缺氧诱导因子脯氨酸羟化酶的调控与缺血缺氧性疾病

缺氧诱导因子脯氨酸羟化酶作为氧感受器,通过氧依赖性地催化缺氧诱导因子特定脯氨酸残基的羟基化反应,从而介导缺氧诱导因子的降解,在缺氧诱导因子转录活性的调控过程中具有重要作用。缺氧诱导因子在各种缺血缺氧性疾病的发生及发展过程中起重要作用,但直接抑制其转录活性十分困难,因此深入研究其特异性的脯氨酸羟化酶的活性调控可能为防治此类疾病提供新的策略。     

NF—κB通过HIF-1α的转录调节连接先天免疫和缺氧反应

缺氧反应是一个由低氧引起的古老的应激反应，并且受缺氧诱导因子-1（HIF-1）的控制，HIF-1的α亚基在含氧量正常的情况下会迅速退化，但是当由缺氧引起的氧依赖性脯氨酰羟化酶（PHDs）抑制时，α亚基很稳定。HIF—1α能控制与能量代谢和血管发生有关的基因，其含量受翻译后调节。另一个古老的应激反应是先天免疫反应，受一些转录因子调节，其中NF—κB起了核心作用。     

脯氨酰羟化酶RNA干扰慢病毒载体的构建与鉴定

背景：慢病毒载体可稳定介导基因沉默且具有较高的转染效率。 目的：构建并鉴定脯氨酰羟化酶 RNA干扰慢病毒载体。 方法：针对脯氨酰羟化酶2基因序列设计RNA干扰靶序列,合成靶序列的寡聚DNA,退火形成双链DNA,与经Age Ⅰ和EcoR Ⅰ酶切的pGCSIL-GFP连接、转化大肠杆菌感受态细胞,产生重组RNA干扰慢病毒表达载体,PCR筛选阳性克隆,测序鉴定。 结果与结论：PCR和DNA测序证实合成的含脯氨酰羟化酶短发卡RNA慢病毒载体寡核苷酸链正确插入pGCSIL-GFP载体。说明实验成功构建脯氨酰羟化酶基因RNA干扰慢病毒载体。     

水蚤在缺氧模型中的应用价值

缺氧诱导因子(HIF)是许多生物在缺氧条件下非常重要的一个转录调节因子,在缺氧耐受性产生中扮演关键角色。有必要建立一种相关缺氧模型,用于HIF和缺氧耐受性的研究。本实验旨在探讨水蚤作为一种动物模型在缺氧处理中的应用价值,通过建立水蚤缺氧预处理模型,发现两个时段的缺氧预处理可明显增加水蚤的缺氧耐受性,而其耐受性的产生与HIF相关。通过比较基因组学分析水蚤、果蝇和人类中HIF基因的同源性,发现水蚤适合作为模式动物用于人类缺氧损伤的研究。     

缺氧应激反应中活性氧与缺氧诱导因子-1的相互作用

在缺氧条件下,线粒体会产生大量的活性氧（ reactive oxygen species, ROS）,随即大量的活性氧将会诱导机体产生缺氧应激反应。缺氧诱导因子1（hypoxia inducible factor 1, HIF?1）是缺氧应激反应中的中枢调控因子。有研究表明, ROS主要通过抑制脯氨酸羟化酶家族（ prolyl hydroxylases, PHDs）的活性来抑制HIF?1α的泛素化降解,从而稳定HIF?1。而HIF?1蛋白水平的升高有助于机体应对缺氧微环境。最近研究还发现, REDD?1可以通过ROS对HIF?1产生负调控作用,从而抑制肿瘤的形成;秀丽线虫呼吸突变体的产生会导致ROS水平增加,从而增强HIF?1的活性,最终延长的线虫寿命;以及ROS、 HIF?1促进自噬的产生。因此,了解缺氧条件下ROS与HIF?1之间的相互作用关系,对于今后肿瘤、衰老和自噬的研究具有重要意义。     

钴引起的缺氧诱导因子活化在环孢素诱导的肾病中可减轻组织损伤和细胞凋亡

缺氧诱导因子(HIF)是一个调节细胞缺氧反应的转录因子。环孢素A(CsA)尽管在治疗器官移植方面有很多益处,但诱导慢性肾病发生的副作用,限制了它的临床应用。韩国科学家探讨了钴引起HIF的活化对CsA诱导的慢性肾病的影响及其相关机制。在动物实验中,给予大鼠0.05%的     

