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Biomedical subjects

C Wicking

Publications and source records attributed to C Wicking.

31 records · Page 2Linked to original sources

Mutations of the human homolog of Drosophila patched in the nevoid basal cell carcinoma syndrome.

The nevoid basal cell carcinoma syndrome (NBCCS) is an autosomal dominant disorder characterized by multiple basal cell carcinomas (BCCs), pits of the palms and soles, jaw keratocysts, a variety of other tumors, and developmental abnormalities. NBCCS maps to chromosome 9q22.3. Familial and sporadic BCCs display loss of heterozygosity in this region, consistent with the gene being a tumor suppressor. A human sequence (PTC) with strong homology to the Drosophila segment polarity gene, patched, was isolated from a YAC and cosmid contig of the NBCCS region. Mutation analysis revealed alterations of PTC in NBCCS patients and in related tumors. We propose that a reduction in expression of the patched gene can lead to the developmental abnormalities observed in the syndrome and that complete loss of patched function contributes to transformation of certain cell types.

Alleles↗

A mammalian patched homolog is expressed in target tissues of sonic hedgehog and maps to a region associated with developmental abnormalities.

Drosophila patched is a segment polarity gene required for the correct patterning of larval segments and imaginal discs during fly development and has a close functional relationship with hedgehog. We have isolated a complete human PATCHED cDNA sequence, which encodes a putative protein of 1296 amino acids, and displays 39% identity and 60% similarity to the Drosophila PATCHED protein. Hydropathy analysis suggests that human PATCHED is an integral membrane protein with a pattern of hydrophobic and hydrophilic stretches nearly identical to that of Drosophila patched. In the developing mouse embryo, patched is initially detected within the ventral neural tube and later in the somites and limb buds. Expression in the limb buds is restricted to the posterior ectoderm surrounding the zone of polarizing activity. The results show that patched is expressed in target tissues of sonic hedgehog, a murine homolog of Drosophila hedgehog suggesting that patched/hedgehog interactions have been conserved during evolution. Human PATCHED maps to human chromosome 9q22.3, the candidate region for the nevoid basal cell carcinoma syndrome. Patched expression is compatible with the congenital defects observed in the nevoid basal cell carcinoma syndrome.

Amino Acid Sequence↗

+P5 (D1S3309E), a novel target binding site for the Wilms' tumour suppressor 1 (WT1) gene, maps to human chromosome 1q21-->22.

The Wilms' tumor suppressor 1 gene (WT1) encodes a zinc finger transcription factor critical for normal urogenital development. We have previously isolated a DNA fragment, +P5 (D1S3309E), to which all WT1 protein isoforms bind. Using PCR of a human x rodent somatic cell hybrid mapping panel, together with two-color fluorescence in situ hybridisation of +P5-containing cosmids and previously localised human chromosome 1q cosmids, we have mapped the +P5 fragment to chromosome 1q21-->q22.

Animals↗

Fine deletion mapping on the long arm of chromosome 9 in sporadic and familial basal cell carcinomas.

Basal cell carcinomas (BCCs) are the most common sporadic cancers worldwide. They are also a cardinal manifestation of a familial cancer predisposition syndrome, naevoid BCC syndrome (NBCCS). The gene responsible for NBCCS is likely to be a tumour suppressor gene and has been genetically mapped to a 2cM region between microsatellite markers, D9S196 and D9S180 at 9q22.3-q31. 101 BCCs (63 sporadic and 38 familial) were examined for loss of heterozygosity (LOH) in the candidate region of the NBCCS gene. Deletions were found in 46% and all LOH is consistent with genetic mapping of the NBCC locus. These findings strongly support the hypothesis that inactivation of the putative tumour suppressor, the NBCCS gene, is important in the formation of sporadic BCCs. One sporadic tumour indicates that the smallest region of overlap of these deletions is within the interval between D9S287 and D9S180. If this is confirmed in additional tumours, it would further narrow down the NBCCS region and exclude one candidate gene, that for the C complementation group of Fanconi anaemia, which maps proximally to D9S287. However, it would not exclude another candidate, the gene for the A complementation group of xeroderma pigmentosum (XPAC). Evidence of imprinting was also sought but preliminary data indicate that it is unlikely to occur at the NBCCS locus.

Adult↗

The human growth-arrest-specific gene GAS1 maps outside the candidate region of the gene for nevoid basal cell carcinoma syndrome.

The human growth-arrest specific gene GAS1 maps to chromosome bands 9q21.3-->q22, the region known to contain the tumour suppressor gene responsible for nevoid basal cell carcinoma syndrome (NBCCS). Because of its putative action as a tumour suppressor gene, the GAS1 gene was analysed as a candidate for the NBCCS gene. Using two-colour fluorescence in situ hybridization, the GAS1 gene maps outside the interval which, by genetic analysis, has been shown to contain the NBCCS gene.

Animals↗

Nevoid basal cell carcinoma syndrome: review of 118 affected individuals.

One hundred eighteen cases of nevoid basal cell carcinoma syndrome (NBCCS, Gorlin's syndrome or basal cell nevus syndrome) are presented in this study. In aiming to ascertain all the affected families in Australia, we have examined the largest series to date. Relative frequencies of associated complications are presented and compared with those of the recent English survey by Evans et al. [J Med Genet 30:460-464, 1993]. The frequencies of most manifestations are similar. However, one major difference is that the multiple basal cell carcinomas are manifest from an earlier age in the Australian population, which probably reflects greater exposure to ultraviolet radiation. Of the 64 families ascertained, 37 represented simplex cases, and, accordingly, the apparent new mutation rate is surprisingly high (14-81%) given the lack of impact of NBCCS on reproductive capabilities. There is some evidence to suggest that this may be attributable to anticipation.

