死亡相关蛋白激酶1促进机械通气肺损伤发生的机制研究

Alveolar epithelial cell apoptosis is a common pathological change in ventilator induced lung injury (VILI) due to overdistension of alveolar epithelial cells. Currently further researches are still needed in the mechanisms of mechanical stretch induced alveolar epithelial cell apoptosis. Death associated protein kinase 1 (DAPK1) is an intracellular protein kinase associated with cell apoptosis, which can induce cell apoptosis by interacting with many signal molecules. Our previous research found mechanical stretch induced alveolar type II epithelial apoptosis was accompanied by DAPK1 activation and expression. DAPK1 combined with P53 after mechanical stretch, and the expression of P53 and phosphorylated P53 protein was elevated. Based on relevant literatures and our study, this project will investigate the activation of DAPK1 is involved in mechanical stretch induced alveolar type II epithelial cell apoptosis: activated DAPK1 combines with P53 and phosphorylates P53; p-P53 migrates to nuclear and induces the transcription of P53-related pro-apoptosis genes, promoting alveolar type II epithelial cell apoptosis and VILI. The study will shed a new light on the prevention and therapy of VILI by researching the transduction of mechanical signal to biological signal.

肺泡上皮细胞凋亡是机械通气肺损伤（VILI）常出现的一种病理改变，常因肺泡上皮细胞被过度牵拉所致。目前对机械牵拉导致肺泡上皮细胞凋亡的机制研究尚不深入。死亡相关蛋白激酶1（DAPK1）是一种与细胞凋亡相关的细胞内蛋白激酶，能通过与多种信号分子作用诱导细胞凋亡。申请者的前期研究提示：机械牵拉在诱导肺泡二型上皮细胞大量凋亡的同时促进DAPK1的表达与激活，并导致DAPK1与P53结合，增加P53和磷酸化P53的表达。基于相关文献及前期研究，本课题拟研究DAPK1参与机械牵拉诱导的肺泡二型上皮细胞凋亡：活化的DAPK1与P53结合，使P53磷酸化，促进p-P53向细胞核内转移并诱导P53相关促凋亡基因的转录，促进二型肺泡上皮细胞凋亡及VILI发生。本课题通过研究机械信号向生物学信号转导的相关机制，为VILI的预防及治疗提供了一个新的方向。

肺泡上皮细胞（AEC）凋亡是导致机械通气肺损伤（VILI）的一个重要因素，但目前相关的发生机制并不明确。死亡相关蛋白激酶1（DAPK1）是与细胞死亡密切相关的蛋白激酶，参与多种病理生理过程。本课题研究了DAPK1在VILI中的重要作用。我们通过细胞研究发现，大幅度周期性牵拉（CS）刺激能明显引发肺泡上皮细胞凋亡，同时促进DAPK1激活，增加DAPK1与P53的结合。采用RNA干扰技术敲除细胞内DAPK1后，机械牵拉诱导的肺泡上皮细胞凋亡明显减少，P53及内源性凋亡信号通路分子Bax表达减少，增加Bcl-2表达；在过表达DAPK1质粒后，无任何机械刺激情况下肺泡上皮细胞凋亡明显增加，同时P53与Bax表达增加，而抑制凋亡信号分子Bcl-2表达下降。动物实验证明大潮气量机械通气导致VILI并引起肺泡上皮细胞凋亡及肺组织内DAPK1激活；肺组织内敲除DAPK1或使用DAPK1抑制剂后，能明显缓解大潮气量机械通气引起的VILI，减轻肺部炎症反应。上述研究结果表明，DAPK1通过P53及内源性促凋亡通路引起肺泡上皮细胞凋亡，从而参与VILI的发生。本课题深入研究了DAPK1在VILI发生中的重要作用，阐明了其相关作用机制，为寻找VILI治疗手段提供了强有力的理论基础和实验依据。