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150 result(s) for "Strom, Tim M."
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Classic Selective Sweeps Revealed by Massive Sequencing in Cattle
Human driven selection during domestication and subsequent breed formation has likely left detectable signatures within the genome of modern cattle. The elucidation of these signatures of selection is of interest from the perspective of evolutionary biology, and for identifying domestication-related genes that ultimately may help to further genetically improve this economically important animal. To this end, we employed a panel of more than 15 million autosomal SNPs identified from re-sequencing of 43 Fleckvieh animals. We mainly applied two somewhat complementary statistics, the integrated Haplotype Homozygosity Score (iHS) reflecting primarily ongoing selection, and the Composite of Likelihood Ratio (CLR) having the most power to detect completed selection after fixation of the advantageous allele. We find 106 candidate selection regions, many of which are harboring genes related to phenotypes relevant in domestication, such as coat coloring pattern, neurobehavioral functioning and sensory perception including KIT, MITF, MC1R, NRG4, Erbb4, TMEM132D and TAS2R16, among others. To further investigate the relationship between genes with signatures of selection and genes identified in QTL mapping studies, we use a sample of 3062 animals to perform four genome-wide association analyses using appearance traits, body size and somatic cell count. We show that regions associated with coat coloring significantly (P<0.0001) overlap with the candidate selection regions, suggesting that the selection signals we identify are associated with traits known to be affected by selection during domestication. Results also provide further evidence regarding the complexity of the genetics underlying coat coloring in cattle. This study illustrates the potential of population genetic approaches for identifying genomic regions affecting domestication-related phenotypes and further helps to identify specific regions targeted by selection during speciation, domestication and breed formation of cattle. We also show that Linkage Disequilibrium (LD) decays in cattle at a much faster rate than previously thought.
Genetic diagnosis of Mendelian disorders via RNA sequencing
Across a variety of Mendelian disorders, ∼50–75% of patients do not receive a genetic diagnosis by exome sequencing indicating disease-causing variants in non-coding regions. Although genome sequencing in principle reveals all genetic variants, their sizeable number and poorer annotation make prioritization challenging. Here, we demonstrate the power of transcriptome sequencing to molecularly diagnose 10% (5 of 48) of mitochondriopathy patients and identify candidate genes for the remainder. We find a median of one aberrantly expressed gene, five aberrant splicing events and six mono-allelically expressed rare variants in patient-derived fibroblasts and establish disease-causing roles for each kind. Private exons often arise from cryptic splice sites providing an important clue for variant prioritization. One such event is found in the complex I assembly factor TIMMDC1 establishing a novel disease-associated gene. In conclusion, our study expands the diagnostic tools for detecting non-exonic variants and provides examples of intronic loss-of-function variants with pathological relevance. Genome sequencing alone fails to provide a genetic diagnosis for many Mendelian disorder patients. Here, the authors utilize RNA sequencing to complement genotyping of patients with a rare mitochondrial disease by detecting aberrant RNA expression, splicing and allele-specific expression.
Mutations in the deubiquitinase gene USP8 cause Cushing's disease
Martin Reincke, Martin Fassnacht and colleagues identify somatic mutations in the USP8 deubiquitinase gene in corticotroph adenomas in Cushing's disease. The mutations enhanced proteolytic cleavage and catalytic activity of USP8, which led to activation of EGF receptor signaling. Cushing's disease is caused by corticotroph adenomas of the pituitary. To explore the molecular mechanisms of endocrine autonomy in these tumors, we performed exome sequencing of 10 corticotroph adenomas. We found somatic mutations in the USP8 deubiquitinase gene in 4 of 10 adenomas. The mutations clustered in the 14-3-3 protein binding motif and enhanced the proteolytic cleavage and catalytic activity of USP8. Cleavage of USP8 led to increased deubiqutination of the EGF receptor, impairing its downregulation and sustaining EGF signaling. USP8 mutants enhanced promoter activity of the gene encoding proopiomelanocortin. In summary, our data show that dominant mutations in USP8 cause Cushing's disease via activation of EGF receptor signaling.
