutations
Human Molecular Genetics, 1995Co-Authors: Melissa H. Little, Veronica Van Heyningen, Nicholas D. Hastie, Gregory Holmes, Wendy A. Bickmore, Brandon J. WainwrightAbstract:Constitutional point mutations in the zinc finger (ZF) region of the Wilms' tumour suppressor gene 1 (WT1) lead to Denys-Drash Syndrome (DDS). Patients with this Syndrome display renal failure, Wilms' tumour (WT) and pseudohermaphroditism. DDS WT1 mutations fall into three major categories: (a) missense mutations altering amino acids which directly interact with the DNA target; (b) substitution of amino acids involved in zinc complexing; and (c) nonsense mutations leading to the removal of at least two zinc fingers. We have expressed the WT1 zinc fingers as glutathione-S-transferase fusion proteins, with the lysine-threonine-serine (KTS) alternate splice between ZF3 and ZF4 either present or absent. WT1 fusion constructs with all three classes of DDS mutation were also created. Wild-type and mutant fusion proteins were assayed for their DNA-binding affinity using four previously identified WT1 DNA targets: an EGR1 consensus site; murine insulin-like growth factor 2 promoter 2 (IGF2P2); a (TCC)n motif from the PDGFA-chain promoter; and +P5, a genomic fragment isolated by its affinity for WT1 + KTS. WT1-KTS bound all four targets, but WT1 + KTS only bound +P5. All three classes of DDS mutation investigated, with or without KTS, abolished binding to all four targets. This provides evidence that DDS mutations act either as dominant-negative antimorphs, or elicit their effect through disturbed isoform dosage balance.
-
DNA binding capacity of the WT1 protein is abolished by Denys—Drash Syndrome WT1 point mutations
Human molecular genetics, 1995Co-Authors: Melissa H. Little, Veronica Van Heyningen, Nicholas D. Hastie, Gregory Holmes, Wendy A. Bickmore, Brandon J. WainwrightAbstract:Constitutional point mutations in the zinc finger (ZF) region of the Wilms' tumour suppressor gene 1 (WT1) lead to Denys-Drash Syndrome (DDS). Patients with this Syndrome display renal failure, Wilms' tumour (WT) and pseudohermaphroditism. DDS WT1 mutations fall into three major categories: (a) missense mutations altering amino acids which directly interact with the DNA target; (b) substitution of amino acids involved in zinc complexing; and (c) nonsense mutations leading to the removal of at least two zinc fingers. We have expressed the WT1 zinc fingers as glutathione-S-transferase fusion proteins, with the lysine-threonine-serine (KTS) alternate splice between ZF3 and ZF4 either present or absent. WT1 fusion constructs with all three classes of DDS mutation were also created. Wild-type and mutant fusion proteins were assayed for their DNA-binding affinity using four previously identified WT1 DNA targets: an EGR1 consensus site; murine insulin-like growth factor 2 promoter 2 (IGF2P2); a (TCC)n motif from the PDGFA-chain promoter; and +P5, a genomic fragment isolated by its affinity for WT1 + KTS. WT1-KTS bound all four targets, but WT1 + KTS only bound +P5. All three classes of DDS mutation investigated, with or without KTS, abolished binding to all four targets. This provides evidence that DDS mutations act either as dominant-negative antimorphs, or elicit their effect through disturbed isoform dosage balance.
-
evidence that wt1 mutations in Denys Drash Syndrome patients may act in a dominant negative fashion
Human Molecular Genetics, 1993Co-Authors: Melissa H. Little, Nicholas D. Hastie, Kathleen A Williamson, Marcel M A M Mannens, Anna Kelsey, C M Gosden, Veronica Van HeyningenAbstract:The triad of nephropathy, partial gonadal dysgenesis and Wilms' tumour (WT) is known as Denys-Drash Syndrome (DDS). The WT predisposition gene WT1, which plays a vital role in both genital and renal development, is known to be mutated in DDS patients. The WT1 mutations in these patients are constitutional point mutations clustered in the zinc finger (ZF) encoding exons, particularly the exons encoding ZF2 and ZF3. The predicted functional alteration in WT1 is thought to underlie DDS aetiology either by abolishing binding of the WT1 ZF domain to its normal target DNA binding site(s), perhaps blocking the binding of the wild type WT1 present (dominant negative mutation), and/or by conferring the ability to recognise novel but inappropriate DNA binding sites (dominant mutation). We report here on the analysis of WT1 in a further five cases of DDS. In each case a constitutional point mutation was detected in either ZF2 or ZF3. Three of these mutations are novel, with two affecting the conserved histidine and cysteine residues crucial for ZF tertiary structure. The protein product of the third is predicted to lack ZF2, 3 and 4 as a result of a chain termination mutation, and is presumably incapable of binding DNA. However since the DDS phenotype is only elicited by mutations which lead to loss or alteration of ZF function (presumably DNA binding) while the N-terminal upstream portion of the gene remains intact, we suggest that a dominant negative mechanism is at work here.
