Angelika Holzmann

The miRNA-212/132 family regulates both cardiac hypertrophy and cardiomyocyte autophagy

Pathological growth of cardiomyocytes (hypertrophy) is a major determinant for the development of heart failure, one of the leading medical causes of mortality worldwide. Here we show that the microRNA (miRNA)-212/132 family regulates cardiac hypertrophy and autophagy in cardiomyocytes. Hypertrophic stimuli upregulate cardiomyocyte expression of miR-212 and miR-132, which are both necessary and sufficient to drive the hypertrophic growth of cardiomyocytes. MiR-212/132 null mice are protected from pressure-overload-induced heart failure, whereas cardiomyocyte-specific overexpression of the miR-212/132 family leads to pathological cardiac hypertrophy, heart failure and death in mice. Both miR-212 and miR-132 directly target the anti-hypertrophic and pro-autophagic FoxO3 transcription factor and overexpression of these miRNAs leads to hyperactivation of pro-hypertrophic calcineurin/NFAT signalling and an impaired autophagic response upon starvation. Pharmacological inhibition of miR-132 by antagomir injection rescues cardiac hypertrophy and heart failure in mice, offering a possible therapeutic approach for cardiac failure.

Circulating Long Noncoding RNA, LIPCAR, Predicts Survival in Patients With Heart Failure

Rationale: Long noncoding RNAs represent a novel class of molecules regulating gene expression. Long noncoding RNAs are present in body fluids, but their potential as biomarkers was never investigated in cardiovascular disease. Objective: To study the role of long noncoding RNAs as potential biomarkers in heart disease. Methods and Results: Global transcriptomic analyses were done in plasma RNA from patients with or without left ventricular remodeling after myocardial infarction. Regulated candidates were validated in 3 independent patient cohorts developing cardiac remodeling and heart failure (788 patients). The mitochondrial long noncoding RNA uc022bqs.1 (LIPCAR) was downregulated early after myocardial infarction but upregulated during later stages. LIPCAR levels identified patients developing cardiac remodeling and were independently to other risk markers associated with future cardiovascular deaths. Conclusions: LIPCAR is a novel biomarker of cardiac remodeling and predicts future death in patients with heart failure.Rationale: Long non-coding RNAs (lncRNAs) represent a novel class of molecules regulating gene expression. LncRNAs are present in body fluids, but their potential as biomarkers was never investigated in cardiovascular disease. Objective: Role of lncRNAs as potential biomarkers in heart disease. Methods and Results: Global transcriptomic analyses were done in plasma RNA from patients with/without left ventricular (LV)-remodeling after myocardial infarction. Regulated candidates were validated in three independent patient cohorts developing cardiac remodeling and heart failure (788 patients). The mitochondrial lncRNA uc022bqs.1 ( LIPCAR ) was down-regulated early after MI but up-regulated during later stages. LIPCAR levels identified patients developing cardiac remodeling and were independently to other risk markers associated with future cardiovascular deaths. Conclusions: LIPCAR is a novel biomarker of cardiac remodeling and predicts future death in heart failure patients.

The Circulating Long Non-Coding RNA LIPCAR Predicts Survival in Heart Failure Patients

