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Bednarek D.,Regeneration and Aging Group | Gonzalez-Rosa J.M.,ITS Group | Gonzalez-Rosa J.M.,Massachusetts General Hospital | Gonzalez-Rosa J.M.,Harvard University | And 12 more authors.
Cell Reports | Year: 2015

After myocardial infarction in humans, lost cardiomyocytes are replaced by an irreversible fibrotic scar. In contrast, zebrafish hearts efficiently regenerate after injury. Complete regeneration of the zebrafish heart is driven by the strong proliferation response of its cardiomyocytes to injury. Here we show that, after cardiac injury in zebrafish, telomerase becomes hyperactivated, and telomeres elongate transiently, preceding a peak of cardiomyocyte proliferation and full organ recovery. Using a telomerase-mutant zebrafish model, we found that telomerase loss drastically decreases cardiomyocyte proliferation and fibrotic tissue regression after cryoinjury and that cardiac function does not recover. The impaired cardiomyocyte proliferation response is accompanied by the absence of cardiomyocytes with long telomeres and an increased proportion of cardiomyocytes showing DNA damage and senescence characteristics. These findings demonstrate the importance of telomerase function in heart regeneration and highlight the potential of telomerase therapy as a means of stimulating cell proliferation upon myocardial infarction. Bednarek et al. find that telomerase, well known for its role in elongating telomere ends, is essential during zebrafish heart regeneration. Cardiac injury hyperactivates telomerase and increases telomere length in cardiac cells. In telomerase-null mutants, cardiac cells accumulate DNA damage and do not efficiently proliferate in response to injury. © 2015 The Authors.

Alonso R.,IIS Fundacion Jimenez Diaz | Andres E.,Bioinformatic Unit | Mata N.,Madrid Health Authority | Fuentes-Jimenez F.,Hospital Universitario Reina Sofia | And 8 more authors.
Journal of the American College of Cardiology | Year: 2014

Objectives The aim of this study was to determine the relationship between lipoprotein(a) [Lp(a)] and cardiovascular disease (CVD) in a large cohort of patients with heterozygous familial hypercholesterolemia (FH). Background Lp(a) is considered a cardiovascular risk factor. Nevertheless, the role of Lp(a) as a predictor of CVD in patients with FH has been a controversial issue. Methods A cross-sectional analysis of 1,960 patients with FH and 957 non-FH relatives recruited for SAFEHEART (Spanish Familial Hypercholesterolemia Cohort Study), a long-term observational cohort study of a molecularly well-defined FH study group, was performed. Lp(a) concentrations were measured in plasma using an immunoturbidimetric method. Results Patients with FH, especially those with CVD, had higher Lp(a) plasma levels compared with their unaffected relatives (p < 0.001). A significant difference in Lp(a) levels was observed when the most frequent null and defective mutations in LDLR mutations were analyzed (p < 0.0016). On multivariate analysis, Lp(a) was an independent predictor of cardiovascular disease. Patients carrying null mutations and Lp(a) levels >50 mg/dl showed the highest cardiovascular risk compared with patients carrying the same mutations and Lp(a) levels <50 mg/dl. Conclusions Lp(a) is an independent predictor of CVD in men and women with FH. The risk of CVD is higher in those patients with an Lp(a) level >50 mg/dl and carrying a receptor-negative mutation in the LDLR gene compared with other less severe mutations.

Calvete O.,Human Genetics Group | Calvete O.,Center for Biomedical Network Research on Rare Diseases | Martinez P.,Telomeres and Telomerase Group | Garcia-Pavia P.,Hospital Universitario Puerta Of Hierro | And 28 more authors.
Nature Communications | Year: 2015

Cardiac angiosarcoma (CAS) is a rare malignant tumour whose genetic basis is unknown. Here we show, by whole-exome sequencing of a TP53-negative Li-Fraumeni-like (LFL) family including CAS cases, that a missense variant (p.R117C) in POT1 (protection of telomeres 1) gene is responsible for CAS. The same gene alteration is found in two other LFL families with CAS, supporting the causal effect of the identified mutation. We extend the analysis to TP53-negative LFL families with no CAS and find the same mutation in a breast AS family. The mutation is recently found once in 121,324 studied alleles in ExAC server but it is not described in any other database or found in 1,520 Spanish controls. In silico structural analysis suggests how the mutation disrupts POT1 structure. Functional and in vitro studies demonstrate that carriers of the mutation show reduced telomere-bound POT1 levels, abnormally long telomeres and increased telomere fragility. © 2015 Macmillan Publishers Limited. All rights reserved.