-
Evidence that WT1 mutations in Denys — Drash Syndrome patients may act in a dominant-negative fashion
Human molecular genetics, 1993Co-Authors: Melissa H. Little, Nicholas D. Hastie, Kathleen A Williamson, Marcel M A M Mannens, Anna Kelsey, Christine Gosden, Veronica Van HeyningenAbstract:The triad of nephropathy, partial gonadal dysgenesis and Wilms' tumour (WT) is known as Denys-Drash Syndrome (DDS). The WT predisposition gene WT1, which plays a vital role in both genital and renal development, is known to be mutated in DDS patients. The WT1 mutations in these patients are constitutional point mutations clustered in the zinc finger (ZF) encoding exons, particularly the exons encoding ZF2 and ZF3. The predicted functional alteration in WT1 is thought to underlie DDS aetiology either by abolishing binding of the WT1 ZF domain to its normal target DNA binding site(s), perhaps blocking the binding of the wild type WT1 present (dominant negative mutation), and/or by conferring the ability to recognise novel but inappropriate DNA binding sites (dominant mutation). We report here on the analysis of WT1 in a further five cases of DDS. In each case a constitutional point mutation was detected in either ZF2 or ZF3. Three of these mutations are novel, with two affecting the conserved histidine and cysteine residues crucial for ZF tertiary structure. The protein product of the third is predicted to lack ZF2, 3 and 4 as a result of a chain termination mutation, and is presumably incapable of binding DNA. However since the DDS phenotype is only elicited by mutations which lead to loss or alteration of ZF function (presumably DNA binding) while the N-terminal upstream portion of the gene remains intact, we suggest that a dominant negative mechanism is at work here.
Nicholas D. Hastie - One of the best experts on this subject based on the ideXlab platform.
-
Murine Denys–Drash Syndrome: evidence of podocyte de-differentiation and systemic mediation of glomerulosclerosis
Human molecular genetics, 2003Co-Authors: Charles E. Patek, Stewart Fleming, Colin G. Miles, Christopher Bellamy, Michael R. Ladomery, Lee Spraggon, John J. Mullins, Nicholas D. Hastie, Martin L. HooperAbstract:Denys-Drash Syndrome (DDS) is caused by dominant mutations of the Wilms' tumour suppressor gene, WT1, and characterized by a nephropathy involving diffuse mesangial sclerosis, male pseudohermaphroditism and/or Wilms' tumourigenesis. Previously, we reported that heterozygosity for the Wt1tmT396 mutation induces DDS in heterozygous and chimeric (Wt1tmT396/+ +/+) mice. In the present study, the fate of Wt1 mutant cells in chimeric kidneys was assessed by in situ marker analysis, and immunocytochemistry was used to re-examine the claim that glomerulosclerosis (GS) is caused by loss of WT1 and persistent Pax-2 expression by podocytes. Wt1 mutant cells colonized glomeruli efficiently, including podocytes, but some sclerotic glomeruli contained no detectable Wt1 mutant cells. The development of GS was preceded by widespread loss of ZO-1 signal in podocytes (even in kidneys where
-
dna binding capacity of the wt1 protein is abolished by Denys Drash Syndrome wt1 point mutations
Human Molecular Genetics, 1995Co-Authors: Melissa H. Little, Veronica Van Heyningen, Nicholas D. Hastie, Gregory Holmes, Wendy A. Bickmore, Brandon J. WainwrightAbstract:Constitutional point mutations in the zinc finger (ZF) region of the Wilms' tumour suppressor gene 1 (WT1) lead to Denys-Drash Syndrome (DDS). Patients with this Syndrome display renal failure, Wilms' tumour (WT) and pseudohermaphroditism. DDS WT1 mutations fall into three major categories: (a) missense mutations altering amino acids which directly interact with the DNA target; (b) substitution of amino acids involved in zinc complexing; and (c) nonsense mutations leading to the removal of at least two zinc fingers. We have expressed the WT1 zinc fingers as glutathione-S-transferase fusion proteins, with the lysine-threonine-serine (KTS) alternate splice between ZF3 and ZF4 either present or absent. WT1 fusion constructs with all three classes of DDS mutation were also created. Wild-type and mutant fusion proteins were assayed for their DNA-binding affinity using four previously identified WT1 DNA targets: an EGR1 consensus site; murine insulin-like growth factor 2 promoter 2 (IGF2P2); a (TCC)n motif from the PDGFA-chain promoter; and +P5, a genomic fragment isolated by its affinity for WT1 + KTS. WT1-KTS bound all four targets, but WT1 + KTS only bound +P5. All three classes of DDS mutation investigated, with or without KTS, abolished binding to all four targets. This provides evidence that DDS mutations act either as dominant-negative antimorphs, or elicit their effect through disturbed isoform dosage balance.
