Granulocyte Macrophage Colony-Stimulating Factor Shows Anti-apoptotic Activity via the PI3K–NF-κB–HIF-1α–Survivin Pathway in Mouse Neural Progenitor Cells

• Published in: Molecular neurobiology 2014-04, Vol.49 (2), p.724-733
• Main Authors: Choi, Jung Kyoung, Kim, Kil Hwan, Park, So Ra, Choi, Byung Hyune
• Format: Article
• Language: English
• Subjects: Animals; Apoptosis - drug effects; Apoptosis - physiology; Biomedical and Life Sciences; Biomedicine; Cell Biology; Cells, Cultured; Chromones - pharmacology; Enzyme Inhibitors - pharmacology; Granulocyte-Macrophage Colony-Stimulating Factor - pharmacology; Hypoxia-Inducible Factor 1, alpha Subunit - biosynthesis; Hypoxia-Inducible Factor 1, alpha Subunit - genetics; Inhibitor of Apoptosis Proteins - biosynthesis; Inhibitor of Apoptosis Proteins - genetics; Male; Mice; Mice, Inbred ICR; Morpholines - pharmacology; Neural Stem Cells - drug effects; Neural Stem Cells - metabolism; Neurobiology; Neurology; Neurosciences; NF-kappa B - biosynthesis; NF-kappa B - genetics; Phosphatidylinositol 3-Kinase - antagonists & inhibitors; Phosphatidylinositol 3-Kinase - biosynthesis; Phosphatidylinositol 3-Kinase - genetics; Repressor Proteins - biosynthesis; Repressor Proteins - genetics; RNA, Small Interfering - genetics
• ISSN: 0893-7648; 1559-1182
• DOI: 10.1007/s12035-013-8550-3

Granulocyte macrophage-colony stimulating factor (GM-CSF) is a hematopoietic cytokine that plays a crucial role in regulating the proliferation, differentiation, and survival of hematopoietic cells. Recent studies have shown that GM-CSF also has anti-apoptotic effects and regulates the expression of anti-apoptotic genes including Bcl-2 family proteins in neuronal cells in vitro and in vivo. However, the mechanism underlying the anti-apoptotic function of GM-CSF is not well understood. In the present work, we examined the role of phosphoinositide 3-kinase (PI3K)–AKT signal pathway in the anti-apoptotic activity of GM-CSF in mouse neural progenitor cells (NPCs). In terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, the anti-apoptotic effect of GM-CSF (apoptotic population of approximately 8.17 %) on staurosporine-induced apoptosis of NPCs (31.09 %) was significantly blocked by LY294002, an inhibitor of PI3K signal (24.04 %). We found that the PI3K–AKT signal pathway induced by GM-CSF treatment activated nuclear factor κB (NF-κB) and increased the expression of hypoxia-inducible factor 1α (HIF-1α) in normoxic conditions. Analyses using specific small interfering RNAs (siRNAs) showed that NF-κB was an upstream molecule of HIF-1α and activated its expression at the mRNA level. Further analyses using the siRNAs and chromatin immunoprecipitation (ChIP) showed that HIF-1α was responsible for the induced expression of survivin, a member of the inhibitor of apoptosis proteins (IAPs). Each of the specific siRNAs for NF-κB, HIF-1α, and survivin inhibited significantly the anti-apoptotic activity of GM-CSF on the staurosporine-induced apoptosis in NPCs in TUNEL assays. The results of this study showed the downstream signals and mechanism of PI3K/AKT-mediated anti-apoptotic activity of GM-CSF in NPCs, particularly revealing the role of the NF-κB–HIF-1α–survivin cascade.