BACKGROUND MicroRNA-223 (miR-223) is a hematopoietic lineage cell-specific microRNA. However, a significant amount of miR-223 has been identified in vascular smooth muscle cells (VSMCs) and vascular walls that should not have endogenous miR-223. OBJECTIVES This study sought to determine the sources of miR-223 in normal and atherosclerotic arteries and the role of miR-223 in atherogenesis. METHODS The levels and sources of miR-223 in blood cells (leukocytes and platelets), serum, blood microparticles, VSMCs, and vascular walls were determined. Both in vivo and in vitro studies were conducted to evaluate miR-223 secretion by blood cells and the ability of miR-223 to enter VSMCs and vascular walls. Subsequent changes in and the effects of miR-223 levels on serum and arteries in atherosclerotic animals and patients were investigated. RESULTS Blood cells were able to secrete miR-223 into serum. MicroRNA-223 from blood cells was the most abundant cell-free miRNA in blood. Blood cell-secreted miR-223 could enter VSMCs and vascular walls, which produced strong biological effects via its target genes. In both atherosclerotic apolipoprotein-E knockout mice and patients with atherosclerosis, miR-223 levels were significantly increased in serum and atherosclerotic vascular walls. The atherosclerotic lesions in apolipoprotein-E knockout mice were exacerbated by miR-223 knockdown. The effect of miR-223 on atherogenesis was verified using miR-223 knockout mice. CONCLUSIONS Blood cell-secreted miR-223 enters vascular cells and walls, and appears to play important roles in VSMC function and atherogenesis. As a novel endocrine genetic signal between blood cells and vascular cells, miR-223 may provide a novel mechanism and new therapeutic target for atherosclerosis.

Autophagy is involved in the development and/or progression of many diseases, including myocardial ischemia/reperfusion (I/R). In this study, we hypothesized a protective role of basic fibroblast growth factor (bFGF) both in vivo and in vitro and demonstrated that excessive autophagy and ubiquitinated protein accumulation is involved in the myocardial I/R model. Our results showed that bFGF improved heart function recovery and increased the survival of cardiomyocytes in myocardial I/R model. The protective effect of bFGF is related to the inhibition of LC3II levels. Additionally, bFGF enhances the clearance of Ub by p62 and increases the survival of H9C2 cells. Moreover, silencing of p62 partially blocks the clearance of Ub and abolishes the anti-apoptosis effect of bFGF. An shRNA against the autophagic machinery Atg7 increased the survival of H9C2 cells co-treated with bFGF and rapamycin. bFGF activates the downstream signaling of the PI3K/Akt/mTOR pathway. These results indicate that the role of bFGF in myocardial I/R recovery is related to the inhibition of excessive autophagy and increased ubiquitinated protein clearance via the activation of PI3K/Akt/mTOR signaling. Overall, our study suggests a new direction for bFGF drug development for heart disease and identifies protein signaling pathways involved in bFGF action.M yocardial ischemia/reperfusion (I/R) has high morbidity and mortality and is a significant burden for patients and society. Despite recent progress in clinical interventions to facilitate early myocardial reperfusion for patients who suffer from acute myocardial infarction, the death rate during the acute phase of myocardial infarction is approximately 10% and the incidence of heart failure reaches 25% during the chronic phase 1 . The current standard treatment for myocardial ischemia is rapid reperfusion, which can attenuate myocardial infarction, reduce cardiomyocyte apoptosis and restore contractile dysfunction. However, reperfusion potentially causes additional injury, disturbances in ionic homeostasis, local edema, ischemia, focal hemorrhage, free radical stress and inflammatory responses. Many studies reported that autophagy also plays a key role in myocardial I/R injury in both animal models and cellular models by causing progressive degeneration of the heart 2,3 .Autophagy is a dynamic process that turns over organelles and proteins through a lysosome-associated degradation process, and serves a critical function in cellular homoeostasis by regulating cell survival and cell death pathways 4 . In addition to its role in cellular homeostasis, autophagy may play a cytoprotective role in instances of nutrient starvation 5 or a specific type of programmed cell death 6 . The functional role of autophagy in myocardial I/R is currently under intense investigation, and prior studies have characterized this process both in vitro and in vivo. Interestingly, up-regulation of autophagy has been reported to both contribute to and cause cell

Mechanisms underlying the vein development remain largely unknown. Tie2 signaling mediates endothelial cell (EC) survival and vascular maturation and its activating mutations are linked to venous malformations. Here we show that vein formation are disrupted in mouse skin and mesentery when Tie2 signals are diminished by targeted deletion of Tek either ubiquitously or specifically in embryonic ECs. Postnatal Tie2 attenuation resulted in the degeneration of newly formed veins followed by the formation of haemangioma-like vascular tufts in retina and venous tortuosity. Mechanistically, Tie2 insufficiency compromised venous EC identity, as indicated by a significant decrease of COUP-TFII protein level, a key regulator in venogenesis. Consistently, angiopoietin-1 stimulation increased COUP-TFII in cultured ECs, while Tie2 knockdown or blockade of Tie2 downstream PI3K/Akt pathway reduced COUP-TFII which could be reverted by the proteasome inhibition. Together, our results imply that Tie2 is essential for venous specification and maintenance via Akt mediated stabilization of COUP-TFII.DOI: http://dx.doi.org/10.7554/eLife.21032.001

Objective-The genetic program underlying lymphatic development is still incompletely understood. This study aims to dissect the role of receptor tyrosine kinase with immunoglobulin-like and EGF (epidermal growth factor)-like domains 1 (Tie1) and Tie2 in lymphatic formation using genetically modified mouse models. Approach and Results-We generated conditional knockout mouse models targeting Tie1, Tie2, and angiopoietin-2 in this study. Tie1 ΔICD/ΔICD mice, with its intracellular domain targeted, appeared normal at E10.5 but displayed subcutaneous edema by E13.5. Lymph sac formation occurred in Tie1 ΔICD/ΔICD mice, but they had defects with the remodeling of primary lymphatic network to form collecting vessels and valvulogenesis. Consistently, induced deletion of Tie1-ICD postnatally using a ubiquitous Cre deleter led to abnormal lymphangiogenesis and valve formation in Tie1-ICD iUCKO/− mice. In comparison with the lymphatic phenotype of Tie1 mutants, we found that the diameter of lymphatic capillaries was significantly less in mice deficient of angiopoietin-2, besides the disruption of collecting lymphatic vessel formation as previously reported. There was also no lymphedema observed in Ang2 −/− mice during embryonic development, which differs from that of Tie1 ΔICD/ΔICD mice. We further investigated whether Tie1 exerted its function via Tie2 during lymphatic development. To our surprise, genetic deletion of Tie2 (Tie2 Key Words: knockout mice ◼ lymphatic abnormality ◼ lymphatic vessel ◼ Tie-1 receptor tyrosine kinase ◼ Tie-2 receptor tyrosine kinase ◼ valve