The overlapping histological and biochemical features underlying the beneficial effect of deacetylase inhibitors and NO donors in dystrophic muscles suggest an unanticipated molecular link among dystrophin, NO signaling, and the histone deacetylases (HDACs). Higher global deacetylase activity and selective increased expression of the class I histone deacetylase HDAC2 were detected in muscles of dystrophin-deficient MDX mice. In vitro and in vivo siRNA-mediated down-regulation of HDAC2 in dystrophic muscles was sufficient to replicate the morphological and functional benefits observed with deacetylase inhibitors and NO donors. We found that restoration of NO signaling in vivo, by adenoviral-mediated expression of a constitutively active endothelial NOS mutant in MDX muscles, and in vitro, by exposing MDX-derived satellite cells to NO donors, resulted in HDAC2 blockade by cysteine S-nitrosylation. These data reveal a special contribution of HDAC2 in the pathogenesis of Duchenne muscular dystrophy and indicate that HDAC2 inhibition by NO-dependent S-nitrosylation is important for the therapeutic response to NO donors in MDX mice. They also define a common target for independent pharmacological interventions in the treatment of Duchenne muscular dystrophy.

The aim of this work was to identify micro‐RNAs (miRNAs) involved in the pathological pathways activated in skeletal muscle damage and regeneration by both dystrophin absence and acute ischemia. Eleven miRNAs were deregulated both in MDX mice and in Duchenne muscular dystrophy patients (DMD signature). Therapeutic interventions ameliorating the mdx ‐phenotype rescued DMD‐signature alterations. The significance of DMD‐signature changes was characterized using a damage/regeneration mouse model of hind‐limb ischemia and newborn mice. According to their expression, DMD‐signature miRNAs were divided into 3 classes. 1 ) Regeneration miRNAs, miR‐31, miR‐34c, miR‐206, miR‐335, miR‐449, and miR‐494, which were induced in MDX mice and in DMD patients, but also in newborn mice and in newly formed myofibers during postischemic regeneration. Notably, miR‐206, miR‐34c, and miR‐335 were up‐regulated following myoblast differentiation in vitro. 2 ) Degenerative‐miRNAs, miR‐1, miR‐29c, and miR‐135a, that were down‐modulated in MDX mice, in DMD patients, in the degenerative phase of the ischemia response, and in newborn mice. Their down‐modulation was linked to myofiber loss and fibrosis. 3 ) Inflammatory miRNAs, miR‐222 and miR‐223, which were expressed in damaged muscle areas, and their expression correlated with the presence of infiltrating inflammatory cells. These findings show an important role of miRNAs in physiopathological pathways regulating muscle response to damage and regeneration.—Greco, S., De Simone, M., Colussi, C., Zaccagnini, G., Fasanaro, P., Pescatori, M., Cardani, R., Perbellini, R., Isaia, E., Sale, P., Meola, G., Capogrossi, M. C., Gaetano, C., Martelli, F. Common micro‐RNA signature in skeletal muscle damage and regeneration induced by Duchenne muscular dystrophy and acute ischemia. FASEB J . 23, 3335–3346 (2009). www.fasebj.org

