Aims

Circ_0020397 has been found to be down-regulated in intracranial aneurysm (IA), and deregulation of circ_0020397 involved in the regulation of vascular smooth muscle cells (VSMCs) proliferation. However, the mechanism by which circ_0020397 implicates in VSMC dysfunction in IA remains vague.

Materials and methods

The expression of circ_0020397, miR-502-5p and Gremlin 1 (GREM1) was detected using quantitative real-time polymerase chain reaction. Cell viability was analyzed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Protein levels of proliferating cell nuclear antigen (PCNA) and GREM1 were measured using western blot. The interaction between miR-502-5p and circ_0020397 or GREM1 was confirmed by dual-luciferase reporter, RNA pull-down and RNA immunoprecipitation assay.

Key findings

Circ_0020397 or GREM1 expression was decreased in VSMCs isolated from IA patients, and overexpression of circ_0020397 or GREM1 promoted VSMC viability and elevated PCNA expression level, while inhibition of them showed opposite effects. MiR-502-5p was confirmed to directly bind to circ_0020397 or GREM1, and miR-502-5p reversed the effects of circ_0020397 on VSMC viability and PCNA level. Besides, miR-502-5p overexpression suppressed VSMC viability and reduced PCNA level, while these effects were attenuated by GREM1 up-regulation. Importantly, circ_0020397 could regulate GREM1 expression via miR-502-5p in VSMCs.

Significance

Circ_0020397 played an important role in phenotypic modulation in IA by promoting VSMC viability via miR-502-5p/GREM1 axis, suggesting a novel insight into IA pathogenesis and new targets for IA molecular therapy.

中文翻译：

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Circ_0020397通过miR-502-5p在颅内动脉瘤中通过上调GREM1表达来调节血管平滑肌细胞的活力

目的

发现circ_0020397在颅内动脉瘤（IA）中被下调，而circ_0020397的失调与血管平滑肌细胞（VSMC）增殖的调节有关。但是，circ_0020397牵连IA中VSMC功能障碍的机制仍然不清楚。

材料和方法

使用实时定量聚合酶链反应检测circ_0020397，miR-502-5p和Gremlin 1（GREM1）的表达。使用3-（4,5-二甲基噻唑-2-基）-2,5-二苯基溴化四氮唑（MTT）分析法分析细胞活力。使用蛋白质印迹法检测增殖细胞核抗原（PCNA）和GREM1的蛋白质水平。miR-502-5p与circ_0020397或GREM1之间的相互作用已通过双荧光素酶报道分子，RNA下拉和RNA免疫沉淀测定法得以证实。

主要发现

IA患者分离的VSMC中circ_0020397或GREM1表达降低，而circ_0020397或GREM1的过表达促进VSMC活力和PCNA表达水平升高，而对它们的抑制却表现出相反的作用。证实MiR-502-5p直接结合circ_0020397或GREM1，而miR-502-5p逆转了circ_0020397对VSMC活力和PCNA水平的影响。此外，miR-502-5p的过表达抑制了VSMC的活力并降低了PCNA的水平，而GREM1的上调减弱了这些作用。重要的是，circ_0020397可以通过miR-502-5p调节VSMC中的GREM1表达。

意义

Circ_0020397通过通过miR-502-5p / GREM1轴促进VSMC活力，在IA的表型调节中发挥了重要作用，表明对IA发病机制和IA分子治疗的新靶点有了新的认识。