内质网应激介导的细胞内铁代谢紊乱在SAH后早期脑损伤的作用

Early brain injury is the primary cause of mortality and disability after subarachnoid hemorrhage (SAH), and apoptosis is its overriding pathomechanism. The enhanced reactivity of reactive oxygen species (ROS) catalyzed by increased brain iron is one of the main reason of apoptosis. The recent study demonstrated that metabolic disorder of intra-cellar iron metabolism is the new mechanism of incremental brain iron. It was reported that iron increased after interference of Hepcin, the core protein of metabolic pathway in iron metabolism, mediated by endoplasmic reticulum stress. Our prophase study revealed that SAH initated endoplasmic reticulum stress by induced increased expression of CHOP, the core transcription factor in its pathway, and resulted in apoptosis. This research planed to adopted rats SAH model and cell model of cerebral vasospasm use molecular biology technology to detect the expression of core protein, index of oxidative stress, content of brain iron in endoplasmic reticulum stress and iron metabolism pathway of cerebral cortex, hippocampus and basilar artery before and after interference, to verify whether disorder of brain iron metabolism mediated by endoplasmic reticulum stress participated in the mechanism of apoptosis after SAH, to illustrate the effect of "SAH→endoplasmic reticulum calcium overload or deprivation→endoplasmic reticulum→iron metabolic disorder→ROS→apoptosis " pathway on EBI after SAH.

早期脑损伤（EBI）是蛛网膜下腔出血（SAH）患者死亡和残疾的首要原因，细胞凋亡是其最主要的病理机制。脑铁含量增加催化的活性氧簇（ROS）反应性增强是导致细胞凋亡的重要原因之一。新近的研究提示，细胞内铁代谢紊乱是脑铁含量增加的新机制。资料显示，内质网应激可通过干扰铁代谢通路中核心蛋白铁调素（Hepc）的表达导致铁含量升高。本课题组前期研究表明，SAH可启动内质网应激，诱导其通路中核心转录因子CHOP表达增高进而导致细胞凋亡。本课题拟采用大鼠SAH模型及脑血管痉挛细胞模型，运用分子生物学等技术，检测干预前后细胞内及大脑皮层、海马和基底动脉等组织中内质网通路和铁代谢通路中核心蛋白的表达、氧化应激指标、脑铁含量以及细胞凋亡的变化，以验证内质网应激介导的脑铁代谢紊乱是否参与SAH后细胞凋亡机制，阐明"SAH→内质网应激→铁代谢紊乱→ROS→细胞凋亡"通路在SAH后EBI中的作用。

蛛网膜下腔出血（SAH）后早期脑损伤（EBI）是导致SAH患者高死亡率和致残率的首要原因。研究发现，神经元凋亡在SAH后EBI的病理过程中发挥至关重要的作用，而内质网应激通路正是除线粒体通路和死亡受体通路之外的细胞凋亡的三大信号通路之一。资料显示，内质网应激可通过干扰铁代谢通路中核心蛋白铁调素（Hepc）的表达导致铁含量升高。本课题组前期研究表明，SAH可启动内质网应激，诱导其通路中核心转录因子CHOP表达增高进而导致细胞凋亡。通过构建体外蛛网膜下腔出血模型，运用分子生物学等技术，检测干预前后细胞内及大脑皮层、海马和基底动脉等组织中内质网通路和铁代谢通路中核心蛋白的表达、氧化应激指标、脑铁含量以及细胞凋亡的变化，验证了内质网应激介导的脑铁代谢紊乱参与SAH后细胞凋亡的具体机制，阐明了“SAH→内质网应激→铁代谢紊乱→ROS→细胞凋亡”通路在SAH后EBI中的作用。此外，研究报道，内质网应激从转录和转录后水平调节硫氧还蛋白相互作用蛋白(TXNIP）的表达，而TXNIP被证实在脑缺血疾病中发挥了促进神经元凋亡的作用，课题组进而对内质网应激诱导的TXNIP参与SAH后EBI的作用机制进行了深入探索。通过构建大鼠SAH模型，检测干预前后内质网应激标志蛋白、TXNIP通路中核心蛋白的表达及凋亡指标的变化，阐明了“SAH→内质网应激→TXNIP表达增加→细胞凋亡”通路在SAH后EBI中的作用。