生命的低氧适应——2019年度诺贝尔生理学或医学奖成果解析

氧的利用和调节是高等生命赖以生存的基本条件,威廉·凯林、彼得·拉特克利夫和格雷格·塞门扎3位科学家因发现细胞感知和适应氧气供应的相关机制而获得了2019年度诺贝尔生理学或医学奖。他们发现低氧诱导因子1(hypoxia-inducible factors 1,HIF-1)广泛存在于急、慢性缺氧细胞中,是细胞适应低氧的重要转录因子。HIF-1水平受氧气含量的调节。高氧条件下,HIF-1被修饰进而降解;低氧条件下,HIF-1不被降解,并通过转录调节引起促红细胞生成素等低氧相关基因的表达。本文通过介绍HIF-1的发现和基本分子机制,探讨其在临床中的应用价值。     

低氧对人支气管上皮细胞HSP70和HIF-1α表达的影响

慢性阻塞性肺病（COPD）是慢性气道炎症性疾病，其发病率及病死率都很高，患者易发生低氧血症．本研究将永生化的人支气管上皮细胞（HBE）在低糖DMEM培养基、1%O2培养不同时间后，分别收集总的RNA和蛋白．用RT-PCR检测细胞HSP70和HIF-1αmRNA的变化，western blot检测两者蛋白表达情况．对照组培养于低糖、常氧条件下．结果表明，低氧可以诱导HBE细胞HSP70和HIF-1α基因的转录和翻译，且都有时间依赖性．提示HBE细胞能够感受低氧刺激并做出应答，从而为COPD发病机制研究提供了一种可供选择的细胞模型．     

SUMO-1在ApoE -/一小鼠PM2.、暴露中调控血管HIF-1a/VEGF信号通路的研究

以气管滴注方法研究了ApoE-/一小鼠经PM2.5暴露后，其主动脉弓中SUMO-1, HIF- la、血管内皮生长因子(VEGF)表达变化规律及HIF- la的SUMO化修饰情况.实验结果显示:PM2.5暴露后，小鼠主动脉SUMO-1,HIF-la,VEGF的表达上调;PM2.5暴露诱导了SUMO-1对HIF- la的SUMO化修饰;低氧条件下SUMO-1敲低导致HIF-la表达的下调结果提示PM2.5暴露通过上调细胞中SUMO-1的表达，稳定或者上调HIF- la的表达，进而影响血管内皮生长因子(VEGF)的表达，造成动脉粥样硬化斑块的不稳定.     

低氧与表观遗传学互作的研究进展

表观遗传学是指基因组DNA序列不发生改变的情况下,基因表达水平发生变化从而导致的可遗传表型变化的现象.表观遗传可通过与低氧诱导因子(HIF)家族协同作用,以促使细胞适应低氧环境,从而参与到低氧应答的调控过程中.现就表观遗传学通过以下四个方面与低氧应答进行综述:1)VHL与PDH3调控HIF稳定性;2)通过影响HIF-1α共激活复合物的活性、HRE位点的修饰、HIF结合位点或附近区域的染色质活性,阻止HIF与HRE位点结合;3)组蛋白脱甲基酶对低氧应答相关基因的转录调控;4)低氧环境引起细胞内整体的组蛋白修饰程度和DNA甲基化水平改变.     

低氧诱导因子在疾病治疗中的新进展——2019年诺贝尔生理学或医学奖成果简析

 低氧诱导因子是一种异二聚体结构的DNA结合转录因子，它可以与特定的核辅因子结合，激活多种基因，在缺氧条件下优化氧的利用。美国癌症学家William G.Kaelin Jr、英国医学家Sir Peter J.Ratcliffe和美国医学家Gregg L.Semenza因发现了细胞如何感知和适应氧可用性，获得了2019年的诺贝尔生理学或医学奖，其中HIF发挥了重要的作用。介绍了HIF在肾性贫血、肿瘤、心血管疾病等治疗中的研究进展，探讨了其对人类健康的意义。     

低氧对人支气管上皮细胞HSP70和HIF-1α表达的影响

将人支气管上皮细胞（HBE）在低糖DMEM培养基、1%O2培养不同时间后,分别用RT-PCR和Western blot方法检测细胞HSP70、HIF-1α的mRNA和蛋白表达水平,同时采用免疫组化技术观察低氧对HSP70蛋白的影响．对照组培养于低糖、常氧条件下．结果表明,低氧条件下,HBE细胞HSP70 mRNA和蛋白表达都有时间依赖性．在1 h时HSP70mRNA转录水平即开始增加,与对照相比差异显著（P<0.05）;在12 h时转录水平最高;而HSP70蛋白的表达略有滞后,在3 h差异显著（P<0.     