-
DNA binding capacity of the WT1 protein is abolished by Denys—Drash Syndrome WT1 point mutations
Human molecular genetics, 1995Co-Authors: Melissa H. Little, Veronica Van Heyningen, Nicholas D. Hastie, Gregory Holmes, Wendy A. Bickmore, Brandon J. WainwrightAbstract:Constitutional point mutations in the zinc finger (ZF) region of the Wilms' tumour suppressor gene 1 (WT1) lead to Denys-Drash Syndrome (DDS). Patients with this Syndrome display renal failure, Wilms' tumour (WT) and pseudohermaphroditism. DDS WT1 mutations fall into three major categories: (a) missense mutations altering amino acids which directly interact with the DNA target; (b) substitution of amino acids involved in zinc complexing; and (c) nonsense mutations leading to the removal of at least two zinc fingers. We have expressed the WT1 zinc fingers as glutathione-S-transferase fusion proteins, with the lysine-threonine-serine (KTS) alternate splice between ZF3 and ZF4 either present or absent. WT1 fusion constructs with all three classes of DDS mutation were also created. Wild-type and mutant fusion proteins were assayed for their DNA-binding affinity using four previously identified WT1 DNA targets: an EGR1 consensus site; murine insulin-like growth factor 2 promoter 2 (IGF2P2); a (TCC)n motif from the PDGFA-chain promoter; and +P5, a genomic fragment isolated by its affinity for WT1 + KTS. WT1-KTS bound all four targets, but WT1 + KTS only bound +P5. All three classes of DDS mutation investigated, with or without KTS, abolished binding to all four targets. This provides evidence that DDS mutations act either as dominant-negative antimorphs, or elicit their effect through disturbed isoform dosage balance.
-
evidence that wt1 mutations in Denys Drash Syndrome patients may act in a dominant negative fashion
Human Molecular Genetics, 1993Co-Authors: Melissa H. Little, Nicholas D. Hastie, Kathleen A Williamson, Marcel M A M Mannens, Anna Kelsey, C M Gosden, Veronica Van HeyningenAbstract:The triad of nephropathy, partial gonadal dysgenesis and Wilms' tumour (WT) is known as Denys-Drash Syndrome (DDS). The WT predisposition gene WT1, which plays a vital role in both genital and renal development, is known to be mutated in DDS patients. The WT1 mutations in these patients are constitutional point mutations clustered in the zinc finger (ZF) encoding exons, particularly the exons encoding ZF2 and ZF3. The predicted functional alteration in WT1 is thought to underlie DDS aetiology either by abolishing binding of the WT1 ZF domain to its normal target DNA binding site(s), perhaps blocking the binding of the wild type WT1 present (dominant negative mutation), and/or by conferring the ability to recognise novel but inappropriate DNA binding sites (dominant mutation). We report here on the analysis of WT1 in a further five cases of DDS. In each case a constitutional point mutation was detected in either ZF2 or ZF3. Three of these mutations are novel, with two affecting the conserved histidine and cysteine residues crucial for ZF tertiary structure. The protein product of the third is predicted to lack ZF2, 3 and 4 as a result of a chain termination mutation, and is presumably incapable of binding DNA. However since the DDS phenotype is only elicited by mutations which lead to loss or alteration of ZF function (presumably DNA binding) while the N-terminal upstream portion of the gene remains intact, we suggest that a dominant negative mechanism is at work here.
