Prosurvival and prodeath effects of hypoxia-inducible factor-1alpha stabilization in a murine hippocampal cell line.
Hypoxia-inducible factor-1 (HIF-1) is a transcriptional activator involved in adaptation to hypoxic stress. Previous studies from our laboratory demonstrated that pharmacological activators of HIF-1 (e.g. deferoxamine, cobalt chloride) could also protect cultured primary neurons or an immortalized hippocampal neuroblast line (HT22) from oxidative stress-induced death. However, whether HIF-1 activation is sufficient to abrogate neuronal death resulting from oxidative stress or other hypoxia-independent death inducers remains unclear. To address this question we utilized a HIF-1alpha fusion protein that partially lacks the domain required for oxygen-dependent degradation of HIF-1alpha and that has a VP16 transcriptional activation domain from herpes simplex virus. HT22 cells were infected with a retrovirus encoding either the HIF-1alpha-VP16 fusion protein or the activation domain of the VP16 protein alone as a control. Expression of HIF-1alpha-VP16, but not VP16 alone, increased luciferase activity driven by a canonical hypoxia response element, increased mRNA of established HIF-1 target genes, and increased activity of one of these HIF-1 target genes. Unexpectedly, enhanced HIF-1 activity in HT22 cells enhanced sensitivity to oxidative death induced by glutathione depletion. Accordingly, suppression of HIF-1alpha expression using RNA interference prevented oxidative death. By contrast, HIF-1alpha-VP16-expressing HT22 cells were more resistant to DNA damage (induced by camptothecin) or endoplasmic reticulum stress (induced by thapsigargin and tunicamycin) than were VP16-expressing cells, and suppression of HIF-1alpha expression using RNA interference rendered HT22 cells more sensitive to death induced by DNA damage or endoplasmic reticulum stress. Together, these data demonstrate that HIF-1 can mediate prodeath or prosurvival responses in the same cell type depending on the injury stimulus.
Aminova
Leila R
LR
Department of Neurology and Program in Neuroscience, Harvard Medical School, Boston, Massachusetts 02115, USA.
Chavez
Juan C
JC
Lee
Junghee
J
Ryu
Hoon
H
Kung
Andrew
A
Lamanna
Joseph C
JC
Ratan
Rajiv R
RR
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002166:Camptothecin / Q000494:pharmacology; D016923:Cell Death / Q000187:drug effects / Q000502:physiology*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D004249:DNA Damage; D004791:Enzyme Inhibitors / Q000494:pharmacology; D017405:Herpes Simplex Virus Protein Vmw65 / Q000235:genetics; D006624:Hippocampus / Q000166:cytology*; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D051379:Mice; D009474:Neurons / Q000166:cytology* / Q000378:metabolism*; D010100:Oxygen / Q000494:pharmacology; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D019284:Thapsigargin / Q000494:pharmacology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014415:Tunicamycin / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D004791:Enzyme Inhibitors; D017405:Herpes Simplex Virus Protein Vmw65; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D014415:Tunicamycin; D019284:Thapsigargin; D010100:Oxygen; D002166:Camptothecin