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Coronavirus disease 2019 (COVID-19) spawned a global health crisis in late 2019 and is caused by the novel coronavirus SARS-CoV-2. SARS-CoV-2 infection can lead to elevated markers of endothelial dysfunction associated with higher risk of mortality. It is unclear whether endothelial dysfunction is caused by direct infection of endothelial cells or is mainly secondary to inflammation. Here, we investigate whether different types of endothelial cells are susceptible to SARS-CoV-2. Human endothelial cells from different vascular beds including umbilical vein endothelial cells, coronary artery endothelial cells (HCAEC), cardiac and lung microvascular endothelial cells, or pulmonary arterial cells were inoculated in vitro with SARS-CoV-2. Viral spike protein was only detected in HCAECs after SARS-CoV-2 infection but not in the other endothelial cells tested. Consistently, only HCAEC expressed the SARS-CoV-2 receptor angiotensin-converting enzyme 2 (ACE2), required for virus infection. Infection with the SARS-CoV-2 variants B.1.1.7, B.1.351, and P.2 resulted in significantly higher levels of viral spike protein. Despite this, no intracellular double-stranded viral RNA was detected and the supernatant did not contain infectious virus. Analysis of the cellular distribution of the spike protein revealed that it co-localized with endosomal calnexin. SARS-CoV-2 infection did induce the ER stress gene EDEM1, which is responsible for clearance of misfolded proteins from the ER. Whereas the wild type of SARS-CoV-2 did not induce cytotoxic or pro-inflammatory effects, the variant B.1.1.7 reduced the HCAEC cell number. Of the different tested endothelial cells, HCAECs showed highest viral uptake but did not promote virus replication. Effects on cell number were only observed after infection with the variant B.1.1.7, suggesting that endothelial protection may be particularly important in patients infected with this variant.
Heart and vessels form a highly complex organ system in which extremely diverse cells have to work together correctly to provide all organs with blood. In past decades, heart biology placed its focus on whole tissues or cell isolates. Now, however, new technologies allow the tracing of a diversity of cell types and their individual responses to signals down to the level of proteins and genes. Researchers hope this will help them better support the regeneration of diseased hearts.
Long non-coding RNAs (lncRNAs) contribute to cardiac (patho)physiology. Aging is the major risk factor for cardiovascular disease with cardiomyocyte apoptosis as one underlying cause. Here, we report the identification of the aging-regulated lncRNA Sarrah (ENSMUST00000140003) that is anti-apoptotic in cardiomyocytes. Importantly, loss of SARRAH (OXCT1-AS1) in human engineered heart tissue results in impaired contractile force development. SARRAH directly binds to the promoters of genes downregulated after SARRAH silencing via RNA-DNA triple helix formation and cardiomyocytes lacking the triple helix forming domain of Sarrah show an increase in apoptosis. One of the direct SARRAH targets is NRF2, and restoration of NRF2 levels after SARRAH silencing partially rescues the reduction in cell viability. Overexpression of Sarrah in mice shows better recovery of cardiac contractile function after AMI compared to control mice. In summary, we identified the anti-apoptotic evolutionary conserved lncRNA Sarrah, which is downregulated by aging, as a regulator of cardiomyocyte survival.
Aims: Long non-coding RNAs (lncRNAs) have been shown to regulate numerous processes in the human genome, but the function of these transcripts in vascular aging is largely unknown. We aim to characterize the expression of lncRNAs in endothelial aging and analyse the function of the highly conserved lncRNA H19.
Methods and results: H19 was downregulated in endothelium of aged mice. In human, atherosclerotic plaques H19 was mainly expressed by endothelial cells and H19 was significantly reduced in comparison to healthy carotid artery biopsies. Loss of H19 led to an upregulation of p16 and p21, reduced proliferation and increased senescence in vitro. Depletion of H19 in aortic rings of young mice inhibited sprouting capacity. We generated endothelial-specific inducible H19 deficient mice (H19iEC-KO), resulting in increased systolic blood pressure compared with control littermates (Ctrl). These H19iEC-KO and Ctrl mice were subjected to hindlimb ischaemia, which showed reduced capillary density in H19iEC-KO mice. Mechanistically, exon array analysis revealed an involvement of H19 in IL-6 signalling. Accordingly, intercellular adhesion molecule 1 and vascular cell adhesion molecule 1 were upregulated upon H19 depletion. A luciferase reporter screen for differential transcription factor activity revealed STAT3 as being induced upon H19 depletion and repressed after H19 overexpression. Furthermore, depletion of H19 increased the phosphorylation of STAT3 at TYR705 and pharmacological inhibition of STAT3 activation abolished the effects of H19 silencing on p21 and vascular cell adhesion molecule 1 expression as well as proliferation.
