0393: Impact of miR-378* and its target desmin intermediate filament on mitochondria distribution in cardiomyocytes

BackgroundMiR-378 and miR-378* microRNAs are derived from an intron of the PGC-1β gene, a regulator of mitochondrial biogenesis. Their expression is either repressed or increased during heart failure depending on the model. Through proteomics approaches, we previously identified new targets of these miRs in H9c2 fetal cardiomyoblasts, among which lactate dehydrogenase for miR-378 and key cytoskeletal proteins for miR-378*.AimsTo better assess its role in energy metabolism and differentiation; we overexpressed miR-378 and miR-378* in primary neonate rat cardiomyocytes (NRC) that are more differentiated and less proliferative than H9c2 cardiomyoblasts.ResultsWe identified desmin as a new target of miR-378* in NRC. Desmin network plays a key role as a structural integrator of myofibrils and mitochondria positioning. MiR-378* overexpression reduced desmin levels and disrupted its organization. Confocal microscopy analysis of NRC stained with the mitochondrial dye MitoTracker revealed that miR-378* overexpression alters mitochondria distribution in the cell. AAV-mediated rescue of desmin expression in presence of miR-378* preserved mitochondria distribution. Mir-378 overexpression had a milder impact on cell organization than miR-378* and did not directly targetted desmin.Conclusion and perspectivesThese results suggest that changes in miR-378* expression level could play an important role in the coupled alteration of cytoskeletal and mitochondrial networks observed in failing myocardium.Abstract 0393 – Figure: Biological functions regulated by miR-378/378

Humeral Artery Aneurysm Revealing a Rare Association between Tuberculosis and Behçet’s Disease

The association of pulmonary tuberculosis and Behçet’s disease revealed by an aneurysm of the humeral artery is exceptional with a complicated management. We report a case in which the two conditions occurred concomitantly with the vascular complication, apart from any use of immunosuppressive therapy, something that has never been reported in the literature. We report an extremely rare case of a spontaneous rupture of an aneurysm of the humeral artery of a 29-year-old woman, with no history. The patient underwent axillo-humeral bypass. Investigations concluded the diagnosis of Behçet’s disease associated with pulmonary and lymph node tuberculosis. Anti-tuberculous chemotherapy followed by corticosteroids, immunosuppressants and colchicine have been administrated. Based on this observation, we insist on the necessity of searching the symptoms of Behçet’s disease in the presence of arterial involvement when having a young patient. Therapeutic management must include medical treatment to control inflammation and limit the risk of recurrence. Endovascular or surgical treatment is necessary if the arterial involvement is threatening. The association with tuberculosis complicates management and requires close monitoring

Proteome Modulation in H9c2 Cardiac Cells by microRNAs miR-378 and miR-378

International audienceMicroRNAs are a novel class of powerful endogenous regulators of gene expression. MiR-378 and miR-378* are localized in the first intron of the Ppargc1b gene that codes the transcriptional co-activator PGC-1. The latter regulates energy expenditure as well as mitochondrial biogenesis. The miR-378:miR-378* hairpin is highly expressed in cardiac cells. To better assess their role in cardiomyocytes, we identified miR-378 and miR-378* targets via a proteomic screen. We established H9c2 cellular models of overexpression of miR-378 and miR-378* and identified a total of 86 down-regulated proteins in the presence of either one of these miRs. Functional annotation clustering showed that miR-378 and miR-378* regulate related pathways in cardiomyocytes, including energy metabolism, notably glycolysis, cytoskeleton, notably actin filaments and muscle contraction. Using bioinformatics algorithms we found that 20 proteins were predicted as direct targets of the miRs. We validated eight of these targets by quantitative RT-PCR and luciferase reporter assay. We found that miR-378 targets lactate dehydrogenase A and impacts on cell proliferation and survival whereas miR-378* targets cytoskeleton proteins actin and vimentin. Proteins involved in endoplasmic reticulum stress response such as chaperone and/or calcium buffering proteins GRP78, PPIA (cyclophilin A), calumenin, and GMMPA involved in glycosylation are repressed by these miRs. Our results show that the miR-378/378* hairpin establishes a connection among energy metabolism, cytoskeleton remodeling, and endoplasmic reticulum function through post-transcriptional regulation of key proteins involved in theses pathways

A tale about an unusual cause of pygalgia in non‐radiographic axial spondyloarthritis

Abstract Schwannoma are tumors of Schwann cells of the peripheral nerve sheath. Sacral location is rarely reported especially in spondyloarthritis patients. Herein, we report a case of uncommon pygalgia in a 25‐year‐old man with history of a non‐radiographic axial spondyloarthritis and in whom the diagnosis of sacral Schwannoma was established

An SRF/miR-1 axis regulates NCX1 and Annexin A5 protein levels in the normal and failing heart

International audienceThe expression of the sodium/calcium exchanger NCX1 increases during cardiac hypertrophy and heart failure, playing an important role in Ca-2 extrusion. This increase is presumed to result from stress signalling induced changes in the interplay between transcriptional and post-transcriptional regulations. We aimed to determine the impact of the SRF transcription factor known to regulate the NCX1 promoter and microRNA genes, on the expression of NCX1 mRNA and protein and Annexin A5 (AnxA5), a Ca-2-binding protein interacting with NCX1 and increased during HF. NCX1 mRNA was decreased while the protein was increased in the failing heart of the cardiomyocyte-restricted SRF knock-out mice (SRFHKO). The induction of NCX1 mRNA by the pro-hypertrophic drug phenylephrine observed in control mice was abolished in the SRFHKO though the protein was strongly increased. AnxA5 protein expression profile paralleled the expression of NCX1 protein in the SRFHKO. MiR-1, a microRNA regulated by SRF, was decreased in the SRFHKO and repressed by phenylephrine. In vitro and in vivo manipulation of miR-1 levels and site-directed mutagenesis showed that NCX1 and AnxA5 mRNAs are targets of miR-1. AnxA5 overexpression slowed down Ca-2 extrusion during caffeine application in adult rat cardiomyocytes. Our study reveals the existence of a complex regulatory loop where SRF regulates the transcription of NCX1 and miR-1, which in turn functions as a rheostat limiting the translation of NCX1 and AnxA5 proteins. The decrease of miR-1 and increase of AnxA5 appear as important modulators of NCX1 expression and activity during heart failure