Rationale: Long noncoding RNAs represent a novel class of molecules regulating gene expression. Long noncoding RNAs are present in body fluids, but their potential as biomarkers was never investigated in cardiovascular disease. Objective: To study the role of long noncoding RNAs as potential biomarkers in heart disease. Methods and Results: Global transcriptomic analyses were done in plasma RNA from patients with or without left ventricular remodeling after myocardial infarction. Regulated candidates were validated in 3 independent patient cohorts developing cardiac remodeling and heart failure (788 patients). The mitochondrial long noncoding RNA uc022bqs.1 (LIPCAR) was downregulated early after myocardial infarction but upregulated during later stages. LIPCAR levels identified patients developing cardiac remodeling and were independently to other risk markers associated with future cardiovascular deaths. Conclusions: LIPCAR is a novel biomarker of cardiac remodeling and predicts future death in patients with heart failure.Rationale: Long non-coding RNAs (lncRNAs) represent a novel class of molecules regulating gene expression. LncRNAs are present in body fluids, but their potential as biomarkers was never investigated in cardiovascular disease. Objective: Role of lncRNAs as potential biomarkers in heart disease. Methods and Results: Global transcriptomic analyses were done in plasma RNA from patients with/without left ventricular (LV)-remodeling after myocardial infarction. Regulated candidates were validated in three independent patient cohorts developing cardiac remodeling and heart failure (788 patients). The mitochondrial lncRNA uc022bqs.1 ( LIPCAR ) was down-regulated early after MI but up-regulated during later stages. LIPCAR levels identified patients developing cardiac remodeling and were independently to other risk markers associated with future cardiovascular deaths. Conclusions: LIPCAR is a novel biomarker of cardiac remodeling and predicts future death in heart failure patients.

miRNA screening reveals a new miRNA family stimulating iPS cell generation via regulation of Meox2

Induced pluripotent stem cells (iPSCs) can be generated by overexpression of Oct4, Sox2 and Klf4 in murine fibroblasts. By conducting a microRNA (miRNA) library screen, we identified a set of miRNAs critically regulating iPSC formation. We revealed a new miRNA family (miR‐130/301/721) as an important regulator of iPSC induction by targeting the homeobox transcription factor Meox2 (also known as Gax). Meox2‐specific silencing mimicked the effects of this miRNA family on reprogramming. Mechanistically, miRNA‐resistant Meox2 overexpression abrogated effects of miR‐130/301/721 on reprogramming. In conclusion, the miRNA family miR‐130/301/721 enhances iPSC generation via repression of Meox2.

Circulating miR-133a and miR-423-5p fail as biomarkers for left ventricular remodeling after myocardial infarction

BACKGROUND Recent studies have suggested that the microRNAs miR-133a and miR-423-5p may serve as useful biomarkers in patients with left ventricular (LV) heart failure or with LV remodeling after myocardial infarction (MI). These results were however obtained in small series of patients and control subjects were used as reference groups. Whether these microRNAs may be indicators of the degree of LV remodeling after MI is unknown. METHODS 246 patients with a first anterior Q-wave MI were included. Serial echocardiographic studies were performed at hospital discharge, 3 months, and 1 year after MI and analyzed at a core laboratory. We investigated the temporal profile (baseline, 1, 3 and 12 months) of circulating miR-133a and miR-423-5p and their relations with cardiac biomarkers (B-type natriuretic peptide, C-reactive protein, and cardiac troponin I) and LV remodeling during the 1 year follow-up. RESULTS There were time-dependent changes in the levels of circulating miR-133a and miR-423-5p with significant increase of miR-133a at 12 months compared to 3 months and significant increase of miR-423-5p at 1, 3, and 12 months compared to baseline. However, miR-133a and miR-423-5p were not associated with indices of LV function and LV remodeling serially assessed during a 1 year period after an acute anterior MI, nor with B-type natriuretic peptide. CONCLUSIONS Circulating levels of miR-133a and miR-423-5p are not useful biomarkers of LV remodeling after MI.

MicroRNA-Mediated Epigenetic Silencing of Sirtuin1 Contributes to Impaired Angiogenic Responses

