Assignment of the mouse Extl1 gene to the distal part of chromosome 4 by in situ hybridization and radiation hybrid mapping.
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Animals↗
Biomedical subjects
W Wuyts
Publications and source records attributed to W Wuyts.
Mechanisms of interleukin 1beta-induced human airway smooth muscle hyporesponsiveness to histamine. Involvement of p38 MAPK NF-kappaB.
We have investigated the effect of IL-1beta on histamine H(1)-receptor (H(1)R)-mediated inositol phosphate (IP) accumulation in human airway smooth muscle cells (HASMC) and on histamine-induced contraction of human bronchial rings. Stimulation of HASMC for 24 h with IL-1beta resulted in significant loss of histamine-induced IP formation, which was associated with a reduction of histamine- induced contraction of IL-1beta-treated human bronchial rings. An inhibitor of NF-kappaB activation, pyrrolidine dithiocarbamate, and a p38 MAPK inhibitor, blocked the IL-1beta-induced H(1)R desensitization, whereas anisomycin, an SAPK/JNK and p38 MAPK activator, mimicked the effect of IL-1beta. IL-1beta has been demonstrated to induce cox-2 expression and PGE(2) synthesis. In our study, indomethacin a cox antagonist, completely inhibited the effect of IL-1beta on H(1)R, whereas exogenously added PGE(2) was able to desensitize H(1)R. Furthermore, H-89, a selective PKA inhibitor, antagonized the effect of IL-1beta. Here, we have demonstrated that IL-1beta desensitizes H(1)R, which involves the activation of p38 MAPK and NF-kappaB, leading to the expression of cox-2 and the synthesis of PGE(2). PGE(2) increases intracellular cAMP resulting in PKA activation, which phosphorylates and functionally uncouples H(1)R. Our results suggest that IL-1beta protects airway smooth muscle against histamine-induced contractile responses and that bronchial hyperreactivity to histamine is not associated with proinflammatory cytokine-induced enhancement in H(1)R signaling.
Blotting, Western↗
Identification of mutations in the MSX2 homeobox gene in families affected with foramina parietalia permagna.
Foramina parietalia permagna (FPP) is an autosomal dominant condition characterized by cranial defects of the parietal bones. It can be present as an isolated feature, but it is also one of the characteristics of a contiguous gene syndrome associated with deletions on chromosome 11p11-p12. One of the proteins known to be involved in skull development is the MSX2 homeobox protein. Previously, MSX2 has been shown to be mutated in patients suffering from Boston type craniosynostosis. We have now analyzed the MSX2 gene in five families affected with FPP. An intragenic microsatellite marker did not reveal any recombination and a cumulated LOD score of +3.2 at theta = 0 was obtained. Sequence analysis further showed that in four out of five families an MSX2 mutation was responsible for the skull defect. Moreover, it appears that FPP is caused by haplo-insufficiency of the MSX2 gene. This implies that Boston type craniosynostosis and FPP are allelic variants of the same gene, with FPP caused by loss of MSX2 function and craniosynostosis Boston type due to gain of MSX2 function.
Base Sequence↗
Molecular basis of multiple exostoses: mutations in the EXT1 and EXT2 genes.
Hereditary multiple exostoses (EXT) is an autosomal dominant disorder characterized by the formation of exostoses, which are cartilage-capped bony protuberances mainly located on long bones. Two genes, EXT1 and EXT2, and at least one other unidentified gene, are known to be involved in the formation of exostoses. To date, 49 different EXT1 and 25 different EXT2 mutations have been found in EXT patients, and there is evidence that mutations in these two genes are responsible for over 70% of the EXT cases. Among the 49 EXT1 mutations there are 9 nonsense, 21 frameshift, and 5 splice site mutations; 2 in-frame deletions of 1 and 5 amino acids respectively; and 12 missense mutations. For EXT2, 8 nonsense, 11 frameshift, 3 splice site and 3 missense mutations are described. The majority of these mutations are mutations causing loss of function, which is consistent with the presumed tumor suppressor function of the EXT genes.
Exostoses, Multiple Hereditary↗
Organization of the ribosomal operon 165-235 gene spacer region in representatives of Neisseria gonorrhoeae.