Time‐ and compartment‐resolved proteome profiling of the extracellular niche in lung injury and repair
The extracellular matrix (ECM) is a key regulator of tissue morphogenesis and repair. However, its composition and architecture are not well characterized. Here, we monitor remodeling of the extracellular niche in tissue repair in the bleomycin‐induced lung injury mouse model. Mass spectrometry quantified 8,366 proteins from total tissue and bronchoalveolar lavage fluid (BALF) over the course of 8 weeks, surveying tissue composition from the onset of inflammation and fibrosis to its full recovery. Combined analysis of proteome, secretome, and transcriptome highlighted post‐transcriptional events during tissue fibrogenesis and defined the composition of airway epithelial lining fluid. To comprehensively characterize the ECM, we developed a quantitative detergent solubility profiling (QDSP) method, which identified Emilin‐2 and collagen‐XXVIII as novel constituents of the provisional repair matrix. QDSP revealed which secreted proteins interact with the ECM, and showed drastically altered association of morphogens to the insoluble matrix upon injury. Thus, our proteomic systems biology study assigns proteins to tissue compartments and uncovers their dynamic regulation upon lung injury and repair, potentially contributing to the development of anti‐fibrotic strategies. Synopsis A proteome‐wide view of lung injury and repair was elucidated by mass spectrometry analysis of the dynamic composition of lung tissue compartments. In particular, the extracellular matrix proteome uncovers potential factors in stem cell mobilization and fibrosis resolution. Proteomic analysis discovers signatures of consecutive phases of lung injury, fibrosis, and repair. Combined proteomics and transcriptomics define the prevalence of post‐transcriptional events. Compartment proteomics uncovers extracellular matrix and epithelial lining fluid composition. In vivo solubility profiling reveals extracellular matrix interactions with secreted proteins. Graphical Abstract A proteome‐wide view of lung injury and repair was elucidated by mass spectrometry analysis of the dynamic composition of lung tissue compartments. In particular, the extracellular matrix proteome uncovers potential factors in stem cell mobilization and fibrosis resolution.
A gain-of-function mutation in the CLCN2 chloride channel gene causes primary aldosteronism
Primary aldosteronism is the most common and curable form of secondary arterial hypertension. We performed whole-exome sequencing in patients with early-onset primary aldosteronism and identified a de novo heterozygous c.71G>A/p.Gly24Asp mutation in the CLCN2 gene, encoding the voltage-gated ClC-2 chloride channel 1 , in a patient diagnosed at 9 years of age. Patch-clamp analysis of glomerulosa cells of mouse adrenal gland slices showed hyperpolarization-activated Cl – currents that were abolished in Clcn2 −/− mice. The p.Gly24Asp variant, located in a well-conserved ‘inactivation domain’ 2 , 3 , abolished the voltage- and time-dependent gating of ClC-2 and strongly increased Cl – conductance at resting potentials. Expression of ClC-2 Asp24 in adrenocortical cells increased expression of aldosterone synthase and aldosterone production. Our data indicate that CLCN2 mutations cause primary aldosteronism. They highlight the important role of chloride in aldosterone biosynthesis and identify ClC-2 as the foremost chloride conductor of resting glomerulosa cells. A gain-of-function mutation in the CLCN2 chloride channel gene (encoding ClC-2) causes primary aldosteronism. The mutation abolishes voltage-dependent gating of ClC-2, highlighting a role for chloride conduction in regulating aldosterone biosynthesis.
Constitutive Activation of PKA Catalytic Subunit in Adrenal Cushing's Syndrome
Corticotropin-independent Cushing's syndrome occurs with adrenocortical tumors or hyperplasia. The authors report that germline duplications of PRKACA lead to bilateral adrenal hyperplasia, whereas somatic mutations lead to unilateral cortisol-producing adrenal adenomas. Endogenous hypercortisolism, referred to as Cushing's syndrome, is associated with substantial morbidity and mortality. 1 When Cushing's syndrome is severe, patients have catabolic symptoms such as muscle weakness, skin fragility, osteoporosis, and severe metabolic sequelae. 2 Hypersecretion of cortisol can be driven by an excess of pituitary or ectopic corticotropin or can be due to adrenocortical tumors or hyperplasias with corticotropin-independent cortisol production. Adrenal adenomas are common, with a prevalence of at least 3% among persons older than 50 years of age. 3 Whereas only a subset of these tumors is associated with overt Cushing's syndrome, some degree of cortisol excess is present, . . .
