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17 result(s) for "Leube, Barbara"
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Establishment of a Conditionally Immortalized Wilms Tumor Cell Line with a Homozygous WT1 Deletion within a Heterozygous 11p13 Deletion and UPD Limited to 11p15
We describe a stromal predominant Wilms tumor with focal anaplasia and a complex, tumor specific chromosome 11 aberration: a homozygous deletion of the entire WT1 gene within a heterozygous 11p13 deletion and an additional region of uniparental disomy (UPD) limited to 11p15.5-p15.2 including the IGF2 gene. The tumor carried a heterozygous p.T41A mutation in CTNNB1. Cells established from the tumor carried the same chromosome 11 aberration, but a different, homozygous p.S45Δ CTNNB1 mutation. Uniparental disomy (UPD) 3p21.3pter lead to the homozygous CTNNB1 mutation. The tumor cell line was immortalized using the catalytic subunit of human telomerase (hTERT) in conjunction with a novel thermolabile mutant (U19dl89-97tsA58) of SV40 large T antigen (LT). This cell line is cytogenetically stable and can be grown indefinitely representing a valuable tool to study the effect of a complete lack of WT1 in tumor cells. The origin/fate of Wilms tumors with WT1 mutations is currently poorly defined. Here we studied the expression of several genes expressed in early kidney development, e.g. FOXD1, PAX3, SIX1, OSR1, OSR2 and MEIS1 and show that these are expressed at similar levels in the parental and the immortalized Wilms10 cells. In addition the limited potential for muscle/ osteogenic/ adipogenic differentiation similar to all other WT1 mutant cell lines is also observed in the Wilms10 tumor cell line and this is retained in the immortalized cells. In summary these Wilms10 cells are a valuable model system for functional studies of WT1 mutant cells.
The ubiquitin pathway in Parkinson's disease
Mutations of the α-synuclein gene 1 , 2 have been identified in some familial forms of Parkinson's disease, and α-synuclein protein has been shown to accumulate in the brains of patients with the disease 3 . These findings suggest that Parkinson's disease may be caused by the abnormal aggregation of α-synuclein protein. Here we have identified in a German family with Parkinson's disease a missense mutation in the ubiquitin carboxy-terminal hydrolase L1 (UCH-L1) gene. We show that this mutation, Ile93Met, causes a partial loss of the catalytic activity of this thiol protease, which could lead to aberrations in the proteolytic pathway and aggregation of proteins.
Blood RNA biomarkers in prodromal PARK4 and rapid eye movement sleep behavior disorder show role of complexin 1 loss for risk of Parkinson's disease
Parkinson's disease (PD) is a frequent neurodegenerative process in old age. Accumulation and aggregation of the lipid-binding SNARE complex component α-synuclein (SNCA) underlies this vulnerability and defines stages of disease progression. Determinants of SNCA levels and mechanisms of SNCA neurotoxicity have been intensely investigated. In view of the physiological roles of SNCA in blood to modulate vesicle release, we studied blood samples from a new large pedigree with gene duplication (PARK4 mutation) to identify effects of SNCA gain of function as potential disease biomarkers. Downregulation of complexin 1 ( ) mRNA was correlated with genotype, but the expression of other Parkinson's disease genes was not. In global RNA-seq profiling of blood from presymptomatic PARK4 indviduals, bioinformatics detected significant upregulations for platelet activation, hemostasis, lipoproteins, endocytosis, lysosome, cytokine, Toll-like receptor signaling and extracellular pathways. In PARK4 platelets, stimulus-triggered degranulation was impaired. Strong , and mRNA upregulations were validated in PARK4. When analysing individuals with rapid eye movement sleep behavior disorder, the most specific known prodromal stage of general PD, only blood levels were altered. Validation experiments confirmed an inverse mutual regulation of and mRNA levels. In the 3'-UTR of the gene we identified a single nucleotide polymorphism that is significantly associated with PD risk. In summary, our data define as a PD risk factor and provide functional insights into the role and regulation of blood SNCA levels. The new blood biomarkers of PARK4 in this Turkish family might become useful for PD prediction.