Ribosomal rRNA gene fragments (rDNA) encompassing part of the 16S rDNA, the 16S-23S rDNA spacer region and part of the 23S rDNA of 229 Neisseria gonorrhoeae strains were enzymatically amplified using conserved primers. The fragments of approximately 1200 bp were subjected to restriction analysis with HinfI. This revealed 13 patterns (patterns I-XIII) of which patterns I (78 strains), II (32 strains), III (38 strains) and IV (56 strains) were the most abundant, comprising 89.1% of the strains. The obtained restriction patterns consisted of 3 to 8 bands, ranging in size from 32 to 854 bp. The sum of the obtained bands was about 1200 bp for patterns I, II, III, IV, V, IX, and XIII. However, for patterns VI, VII, VIII, X, XI and XII, the sum of the bands well exceeded the estimated size of approximately 1200 bp. We demonstrated that this results from sequence divergence in the 4 rRNA operons, present in the genome of N. gonorrhoeae, giving rise to patterns that are a combination of several other patterns.
Base Sequence↗
The ALX4 homeobox gene is mutated in patients with ossification defects of the skull (foramina parietalia permagna, OMIM 168500).
Foramina parietalia permagna (FPP) (OMIM 168500) is caused by ossification defects in the parietal bones. Recently, it was shown that loss of function mutations in the MSX2 homeobox gene on chromosome 5 are responsible for the presence of these lesions in some FPP patients. However, the absence of MSX2 mutations in some of the FPP patients analysed and the presence of FPP associated with chromosome 11p deletions in DEFECT 11 (OMIM 601224) patients or associated with Saethre-Chotzen syndrome suggests genetic heterogeneity for this disorder. Starting from a BAC/P1/cosmid contig of the DEFECT 11 region on chromosome 11, we have now isolated the ALX4 gene, a previously unidentified member of the ALX homeobox gene family in humans. Mutation analysis of the ALX4 gene in three unrelated FPP families without the MSX2 mutation identified mutations in two families, indicating that mutations in ALX4 could be responsible for these skull defects and suggesting further genetic heterogeneity of FPP.
Amino Acid Sequence↗
Characterization and genomic localization of the mouse Extl2 gene.
Human EXTL2 is an alpha1,4-N-acetylhexosaminyltransferase involved in the biosynthesis of heparin/heparan sulfate. We have cloned and characterized the mouse homolog of this gene. Mouse Extl2 encodes a 330 amino acid protein that is 87% identical to its human counterpart. Expression analysis showed that Extl2 is ubiquitously expressed in adult mouse tissues and that the Extl2 transcript is already present in early stages of embryonic development. Determination of the genomic structure revealed that the Extl2 gene spans five exons within a 10-kb region and that the genomic organization between mouse and man is well preserved, with conservation of the number and position of all five exons. By radiation hybrid analysis, Extl2 was mapped to mouse chromosome 3, in a region homologous to the human EXTL2 region on chromosome 1.
Amino Acid Sequence↗
Molecular and clinical examination of an Italian DEFECT11 family.
The DEFECT11 syndrome is a contiguous gene syndrome associated with deletions in the proximal part of chromosome 11p. In this study, we describe in an Italian family the co-existence of multiple exostoses (EXT) and enlarged parietal foramina (FPP), the two major symptoms of this syndrome, with abnormalities of the central nervous system. The latter may be a yet undescribed feature of DEFECT11 syndrome. FISH and molecular analysis allowed us to identify a small deletion on 11p11-p12, further refining the localisation of the FPP gene involved in the DEFECT11 syndrome.
Adult↗
EXT-mutation analysis and loss of heterozygosity in sporadic and hereditary osteochondromas and secondary chondrosarcomas.