封面图片说明：新型冠状病毒

 冠状病毒可分为α、β、γ、δ4个属，与人类疾病相关的冠状病毒均为α和β属冠状病毒。可知可造成人类疾病的冠状病毒有：普通人类冠状病毒229E、NL63、OC43、HKU1，严重急性呼吸综合征冠状病毒（severe acute respiratory syndrome coronavirus，SARS-CoV），中东呼吸综合征冠状病毒（Middle East respiratory syndrome coronavirus，MERS-CoV），以及2019新型冠状病毒（2019 novel coronavirus，2019-nCoV）。     

SUMO-1在ApoE-/-小鼠PM2.5暴露中调控血管HIF-1α/VEGF信号通路的研究

本文研究了ApoE-/-小鼠经PM2.5暴露后,其主动脉弓中SUMO-1、HIF-1及其靶基因血管内皮生长因子（VEGF）表达变化规律及HIF-1的SUMO化修饰情况。利用气管滴注方法将颗粒物滴入ApoE-/-小鼠,利用Western blot、QPCR检测小鼠主动脉中SUMO-1、HIF-1、VEGF的表达情况和CO-IP法检测SUMO-1及HIF-1共修饰情况。 结果显示： PM2.5暴露后,小鼠主动脉SUMO-1、HIF-1、VEGF的表达上调。CO-IP 显示：对照组SUMO-1没有对HIF-1α发生SUMO化修饰,PM2.5暴露后SUMO-1对HIF-1α产生了明显的SUMO化修饰。SUMO化的HIF-1与HIF-1α、HIF-1、VEGF蛋白均呈正相关。 PM2.5暴露可能通过上调细胞中SUMO-1的表达,稳定HIF-1α或者上调HIF-1的表达,进而影响VEGF的表达。     

LRH-1在女性生殖和乳腺癌中的研究进展

肝受体类似物-1 (liver receptor homolog-1, LRH-1;NR5A2)是转录因子家族中的新成员,表达于肝、肠、胰腺和卵巢,尤其在卵巢高表达,参与胚胎发育的调节.近年来发现LRH-1还表达于人类乳腺中未分化脂肪组织的间质层,可能参与前脂细胞功能调节或脂肪细胞分化.因此对LRH-1的研究有助于揭示LRH-1与人类生殖及疾病的关系,为疾病的早期诊断和有效治疗提供了新靶点.     

耐热酵母中海藻糖代谢途径对热胁迫的响应

海藻糖对酵母的耐热性有重要的作用：既是细胞保护剂,又是热激转录因子Hsf1p的正调节子.因此研究耐热酵母在热胁迫下海藻糖代谢途径的响应,有助于理解酵母的热响应机制,并为获得耐热的酿酒酵母提供理论基础.本文从转录及物质代谢角度对热胁迫下耐热酵母中海藻糖的代谢响应进行了研究.结果表明：在热胁迫下海藻糖代谢相关基因表达水平显著的升高,胞内海藻糖积累后有所下降,在耐热酵母海藻糖相关代谢基因水平和代谢物水平上的响应显示出高度的一致.本文的研究结果支持了热胁迫下酿酒酵母海藻糖作为细胞保护剂以及作为Hsf1p的正调节子的观点,进一步证实了海藻糖在酵母适应高温的过程中起重要作用.     

The tumour suppressor protein VHL targets hypoxia-inducible factors for oxygen-dependent proteolysis.

Hypoxia-inducible factor-1 (HIF-1) has a key role in cellular responses to hypoxia, including the regulation of genes involved in energy metabolism, angiogenesis and apoptosis. The alpha subunits of HIF are rapidly degraded by the proteasome under normal conditions, but are stabilized by hypoxia. Cobaltous ions or iron chelators mimic hypoxia, indicating that the stimuli may interact through effects on a ferroprotein oxygen sensor. Here we demonstrate a critical role for the von Hippel-Lindau (VHL) tumour suppressor gene product pVHL in HIF-1 regulation. In VHL-defective cells, HIF alpha-subunits are constitutively stabilized and HIF-1 is activated. Re-expression of pVHL restored oxygen-dependent instability. pVHL and HIF alpha-subunits co-immunoprecipitate, and pVHL is present in the hypoxic HIF-1 DNA-binding complex. In cells exposed to iron chelation or cobaltous ions, HIF-1 is dissociated from pVHL. These findings indicate that the interaction between HIF-1 and pVHL is iron dependent, and that it is necessary for the oxygen-dependent degradation of HIF alpha-subunits. Thus, constitutive HIF-1 activation may underlie the angiogenic phenotype of VHL-associated tumours. The pVHL/HIF-1 interaction provides a new focus for understanding cellular oxygen sensing.     

