TRB3在内质网应激参与低氧肺动脉高压形成中的作用及机制

Hypoxia induces the pulmonary artery smooth muscle cells (PASMCs) endoplasmic reticulum stress (ERS), are finally lead to pulmonary vascular remodeling, which is the main irreversible factor of hypoxic pulmonary hypertension (PH). Its pathogenesis remains uncertain. Tribbles 3 (TRB3) is a major pressure sensor and an important up-regulated gene on the ERS conditions, which need to be directly combined with AKT involved in regulating a variety of cell biological functions. Our preliminary studies suggested that hypoxia-induced autophagy and KLF5 alteration could lead to imbalance of proliferation and apoptosis in PASMCs, and inhibition of autophagy and deletion of KLF5 can effectively relieve pulmonary vascular remodeling. Furthermore, some researchers showed that the endoplasmic reticulum stress(ERS) evoked by hypoxia was the dominant course of inducing autophagy and imbalance of proliferation and apoptosis. We can speculate that TRB3 mediated hypoxia ERS inducing cell autophagy and imbalance of proliferation and apoptosis is critical in the formation of the PH. We intended to explore the mechanism underlying TRB3 links ERS condition resulting in increased autophagy and imbalance of proliferation and apoptosis in cell, tissue and animal body levels in PH. This study will focus on the mechanisms and functions of TRB3/AKT-mTOR and TRB3/AKT-KLF5 signaling pathways in the process of hypoxia-induced ERS regulating autophagy and imbalance of proliferation and apoptosis. We intend to further explore the potential mechanism of ERS stimulating pulmonary vascular remodeling in PH. This research will provide theoretical and scientific experimental basis for new therapeutic targets and further elucidating pathogenesis of PH.

低氧诱导肺动脉平滑肌细胞（PASMCs）内质网应激（ERS）参与肺血管重构，是低氧肺动脉高压（PH）的重要致病因素，其机制尚未阐明。毛球族同源蛋白3（TRB3）是ERS主要的压力传感器和重要的上调应激基因，它与AKT直接结合参与调控细胞的多种生物功能。我们前期研究发现，低氧诱导PASMCs自噬及低氧KLF5调控的增殖凋亡失衡均参与肺血管重构。最新研究提示，低氧ERS是诱导自噬及调控增殖失衡的主导环节。探讨TRB3在低氧ERS诱导细胞自噬及增殖凋亡失衡中的作用对于阐明PH的形成机制有重要意义。本课题拟在细胞、组织、动物等多个水平，探讨TRB3在低氧ERS参与PH中的作用及机制，重点研究TRB3/AKT-mTOR和TRB3/AKT-KLF5信号通路在低氧ERS调控自噬及增殖凋亡失衡中的功能。进一步阐明ERS导致低氧肺血管重构的潜在机制，为寻找新的PH治疗靶点提供科学的理论依据。

目的：低氧性肺动脉高压(pulmonary hypertension，PH)是一种难治性肺血管重构疾病。目前对PH治疗效果仍不理想。Tribbles homolog 3 (TRB3)是假激酶家族的成员，在不同类型的应激环境中上调，并依其所处微环境不同发挥促增殖或促凋亡的作用。TRB3在低氧PH形成中的调节机制尚不清楚。探讨TRB3在缺氧PH发病机制中的作用，将为PH的治疗提供新的靶点。.方法与结果：大鼠全基因组mRNA芯片检测结果显示低氧肺动脉平滑肌细胞（pulmonary artery smooth muscle cells，PASMCs）中TRB3和内质网应激(endoplasmic reticulum stress，ERS)相关基因表达上调。缺氧和thapsigargin显著上调TRB3蛋白表达。4- PBA和4μ8C均为ERS抑制剂，抑制低氧PASMCs中TRB3的表达。TRB3沉默可促进低氧PASMCs凋亡，抑制低氧PASMCs的增殖和迁移能力并抑制MAPK信号通路的激活。TRB3过表达可促进PASMCs的增殖、迁移，抑制细胞凋亡，而特异性抑制剂ERK、JNK、p38 MAPK可部分逆转这一现象。免疫共沉淀结果显示TRB3直接与ERK、JNK和p38 MAPK相互结合。在低氧PH大鼠模型肺组织中敲减TRB3可降低右心室收缩压，肺动脉中膜厚度。.结论：TRB3在低氧PASMCs中表达上调，并受ERS的调控。TRB3通过结合并激活ERK、JNK和p38 MAPK通路，在低氧诱导的PH发病机制中发挥关键作用。TRB3可能是治疗缺氧PH的潜在靶点。