LncRNA MALAT1 up-regulates VEGF-A and ANGPT2 to promote angiogenesis in brain microvascular endothelial cells against oxygen-glucose deprivation via targetting miR-145.

Lanfen Ren,Zuneng Lu,Kui Li,Chunxia Wei

doi:10.1042/bsr20180226

Abstract

Stroke is one of the leading causes of death and long-term disability around the world. Angiogenesis is supposed to protect brain microvascular endothelial cells (BMECs) from oxidative and ischemic stress. Previous studies indicated that interaction between metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) and miR-145 was involved in myocardial ischemia reperfusion, suggesting MALAT1 and miR-145 were also mediated with the progress of angiogenesis and cell migration in oxygen–glucose deprivation (OGD)-induced BMECs. The present study aimed to investigate the functional roles of MALAT1 in regulating miR-145 and its downstream pro-angiogenesis factors, vascular endothelial growth factor (VEGF)-A and Angiopoietin-2 (ANGPT2) during the progress of angiogenesis in OGD-induced BMECs. An in vitro OGD model was employed in mouse BMECs to mimic brain hypoxic and ischemic conditions; MTT was used to determine cell viability. qRT-PCR was used to determine the expression of long non-coding RNA (lncRNA)-MALAT1 and miR-145 under OGD conditions; in vitro tube formation assay was used to investigate angiogenic effect of MALAT1 and miR-145. The relationship between lncRNA-MALAT1/miR-145 and miR-145/VEGF-A/ANGPT2 was evaluated by qRT-PCR and Western blot, and direct binding was assessed using dual luciferase assay. Results showed that the levels of lncRNA-MALAT1 and miR-145 were up-regulated in OGD-induced BMECs. miR-145 functioned as an anti-angiogenic and pro-apoptotic factor in OGD treated BMECs via down-regulating VEGF-A and ANGPT2 directly. While lncRNA-MALAT1 enhanced the expressions of VEGF-A and ANGPT2 by targetting miR-145 to promote angiogenesis and proliferation of BMECs under OGD conditions. Our present study revealed the inhibitory functions of miR-145 on angiogenesis through direct targetting on VEGF-A and ANGPT2 for the first time and proved the protective role of lncRNA-MALAT1 for BMECs under OGD conditions through the direct regulation of miR-145.

Highlights

Stroke is reported to be one of the major diseases leading to deaths worldwide, which is accompanied with symptoms such as cerebral ischemia or hypoxia
The results demonstrated that long non-coding RNA (lncRNA)-metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) promoted angiogenesis in mouse brain microvascular endothelial cell (BMEC) and played an important role in microtubule formation as well as BMEC migration via up-regulating the expressions of pro-angiogenic factors vascular endothelial growth factor (VEGF)-A and ANGPT2. miR-145 was shown to suppress angiogenesis in BMECs and down-regulate the expressions of pro-angiogenesis factors mentioned above through targetting their 3 -UTR regions
Given that function recovery was observed in BMECs that underwent ischemic injury where angiogenesis was promoted [10,12], the induction of angiogenesis in brain tissues injured by hypoxic/ischemic damages may provide new insights into treating ischemic stroke

Summary

Introduction

Stroke is reported to be one of the major diseases leading to deaths worldwide, which is accompanied with symptoms such as cerebral ischemia or hypoxia. Current strategies to treat patients suffering from ischemic stroke include recanalization and neuroprotective strategies. The. administration of intravenous recombinant tissue-type plasminogen activator (tPA) to establish revascularization, use of intra-arterial fibrinolysis, or mechanical clot retrieval is common in recanalization strategies, while the effectiveness of this type of treatment highly relies on the time period in which it is administrated [3]. Neuroprotective strategies are implemented to preserve the penumbral tissues as well as extending the time window for revascularization treatment. Neuroprotection was shown to insufficient to treat stroke due to the lack of clinical effectiveness [4]. Possible reasons may include the complexity of interplays in multiple pathways, the acute cerebral injury/neurological impairments following ischemia, and the lack of defining treatments for specific targets [5]

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Conclusion