HIF-1 or HIF-2 induction is sufficient to achieve cell cycle arrest in NIH3T3 mouse fibroblasts independent from hypoxia
HIF-1 or HIF-2 induction is sufficient to achieve cell cycle arrest in NIH3T3 mouse fibroblasts independent from hypoxia
复制标题
DOI：
10.4161/cc.8.9.8306
复制
发表时间：
2009-05-01
期刊：
影响因子：
4.3
通讯作者：
Wiesener, Michael Sean
中科院分区：
文献类型：
--
作者：
Hackenbeck, Thomas;Knaup, Karl Xaver;Wiesener, Michael Sean
低氧是一种诱导生理和分子适应的严重应激，而后者是由低氧诱导转录因子(HIF)主导的。细胞水平上对低氧的反应是可逆的细胞周期停滞，这可能使细胞对困难的环境更具抵抗力。低氧本身及其亚型HIF-1α和HIF-2α在细胞周期调控中的单独作用尚不清楚，也存在争议。为了表征这两种亚型对细胞周期的单独影响，我们建立了四环素诱导的表达HIF-1α和-2α的NIH3T3细胞。在常氧条件下，HIFA的cDNA发生突变，以产生稳定和活性的HIF。当两个HIFα亚基都被激活时，活细胞总数减少，长期的HIF刺激导致转基因表达完全丧失，这意味着强大的负选择压力。同样，两个HIFA亚基的激活也降低了集落形成活性。细胞周期分析显示，HIF激活导致细胞周期明显停滞于G(1)期，与缺氧效应相似。HIF-1α和HIF-2α均能在报告基因和蛋白水平上诱导细胞周期蛋白依赖性激酶抑制因子p27的表达，我们的研究表明，HIF-1和HIF-2可以独立于低氧诱导细胞周期。这些发现不仅对肿瘤细胞对环境和治疗的抵抗力有影响，而且对生理细胞也有影响。重要的是，最近在常氧条件下稳定HIFA的方法可能会对增殖组织产生有害影响。
Hypoxia is a severe stress which induces physiological and molecular adaptations, where the latter is dominated by the Hypoxia-inducible transcription Factor (HIF). A well described response on cellular level upon exposure to hypoxia is a reversible cell cycle arrest, which probably renders the cells more resistant to the difficult environment. The individual roles of hypoxia itself and of the isoforms HIF-1 alpha and HIF-2 alpha in cell cycle regulation are poorly understood and discussed controversially.In order to characterize the isolated effect of both HIF alpha isoforms on the cell cycle we generated tetracycline inducible, HIF-1 alpha and -2 alpha expressing NIH3T3 cells. The cDNAs for HIFa were mutated to generate stable and active HIF under normoxia. Upon activation of both HIF alpha subunits, the total number of living cells was reduced and long-term stimulation of HIF led to complete loss of transgene expression, implicating a strong negative selection pressure. Equally, colony forming activity was reduced by activation of both HIFa subunits. Cell cycle analyses showed that HIF activation resulted in a prominent cell cycle arrest in G(1)-phase, similarly to the hypoxic effect. Both, HIF-1 alpha and HIF-2 alpha were able to induce the expression of the cyclin-dependent kinase inhibitor p27 on reporter gene and protein level.Our study shows that HIF-1 and HIF-2 can individually arrest the cell cycle independent from hypoxia. These findings have implications for the resistance of tumor cells to the environment and treatment, but also for physiological cells. Importantly, recent approaches to stabilize HIFa in normoxia could have deleterious effects on proliferating tissues.