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Alterations in the balance of cytoskeleton as well as energetic proteins are involved in the cardiac remodeling occurring in dilated cardiomyopathy (DCM). We used two-dimensional DIGE proteomics as a discovery approach to identify key molecular changes taking place in a temporally controlled model of DCM triggered by cardiomyocyte-specific serum response factor (SRF) knock-out in mice. We identified muscle creatine kinase (MCK) as the primary down-regulated protein followed by ␣-actin and ␣-tropomyosin down-regulation leading to a decrease of polymerized F-actin. The early response to these defects was an increase in the amount of desmin intermediate filaments and phosphorylation of the ␣B-crystallin chaperone. We found that ␣B-crystallin and desmin progressively lose their striated pattern and accumulate at the intercalated disk and the sarcolemma, respectively. We further show that desmin is a preferential target of advanced glycation end products (AGE) in mouse and human DCM. Inhibition of CK in cultured cardiomyocytes is sufficient to recapitulate both the actin depolymerization defect and the modification of desmin by AGE. Treatment with either cytochalasin D or glyoxal, a cellular AGE, indicated that both actin depolymerization and AGE contribute to desmin disorganization. Heat shock-induced phosphorylation of ␣B-crystallin provides a transient protection of desmin against glyoxal in a p38 MAPK-dependent manner. Our results show that the strong down-regulation of MCK activity contributes to F-actin instability and induces post-translational modification of ␣B-crystallin and desmin. Our results suggest that AGE may play an important role in DCM because they alter the organization of desmin filaments that normally support stress response and mitochondrial functions in cardiomyocytes.

BackgroundThe impact of overweight among men of reproductive-age may affect fertility. Abdominal fat, more than body mass index, is an indicator of higher metabolic risk, which seems to be involved in decreasing sperm quality. This study aims to assess the relationship between abdominal fat and sperm DNA fragmentation and the effect of abdominal fat loss, among 6 men in subfertile couples.MethodsSperm DNA fragmentation, abdominal fat and metabolic and hormonal profiles were measured in the 6 men before and after dietary advices. Seminal oxidative stress and antioxidant markers were determined.ResultsAfter several months of a lifestyle program, all 6 men lost abdominal fat (patient 1: loss of 3 points of abdominal fat, patient 2: loss of 3 points, patient 3: loss of 2 points, patient 4: loss of 1 point, patient 5: loss of 4 points and patient 6: loss of 13 points). At the same time, their rate of sperm DNA fragmentation decreased: 9.5% vs 31%, 24% vs 43%, 18% vs 47%, 26.3% vs 66%, 25.4% vs 35% and 1.7% vs 25%. Also, an improvement in both metabolic (significant decrease in triglycerides and total cholesterol; p = 0.0139) and hormonal (significant increase in testosterone/oestradiol ratio; p = 0.0139) blood profiles was observed after following the lifestyle program. In seminal plasma, the amount of SOD2 has significantly increased (p = 0.0139) while in parallel carbonylated proteins have decreased. Furthermore, all spouses got pregnant. All pregnancies were brought to term.ConclusionThis study shows specifically that sperm DNA fragmentation among men in subfertile couples could be affected by abdominal fat, but improvement of lifestyle factor may correct this alteration. The effect of specific abdominal fat loss on sperm quality needs further investigation. The reduction of oxidative stress may be a contributing factor.

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MicroRNAs 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. Molecular & Cellular Proteomics 13: 10.1074/mcp.M113.030569, 18-29, 2014.