ABSTRACT
About 5-10% of sporadic Wilms' tumors (WT) are associated with mutations in the Wilms' tumor 1 gene (WT1). More than 90% of patients with Denys-Drash syndrome (DDS; characterized by renal nephropathy, gonadal anomaly, and predisposition to WT) show constitutional intragenic WT1 mutations. We describe a novel WT1 stop-mutation in exon 2. This heterozygous germline mutation was detected in a one-year-old girl who was bilaterally affected with Wilms' tumor but without any other clinical manifestations of DDS. The C-to-A transversion is predicted to result in a polypeptide comprising only the first 165 amino acids of the WT1 protein. Loss of heterozygosity (LOH) studies comparing tumor DNA with lymphocyte DNA revealed LOH for the entire short arm of chromosome 11 in tumor tissue. In addition to the chromosome 11 lesions, the tumor showed a seemingly balanced chromosomal translocation t(7;12) (p22;q22) as the only visible cytogenetic aberration.
Subject(s)
Chromosomes, Human, Pair 11/genetics , Chromosomes, Human, Pair 12/genetics , Chromosomes, Human, Pair 7/genetics , DNA-Binding Proteins/genetics , Germ-Line Mutation/genetics , Loss of Heterozygosity/genetics , Transcription Factors/genetics , Translocation, Genetic/genetics , Wilms Tumor/genetics , DNA Mutational Analysis , Female , Humans , Infant , WT1 ProteinsABSTRACT
We have used the cDNA differential display of mRNA technique to isolate genes differentially regulated during kidney development. Here we report the identification of a novel gene, TM7SF1, which is upregulated in the course of kidney development. The full-length cDNA of TM7SF1 is about 2.4 kb and contains an open reading frame of 1197 nucleotides. The predicted secondary structure of the corresponding protein displays seven putative helical transmembrane domains, a structural feature shared by all members of the G-protein-coupled receptor class of transmembrane proteins. Two minor alternatively spliced versions of approximately 2.3 and approximately 2.2 kb could be detected, one of which contains a nearly identical open reading frame with a truncated carboxy-terminus of the deduced protein. The second alternatively spliced version harbors a completely shifted open reading frame with a potential new ATG start codon. By the use of single-chromosome hybrid cells and fluorescence in situ hybridization experiments, TM7SF1 could be localized to chromosome 1q42-q43. Human multiple tissue Northern blot analysis revealed TM7SF1 transcripts in human kidney, heart, brain, and placenta tissue. Studies on Wilms tumor samples showed variable TM7SF1 expression, ranging from nearly undetectable levels to an abundant level of expression comparable to that of adult kidney tissue.
Subject(s)
Gene Expression Regulation, Developmental/genetics , Kidney/growth & development , Kidney/metabolism , Membrane Proteins/genetics , Up-Regulation/genetics , Adult , Blotting, Northern , Chromosome Mapping , Chromosomes, Human, Pair 1/genetics , Cloning, Molecular , DNA, Complementary/isolation & purification , Fetus , GTP-Binding Proteins/biosynthesis , GTP-Binding Proteins/genetics , GTP-Binding Proteins/isolation & purification , Humans , Kidney/embryology , Membrane Proteins/biosynthesis , Membrane Proteins/isolation & purification , Molecular Sequence Data , Receptors, G-Protein-Coupled , Sequence Analysis, DNAABSTRACT
We have cloned the coding region of a human gene, whose predicted amino acid sequence shows 88% homology and higher correspondence in functional domains to the rat cGMP inhibited phosphodiesterase gene (PDE3A). In concordance with the expression data of the rat PDE3A gene, a 5.3-kb transcript of the human cGMP-inhibited phosphodiesterase gene is shown in Northern blot analysis to be highly expressed in adipose tissue. In addition, weaker expression is seen in pancreas, skeletal muscle, liver, placenta, and heart. cDNA clones from the homologue mouse gene were isolated and sequenced spanning a highly conserved region coding for a C-terminal located catalytic core region of this enzyme family. Using a genomic cosmid clone of human PDE3A for fluorescence in situ hybridization, the gene was mapped to chromosomal region 11p15 and regionally sublocalized by PCR on a human-hamster somatic hybrid-cell mapping panel to 11p15.1-p2. Based on comparative linkage data in mouse and rat this chromosomal location is suggested to contain genes involved in complex diseases like obesity and diabetes mellitus type II. Therefore, a possible involvement of the human PDE3A gene in these polygenic traits is discussed, taking into account the prominent role of the rat PDE3A gene product in the antilipolytic action of insulin in adipocytes.
