Showing papers by "Benjamin Meder published in 2011"

Toward the blood-borne miRNome of human diseases

Abstract: In a multicenter study, we determined the expression profiles of 863 microRNAs by array analysis of 454 blood samples from human individuals with different cancers or noncancer diseases, and validated this 'miRNome' by quantitative real-time PCR. We detected consistently deregulated profiles for all tested diseases; pathway analysis confirmed disease association of the respective microRNAs. We observed significant correlations (P = 0.004) between the genomic location of disease-associated genetic variants and deregulated microRNAs.

MicroRNA signatures in total peripheral blood as novel biomarkers for acute myocardial infarction

Abstract: MicroRNAs (miRNAs) are important regulators of adaptive and maladaptive responses in cardiovascular diseases and hence are considered to be potential therapeutical targets. However, their role as novel biomarkers for the diagnosis of cardiovascular diseases still needs to be systematically evaluated. We assessed here for the first time whole-genome miRNA expression in peripheral total blood samples of patients with acute myocardial infarction (AMI). We identified 121 miRNAs, which are significantly dysregulated in AMI patients in comparison to healthy controls. Among these, miR-1291 and miR-663b show the highest sensitivity and specificity for the discrimination of cases from controls. Using a novel self-learning pattern recognition algorithm, we identified a unique signature of 20 miRNAs that predicts AMI with even higher power (specificity 96%, sensitivity 90%, and accuracy 93%). In addition, we show that miR-30c and miR-145 levels correlate with infarct sizes estimated by Troponin T release. The here presented study shows that single miRNAs and especially miRNA signatures derived from peripheral blood, could be valuable novel biomarkers for cardiovascular diseases.

Targeted Next-Generation Sequencing for the Molecular Genetic Diagnostics of Cardiomyopathies

Abstract: Background— Today, mutations in more than 30 different genes have been found to cause inherited cardiomyopathies, some associated with very poor prognosis. However, because of the genetic heterogeneity and limitations in throughput and scalability of current diagnostic tools up until now, it is hardly possible to genetically characterize patients with cardiomyopathy in a fast, comprehensive, and cost-efficient manner. Methods and Results— We established an array-based subgenomic enrichment followed by next-generation sequencing to detect mutations in patients with hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM). With this approach, we show that the genomic region of interest can be enriched by a mean factor of 2169 compared with the coverage of the whole genome, resulting in high sequence coverage of selected disease genes and allowing us to define the genetic pathogenesis of cardiomyopathies in a single sequencing run. In 6 patients, we detected disease-causing mutations, 2 microdeletions, and 4 point mutations. Furthermore, we identified several novel nonsynonymous variants, which are predicted to be harmful, and hence, might be potential disease mutations or modifiers for DCM or HCM. Conclusions— The approach presented here allows for the first time a comprehensive genetic screening in patients with hereditary DCM or HCM in a fast and cost-efficient manner.

The myosin-interacting protein SMYD1 is essential for sarcomere organization.

Abstract: Assembly, maintenance and renewal of sarcomeres require highly organized and balanced folding, transport, modification and degradation of sarcomeric proteins. However, the molecules that mediate these processes are largely unknown. Here, we isolated the zebrafish mutant flatline (fla), which shows disturbed sarcomere assembly exclusively in heart and fast-twitch skeletal muscle. By positional cloning we identified a nonsense mutation within the SET- and MYND-domain-containing protein 1 gene (smyd1) to be responsible for the fla phenotype. We found SMYD1 expression to be restricted to the heart and fast-twitch skeletal muscle cells. Within these cell types, SMYD1 localizes to both the sarcomeric M-line, where it physically associates with myosin, and the nucleus, where it supposedly represses transcription through its SET and MYND domains. However, although we found transcript levels of thick filament chaperones, such as Hsp90a1 and UNC-45b, to be severely upregulated in fla, its histone methyltransferase activity - mainly responsible for the nuclear function of SMYD1 - is dispensable for sarcomerogenesis. Accordingly, sarcomere assembly in fla mutant embryos can be reconstituted by ectopically expressing histone methyltransferase-deficient SMYD1. By contrast, ectopic expression of myosin-binding-deficient SMYD1 does not rescue fla mutants, implicating an essential role for the SMYD1-myosin interaction in cardiac and fast-twitch skeletal muscle thick filament assembly.