肽-DNA纳米颗粒用于HIF-1αΔODD转染脊髓损伤动物模型的研究

为了探讨肽-DNA纳米颗粒技术用于转染脊髓损伤动物模型的可能性,本研究在克隆得到氧浓度非敏感性的HIF-1α突变体基因(HIF-1αΔODD)并构建其真核重组表达载体(pEGFPC1-HIF-1αΔODD)的基础上,构建用于转染动物模型的肽-DNA纳米颗粒,将其转染脊髓损伤大鼠模型,用组织免疫荧光方法检测内/外源性HIF-1α在动物模型中的表达情况.结果显示,外源性HIF-1α在实验组脊髓组织中正确表达,说明构建的pEGFPC1-HIF-1αΔODD的肽-DNA纳米颗粒成功转染了稳定的脊髓损伤大鼠模型,肽-DNA纳米颗粒技术可作为中枢神经系统损伤动物模型的分子干预研究的一种新的选择.     

PML inhibits HIF-1alpha translation and neoangiogenesis through repression of mTOR

Loss of the promyelocytic leukaemia (PML) tumour suppressor has been observed in several human cancers. The tumour-suppressive function of PML has been attributed to its ability to induce growth arrest, cellular senescence and apoptosis. Here we identify PML as a critical inhibitor of neoangiogenesis (the formation of new blood vessels) in vivo, in both ischaemic and neoplastic conditions, through the control of protein translation. We demonstrate that in hypoxic conditions PML acts as a negative regulator of the synthesis rate of hypoxia-inducible factor 1alpha (HIF-1alpha) by repressing mammalian target of rapamycin (mTOR). PML physically interacts with mTOR and negatively regulates its association with the small GTPase Rheb by favouring mTOR nuclear accumulation. Notably, Pml-/- cells and tumours display higher sensitivity both in vitro and in vivo to growth inhibition by rapamycin, and lack of PML inversely correlates with phosphorylation of ribosomal protein S6 and tumour angiogenesis in mouse and human tumours. Thus, our findings identify PML as a novel suppressor of mTOR and neoangiogenesis.     

氧气的适应性机制及低氧预适应研究进展

氧气是有氧代谢和能量产生的必要条件,对于大多数生物来说都是必不可少的。过多或过少的氧气都可能危害生命,因此研究生物快速响应变化的氧气水平的机制至关重要。当氧气需求超过氧气供应时,细胞就会变得低氧。介绍了氧气的特性以及生理、病理条件下低氧的适应机制,论述了低氧作为的积极方面——低氧预适应的历史和研究进展,展望了低氧预适应在高空、高原等极端环境中以及在卒中等相关临床疾病中的治疗前景。     

Human endothelial senescence induced by IL-1α in vitro

Interleukin 1(IL-1) is an important proinflammatory cytokine that causes pleiotropic effects. Vascular endothelial cells stimulated by IL-1α can lead to the inflammatory response. Reactive oxygen species (ROS) are also generated at the site of inflammation and serve as an important factor against foreign invader. Here we report that long-term stimulation of human vein endothelial cells with IL-1α can accelerate their senescence associated with β-galactosidase activity. The flow cytometric analyses showed that most of the induced cells entered G0-G1 phase. DNA damage was more severe in senescent cells by comet assay. The induced cells by IL-1α had higher levels of ROS and malonyldialdehyde (MDA), lower activity of antioxidant enzymes and lower capacity of total antioxidant systems than control, which led to cell damage and cell degeneration, that is to say, which contributed to cellular senescence. Our results gave a direct proof to a new hypothesis-"the inflammation hypothesis of aging" on cellular level, and also provided a basis for the study on anti-aging and aging-related diseases.     

HIF-1-modified BMSCs improve migration and reduce neuronal apoptosis after stroke in rats

Bone marrow-derived mesenchymal stem cells (BMSCs) have been demonstrated ameliorating neurologic deficits after stroke. Hypoxia-inducible factor-1 (HIF-1), the key regulator of cellular responses to low oxygen concentration, can activate multiple genes involving in crucial aspects for neurologic recovery. In this study, we present that rat BMSCs overexpression of HIF-1 α showed higher expression of HIF-1 target genes in HIF-1-BMSCs, including CXCR4, EPO, and VEGF. BMSCs-mHIF-1α also exhibited an enhanced mobility towards the ischemic area within rat brain. Neural cell apoptosis in ischemic brain shown less severe in rats transplanted with HIF-1-BMSCs. Furthermore, the number of cells expressing neural progenitor markers PAX6 and DCX were increased in BMSCs-mHIF-1α-transplanted rats. These results suggest that HIF-1α in BMSCs reduces neuronal apoptosis and promotes neurogenesis after stroke in rats.