Abstract 72: Long Non-coding RNAs Mediate Cerebrovascular Endothelial Pathologies in Ischemic Stroke

Abstract

The structural and functional changes in the cerebral endothelium during cerebral ischemia are well-known to affect the extent of ischemic brain injury and stroke outcome. Therefore, the brain endothelium becomes an important therapeutic target for the inhibition of cerebrovascular dysfunction in ischemic stroke. However, the regulatory mechanisms of cerebral endothelial dysfunction after cerebral ischemia remain largely unexplored. Previously we have documented the important regulatory roles of microRNAs in the cerebral vasculature, in particular the cerebral vascular endothelium. However, the functional significance and molecular mechanisms of other classes of non-coding RNAs in the regulation of cerebrovascular endothelial pathophysiology after stroke are completely unknown. Using RNA-sequencing technology, we profiled long non-coding RNAs (lncRNAs) expressional signatures in primary brain microvascular endothelial cells (BMECs) after oxygen-glucose deprivation (OGD). After 16h of OGD exposure, the expression levels for 362 of the 10,677 lncRNAs analyzed changed significantly, including a total of 147 lncRNAs increased and 70 lncRNAs decreased by more than 2-fold. Interestingly, metastasis associated lung adenocarcinoma transcript 1 (Malat1) is one of the most highly upregulated OGD-responsive endothelial lncRNAs, which has been initially discovered as a tumor-associated lncRNA involved in epigenetic control of gene expression. Increased Malat1 levels were further confirmed in cultured BMECs after OGD as well as isolated cerebral microvessels in mice after 1h MCAO and 24h reperfusion by qPCR. Of note, Malat1 was not pathologically increased in whole mouse brains in response to the same ischemic insult. The expression and nuclear localization of Malat1 were also shown in BMECs by in situ hybridization. Furthermore, loss-of-Malat1 function by LNA-GapmeR significantly increased OGD-induced loss of endothelial markers and endothelial inflammation in BMECs, implying Malat1 a critical role in protecting the cerebral microvasculature from cerebral ischemic insults. These findings suggest that lncRNAs may function as a class of novel master regulators in cerebrovascular endothelial pathologies after ischemic stroke.