基因的缺氧诱导性表达调控

细胞可以通过改变基因表达方式而对细胞内外各种环境刺激产生应答反应，以维持其稳态（horn。tasis）。越来越多的研究表明，缺氧可以上调某些基因的表达，其中包括红细胞生成素（EPO）、血管内皮生长因子（VEGF）、血小板衍生生长因子（PDGF）、糖酵解西、转录因子和某些原癌基因等”’。这种基因的缺氧诱导性表达调控是通过特异的反式作用因于与DNA上的氧调节性顺式作用元件相互作用而实现的。一、HIF－l的生成与转录调节作用缺氧诱导因子河（hypoXia－induciblefactor－l，HIF－l）“’是从缺氧培养的细胞核粗提液中提取的一种…     

缺氧诱导因子HIF-α在固有免疫细胞参与炎症相关疾病的调控作用

氧消耗过多或供给不足造成的低氧分压状态,即缺氧,是一种常见的病理状态,尤其在一些炎症发生的细胞组织中。缺氧状态下,机体通过各种机制激活缺氧诱导因子(Hypoxia inducible factor,HIF),HIF 入核后转录调控下游靶基因,使细胞适应缺氧应激。研究发现,HIF 在炎症中发挥重要的作用。本文综述了近年来关于缺氧诱导因子HIF-α在固有免疫细胞参与的炎症相关疾病中的调控作用及其机制的研究进展。     

缺氧反应基因及调控机制研究进展

细胞在缺氧情况下,可诱导缺氧反应基因转录增加,维持血氧稳定。缺氧诱导因子-1和包含有启动子、增强子序列的顺序作用元件为转录调控的关键环节,缺氧诱导因子-1可通过顺式作用元件内的缺氧诱导因子-1结合位点与之相结合,二者通过复杂的相互作用来实现转录调控。     

缺氧诱导因子1研究进展

缺氧诱导因子1(hypoxia-inducible factor-1,HIF-1)是由两个蛋白质亚基组成的二聚体转录因子,对缺氧具有特异感受性,它的表达受细胞内氧分压的严密调节。HIF-1参与体内许多缺氧反应性基因的转录调节,是机体缺氧应答反应中的关键作用因子。     

Accumulation of Krebs cycle intermediates and over-expression of HIF1alpha in tumours which result from germline FH and SDH mutations

The nuclear-encoded Krebs cycle enzymes, fumarate hydratase (FH) and succinate dehydrogenase (SDHB, -C and -D), act as tumour suppressors. Germline mutations in FH predispose individuals to leiomyomas and renal cell cancer (HLRCC), whereas mutations in SDH cause paragangliomas and phaeochromocytomas (HPGL). In this study, we have shown that FH-deficient cells and tumours accumulate fumarate and, to a lesser extent, succinate. SDH-deficient tumours principally accumulate succinate. In situ analyses showed that these tumours also have over-expression of hypoxia-inducible factor 1alpha (HIF1alpha), activation of HIF1alphatargets (such as vascular endothelial growth factor) and high microvessel density. We found no evidence of increased reactive oxygen species in our cells. Our data provide in vivo evidence to support the hypothesis that increased succinate and/or fumarate causes stabilization of HIF1alpha a plausible mechanism, inhibition of HIF prolyl hydroxylases, has previously been suggested by in vitro studies. The basic mechanism of tumorigenesis in HPGL and HLRCC is likely to be pseudo-hypoxic drive, just as it is in von Hippel-Lindau syndrome.     

HIF prolyl hydroxylase-3 mediates alpha-ketoglutarate-induced apoptosis and tumor suppression

Many solid tumors consist of large regions of poorly perfused cells, resulting in areas of low oxygen (hypoxia) throughout the cell mass. Cells subjected to hypoxia turn on a complex set of responses that alter their metabolism, rebalance their survival mechanisms, increase their invasive capacity, and stimulate angiogenesis. This allows them to at least temporarily escape the nutrient starvation and cell death resulting from this hostile environment. Accordingly, the hypoxic regions of tumors are often sources of the most aggressive and therapy-resistant cells, and therefore those cells that drive tumorigenesis. The hypoxia inducible factor (HIF) prolyl hydroxylases (PHDs) are enzymes that are functionally inactivated in hypoxia, as they use both oxygen and α-ketoglutarate as substrates to hydroxylate target prolyl residues. Although HIF1α, the most highly characterized PHD target, orchestrates many of the cellular responses to hypoxia observed in tumors, PHDs themselves have previously been shown to regulate some hypoxia responses, including apoptosis, in a HIF-independent mechanism. We have previously shown that PHDs can be reactivated under hypoxia and that this results in a metabolic defect, both in vitro and in vivo. This led us to investigate whether chronic reactivation of these enzymes may inhibit tumor progression. We show here that esterified α-ketoglutarate given daily will induce apoptosis and inhibit tumor growth, in vivo. The effects are independent of HIF1α but dependent on the presence of PHD3. These data suggest that PHD3 may be a valid target in vivo for anti-tumor therapy.