Oncogenic KIT mutations in different exons lead to specific changes in melanocyte phospho-proteome.

UNLABELLED: Mutations in the proto-oncogene c-KIT (KIT) are found in several cancers, and the site of these mutations differs markedly between cancer types. We used site directed mutagenesis to induce KIT(559), KIT(642) and KIT(816) mutations in primary human melanocytes (PHM) and we investigated the impact of each mutation on KIT function. We studied canonical KIT-signaling pathways by immunoblotting, and we used stable isotope labeling by amino acids in cell culture (SILAC) and kinase prediction models to identify kinases differently activated in respective mutants. We validated our results with the analysis of phosphorylation levels of selected substrates for each kinase. We concluded that CK1 ε and δ are more active in cell clones harboring KIT(559) and KIT(642) mutations, whereas PAK4 is more active in clones with KIT(816) mutation. Our findings might help to develop further therapeutic options for tumors with specific KIT mutations in different domains. BIOLOGICAL SIGNIFICANCE: Different types of cancers harbor mutations in the oncogene KIT. The use of small molecules inhibitors directly targeting KIT had a limited success in the treatment of patients with KIT mutant cancers. Our study describes specific phospho-proteome changes due to different KIT mutations, and provides targets of further therapeutic options.

Incidence and prevalence of the 22q11 deletion syndrome: a population-based study in Western Sweden.

BACKGROUND: Almost all cases of DiGeorge syndrome, velo-cardio-facial syndrome and conotruncal anomaly face syndrome result from a common deletion of chromosome 22q11.2. These syndromes are usually referred to as the 22q11 deletion syndrome (22q11DS), which has a wide phenotypic spectrum and an estimated incidence of one in 4000 births. AIMS: To assess the incidence and prevalence of the 22q11 deletion syndrome in the Western Götaland Region of western Sweden METHODS: Children below 16 years of age with 22q11DS in a well defined catchment area and population of the Western Götaland Region were recruited. Diagnosis of 22q11DS was confirmed using a FISH (fluorescence in situ hybridisation) test. Proven 22q11 deletion was the demonstration of one signal in 11 metaphase spreads with fair quality. RESULTS: During the study period in the Western Götaland Region the mean annual incidence of 22q11DS was 14.1 per 100 000 live births. During the first five years the incidence was 18.1 per 100 000 live births for the whole region and 23.4 per 100 000 live births in Gothenburg, where a multidisciplinary specialist team for 22q11 DS is based. The prevalence was 13.2 per 100 000 children below 16 years of age in the whole region and 23.3 per 100 000 in Gothenburg. CONCLUSION: The number of individuals diagnosed depends on the experience and awareness of the syndrome among specialists who encounter these children and also the severity of the phenotype. The higher frequency of 22q11DS found in Gothenburg is an example of increased awareness. The true incidence and prevalence of this syndrome will only be found through population-based screening, but this would be too expensive and ethically questionable. Screening of specific risk populations would be more justified.

Repression of inflammatory responses in the absence of DNA binding by the glucocorticoid receptor.

The glucocorticoid receptor (GR) acts both as a transcription factor itself on genes carrying GR response elements (GREs) and as a modulator of other transcription factors. Using mice with a mutation in the GR, which cannot activate GRE promoters, we examine whether the important anti-inflammatory and immune suppressive functions of glucocorticoids (GCs) can be established in this in vivo animal model. We find that most actions are indeed exerted in the absence of the DNA-binding ability of the GR: inhibition of the inflammatory response of locally irritated skin and of the systemic response to lipopolysaccharides. GCs repress the expression and release of numerous cytokines both in vivo and in isolated primary macrophages, thymocytes and CD4(+) splenocytes. A transgenic reporter gene controlled by NF-kappa B exclusively is also repressed, suggesting that protein- protein interaction with other transcription factors such as NF-kappa B forms the basis of the anti-inflammatory activity of GR. The only defect of immune suppression detected so far concerns the induced apoptosis of thymocytes and T lymphocytes.

Congenital variant Rett syndrome in a girl with terminal deletion of chromosome 3p.

A girl fulfilling four/five of six inclusion criteria and eight/nine of 11 supportive criteria for atypical Rett syndrome had a cytogenetic deletion of chromosome 3p, del(3)(pter-->3p25.1 approximately 25.2). The deletion was situated on the maternally derived chromosome and by molecular analysis the deletion breakpoint was shown to be between DNA markers D3S3589 and D3S1263.

Identification of the gene responsible for Best macular dystrophy.