Next-generation sequencing identifies novel microRNAs in peripheral blood of lung cancer patients

Abstract: MicroRNAs (miRNAs) are increasingly envisaged as biomarkers for various tumor and non-tumor diseases. MiRNA biomarker identification is, as of now, mostly performed in a candidate approach, limiting discovery to annotated miRNAs and ignoring unknown ones with potential diagnostic value. Here, we applied high-throughput SOLiD transcriptome sequencing of miRNAs expressed in human peripheral blood of patients with lung cancer. We developed a bioinformatics pipeline to generate profiles of miRNA markers and to detect novel miRNAs with diagnostic information. Applying our approach, we detected 76 previously unknown miRNAs and 41 novel mature forms of known precursors. In addition, we identified 32 annotated and seven unknown miRNAs that were significantly altered in cancer patients. These results demonstrate that deep sequencing of small RNAs bears high potential to quantify miRNAs in peripheral blood and to identify previously unknown miRNAs serving as biomarker for lung cancer.

Protein Kinase D2 Controls Cardiac Valve Formation in Zebrafish by Regulating Histone Deacetylase 5 Activity

Abstract: Background—The molecular mechanisms that guide heart valve formation are not well understood. However, elucidation of the genetic basis of congenital heart disease is one of the prerequisites for the development of tissue-engineered heart valves. Methods and Results—We isolated here a mutation in zebrafish, bungee (bngjh177), which selectively perturbs valve formation in the embryonic heart by abrogating endocardial Notch signaling in cardiac cushions. We found by positional cloning that the bng phenotype is caused by a missense mutation (Y849N) in zebrafish protein kinase D2 (pkd2). The bng mutation selectively impairs PKD2 kinase activity and hence Histone deacetylase 5 phosphorylation, nuclear export, and inactivation. As a result, the expression of Histone deacetylase 5 target genes Kruppel-like factor 2a and 4a, transcription factors known to be pivotal for heart valve formation and to act upstream of Notch signaling, is severely downregulated in bungee (bng) mutant embryos. Accordingly, the expressi...

PINCH proteins regulate cardiac contractility by modulating integrin-linked kinase-protein kinase B signaling.

Abstract: Integrin-linked kinase (ILK) is an essential component of the cardiac mechanical stretch sensor and is bound in a protein complex with parvin and PINCH proteins, the so-called ILK-PINCH-parvin (IPP) complex. We have recently shown that inactivation of ILK or β-parvin activity leads to heart failure in zebrafish via reduced protein kinase B (PKB/Akt) activation. Here, we show that PINCH proteins localize at sarcomeric Z disks and costameres in the zebrafish heart and skeletal muscle. To investigate the in vivo role of PINCH proteins for IPP complex stability and PKB signaling within the vertebrate heart, we inactivated PINCH1 and PINCH2 in zebrafish. Inactivation of either PINCH isoform independently leads to instability of ILK, loss of stretch-responsive anf and vegf expression, and progressive heart failure. The predominant cause of heart failure in PINCH morphants seems to be loss of PKB activity, since PKB phosphorylation at serine 473 is significantly reduced in PINCH-deficient hearts and overexpression of constitutively active PKB reconstitutes cardiac function in PINCH morphants. These findings highlight the essential function of PINCH proteins in controlling cardiac contractility by granting IPP/PKB-mediated signaling.

Identification of Novel SNPs in Glioblastoma Using Targeted Resequencing

Abstract: High-throughput sequencing opens avenues to find genetic variations that may be indicative of an increased risk for certain diseases. Linking these genomic data to other “omics” approaches bears the potential to deepen our understanding of pathogenic processes at the molecular level. To detect novel single nucleotide polymorphisms (SNPs) for glioblastoma multiforme (GBM), we used a combination of specific target selection and next generation sequencing (NGS). We generated a microarray covering the exonic regions of 132 GBM associated genes to enrich target sequences in two GBM tissues and corresponding leukocytes of the patients. Enriched target genes were sequenced with Illumina and the resulting reads were mapped to the human genome. With this approach we identified over 6000 SNPs, including over 1300 SNPs located in the targeted genes. Integrating the genome-wide association study (GWAS) catalog and known disease associated SNPs, we found that several of the detected SNPs were previously associated with smoking behavior, body mass index, breast cancer and high-grade glioma. Particularly, the breast cancer associated allele of rs660118 SNP in the gene SART1 showed a near doubled frequency in glioblastoma patients, as verified in an independent control cohort by Sanger sequencing. In addition, we identified SNPs in 20 of 21 GBM associated antigens providing further evidence that genetic variations are significantly associated with the immunogenicity of antigens.