Abnormalities, Multiple↗

Fine genetic mapping of the gene for nevoid basal cell carcinoma syndrome.

Nevoid basal cell carcinoma syndrome (NBCCS, or Gorlin syndrome) is a cancer predisposition syndrome characterized by multiple basal cell carcinomas and diverse developmental defects. The gene responsible for NBCCS, which is most likely to be a tumor suppressor gene, has previously been mapped to 9q22.3-q31 in a 12-cM interval between the microsatellite marker loci D9S12.1 and D9S109. Combined multipoint and haplotype analyses of additional polymorphisms in this region in our collection of Australasian pedigrees have further refined the localization of the gene to between the markers D9S196 and D9S180, an interval reported to be approximately 2 cM.

Adult↗

Further localization of the gene for nevoid basal cell carcinoma syndrome (NBCCS) in 15 Australasian families: linkage and loss of heterozygosity.

Nevoid basal cell carcinoma syndrome (NBCCS; basal cell nevus syndrome or Gorlin syndrome) is a cancer-predisposition syndrome characterized by multiple basal cell carcinomas (BCCs) and diverse developmental defects. The gene for NBCCS has been mapped to 9q23.1-q31 in North American and European families. In addition, loss of heterozygosity (LOH) for genetic markers in this region has been detected in sporadic BCCs, indicating that the NBCCS gene is probably a tumor-suppressor gene. In this study we have determined that the NBCCS gene is also linked to this region in Australasian pedigrees and that there is no significant evidence of heterogeneity. We have defined the localization of the gene by multipoint and haplotype analysis of 15 families, using four microsatellite markers. LOH at these loci was detected in 50% of sporadic BCCs, a rate that is significantly higher than that in other skin lesions used as controls.

Adult↗

From linked marker to gene.

An area of increasing importance in human genetics research is the strategy of 'reverse genetics' or 'positional cloning', whereby a gene associated with a genetic disease is isolated on the basis of its approximate chromosomal position. This article and the accompanying centrepage diagram describe the main features of this strategy and outline the techniques involved; they are designed to be used for teaching purposes and as a general reference for those from other fields of genetics research.

Chromosome Mapping↗

Cloning the mouse homolog of the human cystic fibrosis transmembrane conductance regulator gene.

The cystic fibrosis transmembrane conductance regulator is encoded by the gene known to be mutated in patients with cystic fibrosis. This paper reports the cloning and sequencing of cDNAs for the murine homolog of the human cystic fibrosis transmembrane conductance regulator gene. A clone that, by analogy to the human sequence, extends 3' from exon 9 to the poly(A) tail was isolated from a mouse lung cDNA library. cDNA clones containing exons 4 and 6b were also isolated and sequenced, but the remainder of the mRNA proved difficult to obtain by conventional cDNA library screening. Sequences spanning exons 1-9 were cloned by PCR from mouse RNA. The deduced mouse protein sequence is 78% identical to the human cystic fibrosis transmembrane regulator, with higher conservation in the transmembrane and nucleotide-binding domains. Amino acid sequences in which known cystic fibrosis missense mutations occur are conserved between man and mouse; in particular, the predicted mouse protein has a phenylalanine residue corresponding to that deleted in the most common human cystic fibrosis mutation (delta F508), which should allow the use of transgenic strategies to introduce this mutation in attempts to create a "cystic fibrosis mouse".

Amino Acid Sequence↗

A new polymorphic locus, D7S411, isolated by cloning from preparative pulse-field gels is close to the mutation causing cystic fibrosis.

The mutation causing cystic fibrosis (CF) has been localized to the DNA sequence of 700 kb bounded by the loci identified by the markers pMP6d-9 (D7S399) and pJ3.11 (D7S8). A 560-kb fragment obtained after SacII digestion of DNA from a cell line containing this region of human chromosome 7 in a mouse background was separated using pulse-field gel electrophoresis and isolated from the gel. The DNA was digested with BamHI prior to cloning into lambda EMBL3. Approximately 0.1% of the resulting clones contained human repetitive sequences, and 24 such recombinants were studied. Of these, 23 are on chromosome 7; 8 clones were duplicated, and of the 15 different recombinants, 7 are between MET and INT1L1, and a further 7 are between INT1L1 and pMP6d-9, leaving a single marker, pG2, which is between pMP6d-9 and pJ3.11. pG2 recognizes an RFLP with XbaI. A cosmid walk from pG2 has generated a further marker, H80, which recognizes an RFLP with PstI. This new locus (D7S411) divides the remaining region between the CF flanking markers, thereby making it more accessible to fine pulse-field mapping and allowing the precise localization of further clones to this region. Although it is not possible to position the CF locus unequivocally with respect to D7S411, both polymorphic markers at this locus exhibit low but significant linkage disequilibrium with CF, placing the emphasis for the search for the gene on the D7S399 to D7S411 interval of 250 kb.

Blotting, Southern↗

Isolation of a human gene with protein sequence similarity to human and murine int-1 and the Drosophila segment polarity mutant wingless.

An expressed gene sequence which was identified by the isolation of a methylation free CpG island from human chromosome 7 has been cloned from a human lung cDNA library. The deduced protein sequence contains 360 amino acids and has several features of a secreted protein; it is cysteine rich with a signal peptide sequence and two potential asn-linked glycosylation sites. The protein sequence shows marked similarity with human and murine int-1 and their Drosophila homolog wingless (Dint-1). This human int-1 related protein, int-1 and Dint-1 have diverse patterns of expression, but the inferred structural similarities suggest that some of the functional characteristics of these proteins may be shared.

Amino Acid Sequence↗