Best macular dystrophy (BMD), also known as vitelliform macular dystrophy (VMD2; OMIM 153700), is an autosomal dominant form of macular degeneration characterized by an abnormal accumulation of lipofuscin within and beneath the retinal pigment epithelium cells. In pursuit of the disease gene, we limited the minimum genetic region by recombination breakpoint analysis and mapped to this region a novel retina-specific gene (VMD2). Genetic mapping data, identification of five independent disease-specific mutations and expression studies provide evidence that mutations within the candidate gene are a cause of BMD. The 3' UTR of the candidate gene contains a region of antisense complementarity to the 3' UTR of the ferritin heavy-chain gene (FTH1), indicating the possibility of antisense interaction between VMD2 and FTH1 transcripts.

Maternal origin of inv dup(15) chromosomes in infantile autism.

Six male patients with infantile autism and an extra inverted duplicated chromosome 15[inv dup(15)] were reported in a previous study. These patients had four copies of the chromosome region 15pter-q13, or an inv dup(15)(pter-->q13; q13-->pter). In this new study, DNA from the families of four of the patients were analysed using Southern based RFLPs and microsatellite polymorphisms from the region. In all four cases the inv dup(15) chromosome was of maternal origin. Furthermore, the data suggests that it originated in the maternal meiotic process rather than in an early mitosis in the developmental process of the embryo. The extra chromosome contained material from both of the maternally derived 15-chromosomes. Based on the molecular data presented here, a model for the origin of chromosome markers of this type is proposed.

Localization of a gene for autosomal dominant Larsen syndrome to chromosome region 3p21.1-14.1 in the proximity of, but distinct from, the COL7A1 locus.

Larsen syndrome (LS) is a skeletal dysplasia (osteochondrodysplasia) in which multiple dislocations of the large joints are the major feature. Nosology in this group of diseases, which constitutes 8% of Mendelian disorders in man, is primarily based on clinical and radiographic features. Hopes for more accurate classification grounds are currently being met by progress in elucidation of underlying genetic defects. We have performed linkage analysis in a large Swedish kindred with autosomal dominant LS and found the gene (LAR1) to be strongly linked to chromosome 3p markers (Zmax = 13.4 at (theta = .00). Recombination analysis indicates that the LAR1 locus is located in a region defined distally by D3S1581 and proximally by D3S1600, which cytogenetically maps to chromosome region 3p21.1-14.1. Linkage and recombination analysis of a COL7A1 PvuII intragenic polymorphism versus LS and chromosome 3 markers indicate that COL7A1 is located close to, but distinct from, the LAR1 locus.

Swedish survey on extra structurally abnormal chromosomes in 39 105 consecutive prenatal diagnoses: prevalence and characterization by fluorescence in situ hybridization.

During 7 years (1985-1992), 39,105 consecutive prenatal diagnoses (34,908 amniocenteses and 4197 chorionic villus samples) were made at the five largest clinical genetic laboratories in Sweden. Thirty-one cases of extra structurally abnormal chromosomes (ESACs) were found, giving a total prevalence of 0.8 per 1000. Twelve ESACs were inherited, 14 were de novo and in five the parental origin was unknown. This gives an estimated prevalence of 0.3-0.4 per 1000 for familial and 0.4-0.5 per 1000 for de novo ESACs. Retrospectively, the ESACs were characterized by fluorescence in situ hybridization (FISH). In nine cases, no material was available for this analysis. In 21 of the remaining 22 cases, the chromosomal origin could be identified by FISH. Seventeen of these (81 per cent) were derived from the acrocentric chromosomes, of which 13 originated from chromosome 15 (62 per cent). The most common ESAC was the inv dup(15) (57 per cent). Two cases were derived from chromosome 22, one from chromosome 14, and one from either chromosome 13 or chromosome 21. The four remaining cases consisted to two i(18p)s and two small ring chromosomes derived from chromosomes 4 and 19, respectively.

Localization of the human tripeptidyl peptidase II gene (TPP2) to 13q32-q33 by nonradioactive in situ hybridization and somatic cell hybrids.

We have assigned the human tripeptidyl peptidase II (TPP2) gene to chromosome region 13q32-q33 using two different methods. First, a full-length TPP2 cDNA was used as a probe on Southern blots of DNA from a panel of human/rodent somatic cell hybrids. The TPP2 sequences were found to segregate with the human chromosome 13. Second, fluorescence in situ hybridization analysis was performed with the same probe. This analysis supported the chromosome 13 localization and further refined it to region 13q32-q33.