Blood RNA biomarkers in prodromal PARK4 and REM sleep behavior disorder show role of complexin-1 loss for risk of Parkinson's disease
Parkinson's disease (PD) is a frequent neurodegenerative process at old age. Accumulation and aggregation of the lipid-binding SNARE complex component alpha-synuclein (SNCA) underlies this vulnerability and defines stages of disease progression. Determinants of SNCA levels and mechanisms of SNCA neurotoxicity are intensely investigated. In view of physiological SNCA roles in blood to modulate vesicle release, we studied blood samples from a new large pedigree with SNCA gene duplication (PARK4 mutation), to identify effects of SNCA gain-of-function as potential disease biomarkers. The expression of other Parkinson's disease gene was not, but complexin-1 (CPLX1) mRNA downregulation was correlated with genotype. In global RNAseq profiling of blood from presymptomatic PARK4, bioinformatics detected significant upregulations for platelet activation, hemostasis, lipoproteins, endocytosis, lysosome, cytokine, toll like receptor signalling and extracellular pathways. In PARK4 platelets, stimulus-triggered degranulation was impaired. Strong SPP1, GZMH, and PLTP mRNA upregulations were validated in PARK4. When analysing cases with REM sleep behaviour disorder (RBD), the most specific known prodromal stage of general PD, only blood CPLX1 levels were altered. Validation experiments confirmed an inverse mutual regulation of SNCA and CPLX1 mRNA levels. In the 3′-UTR of the CPLX1 gene we identified a SNP that is significantly associated with PD risk. In summary, our data define CPLX1 as PD risk factor and provide functional insights into the role and regulation of blood alpha-synuclein levels. The novel blood biomarkers of PARK4 in this Turkish family may become useful for PD prediction.
Biallelic variants in YRDC cause a developmental disorder with progeroid features
The highly conserved YrdC domain-containing protein (YRDC) interacts with the well-described KEOPS complex, regulating specific tRNA modifications to ensure accurate protein synthesis. Previous studies have linked the KEOPS complex to a role in promoting telomere maintenance and controlling genome integrity. Here, we report on a newborn with a severe neonatal progeroid phenotype including generalized loss of subcutaneous fat, microcephaly, growth retardation, wrinkled skin, renal failure, and premature death at the age of 12 days. By trio whole-exome sequencing, we identified a novel homozygous missense mutation, c.662T > C, in YRDC affecting an evolutionary highly conserved amino acid (p.Ile221Thr). Functional characterization of patient-derived dermal fibroblasts revealed that this mutation impairs YRDC function and consequently results in reduced t6A modifications of tRNAs. Furthermore, we established and performed a novel and highly sensitive 3-D Q-FISH analysis based on single-telomere detection to investigate the impact of YRDC on telomere maintenance. This analysis revealed significant telomere shortening in YRDC-mutant cells. Moreover, single-cell RNA sequencing analysis of YRDC-mutant fibroblasts revealed significant transcriptome-wide changes in gene expression, specifically enriched for genes associated with processes involved in DNA repair. We next examined the DNA damage response of patient’s dermal fibroblasts and detected an increased susceptibility to genotoxic agents and a global DNA double-strand break repair defect. Thus, our data suggest that YRDC may affect the maintenance of genomic stability. Together, our findings indicate that biallelic variants in YRDC result in a developmental disorder with progeroid features and might be linked to increased genomic instability and telomere shortening.
Synergistic mutations in SLC3A1 and SLC7A9 leading to heterogeneous cystinuria phenotypes: pitfalls in the diagnostic workup
Background Cystinuria is an inherited disorder of a renal tubular amino acid transporter and leads to increased cystine excretion with the risk of urinary stone formation. Phenotypical classification is based on urinary amino acid concentration as type I (silent), type non-I (hyper-excretors), mixed or untyped. Genotypic classification is based on mutations in SLC3A1 (type A) or SLC7A9 (type B). Case-Diagnosis/Treatment We present six family members with a complex phenotypic profile based on mutations in both genes. The index patient presents a known homozygous mutation (p.T189M) in SLC3A1 and a homozygous mutation (c.225C > T) in SLC7A9 . Based on a bioinformatics analysis and published findings, we considered p.T189M to be pathogenic and initially classified c.225C > T as a silent variant. However, segregation analysis detected homozygosity for p.T189M also in non-affected individuals, whereas homozygous c.225C > T segregated with the phenotype. RNA studies confirmed c.225C > T to cause aberrant splicing. Conclusions Based on our findings, we conclude that c.225C > T in SLC7A9 determines the clinical phenotype in this family, whereas additional SLC3A1 mutations aggravate the phenotype in heterozygotes for c.225C > T in SLC7A9 without resulting in cystinuria in the homozygous state. Our results underline the need for careful biochemical characterization of family members of an index case of cystinuria. Genetic analysis of both cystinuria genes may be necessary due to the synergistic effects of mutations in two genes.
Utility of MLPA in deletion analysis of GCH1 in dopa-responsive dystonia
We applied multiple ligation-dependent probe amplification (MLPA) to patients from three families with characteristic dopa-responsive dystonia (DRD) but no base change in the gene GCH1. We found a complete deletion of GCH1 in affected members of family 1, and partial deletions in affected individuals of family 2 (exons 4-6) and of family 3 (exons 2-6). The findings were confirmed by quantitative real-time PCR. Our investigations demonstrate the utility of MLPA for routine deletion analysis of GCH1 in DRD patients with no sequence changes in this gene.