缺氧条件下HIF-1α对舌鳞癌细胞VEGF-C及FAS表达的影响

目的探讨缺氧条件下人舌鳞癌Tca8113细胞株HIF-1α对VEGF-C及FAS基因表达的影响。方法采用RT-PCR技术半定量检测人Tca8113细胞常氧和缺氧培养0.5、1、3、6、12和24h HIF-1α、VEGF-C和FAS基因的表达。结果缺氧条件下HIF-1α与VEGF-C基因表达呈先升后降的趋势,二者表达呈显著正相关性(rs=0.979,P<0.01)。FAS基因表达呈上升趋势,与HIF-1α表达无明显相关性(rs=0.556,P>0.05)。结论缺氧条件下Tca8113细胞中HIF-1α可上调VEGF-C的表达,促进癌细胞的转移;HIF-1α参与促进肿瘤细胞FAS的表达,影响舌癌细胞的凋亡。

Hif-1α/Hsf1/Hsp70 signaling pathway regulates redox homeostasis and apoptosis in large yellow croaker(Larimichthys crocea)under environmental hypoxia

Oxygen is an essential molecule for animal respiration,growth,and survival.Unlike in terrestrial environments,contamination and climate change have led to the frequent occurrence of hypoxia in aquatic environments,thus impacting aquatic animal survival.However,the adaptative mechanisms underlying fish responses to environmental hypoxia remain largely unknown.Here,we used large yellow croaker(Larimichthys crocea)and large yellow croaker fry(LYCF)cells to investigate the roles of the Hif-1α/Hsf1/Hsp70 signaling pathway in the regulation of cellular redox homeostasis,and apoptosis.We confirmed that hypoxia induced the expression of Hif-1α,Hsf1,and Hsp70 in vivo and in vitro.Genetic Hsp70 knockdown/overexpression indicated that Hsp70 was required for maintaining redox homeostasis and resisting oxidative stress in LYCF cells under hypoxic stress.Hsp70 inhibited caspase-dependent intrinsic apoptosis by maintaining normal mitochondrial membrane potential,enhancing Bcl-2 mRNA and protein expression,inhibiting Bax and caspase3 mRNA expression,and suppressing caspase-3 and caspase-9 activation.Hsp70 suppressed caspaseindependent intrinsic apoptosis by inhibiting nuclear translocation of apoptosis-inducing factor(AIF)and disturbed extrinsic apoptosis by inactivating caspase-8.Genetic knockdown/overexpression of Hif-1αand dual-luciferase reporter assay indicated that Hif-1αactivated the Hsf1 DNA promoter and enhanced Hsf1 mRNA transcription.Hsf1 enhanced Hsp70 mRNA transcription in a similar manner.In summary,the Hif-1α/Hsf1/Hsp70 signaling pathway plays an important role in regulating redox homeostasis and anti-apoptosis in L.crocea under hypoxic stress.

Influence of hypoxia-inducible factor 1-alpha on neuronal apoptosis in a rat model of hypoxia-or hypoxia-ischemia-induced brain injury