Rationale: Transforming growth factor (TGF)-&bgr; was linked to abnormal vessel function and can mediate impairment of endothelial angiogenic responses. Its effect on microRNAs and downstream targets in this context is not known. Objective: To study the role of microRNAs in TGF-&bgr;–mediated angiogenic activity. Methods and Results: MicroRNA profiling after TGF-&bgr; treatment of endothelial cells identified miR-30a-3p, along with other members of the miR-30 family, to be strongly silenced. Supplementation of miR-30a-3p restored function in TGF-&bgr;–treated endothelial cells. We identified the epigenetic factor methyl-CpG-binding protein 2 (MeCP2) to be a direct and functional target of miR-30a-3p. Viral overexpression of MeCP2 mimicked the effects of TGF-&bgr;, suggesting that derepression of MeCP2 after TGF-&bgr; treatment may be responsible for impaired angiogenic responses. Silencing of MeCP2 rescued detrimental TGF-&bgr; effects on endothelial cells. Microarray transcriptome analysis of MeCP2-overexpressing endothelial cells identified several deregulated genes important for endothelial cell function including sirtuin1 (Sirt1). In vivo experiments using endothelial cell–specific MeCP2 null or Sirt1 transgenic mice confirmed the involvement of MeCP2/Sirt1 in the regulation of angiogenic functions of endothelial cells. Additional experiments identified that MeCP2 inhibited endothelial angiogenic characteristics partly by epigenetic silencing of Sirt1. Conclusions: TGF-&bgr; impairs endothelial angiogenic responses partly by downregulating miR-30a-3p and subsequent derepression of MeCP2-mediated epigenetic silencing of Sirt1.

Functional microRNA library screening identifies the hypoxamir miR-24 as a potent regulator of smooth muscle cell proliferation and vascularization.

UNLABELLED Smooth muscle cells (SMCs) are key components within the vasculature. Dependent on the stimulus, SMC can either be in a proliferative (synthetic) or differentiated state. Alterations of SMC phenotype also appear in several disease settings, further contributing to disease progression. AIMS Here, we asked whether microRNAs (miRNAs, miRs), which are strong posttranscriptional regulators of gene expression, could alter SMC proliferation. Results and Innovation: Employing a robotic-assisted high-throughput screening method using miRNA libraries, we identified hypoxia-regulated miR-24 as a master regulator of SMC proliferation. Proteome profiling showed a strong miR-24-dependent impact on cellular stress-associated factors, overall resulting in reduced stress resistance. In vitro, synthetic miR-24 overexpression had detrimental effects on SMC functional capacity inducing apoptosis, migration defects, enhanced autophagy, and loss of contractile marker genes. Impaired SMC function was mediated in part by the herein identified direct target gene heme oxygenase 1. Ex vivo, miR-24 was shown to inhibit the development of vasculature in a model of engineered heart tissue. CONCLUSION Collectively, we report the identification of the hypoxamir-24 as an inhibitor of SMC proliferation, contributing to loss of vascularization.

MicroRNAs in the bile of patients with biliary strictures after liver transplantation

Biliary complications after liver transplantation remain a major cause of morbidity and reduced graft survival. Ischemic‐type biliary lesions (ITBLs) are common and difficult to treat. The pathophysiology of ITBLs remains unclear, and diagnostic markers are still missing. The analysis of microRNA (miRNA) profiles is an evolving field in hepatology. Our aim was to identify specific miRNA patterns in the bile of patients with ITBLs after liver transplantation. Liver transplant patients with biliary complications were included in a cross‐sectional study. Patients with ITBLs (n = 37), anastomotic strictures (ASs; n = 39), and bile duct stones (BDSs; n = 12) were compared. Patients with ITBLs were categorized by disease severity. The miRNA concentrations in bile were determined with global miRNA profiling and subsequent miRNA‐specific polymerase chain reaction–mediated validation. The concentrations of microRNA 517a (miR‐517a), miR‐892a, and miR‐106a* in bile were increased for patients with ITBLs versus patients with ASs or BDSs (P < 0.05). Categorization by ITBL severity showed higher median concentrations in patients with intrahepatic and extrahepatic strictures (P > 0.05). miR‐210, miR‐337‐5p, miR‐577, and miR‐329 displayed no statistical differences. In conclusion, miR‐517a, miR‐892a, and miR‐106a* are increased in the bile fluid of patients with ITBLs versus patients with ASs or BDSs. An analysis of miRNA profiles may be useful in the diagnosis and management of patients with ITBLs. Future studies are needed to prove the potential prognostic value of these miRNAs. Liver Transpl 20:673‐678, 2014.