Osteochondromas occur as sporadic solitary lesions or as multiple lesions, characterizing the hereditary multiple exostoses syndrome (EXT). Approximately 15% of all chondrosarcomas arise within the cartilaginous cap of an osteochondroma. EXT is genetically heterogeneous, and two genes, EXT1 and EXT2, located on 8q24 and 11p11-p12, respectively, have been cloned. It is still unclear whether osteochondroma is a developmental disorder or a true neoplasm. Furthermore, it is unclear whether inactivation of both alleles of an EXT gene, according to the tumor-suppressor model, is required for osteochondroma development, or whether a single EXT germline mutation acts in a dominant negative way. We therefore studied loss of heterozygosity and DNA ploidy in eight sporadic and six hereditary osteochondromas. EXT1- and EXT2-mutation analysis was performed in a total of 34 sporadic and hereditary osteochondromas and secondary peripheral chondrosarcomas. We demonstrated osteochondroma to be a true neoplasm, since aneuploidy was found in 4 of 10 osteochondromas. Furthermore, LOH was almost exclusively found at the EXT1 locus in 5 of 14 osteochondromas. Four novel constitutional cDNA alterations were detected in exon 1 of EXT1. Two patients with multiple osteochondromas demonstrated a germline mutation combined with loss of the remaining wild-type allele in three osteochondromas, indicating that, in cartilaginous cells of the growth plate, inactivation of both copies of the EXT1 gene is required for osteochondroma formation in hereditary cases. In contrast, no somatic EXT1 cDNA alterations were found in sporadic osteochondromas. No mutations were found in the EXT2 gene.
Adolescent↗
Refined physical mapping and genomic structure of the EXTL1 gene.
Recently, the EXTL1 gene, a member of the EXT tumor suppressor gene family, has been mapped to 1p36, a chromosome region which is frequently implicated in a wide variety of malignancies, including breast carcinoma, colorectal cancer and neuroblastoma. In this study, we show that the EXTL1 gene is located between the genetic markers D1S511 and D1S234 within 200 kb of the LAP18 gene on chromosome 1p36. 1, a region which has been proposed to harbor a tumor suppressor gene implicated in MYCN-amplified neuroblastomas. In addition, we determined the genomic structure of the EXTL1 gene, revealing that the EXTL1 coding sequence spans 11 exons within a 50-kb region.
Breast Neoplasms↗
Identification of a third EXT-like gene (EXTL3) belonging to the EXT gene family.
Two homologous genes, EXT1 and EXT2, responsible for the development of benign multiple cartilagenous bone tumors (exostoses) on the long bones, have been identified in the past 2 years. Several arguments have been provided to support the hypothesis that these genes have tumor suppressor activity and that loss of function of these genes may contribute to the development of bone tumors. The recent identification of two EXT-like genes, EXTL1 and EXTL2, homologous to the EXT genes and to each other, revealed the existence of a larger family of genes. We now report the identification of a homologous EST (EST01365), not derived from the known EXT and EXTL genes, indicating the existence of one additional member of this gene family. We characterized this third EXT-like gene, EXTL3, and compared it with the other four members of the EXT-EXTL family. In view of its putative tumor suppressor function, the EXTL3 gene can be considered a candidate gene for the breast cancer locus on chromosome 8p12-p22.
Blotting, Northern↗
Mutations in the EXT1 and EXT2 genes in hereditary multiple exostoses.
Hereditary multiple exostoses (EXT; MIM 133700) is an autosomal dominant bone disorder characterized by the presence of multiple benign cartilage-capped tumors (exostoses). Besides suffering complications caused by the pressure of these exostoses on the surrounding tissues, EXT patients are at an increased risk for malignant chondrosarcoma, which may develop from an exostosis. EXT is genetically heterogeneous, and three loci have been identified so far: EXT1, on chromosome 8q23-q24; EXT2, on 11p11-p12; and EXT3, on the short arm of chromosome 19. The EXT1 and EXT2 genes were cloned recently, and they were shown to be homologous. We have now analyzed the EXT1 and EXT2 genes, in 26 EXT families originating from nine countries, to identify the underlying disease-causing mutation. Of the 26 families, 10 families had an EXT1 mutation, and 10 had an EXT2 mutation. Twelve of these mutations have never been described before. In addition, we have reviewed all EXT1 and EXT2 mutations reported so far, to determine the nature, frequency, and distribution of mutations that cause EXT. From this analysis, we conclude that mutations in either the EXT1 or the EXT2 gene are responsible for the majority of EXT cases. Most of the mutations in EXT1 and EXT2 cause premature termination of the EXT proteins, whereas missense mutations are rare. The development is thus mainly due to loss of function of the EXT genes, consistent with the hypothesis that the EXT genes have a tumor- suppressor function.
Chromosome Mapping↗
Localization of a gene for autosomal dominant osteopetrosis (Albers-Schönberg disease) to chromosome 1p21.