BACKGROUND： In addition to neuroprotective genes, the targeted genes of hypoxia-inducible factor 1α （HIF-1α） include pro-apoptotic genes. However, the influence of HIF-1α on neuronal apoptosis in hypoxia-ischemia remains poorly understood. OBJECTIVE： To investigate the relationship between HIF-1α expression and neuronal apoptosis in hypoxia or hypoxia-ischemia brain injury and to determine the role of HIF-1α in regulating neuronal apoptosis. DESIGN, TIME AND SETTING： A randomized, controlled animal experiment was performed at the Laboratory of Children Neurology of Sichuan University between May 2006 and May 2007. MATERIALS： In situ cell death detected kit was provided by Roche, USA; rabbit anti-mouse HIF-1α polyclonal antibody was purchased from Santa Cruz Biotechnologies, USA; rabbit anti-mouse cleaved caspase-3 polyclonal antibody was purchased from Chemicon, USA. METHODS： A total of 36 Sprague Dawley rats aged 10 days were randomly assigned to 3 groups： sham-surgery, hypoxia, and hypoxia-ischemia, with 12 rats per group. The rats were treated at 3 time points： 4, 8, and 24 hours, with 4 rats per time point. In the hypoxia-ischemia group, the right common carotid artery was exposed and permanently ligated through a midline cervical incision. A 2.5-hour exposure to hypoxia （8% O2/92% N2） was used to induce hypoxia-ischemia injury. In the hypoxia group, rats were exposed to hypoxia without ligation of the common carotid artery. In the sham-surgery group, the common carotid artery was exposed without ligation or hypoxia. MAIN OUTCOME MEASURES： Histopathological changes, HIF-1α and activated caspase-3 protein expression, integrated optical density of positive cells, and apoptosis-positive cells. RESULTS： Hematoxylin and eosin staining showed that neuronal degeneration and edema was most prominent at 24 hours after hypoxia-ischemia. HIF-1α protein expression was significantly upregulated at 4 hours, peaked at 8 hours, and decreased at 24 hours after hypoxia or hypoxia-ischemia. HIF-1α protein expression was significant greater in the hypoxia and hypoxia-ischemia groups compared with the sham-surgery group （P 〈 0.01）. Activated caspase-3 protein expression began to increase at 4 and 8 hours following hypoxia or hypoxia-ischemia and was significantly upregulated at 24 hours. Activated caspase-3 protein expression remained at low levels in the sham controls compared with the hypoxia and hypoxia-ischemia groups （P〈 0.01）. TUNEL staining showed that the number of apoptotic cells significantly increased at 24 hours after hypoxia or hypoxia-ischemia. In addition, HIF-1α protein expression was greater in the hypoxia group compared with the hypoxia-ischemia group at the same time point （P 〈 0.05）. However, activated caspase-3 expression and the number of TUNEL-positive cells were less in the hypoxia group compared with the hypoxia-ischemia group at the same time point （P〈 0.05）. CONCLUSION： HIF-1α played a neuroprotective role following hypoxia-ischemia brain injury.

Hypoxia induced apoptosis of rat gastric mucosal cells by activating autophagy through HIF-1α/TERT/mTORC1 pathway

The pathogenesis of high altitude-related gastric mucosal injury remains poorly understood,this study aimed to investigate the role of autophagy in hypoxia-induced apoptosis of rat gastric mucosal cells.Rats were randomized into four groups which were maintained at an altitude of 400 m(P)or received no treatment(H),autophagy inducer rapamycin(H+AI)or autophagy inhibitor 3-MA(H+AB)at an altitude of 4,300 m for 1,7,14 and 21 days,respectively,and the morphology,ultrastructure,autophagy,and apoptosis of gastric mucosal tissues were examined.Gastric mucosal epithelial cells CC-R039 were cultured under conditions of normoxia,2%O2(hypoxia),or 2%O2+anti-mTORC1 for 0,24,48,and 72 h,respectively,and the autophagy and apoptosis were analyzed.CC-R039 cells were transfected with siHIF-1α,siTERT,or siRNA and the autophagy was examined.The results showed that the exposure to hypoxia increased the autophagy and apoptosis of gastric mucosal cells in rats,and apoptosis was aggravated by rapamycin treatment but alleviated by 3-MA treatment.Increased duration of hypoxia from 0 to 72 h could increase the autophagy and apoptosis but decrease the proliferation of gastric mucosal cells.Inhibition of mTORC1 with rapamycin led to further increase in apoptosis and even substantial cell death,and inhibition of HIF-1αand TERT increased mTORC1 expression and reduced autophagy.Moreover,the inhibition of HIF-1αreduced TERT expression.In conclusion,hypoxia could induce apoptosis of rat gastric mucosal cells by activating autophagy through HIF-1α/TERT/mTORC1 pathway.