异丙酚通过microRNA-20b调节ULK1抑制心肌缺血/再灌注损伤诱导的自噬性细胞凋亡

Protective mechanism of ischemic reperfusion injury is a hot topic in cardiovascular area. Recent research shows that propofol can inhibit the ischemia reperfusion- induced autophagic cell death through the regulation of autophagy-related genes, but the microRNAs that regulating autophagy-related gene are largly unknown. By using the miRNA microarray screen, we got 6 autophagy-related miRNAs in a cellular hypoxia/reoxygenation model upon propofol post treatment, presumably showing that these microRNAs may play important roles in heart ischemia reperfusion injury. We selected miR-20b, because their predicted targets are ULK1 and Beclin-1 which are important autophagy genes. We are using the biochemical and molecular methods combined with optical microscope and electron microscopy to study inhibitory role of miR-20b in excessive autophagy caused by hypoxia/reoxygenation as well as their protective effects in cells. This study will elucidate the molecular mechanism of autophagy related microRNA in inhibiting excessive autophagy by regulation of the autophagic core protein ULK1 and provide the possibility whether some significant microRNAs can be used as biomarkers for clinical cardiac ischemia reperfusion injury.

缺血再灌注损伤（IR）可导致细胞自噬性死亡，而我们及他人的研究证实异丙酚可通过调节自噬相关基因的表达产生心肌保护作用，进一步研究发现异丙酚后处理可引起缺氧复氧细胞中miR-20b等6个miRNAs差异性表达，并与自噬基因明显相关, 推测这些microRNAs在异丙酚后处理抑制细胞自噬性死亡中起重要作用，但机制不明。本课题拟采用基因转染、荧光素酶等细胞和分子生物学技术，首先在分子、细胞水平上验证hsa-miR-20靶向调控自噬关键蛋白ULK1，随后在整体水平上研究异丙酚后处理对miR-20、ULK1表达及细胞自噬性死亡的影响，并进一步观察它们在调控细胞自噬性死亡中的相互关系，旨在阐明异丙酚通过miR-20b调控自噬核心蛋白ULK1抑制细胞过度自噬的分子机制，揭示异丙酚后处理激活内源性保护作用的新机制，为临床异丙酚有效防治IR以及寻找IR分子标志物提供理论依据。

缺血再灌注损伤（IR）可导致细胞自噬性死亡，而我们及他人的研究证实异丙酚可通过调节自噬相关基因的表达产生心肌保护作用，我们通过异丙酚处理缺氧复氧细胞模型，筛选出一系列可能作为分子探针的候选microRNA, 从中挑选miR-20b进行深入研究。实验证明H/R诱导的自噬水平与miR-20b的表达负相关，异丙酚后处理可以减轻这种自噬性损伤；进一步研究发现，miR-20b靶向作用于ULK1减轻H/R诱导的自噬性损伤，抑制miR-20b表达减弱异丙酚对H/R的保护作用，而外源过表达ULK1可以逆转miR-20b抑制的H/R诱导的自噬性损伤。我们的结果阐明了异丙酚通过 miR-20b 调控自噬核心蛋白 ULK1 抑制细胞过度自噬的分子机制，揭示异丙酚后处理激活内源性保护作用的新机制，为临床异丙酚有效防治 IR 以及寻找 IR 分子标志物提供理论依据。