Nebulette knockout mice have normal cardiac function, but show Z-line widening and up-regulation of cardiac stress markers

Aims: Nebulette is a 109 kDa modular protein localized in the sarcomeric Z-line of the heart. In vitro studies have suggested a role of nebulette in stabilizing the thin filament, and missense mutations in the nebulette gene were recently shown to be causative for dilated cardiomyopathy and endocardial fibroelastosis in human and mice. However, the role of nebulette in vivo has remained elusive. To provide insights into the function of nebulette in vivo, we generated and studied nebulette-deficient (nebl-/-) mice. Methods and results: Nebl-/- mice were generated by replacement of exon 1 by Cre under the control of the endogenous nebulette promoter, allowing for lineage analysis using the ROSA26 Cre reporter strain. This revealed specific expression of nebulette in the heart, consistent with in situ hybridization results. Nebl-/- mice exhibited normal cardiac function both under basal conditions and in response to transaortic constriction as assessed by echocardiography and haemodynamic analyses. Furthermore, histological, IF, and western blot analysis showed no cardiac abnormalities in nebl-/- mice up to 8 months of age. In contrast, transmission electron microscopy showed Z-line widening starting from 5 months of age, suggesting that nebulette is important for the integrity of the Z-line. Furthermore, up-regulation of cardiac stress responsive genes suggests the presence of chronic cardiac stress in nebl-/- mice. Conclusion: Nebulette is dispensable for normal cardiac function, although Z-line widening and up-regulation of cardiac stress markers were found in nebl-/- heart. These results suggest that the nebulette disease causing mutations have dominant gain-of-function effects

MicroRNA-134 as a potential plasma biomarker for the diagnosis of acute pulmonary embolism

<p>Abstract</p> <p>Background</p> <p>Acute pulmonary embolism (APE) remains a diagnostic challenge due to a variable clinical presentation and the lack of a reliable screening tool. MicroRNAs (miRNAs) regulate gene expression in a wide range of pathophysiologic processes. Circulating miRNAs are emerging biomarkers in heart failure, type 2 diabetes and other disease states; however, using plasma miRNAs as biomarkers for the diagnosis of APE is still unknown.</p> <p>Methods</p> <p>Thirty-two APE patients, 32 healthy controls, and 22 non-APE patients (reported dyspnea, chest pain, or cough) were enrolled in this study. The TaqMan miRNA microarray was used to identify dysregulated miRNAs in the plasma of APE patients. The TaqMan-based miRNA quantitative real-time reverse transcription polymerase chain reactions were used to validate the dysregulated miRNAs. The receiver-operator characteristic (ROC) curve analysis was conducted to evaluate the diagnostic accuracy of the miRNA identified as the candidate biomarker.</p> <p>Results</p> <p>Plasma miRNA-134 (miR-134) level was significantly higher in the APE patients than in the healthy controls or non-APE patients. The ROC curve showed that plasma miR-134 was a specific diagnostic predictor of APE with an area under the curve of 0.833 (95% confidence interval, 0.737 to 0.929; P < 0.001).</p> <p>Conclusions</p> <p>Our findings indicated that plasma miR-134 could be an important biomarker for the diagnosis of APE. Because of this finding, large-scale investigations are urgently needed to pave the way from basic research to clinical utilization.</p

c-Jun N-Terminal Phosphorylation: Biomarker for Cellular Stress Rather than Cell Death in the Injured Cochlea.

Peer reviewe

PINCH1 Plays an Essential Role in Early Murine Embryonic Development but Is Dispensable in Ventricular Cardiomyocytes

PINCH1, an adaptor protein composed of five LIM domains, mediates protein-protein interactions and functions as a component of the integrin-integrin-linked kinase (ILK) complex. The integrin-ILK signaling complex plays a pivotal role in cell motility, proliferation, and survival during embryonic development of many animal species. To elucidate the physiological function of PINCH1 in mouse embryonic development, we have deleted the mouse PINCH1 gene by homologous recombination. Mice heterozygous for PINCH1 are viable and indistinguishable from wild-type littermates. However, no viable homozygous offspring were observed from PINCH1(+/)(−) intercrosses. Histological analysis of homozygous mutant embryos revealed that they had a disorganized egg cylinder by E5.5, which degenerated by E6.5. Furthermore, E5.5 PINCH1(−)(/)(−) embryos exhibited decreased cell proliferation and excessive cell death. We have also generated and analyzed mice in which PINCH1 has been specifically deleted in ventricular cardiomyocytes. These mice exhibit no basal phenotype, with respect to mouse survival, cardiac histology, or cardiac function as measured by echocardiography. Altogether, these data indicate that PINCH1 plays an essential role in early murine embryonic development but is dispensable in ventricular cardiomyocytes