Somatic mutations in ATP1A1 and ATP2B3 lead to aldosterone-producing adenomas and secondary hypertension
Felix Beuschlein, Martin Reincke and colleagues identify recurrent somatic mutations in ATP1A1 and ATP2B3 in aldosterone-producing adenomas with wild-type KCNJ5 . The ATP1A1 and ATP2B3 mutations alter conserved residues and lead to impaired sodium, potassium and calcium ion homeostasis. Primary aldosteronism is the most prevalent form of secondary hypertension. To explore molecular mechanisms of autonomous aldosterone secretion, we performed exome sequencing of aldosterone-producing adenomas (APAs). We identified somatic hotspot mutations in the ATP1A1 (encoding an Na + /K + ATPase α subunit) and ATP2B3 (encoding a Ca 2+ ATPase) genes in three and two of the nine APAs, respectively. These ATPases are expressed in adrenal cells and control sodium, potassium and calcium ion homeostasis. Functional in vitro studies of ATP1A1 mutants showed loss of pump activity and strongly reduced affinity for potassium. Electrophysiological ex vivo studies on primary adrenal adenoma cells provided further evidence for inappropriate depolarization of cells with ATPase alterations. In a collection of 308 APAs, we found 16 (5.2%) somatic mutations in ATP1A1 and 5 (1.6%) in ATP2B3 . Mutation-positive cases showed male dominance, increased plasma aldosterone concentrations and lower potassium concentrations compared with mutation-negative cases. In summary, dominant somatic alterations in two members of the ATPase gene family result in autonomous aldosterone secretion.
Comprehensive analysis of the mutation spectrum in 301 German ALS families
ObjectivesRecent advances in amyotrophic lateral sclerosis (ALS) genetics have revealed that mutations in any of more than 25 genes can cause ALS, mostly as an autosomal-dominant Mendelian trait. Detailed knowledge about the genetic architecture of ALS in a specific population will be important for genetic counselling but also for genotype-specific therapeutic interventions.MethodsHere we combined fragment length analysis, repeat-primed PCR, Southern blotting, Sanger sequencing and whole exome sequencing to obtain a comprehensive profile of genetic variants in ALS disease genes in 301 German pedigrees with familial ALS. We report C9orf72 mutations as well as variants in consensus splice sites and non-synonymous variants in protein-coding regions of ALS genes. We furthermore estimate their pathogenicity by taking into account type and frequency of the respective variant as well as segregation within the families.Results49% of our German ALS families carried a likely pathogenic variant in at least one of the earlier identified ALS genes. In 45% of the ALS families, likely pathogenic variants were detected in C9orf72, SOD1, FUS, TARDBP or TBK1, whereas the relative contribution of the other ALS genes in this familial ALS cohort was 4%. We identified several previously unreported rare variants and demonstrated the absence of likely pathogenic variants in some of the recently described ALS disease genes.ConclusionsWe here present a comprehensive genetic characterisation of German familial ALS. The present findings are of importance for genetic counselling in clinical practice, for molecular research and for the design of diagnostic gene panels or genotype-specific therapeutic interventions in Europe.
Spinal poly-GA inclusions in a C9orf72 mouse model trigger motor deficits and inflammation without neuron loss
Translation of the expanded (ggggcc) n repeat in C9orf72 patients with amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) causes abundant poly-GA inclusions. To elucidate their role in pathogenesis, we generated transgenic mice expressing codon-modified (GA) 149 conjugated with cyan fluorescent protein (CFP). Transgenic mice progressively developed poly-GA inclusions predominantly in motoneurons and interneurons of the spinal cord and brain stem and in deep cerebellar nuclei. Poly-GA co-aggregated with p62, Rad23b and the newly identified Mlf2, in both mouse and patient samples. Consistent with the expression pattern, 4-month-old transgenic mice showed abnormal gait and progressive balance impairment, but showed normal hippocampus-dependent learning and memory. Apart from microglia activation we detected phosphorylated TDP-43 but no neuronal loss. Thus, poly-GA triggers behavioral deficits through inflammation and protein sequestration that likely contribute to the prodromal symptoms and disease progression of C9orf72 patients.
Mutation Detection in Patients with Retinal Dystrophies Using Targeted Next Generation Sequencing
Retinal dystrophies (RD) constitute a group of blinding diseases that are characterized by clinical variability and pronounced genetic heterogeneity. The different nonsyndromic and syndromic forms of RD can be attributed to mutations in more than 200 genes. Consequently, next generation sequencing (NGS) technologies are among the most promising approaches to identify mutations in RD. We screened a large cohort of patients comprising 89 independent cases and families with various subforms of RD applying different NGS platforms. While mutation screening in 50 cases was performed using a RD gene capture panel, 47 cases were analyzed using whole exome sequencing. One family was analyzed using whole genome sequencing. A detection rate of 61% was achieved including mutations in 34 known and two novel RD genes. A total of 69 distinct mutations were identified, including 39 novel mutations. Notably, genetic findings in several families were not consistent with the initial clinical diagnosis. Clinical reassessment resulted in refinement of the clinical diagnosis in some of these families and confirmed the broad clinical spectrum associated with mutations in RD genes.