世居高原藏族脑结构和功能适应神经影像及相关基因机制研究

Hypoxic adaptation is of critical importance for human survival at High altitude (HA). Tibetan natives at HA have developed optimal adaptations in the circulation, respiration, and blood systems. However, how the brain in Tibetan natives through modulating its structures and functions to regulate the activities of these systems remain still unclear. In recent years, the most important progress is the clarification of the mechanisms underlying Tibetan's adaptation to HA, showing the EPAS1, EGLN1 and PPARA gene SNPs were related to HA adaption. In the present study, multiple MRI data were first used to study brain gray matter and white matter volumes, cortical thickness, resting-state and task-activated neuronal activity, and structural and functional networks in Tibetan natives at Qinghai-Tibet Plateau. Control subjects were matched lowland Tibetan natives. Second, the correlations between SNPs of EPAS1, EGLN1 and PPARA gene and brain modifications were analyzed. Finally, two SNPs, which showing most correlations with Tibetan native brain modifications, were mutated in mice. These gene mutant mice were used for verifying brain modifications in Tibetan native, detecting the constructions of cells and blood vessels in the brain, and exploring the signal pathway that regulating neurogenesis and angiogenesis. The present study will clarify brain modifications and the mechanisms underlying these alterations in Tibetan native under HA hypoxia environ in the organ, tissue, and molecular level.

高原低氧适应关系到高原人类的生存。世居高原藏族在循环、呼吸和血液系统获得了最佳适应。然而，脑如何重塑来调节这些系统的活动目前尚不清楚。近年高原研究最重要进展是揭示了藏族适应的遗传学机制，发现EPAS1、EGLN1和PPARA基因单核苷酸多态性（SNP）与高海拔低氧适应有关。本项目首先采集多模态脑磁共振数据，通过与匹配的世居低海拔藏族比较，观察世居高原藏族脑灰质和白质体积、皮层厚度、静息态和任务态局部神经细胞活动及结构和功能网络的重塑特征；其次，分析候选EPAS1、EGLN1和PPARA基因SNP与重塑脑区结构和功能的相关性；最后，选择与高原藏族脑重塑相关性最显著的2个SNP，制备单基因和双基因突变小鼠模型，用来验证人体脑研究结果，并探讨皮质和髓质内细胞和血管构筑及调控神经和血管发生的分子信号通路。本项目将在器官、组织和分子水平揭示世居高原藏族低氧脑适应性重塑的特征及其基因调节机制。

近年高原研究最重要进展是揭示了藏族适应的遗传学机制，发现EPAS1、EGLN1 和PPARA 基因单核苷酸多态性（SNP）与高海拔低氧适应有关。然而，这些基因如何作用于脑目前尚不清楚。首先，本项目采集多模态脑磁共振数据，与世居低海拔藏族比较，观察世居高原藏族脑灰质和白质体积、皮层厚度、静息态和任务态局部神经细胞活动及结构和功能网络的适应性重塑特征。其次，根据文献选择EPAS1、EGLN1和PPARA的突变60个SNP与重塑脑区结构和功能的相关性。最后，选择高原藏族基因型频率分布高，并与脑区，尤其是与岛叶和视觉皮层重塑相关最显著的2个SNP位点，制备单基因和双基因小鼠突变模型，用来验证人体脑研究结果，并探讨皮质和髓质内细胞和血管构筑及调控神经发生和血管形成的分子信号通路。本研究发现基因和环境共同作用的脑区主要是岛叶、视觉皮层和扣带前回；高原适应优势基因型与皮层厚度和体积正相关；环境对皮层的作用远远大于基因的作用；环境和基因的作用相反，即环境损害，而优势基因型保护脑结构。该研究揭示了高原环境下，脑在低氧通路相关基因突变作用下导致了结构和功能上的重塑，这些重塑与调节高原环境特殊的心肺功能有关。