Conclusion: These data reveal a pivotal role for the lncRNA H19 in controlling endothelial cell aging.
Ein Zell-Atlas des kranken Herzens : Einzelzelltechniken ermöglichen neue Einsichten auf Zellebene
(2019)
Herz und Gefäße bilden ein hochkomplexes Organsystem, in dem unterschiedlichste Zellen korrekt zusammenarbeiten müssen, um alle Organe mit Blut zu versorgen. In den vergangenen Jahrzehnten hat die Herzbiologie ganze Gewebe oder Zellisolate in den Blick genommen. Doch jetzt erlauben neue Technologien, die Vielfalt der Zelltypen und ihre individuelle Antwort auf Signale bis auf die Ebene von Proteinen und Genen zu verfolgen. Forscher hoffen, kranken Herzen dadurch besser bei der Regeneration helfen zu können.
In einem Wurm wurden sie 1993 zuerst entdeckt: kleine Ribonukleinsäuren (microRNAs), die nicht für ein Protein kodieren, sondern gezielt mit Boten-RNA (mRNA) paaren. Damit stoppen sie die Übersetzung der mRNA in Protein (Translation) oder lösen den Abbau der Ziel-mRNA aus. In den folgenden Jahren wurde deutlich, dass microRNAs auch beim Menschen eine wichtige Rolle spielen. Möglicherweise ist jedes dritte oder vierte Gen durch microRNA reguliert. Nur zwei bis drei Prozent des humanen Genoms kodiert Proteine; die Mehrzahl der gebildeten RNAs (über 80 Prozent) haben unbekannte oder regulatorische Funktionen. ...
Bone marrow and plasma FGF‐23 in heart failure patients : novel insights into the heart–bone axis
(2019)
Aims: Fibroblast growth factor 23 (FGF‐23) is known to be elevated in patients with congestive heart failure (CHF). As FGF‐23 is expressed in the bone but can also be expressed in the myocardium, the origin of serum FGF‐23 in CHF remains unclear. It is also unclear if FGF‐23 expressed in the bone is associated with outcome in CHF. The aim of the present study was to investigate FGF‐23 levels measured in bone marrow plasma (FGF‐23‐BM) and in peripheral blood (FGF‐23‐P) in CHF patients to gain further insights into the heart–bone axis of FGF‐23 expression. We also investigated possible associations between FGF‐23‐BM as well as FGF‐23‐P and outcome in CHF patients.
Methods and results: We determined FGF‐23‐P and FGF‐23‐BM levels in 203 CHF patients (85% male, mean age 61.3 years) with a left ventricular ejection fraction (LVEF) ≤45% and compared them with those of 48 healthy controls (48% male, mean age 39.2 years). We investigated the association between FGF‐23‐BM and FGF‐23‐P with all‐cause mortality in CHF patients, 32 events, median follow‐up 1673 days, interquartile range [923, 1828]. FGF‐23‐P (median 60.3 vs. 22.0 RU/mL, P < 0.001) and FGF‐23‐BM (median 130.7 vs. 93.1 RU/mL, P < 0.001) levels were higher in CHF patients compared with healthy controls. FGF‐23‐BM levels were significantly higher than FGF‐23‐P levels in both CHF patients and in healthy controls (P < 0.001). FGF‐23‐P and FGF‐23‐BM correlated significantly with LVEF (r = −0.37 and r = −0.33, respectively), N terminal pro brain natriuretic peptide levels (r = 0.57 and r = 0.6, respectively), New York Heart Association status (r = 0.28 and r = 0.25, respectively), and estimated glomerular filtration rate (r = −0.43 and r = −0.41, respectively) (P for all <0.001) and were independently associated with all‐cause mortality in CHF patients after adjustment for LVEF, estimated glomerular filtration rate, New York Heart Association status, and N terminal pro brain natriuretic peptide, hazard ratio 2.71 [confidence interval: 1.18–6.20], P = 0.018, and hazard ratio 2.80 [confidence interval: 1.19–6.57], P = 0.018, respectively.