Menezes J.,Molecular Cytogenetics Group | Acquadro F.,Molecular Cytogenetics Group | Wiseman M.,NIMGenetics | Gomez-Lopez G.,Bioinformatic Unit | And 14 more authors.
Leukemia | Year: 2014

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a very rare disease that currently lacks genomic and genetic biomarkers to assist in its clinical management. We performed whole-exome sequencing (WES) of three BPDCN cases. Based on these data, we designed a resequencing approach to identify mutations in 38 selected genes in 25 BPDCN samples. WES revealed 37-99 deleterious gene mutations per exome with no common affected genes between patients, but with clear overlap in terms of molecular and disease pathways (hematological and dermatological disease). We identified for the first time deleterious mutations in IKZF3, HOXB9, UBE2G2 and ZEB2 in human leukemia. Target sequencing identified 29 recurring genes, ranging in prevalence from 36% for previously known genes, such as TET2, to 12-16% for newly identified genes, such as IKZF3 or ZEB2. Half of the tumors had mutations affecting either the DNA methylation or chromatin remodeling pathways. The clinical analysis revealed that patients with mutations in DNA methylation pathway had a significantly reduced overall survival (P=0.047). We provide the first mutational profiling of BPDCN. The data support the current WHO classification of the disease as a myeloid disorder and provide a biological rationale for the incorporation of epigenetic therapies for its treatment. © 2014 Macmillan Publishers Limited.

Voellenkle C.,Laboratorio Of Cardiologia Molecolare | Van Rooij J.,Laboratorio Of Cardiologia Molecolare | Cappuzzello C.,Centro Cardiologico Monzino IRCCS | Greco S.,Laboratorio Of Cardiologia Molecolare | And 9 more authors.
Physiological Genomics | Year: 2010

MicroRNAs (miRNAs) are noncoding RNAs that act as negative regulators of gene expression. Interestingly, specific alterations of miRNA expression have been found in failing hearts of different etiologies. The aim of this study was to identify the miRNA expression pattern of peripheral blood mononuclear cells (PBMCs) derived from chronic heart failure (CHF) patients affected by ischemic (ICM) and nonischemic dilated (NIDCM) cardiomyopathy. The expression profile of 257 miRNAs was assessed in 7 NIDCM patients, 8 ICM patients, and 9 control subjects by quantitative real-time PCR. Significantly modulated miRNAs were validated by using an independent set of 34 CHF patients (NIDCM = 19, ICM = 15) and 19 control subjects. Three miRNAs (miR-107, -139, and -142-5p) were downmodulated in both NIDCM and ICM patients versus control subjects. Other miRNAs were deregulated in only one of the CHF classes analyzed compared with control subjects: miR-142-3p and -29b were increased in NIDCM patients, while miR-125b and -497 were decreased in ICM patients. Bioinformatic analysis of miRNA predicted targets and of gene expression modifications associated with CHF in PBMCs indicated a significant impact of the miRNA signature on the transcriptome. Furthermore, miRNAs of both the NIDCM and the ICM signature shared predicted targets among CHF-modulated genes, suggesting potential additive or synergistic effects. The present study identified miRNAs specifically modulated in the PBMCs of NIDCM and ICM patients. Intriguingly, most of these miRNAs were previously reported as deregulated in human and/or mouse failing hearts. The identified miRNAs might have a potential diagnostic and/or prognostic use in CHF. Copyright © 2010 the American Physiological Society.

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