Hypoxia induces the activation of the phosphatidylinositol 3-kinase/Akt cell survival pathway in PC12 cells: protective role in apoptosis.
Hypoxia is a common environmental stress that influences signaling pathways and cell function. Several cell types, including neuroendocrine chromaffin cells, have evolved to sense oxygen levels and initiate specific adaptive responses to hypoxia. Here we report that under hypoxic conditions, rat pheochromocytoma PC12 cells are resistant to apoptosis induced by serum withdrawal and chemotherapy treatment. This effect is also observed after treatment with deferoxamine, a compound that mimics many of the effects of hypoxia. The hypoxia-dependent protection from apoptosis correlates with activation of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway, which is detected after 3-4 h of hypoxic or deferoxamine treatment and is sustained while hypoxic conditions are maintained. Hypoxia-induced Akt activation can be prevented by treatment with cycloheximide or actinomycin D, suggesting that de novo protein synthesis is required. Finally, inhibition of PI3K impairs both the protection against apoptosis and the activation of Akt in response to hypoxia, suggesting a functional link between these two phenomena. Thus, reduced oxygen tension regulates apoptosis in PC12 cells through activation of the PI3K/Akt survival pathway.
Alvarez-Tejado
M
M
Servicio de Inmunologia, Hospital de la Princesa, Universidad Autónoma de Madrid, 28006 Madrid, Spain.
Naranjo-Suarez
S
S
Jiménez
C
C
Carrera
A C
AC
Landázuri
M O
MO
del Peso
L
L
D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis; D015687:Cell Hypoxia; D002867:Chromones / Q000494:pharmacology; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D009025:Morpholines / Q000494:pharmacology; D016716:PC12 Cells; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D000077191:Wortmannin
D000730:Androstadienes; D002867:Chromones; D004791:Enzyme Inhibitors; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D000077191:Wortmannin; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C494920:Akt1 protein, rat