-
Evidence that WT1 mutations in Denys — Drash Syndrome patients may act in a dominant-negative fashion
Human molecular genetics, 1993Co-Authors: Melissa H. Little, Nicholas D. Hastie, Kathleen A Williamson, Marcel M A M Mannens, Anna Kelsey, Christine Gosden, Veronica Van HeyningenAbstract:The triad of nephropathy, partial gonadal dysgenesis and Wilms' tumour (WT) is known as Denys-Drash Syndrome (DDS). The WT predisposition gene WT1, which plays a vital role in both genital and renal development, is known to be mutated in DDS patients. The WT1 mutations in these patients are constitutional point mutations clustered in the zinc finger (ZF) encoding exons, particularly the exons encoding ZF2 and ZF3. The predicted functional alteration in WT1 is thought to underlie DDS aetiology either by abolishing binding of the WT1 ZF domain to its normal target DNA binding site(s), perhaps blocking the binding of the wild type WT1 present (dominant negative mutation), and/or by conferring the ability to recognise novel but inappropriate DNA binding sites (dominant mutation). We report here on the analysis of WT1 in a further five cases of DDS. In each case a constitutional point mutation was detected in either ZF2 or ZF3. Three of these mutations are novel, with two affecting the conserved histidine and cysteine residues crucial for ZF tertiary structure. The protein product of the third is predicted to lack ZF2, 3 and 4 as a result of a chain termination mutation, and is presumably incapable of binding DNA. However since the DDS phenotype is only elicited by mutations which lead to loss or alteration of ZF function (presumably DNA binding) while the N-terminal upstream portion of the gene remains intact, we suggest that a dominant negative mechanism is at work here.
Veronica Van Heyningen - One of the best experts on this subject based on the ideXlab platform.
-
Hemolytic uremic Syndrome associated with Denys-Drash Syndrome.
Pediatric nephrology (Berlin Germany), 2000Co-Authors: Joseph R. Sherbotie, Veronica Van Heyningen, Richard Axton, Kathy Williamson, L S Finn, Bernard S. KaplanAbstract:The Denys-Drash Syndrome is defined by the occurrence of combinations of pseudohermaphroditism, nephrotic Syndrome with diffuse mesangial sclerosis, Wilms' tumor, and constitutional mutations in the WT1 suppressor gene. Most patients develop end-stage renal failure. Atypical hemolytic uremic Syndrome (HUS) is defined by onset of acute hemolytic anemia with fragmented erythrocytes, thrombocytopenia, and renal failure in the absence of a gastrointestinal prodromal illness of bloody diarrhea. The purpose of this report is to describe the occurrence of features of atypical HUS and Denys-Drash Syndrome in two African-American boys aged 13 and 16 months. Each had nephrotic Syndrome, diffuse mesangial sclerosis, and WT1 point mutations. Both had grade III hypospadias and undescended testes. They had normal serum creatinine concentrations and hematology a month before presenting with HUS. Stool cultures for Escherichia coli O157:H7 were negative. Each patient has been transplanted with cadaver kidneys without recurrence of HUS.