Complex mirna sets as novel biomarkers for an acute coronary syndrome

Abstract: The present invention relates to single polynucleotides or sets of polynucleotides for detecting single miRNAs or sets of miRNAs for diagnosing and/or prognosing of an acute coronary syndrome in a blood sample from a human. Further, the present invention relates to means for diagnosing and/or prognosing of an acute coronary syndrome comprising said polynucleotides or sets of polynucleotides. Furthermore, the present invention relates to a method for diagnosing and/or prognosing of an acute coronary syndrome based on the determination of expression profiles of single miRNAs or sets of miRNAs representative for an acute coronary syndrome compared to a reference. In addition, the present invention relates to a kit for diagnosing and/or prognosing of an acute coronary syndrome comprising means for determining expression profiles of single miRNAs or sets of miRNAs representative for an acute coronary syndrome and at least one reference.

Sudden cardiac death in a patient with lamin A/C mutation in the absence of dilated cardiomyopathy or conduction disease.

Abstract: Dilated cardiomyopathy (DCM) is a frequent form among the cardiomyopathies and displays a very heterogeneous etiology. It is a familial disease in about one-third of DCM cases [8, 14, 16]. More than 20 DCM candidate genes were already identified [2, 4], but the genetic defects in the large majority of familial cases are still unknown. LMNA is among the most common genes affected in familial DCM and is coding for lamin A/C, which is a ubiquitous component of the nuclear skeleton and involved in the regulation of gene expression. However, there are many other non-cardiac diseases like Emery-Dreifuss muscular dystrophy (EDMD2; OMIM 181350), Limb-girdle muscular dystrophy type 1B (LGMD1B; OMIM 159001), Dunnigantype familial partial lipodystrophy (OMIM 151660), Charcot-Marie-Tooth disease (CMT2B1; OMIM 605588), Hutchinson-Gilford progeria syndrome (HGPS; OMIM 176670) and restrictive dermopathy (OMIM 275210), which can result from defects in this gene and are summarized under the term laminopathies [5]. DCM caused by LMNA mutations is attributed to a characteristic phenotype showing atrial fibrillation, skeletal muscle involvement, cardiac conduction defects and a high incidence of sudden death [3, 9, 20, 25, 26]. Due to these complications, DCM patients with LMNA mutations are reported to have a worse prognosis compared to other DCM patients [23, 28] and a nearly complete disease penetrance with disease expression between 20 and 60 years of age [19]. It is estimated that up to 5% of all DCM cases are caused by LMNA mutations [24]. Here we report about a family with a gene mutation in the lamin A/C gene (LMNA) with the incidence of sudden cardiac death even before the manifestation of dilated cardiomyopathy. A 32-year-old woman presented at the outpatient department after a sudden loss of consciousness for seconds, while she was driving a car on a motorway. There were no prodromi before this event and no diseases in the medical history. However, she reported about a premature death of her father at the age of 42 years, which was interpreted as related to myocardial infarction. There were no abnormal clinical findings and the ECG was interpreted as normal. Echocardiography revealed regular findings, with the exception, that in the apex of the right ventricle a small sacculation was suspected. In regard to the clinical event and family history further thorough examination was initiated (Table 1):

The myosin-interacting protein SMYD1 is essential for sarcomere organization

Abstract: Assembly, maintenance and renewal of sarcomeres require highly organized and balanced folding, transport, modification and degradation of sarcomeric proteins. However, the molecules that mediate these processes are largely unknown. Here, we isolated the zebrafish mutant flatline (fla), which shows disturbed sarcomere assembly exclusively in heart and fast-twitch skeletal muscle. By positional cloning we identified a nonsense mutation within the SET- and MYND-domain-containing protein 1 gene (smyd1) to be responsible for the fla phenotype. We found SMYD1 expression to be restricted to the heart and fast-twitch skeletal muscle cells. Within these cell types, SMYD1 localizes to both the sarcomeric M-line, where it physically associates with myosin, and the nucleus, where it supposedly represses transcription through its SET and MYND domains. However, although we found transcript levels of thick filament chaperones, such as Hsp90a1 and UNC-45b, to be severely upregulated in fla, its histone methyltransferase activity - mainly responsible for the nuclear function of SMYD1 - is dispensable for sarcomerogenesis. Accordingly, sarcomere assembly in fla mutant embryos can be reconstituted by ectopically expressing histone methyltransferase-deficient SMYD1. By contrast, ectopic expression of myosin-binding-deficient SMYD1 does not rescue fla mutants, implicating an essential role for the SMYD1-myosin interaction in cardiac and fast-twitch skeletal muscle thick filament assembly.