Conclusions: In CHF patients, FGF‐23 is elevated in bone marrow plasma and is independently associated with heart failure severity and all‐cause mortality. The failing heart seems to interact via FGF‐23 within a heart–bone axis.
Endothelial to mesenchymal transition in cardiovascular disease : JACC state-of-the-art review
(2019)
Endothelial to mesenchymal transition (EndMT) is a process whereby an endothelial cell undergoes a series of molecular events that lead to a change in phenotype toward a mesenchymal cell (e.g., myofibroblast, smooth muscle cell). EndMT plays a fundamental role during development, and mounting evidence indicates that EndMT is involved in adult cardiovascular diseases (CVDs), including atherosclerosis, pulmonary hypertension, valvular disease, and fibroelastosis. Therefore, the targeting of EndMT may hold therapeutic promise for treating CVD. However, the field faces a number of challenges, including the lack of a precise functional and molecular definition, a lack of understanding of the causative pathological role of EndMT in CVDs (versus being a “bystander-phenomenon”), and a lack of robust human data corroborating the extent and causality of EndMT in adult CVDs. Here, we review this emerging but exciting field, and propose a framework for its systematic advancement at the molecular and translational levels.
Improved risk stratification in prevention by use of a panel of selected circulating microRNAs
(2017)
Risk stratification is crucial in prevention. Circulating microRNAs have been proposed as biomarkers in cardiovascular disease. Here a miR panel consisting of miRs related to different cardiovascular pathophysiologies, was evaluated to predict outcome in the context of prevention. MiR-34a, miR-223, miR-378, miR-499 and miR-133 were determined from peripheral blood by qPCR and combined to a risk panel. As derivation cohort, 178 individuals of the DETECT study, and as validation cohort, 129 individuals of the SHIP study were used in a case-control approach. Overall mortality and cardiovascular events were outcome measures. The Framingham Risk Score(FRS) and the SCORE system were applied as risk classification systems. The identified miR panel was significantly associated with mortality given by a hazard ratio(HR) of 3.0 (95% (CI): 1.09–8.43; p = 0.034) and of 2.9 (95% CI: 1.32–6.33; p = 0.008) after adjusting for the FRS in the derivation cohort. In a validation cohort the miR-panel had a HR of 1.31 (95% CI: 1.03–1.66; p = 0.03) and of 1.29 (95% CI: 1.02–1.64; p = 0.03) in a FRS/SCORE adjusted-model. A FRS/SCORE risk model was significantly improved to predict mortality by the miR panel with continuous net reclassification index of 0.42/0.49 (p = 0.014/0.005). The present miR panel of 5 circulating miRs is able to improve risk stratification in prevention with respect to mortality beyond the FRS or SCORE.
Crescentic rapidly progressive glomerulonephritis (RPGN) represents the most aggressive form of acquired glomerular disease. While most therapeutic approaches involve potentially toxic immunosuppressive strategies, the pathophysiology remains incompletely understood. Podocytes are glomerular epithelial cells that are normally growth-arrested because of the expression of cyclin-dependent kinase (CDK) inhibitors. An exception is in RPGN where podocytes undergo a deregulation of their differentiated phenotype and proliferate. Here we demonstrate that microRNA-92a (miR-92a) is enriched in podocytes of patients and mice with RPGN. The CDK inhibitor p57Kip2 is a major target of miR-92a that constitutively safeguards podocyte cell cycle quiescence. Podocyte-specific deletion of miR-92a in mice de-repressed the expression of p57Kip2 and prevented glomerular injury in RPGN. Administration of an anti-miR-92a after disease initiation prevented albuminuria and kidney failure, indicating miR-92a inhibition as a potential therapeutic strategy for RPGN. We demonstrate that miRNA induction in epithelial cells can break glomerular tolerance to immune injury.