Platelets docking to VWF prevent leaks during leukocyte extravasation by stimulating Tie-2
BLOOD
Authors: Braun, Laura J.; Stegmeyer, Rebekka I.; Schaefer, Kerstin; Volkery, Stefan; Currie, Silke M.; Kempe, Birgit; Nottebaum, Astrid F.; Vestweber, Dietmar
Abstract
Neutrophil extravasation requires opening of the endothelial barrier but does not nec-essarily cause plasma leakage. Leaks are prevented by contractile actin filaments sur-rounding the diapedesis pore, keeping this opening tightly closed around the transmigrating neutrophils. We have identified the receptor system that is responsible for this. We show that silencing, or gene inactivation, of endothelial Tie-2 results in leak formation in postcapillary venules of the inflamed cremaster muscle at sites of neutrophil extravasation, as visualized by fluorescent microspheres. Leakage was dependent on neutrophil extravasation, because it was absent upon neutrophil depletion. We identified the Cdc42 GTPase exchange factor FGD5 as a downstream target of Tie-2 that is essential for leakage prevention during neutrophil extravasation. Looking for the Tie-2 agonist and its source, we found that platelet-derived angiopoietin-1 (Angpt1) was required to prevent neutrophil-induced leaks. Intriguingly, blocking von Willebrand factor (VWF) resulted in vascular leaks during transmigration, indicating that platelets interacting with endothelial VWF activate Tie-2 by secreting Angpt1, thereby preventing diapedesis-induced leakiness.
LncRNA FGD5-AS1 acts as a competing endogenous RNA for miRNA-223 to lessen oxygen-glucose deprivation and simulated reperfusion (OGD/R)-induced neurons injury
FOLIA NEUROPATHOLOGICA
Authors: Zhang, Xue-Qiang; Song, Li-Hong; Feng, She-Jun; Dai, Xiao-Min
Abstract
The purpose of this study was to evaluate whether FGD5-AS1 participates in oxygen-glucose deprivation and simulated reperfusion (OGD/R)-induced neurons injury and the detailed mechanism. An OGD/R model was established using the primary cortical neuron isolated from the brains of Sprague-Dawley rats. qRT-PCR and western blot were performed to de-tect the RNA and protein expression levels, respectively. Cell counting kit 8 (CCK8) and flow cytometry assays were used to evaluate the proliferation and apoptosis of neurons. The luciferase reporter assay was used to verify the interaction between lncRNA FGD5-AS1 and miRNA-223. We found that the expression of FGD5-AS1 is decreased in neurons suffering from OGD/R. Up-regulation of FGD5-AS1 could recover proliferation and inhibit apoptosis of OGD/R-injured neurons. In addition, the interaction between FGD5-AS1 and miRNA-223 were verified. The expression of miRNA-223 was nega-tively correlated with the level of FGD5-AS1. In turn, the expression of insulin-like growth factor-1 receptor (IGFIR, a target gene of miR-223) was positively associated with the level of FGD5-AS1. Simultaneously down-regulating miR-223 and over-expressing FGD5-AS1 as well as IGF1R exhibited an additional effect of extenuating OGD/R damage i.e. increasing neuron proliferation and reducing neuron apoptosis. In conclusion, our findings indicated that FGD5-AS1 may protect the neuron against OGD/R injury via acting as a ceRNA for miR-223 to mediate IGF1R expression, which contributes to a deeper understanding of ischemic stroke and provide a promising therapeutic target for this disease.