A small RNA response at DNA ends in Drosophila

Small RNAs have been implicated in numerous cellular processes, including effects on chromatin structure and the repression of transposons. We describe the generation of a small RNA response at DNA ends in Drosophila that is analogous to the recently reported double-strand break (DSB)-induced RNAs or Dicer- and Drosha-dependent small RNAs in Arabidopsis and vertebrates. Active transcription in the vicinity of the break amplifies this small RNA response, demonstrating that the normal messenger RNA contributes to the endogenous small interfering RNAs precursor. The double-stranded RNA precursor forms with an antisense transcript that initiates at the DNA break. Breaks are thus sites of transcription initiation, a novel aspect of the cellular DSB response. This response is specific to a double-strand break since nicked DNA structures do not trigger small RNA production. The small RNAs are generated independently of the exact end structure (blunt, 3′- or 5′-overhang), can repress homologous sequences in trans and may therefore—in addition to putative roles in repair—exert a quality control function by clearing potentially truncated messages from genes in the vicinity of the break

Laminar shear stress inhibits endothelial cell metabolism via KLF2-mediated repression of PFKFB3

Objective: Cellular metabolism was recently shown to regulate endothelial cell phenotype profoundly. Whether the atheroprotective biomechanical stimulus elicited by laminar shear stress modulates endothelial cell metabolism is not known. Approach and Results: Here, we show that laminar flow exposure reduced glucose uptake and mitochondrial content in endothelium. Shear stress-mediated reduction of endothelial metabolism was reversed by silencing the flow-sensitive transcription factor Krüppel-like factor 2 (KLF2). Endothelial-specific deletion of KLF2 in mice induced glucose uptake in endothelial cells of perfused hearts. KLF2 overexpression recapitulates the inhibitory effects on endothelial glycolysis elicited by laminar flow, as measured by Seahorse flux analysis and glucose uptake measurements. RNA sequencing showed that shear stress reduced the expression of key glycolytic enzymes, such as 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase-3 (PFKFB3), phosphofructokinase-1, and hexokinase 2 in a KLF2-dependent manner. Moreover, KLF2 represses PFKFB3 promoter activity. PFKFB3 knockdown reduced glycolysis, and overexpression increased glycolysis and partially reversed the KLF2-mediated reduction in glycolysis. Furthermore, PFKFB3 overexpression reversed KLF2-mediated reduction in angiogenic sprouting and network formation. Conclusions: Our data demonstrate that shear stress-mediated repression of endothelial cell metabolism via KLF2 and PFKFB3 controls endothelial cell phenotype

Long noncoding RNA MALAT1 regulates endothelial cell function and vessel growth

Rationale: The human genome harbors a large number of sequences encoding for RNAs that are not translated but control cellular functions by distinct mechanisms. The expression and function of the longer transcripts namely the long noncoding RNAs in the vasculature are largely unknown. OBJECTIVE:: Here, we characterized the expression of long noncoding RNAs in human endothelial cells and elucidated the function of the highly expressed metastasis-associated lung adenocarcinoma transcript 1 (MALAT1). METHODS AND RESULTS:: Endothelial cells of different origin express relative high levels of the conserved long noncoding RNAs MALAT1, taurine upregulated gene 1 (TUG1), maternally expressed 3 (MEG3), linc00657, and linc00493. MALAT1 was significantly increased by hypoxia and controls a phenotypic switch in endothelial cells. Silencing of MALAT1 by small interfering RNAs or GapmeRs induced a promigratory response and increased basal sprouting and migration, whereas proliferation of endothelial cells was inhibited. When angiogenesis was further stimulated by vascular endothelial growth factor, MALAT1 small interfering RNAs induced discontinuous sprouts indicative of defective proliferation of stalk cells. In vivo studies confirmed that genetic ablation of MALAT1 inhibited proliferation of endothelial cells and reduced neonatal retina vascularization. Pharmacological inhibition of MALAT1 by GapmeRs reduced blood flow recovery and capillary density after hindlimb ischemia. Gene expression profiling followed by confirmatory quantitative reverse transcriptase-polymerase chain reaction demonstrated that silencing of MALAT1 impaired the expression of various cell cycle regulators. CONCLUSIONS:: Silencing of MALAT1 tips the balance from a proliferative to a migratory endothelial cell phenotype in vitro, and its genetic deletion or pharmacological inhibition reduces vascular growth in vivo

Studies on Leprosy in Taiwan:(III) Negative Factors During Long-Term Chemotherapy of Leprosy in the Sanitorium

BACKGROUND: The majority of the human genome comprises noncoding sequences, which are in part transcribed as long noncoding RNAs (lncRNAs). lncRNAs exhibit multiple functions, including the epigenetic control of gene expression. In this study, the effect of the lncRNA MALAT1 (metastasis-associated lung adenocarcinoma transcript 1) on atherosclerosis was examined. METHODS: The effect of MALAT1 on atherosclerosis was determined in apolipoprotein E-deficient (Apoe-/-) MALAT1-deficient (Malat1-/-) mice that were fed with a high-fat diet and by studying the regulation of MALAT1 in human plaques. RESULTS: Apoe-/- Malat1-/- mice that were fed a high-fat diet showed increased plaque size and infiltration of inflammatory CD45+ cells compared with Apoe-/- Malat1+/+ control mice. Bone marrow transplantation of Apoe-/- Malat1-/- bone marrow cells in Apoe-/- Malat1+/+ mice enhanced atherosclerotic lesion formation, which suggests that hematopoietic cells mediate the proatherosclerotic phenotype. Indeed, bone marrow cells isolated from Malat1-/- mice showed increased adhesion to endothelial cells and elevated levels of proinflammatory mediators. Moreover, myeloid cells of Malat1-/- mice displayed enhanced adhesion to atherosclerotic arteries in vivo. The anti-inflammatory effects of MALAT1 were attributed in part to reduction of the microRNA miR-503. MALAT1 expression was further significantly decreased in human plaques compared with normal arteries and was lower in symptomatic versus asymptomatic patients. Lower levels of MALAT1 in human plaques were associated with a worse prognosis. CONCLUSIONS: Reduced levels of MALAT1 augment atherosclerotic lesion formation in mice and are associated with human atherosclerotic disease. The proatherosclerotic effects observed in Malat1-/- mice were mainly caused by enhanced accumulation of hematopoietic cells

Analysis of Outcomes in Ischemic vs Nonischemic Cardiomyopathy in Patients With Atrial Fibrillation A Report From the GARFIELD-AF Registry

IMPORTANCE Congestive heart failure (CHF) is commonly associated with nonvalvular atrial fibrillation (AF), and their combination may affect treatment strategies and outcomes