-
dna binding capacity of the wt1 protein is abolished by Denys Drash Syndrome wt1 point mutations
Human Molecular Genetics, 1995Co-Authors: Melissa H. Little, Veronica Van Heyningen, Nicholas D. Hastie, Gregory Holmes, Wendy A. Bickmore, Brandon J. WainwrightAbstract:Constitutional point mutations in the zinc finger (ZF) region of the Wilms' tumour suppressor gene 1 (WT1) lead to Denys-Drash Syndrome (DDS). Patients with this Syndrome display renal failure, Wilms' tumour (WT) and pseudohermaphroditism. DDS WT1 mutations fall into three major categories: (a) missense mutations altering amino acids which directly interact with the DNA target; (b) substitution of amino acids involved in zinc complexing; and (c) nonsense mutations leading to the removal of at least two zinc fingers. We have expressed the WT1 zinc fingers as glutathione-S-transferase fusion proteins, with the lysine-threonine-serine (KTS) alternate splice between ZF3 and ZF4 either present or absent. WT1 fusion constructs with all three classes of DDS mutation were also created. Wild-type and mutant fusion proteins were assayed for their DNA-binding affinity using four previously identified WT1 DNA targets: an EGR1 consensus site; murine insulin-like growth factor 2 promoter 2 (IGF2P2); a (TCC)n motif from the PDGFA-chain promoter; and +P5, a genomic fragment isolated by its affinity for WT1 + KTS. WT1-KTS bound all four targets, but WT1 + KTS only bound +P5. All three classes of DDS mutation investigated, with or without KTS, abolished binding to all four targets. This provides evidence that DDS mutations act either as dominant-negative antimorphs, or elicit their effect through disturbed isoform dosage balance.
-
DNA binding capacity of the WT1 protein is abolished by Denys—Drash Syndrome WT1 point mutations
Human molecular genetics, 1995Co-Authors: Melissa H. Little, Veronica Van Heyningen, Nicholas D. Hastie, Gregory Holmes, Wendy A. Bickmore, Brandon J. WainwrightAbstract:Constitutional point mutations in the zinc finger (ZF) region of the Wilms' tumour suppressor gene 1 (WT1) lead to Denys-Drash Syndrome (DDS). Patients with this Syndrome display renal failure, Wilms' tumour (WT) and pseudohermaphroditism. DDS WT1 mutations fall into three major categories: (a) missense mutations altering amino acids which directly interact with the DNA target; (b) substitution of amino acids involved in zinc complexing; and (c) nonsense mutations leading to the removal of at least two zinc fingers. We have expressed the WT1 zinc fingers as glutathione-S-transferase fusion proteins, with the lysine-threonine-serine (KTS) alternate splice between ZF3 and ZF4 either present or absent. WT1 fusion constructs with all three classes of DDS mutation were also created. Wild-type and mutant fusion proteins were assayed for their DNA-binding affinity using four previously identified WT1 DNA targets: an EGR1 consensus site; murine insulin-like growth factor 2 promoter 2 (IGF2P2); a (TCC)n motif from the PDGFA-chain promoter; and +P5, a genomic fragment isolated by its affinity for WT1 + KTS. WT1-KTS bound all four targets, but WT1 + KTS only bound +P5. All three classes of DDS mutation investigated, with or without KTS, abolished binding to all four targets. This provides evidence that DDS mutations act either as dominant-negative antimorphs, or elicit their effect through disturbed isoform dosage balance.
-
Evidence that WT1 mutations in Denys — Drash Syndrome patients may act in a dominant-negative fashion
Human molecular genetics, 1993Co-Authors: Melissa H. Little, Nicholas D. Hastie, Kathleen A Williamson, Marcel M A M Mannens, Anna Kelsey, Christine Gosden, Veronica Van HeyningenAbstract:The triad of nephropathy, partial gonadal dysgenesis and Wilms' tumour (WT) is known as Denys-Drash Syndrome (DDS). The WT predisposition gene WT1, which plays a vital role in both genital and renal development, is known to be mutated in DDS patients. The WT1 mutations in these patients are constitutional point mutations clustered in the zinc finger (ZF) encoding exons, particularly the exons encoding ZF2 and ZF3. The predicted functional alteration in WT1 is thought to underlie DDS aetiology either by abolishing binding of the WT1 ZF domain to its normal target DNA binding site(s), perhaps blocking the binding of the wild type WT1 present (dominant negative mutation), and/or by conferring the ability to recognise novel but inappropriate DNA binding sites (dominant mutation). We report here on the analysis of WT1 in a further five cases of DDS. In each case a constitutional point mutation was detected in either ZF2 or ZF3. Three of these mutations are novel, with two affecting the conserved histidine and cysteine residues crucial for ZF tertiary structure. The protein product of the third is predicted to lack ZF2, 3 and 4 as a result of a chain termination mutation, and is presumably incapable of binding DNA. However since the DDS phenotype is only elicited by mutations which lead to loss or alteration of ZF function (presumably DNA binding) while the N-terminal upstream portion of the gene remains intact, we suggest that a dominant negative mechanism is at work here.