Long noncoding RNAs (lncRNAs) are non-protein coding transcripts regulating a variety of physiological and pathological functions. However, their implication in heart failure is still largely unknown. The aim of this study is to identify and characterize lncRNAs deregulated in patients affected by ischemic heart failure. LncRNAs were profiled and validated in left ventricle biopsies of 18 patients affected by non end-stage dilated ischemic cardiomyopathy and 17 matched controls. Further validations were performed in left ventricle samples derived from explanted hearts of end-stage heart failure patients and in a mouse model of cardiac hypertrophy, obtained by transverse aortic constriction. Peripheral blood mononuclear cells of heart failure patients were also analyzed. LncRNA distribution in the heart was assessed by in situ hybridization. Function of the deregulated lncRNA was explored analyzing the expression of the neighbor mRNAs and by gene ontology analysis of the correlating coding transcripts. Fourteen lncRNAs were significantly modulated in non end-stage heart failure patients, identifying a heart failure lncRNA signature. Nine of these lncRNAs (CDKN2B-AS1/ANRIL, EGOT, H19, HOTAIR, LOC285194/TUSC7, RMRP, RNY5, SOX2-OT and SRA1) were also confirmed in end-stage failing hearts. Intriguingly, among the conserved lncRNAs, h19, rmrp and hotair were also induced in a mouse model of heart hypertrophy. CDKN2B-AS1/ANRIL, HOTAIR and LOC285194/TUSC7 showed similar modulation in peripheral blood mononuclear cells and heart tissue, suggesting a potential role as disease biomarkers. Interestingly, RMRP displayed a ubiquitous nuclear distribution, while H19 RNA was more abundant in blood vessels and was both cytoplasmic and nuclear. Gene ontology analysis of the mRNAs displaying a significant correlation in expression with heart failure lncRNAs identified numerous pathways and functions involved in heart failure progression. These data strongly suggest lncRNA implication in the molecular mechanisms underpinning HF.

Long noncoding RNAs (lncRNAs) are non-protein coding RNAs regulating gene expression. Although for some lncRNAs a relevant role in hypoxic endothelium has been shown, the regulation and function of lncRNAs is still largely unknown in the vascular physio-pathology. Taking advantage of next-generation sequencing techniques, transcriptomic changes induced by endothelial cell exposure to hypoxia were investigated. Paired-end sequencing of polyadenylated RNA derived from human umbilical vein endothelial cells (HUVECs) exposed to 1% O₂ or normoxia was performed. Bioinformatics analysis identified ≈2000 differentially expressed genes, including 122 lncRNAs. Extensive validation was performed by both microarray and qPCR. Among the validated lncRNAs, H19, MIR210HG, MEG9, MALAT1 and MIR22HG were also induced in a mouse model of hindlimb ischemia. To test the functional relevance of lncRNAs in endothelial cells, knockdown of H19 expression was performed. H19 inhibition decreased HUVEC growth, inducing their accumulation in G1 phase of the cell cycle; accordingly, p21 (CDKN1A) expression was increased. Additionally, H19 knockdown also diminished HUVEC ability to form capillary like structures when plated on matrigel. In conclusion, a high-confidence signature of lncRNAs modulated by hypoxia in HUVEC was identified and a significant impact of H19 lncRNA was shown.

Background— Oxidative stress plays a pivotal role in ischemia and ischemia/reperfusion injury. Because p66 ^ShcA -null (p66 ^ShcA −/−) mice exhibit both lower levels of intracellular reactive oxygen species and increased resistance to cell death induced by oxidative stress, we investigated whether tissue damage that follows acute ischemia or ischemia/reperfusion was altered in p66 ^ShcA −/− mice. Methods and Results— Unilateral hindlimb ischemia was induced by femoral artery dissection, and ischemia/reperfusion was induced with an elastic tourniquet. Both procedures caused similar changes in blood perfusion in p66 ^ShcA wild-type (p66 ^ShcA wt) and p66 ^ShcA −/− mice. However, significant differences in tissue damage were found: p66 ^ShcA wt mice displayed marked capillary density decrease and muscle fiber necrosis. In contrast, in p66 ^ShcA −/− mice, minimal capillary density decrease and myofiber death were present. When apoptosis after ischemia was assayed, significantly lower levels of apoptotic endothelial cells and myofibers were found in p66 ^ShcA −/− mice. In agreement with these data, both satellite muscle cells and endothelial cells isolated from p66 ^ShcA −/− mice were resistant to apoptosis induced by simulated ischemia in vitro. Lower apoptosis levels after ischemia in p66 ^ShcA −/− cells correlated with decreased levels of oxidative stress both in vivo and in vitro. Conclusions— p66 ^ShcA plays a crucial role in the cell death pathways activated by acute ischemia and ischemia/reperfusion, indicating p66 ^ShcA as a potential therapeutic target for prevention and treatment of ischemic tissue damage.