A central role for Islet1 in sensory neuron development linking sensory and spinal gene regulatory programs

We have used conditional knockout strategies in mice to determine the developmental events and gene expression program regulated by the LIM-homeodomain factor Islet1 in developing sensory neurons. Early development of the trigeminal and dorsal root ganglia are grossly normal in the absence of Islet1. However, from E12.5 onward, Islet1 mutant embryos exhibit loss of the nociceptive markers TrkA and Runx1 and a near absence of cutaneous innervation. Proprioceptive neurons characterized by the expression of TrkC/Runx3/Etv1 are relatively spared. Microarray analysis of Islet1 mutant ganglia reveals prolonged expression of developmental regulators normally restricted to early sensory neurogenesis, and ectopic expression of transcription factors normally found in the CNS but not in sensory ganglia. Later excision of Islet1 does not reactivate early genes, but results in decreased expression of transcripts related to specific sensory functions. Together these results establish a central role for Islet1 in the transition from sensory neurogenesis to subtype specification

Islet 1 is expressed in distinct cardiovascular lineages, including pacemaker and coronary vascular cells

AbstractIslet1 (Isl1) is a LIM homedomain protein that plays a pivotal role in cardiac progenitors of the second heart field. Here, lineage studies with an inducible isl1-cre demonstrated that most Isl1 progenitors have migrated into the heart by E9. Although Isl1 expression is downregulated in most cardiac progenitors as they differentiate, analysis of an isl1-nlacZ mouse and coimmunostaining for Isl1 and lineage markers demonstrated that Isl1 is expressed in distinct subdomains of the heart, and in diverse cardiovascular lineages. Isl1 expression was observed in myocardial lineages of the distal outflow tract, atrial septum, and in sinoatrial and atrioventricular node. The myocardialized septum of the outflow tract was found to derive from Isl1 expressing cells. Isl1 expressing cells also contribute to endothelial and vascular smooth muscle lineages including smooth muscle of the coronary vessels. Our data indicate that Isl1 is a specific marker for a subset of pacemaker cells at developmental stages examined, and suggest genetic heterogeneity within the central conduction system and coronary smooth muscle. Our studies suggest a role for Isl1 in these distinct domains of expression within the heart

Isl1 is required for multiple aspects of motor neuron development

The LIM homeodomain transcription factor Islet1 (Isl1) is expressed in multiple organs and plays essential roles during embryogenesis. Isl1 is required for the survival and specification of spinal cord motor neurons. Due to early embryonic lethality and loss of motor neurons, the role of Isl1 in other aspects of motor neuron development remains unclear. In this study, we generated Isl1 mutant mouse lines expressing graded doses of Isl1. Our study has revealed essential roles of Isl1 in multiple aspects of motor neuron development, including motor neuron cell body localization, motor column formation and axon growth. In addition, Isl1 is required for survival of cranial ganglia neurons.Fil: Liang, Xingqun. Tongji University. School of Medicine. Key Laboratory of Arrhythmia; China. University Of California At San Diego; Estados UnidosFil: Song, Mi Ryoung. School of Life Sciences Gwangju Institute of Science and Technology. Bioimaging Research Center and Cell Dynamics Research Center; Corea del SurFil: Xu, ZengGuang. Tongji University. School of Medicine. Key Laboratory of Arrhythmia; ChinaFil: Lanuza, Guillermo Marcos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquimicas de Buenos Aires; Argentina. Fundación Instituto Leloir; ArgentinaFil: Liu, Yali. Tongji University. School of Medicine. Key Laboratory of Arrhythmia; ChinaFil: Zhuang, Tao. Tongji University. School of Medicine. Key Laboratory of Arrhythmia; ChinaFil: Chen, Yihan. Tongji University. School of Medicine. Key Laboratory of Arrhythmia; ChinaFil: Pfaff, Samuel L. The Salk Institute. Gene Expression Laboratory; Estados UnidosFil: Evans, Sylvia M. Institute of Science and Technology; Corea del Sur. University Of California At San Diego; Estados UnidosFil: Sun, Yunfu. Tongji University. School of Medicine. Key Laboratory of Arrhythmia; China. University Of California At San Diego; Estados Unido