Albers-Schönberg disease, the classical form of osteopetrosis, is an autosomal dominant condition with generalized increased skeletal density due to reduced bone resorption. Characteristic radiological findings are generalized osteosclerosis, with, most typically, end-plate sandwichlike thickening of the vertebrae (Rugger-Jersey spine) and the bone-within-bone (endobones) phenomenon. We studied an extended kindred with Albers-Schönberg disease and found linkage with several markers from chromosome 1p21. The Albers-Schönberg gene is located in a candidate region of approximately 8.5 cM flanked by markers D1S486 and D1S2792. A maximum LOD score (Z(max)) of 4.09 was obtained in multipoint analysis at loci D1S239/D1S248. Possible linkage of osteopetrosis to this chromosomal region was analyzed because the CSF-1 gene, which is mutated in the op/op mouse model for osteopetrosis, is located in 1p21. However, SSCP and mutation analysis in patients did not reveal any abnormality, which excludes the CSF-1 gene as the disease-causing gene. This was confirmed by refined physical mapping of the CSF-1 gene outside the candidate region for the Albers-Schönberg gene. The identification of the molecular defect underlying Albers-Schönberg disease will therefore be dependent on the isolation of other genes from an 8.5-cM candidate region on chromosome 1p21.
Chromosomes, Human, Pair 1↗
Positional cloning of a gene involved in hereditary multiple exostoses.
Hereditary multiple exostosis (EXT) is an autosomal dominant condition mainly characterized by the presence of multiple exostoses on the long bones. These exostoses are benign cartilaginous tumors (enchondromata). Three different EXT loci on chromosomes 8q (EXT1), 11p (EXT2) and 19p (EXT3) have been reported, and recently the EXT1 gene was identified by positional cloning. To isolate the EXT2 gene, we constructed a contig of yeast artificial chromosomes (YAC) and P1 clones covering the complete EXT2 candidate region on chromosome 11p11-p12. One of the transcribed sequences isolated from this region corresponds to a novel gene with homology to the EXT1 gene, and harbours inactivating mutations in different patients with hereditary multiple exostoses. This indicates that this gene is the EXT2 gene. EXT2 has an open reading frame encoding 718 amino acids with an overall homology of 30.9% with EXT1, suggesting that a family of related genes might be responsible for the development of EXT.
Amino Acid Sequence↗
Delineation of a contiguous gene syndrome with multiple exostoses, enlarged parietal foramina, craniofacial dysostosis, and mental retardation, caused by deletions in the short arm of chromosome 11.
A contiguous gene syndrome due to deletions of the proximal short arm of chromosome 11 is described in eight patients belonging to four families. The main clinical features are multiple exostoses, enlarged parietal foramina, craniofacial dysostosis, and mental retardation. The patients have cytogenetic and/or molecular deletions of chromosome 11p11-p13. These deletions are located between the centromere and D11S914 in a region of approximately 20cM. The present study confirms the presence of a multiple exostoses gene on chromosome 11p. Furthermore, it suggests that the gene for isolated foramina parietalie permagna and genes associated with craniofacial dysostosis and mental retardation reside in the same chromosomal region.
Abnormalities, Multiple↗
Refinement of the multiple exostoses locus (EXT2) to a 3-cM interval on chromosome 11.
Hereditary multiple exostoses (EXT) is an autosomal dominant skeletal disorder characterized by the formation of multiple exostoses on the long bones. EXT is genetically heterogeneous, with at least three loci involved: one (EXT1) in the Langer-Giedion region on 8q23-q24, a second (EXT2) in the pericentromeric region of chromosome 11, and a third (EXT3) on chromosome 19p. In this study, linkage analysis in seven extended EXT families, all linked to the EXT2 locus, refined the localization of the EXT2 gene to a 3-cM region flanked by D11S1355 and D11S1361/D11S554. This implies that the EXT2 gene is located at the short arm of chromosome 11, in band 11p11-p12. The refined localization of EXT2 excludes a number of putative candidate genes located in the pericentromeric region of chromosome 11 and facilitates the process of isolating the EXT2 gene.
Chromosomes, Human, Pair 11↗
Separation of ninhydrin-positive compounds on a single-column amino acid analyzer using lithium buffers.
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Amino Acids↗
Bile acid-binding activity of dodeca-N-methyl neomycin hexamethochloride and dimethylaminopropyl neomycin.
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Animals↗