TY - JOUR
T1 - Phosphoinositide 3-kinases upregulate system xc- via eukaryotic initiation factor 2α and activating transcription factor 4-A pathway active in glioblastomas and epilepsy
AU - Lewerenz, Jan
AU - Baxter, Paul
AU - Kassubek, Rebecca
AU - Albrecht, Philipp
AU - Van Liefferinge, Joeri
AU - Westhoff, Mike-Andrew
AU - Halatsch, Marc-Eric
AU - Karpel-Massler, Georg
AU - Meakin, Paul J.
AU - Hayes, John D.
AU - Aronica, Eleonora
AU - Smolders, Ilse
AU - Ludolph, Albert C.
AU - Methner, Axel
AU - Conrad, Marcus
AU - Massie, Ann
AU - Hardingham, Giles E.
AU - Maher, Pamela
PY - 2014/5/28
Y1 - 2014/5/28
N2 - Aims: Phosphoinositide 3-kinases (PI3Ks) relay growth factor signaling and mediate cytoprotection and cell growth. The cystine/glutamate antiporter system xc- imports cystine while exporting glutamate, thereby promoting glutathione synthesis while increasing extracellular cerebral glutamate. The aim of this study was to analyze the pathway through which growth factor and PI3K signaling induce the cystine/glutamate antiporter system xc- and to demonstrate its biological significance for neuroprotection, cell growth, and epilepsy. Results: PI3Ks induce system xc- through glycogen synthase kinase 3ß (GSK-3ß) inhibition, general control non-derepressible-2-mediated eukaryotic initiation factor 2a phosphorylation, and the subsequent translational up-regulation of activating transcription factor 4. This pathway is essential for PI3Ks to modulate oxidative stress resistance of nerve cells and insulin-induced growth in fibroblasts. Moreover, the pathway is active in human glioblastoma cells. In addition, it is induced in primary cortical neurons in response to robust neuronal activity and in hippocampi from patients with temporal lobe epilepsy. Innovation: Our findings further extend the concepts of how growth factors and PI3Ks induce neuroprotection and cell growth by adding a new branch to the signaling network downstream of GSK-3ß, which, ultimately, leads to the induction of the cystine/glutamate antiporter system xc-. Importantly, the induction of this pathway by neuronal activity and in epileptic hippocampi points to a potential role in epilepsy. Conclusion: PI3K-regulated system xc- activity is not only involved in the stress resistance of neuronal cells and in cell growth by increasing the cysteine supply and glutathione synthesis, but also plays a role in the pathophysiology of tumor- and non-tumor-associated epilepsy by up-regulating extracellular cerebral glutamate.
AB - Aims: Phosphoinositide 3-kinases (PI3Ks) relay growth factor signaling and mediate cytoprotection and cell growth. The cystine/glutamate antiporter system xc- imports cystine while exporting glutamate, thereby promoting glutathione synthesis while increasing extracellular cerebral glutamate. The aim of this study was to analyze the pathway through which growth factor and PI3K signaling induce the cystine/glutamate antiporter system xc- and to demonstrate its biological significance for neuroprotection, cell growth, and epilepsy. Results: PI3Ks induce system xc- through glycogen synthase kinase 3ß (GSK-3ß) inhibition, general control non-derepressible-2-mediated eukaryotic initiation factor 2a phosphorylation, and the subsequent translational up-regulation of activating transcription factor 4. This pathway is essential for PI3Ks to modulate oxidative stress resistance of nerve cells and insulin-induced growth in fibroblasts. Moreover, the pathway is active in human glioblastoma cells. In addition, it is induced in primary cortical neurons in response to robust neuronal activity and in hippocampi from patients with temporal lobe epilepsy. Innovation: Our findings further extend the concepts of how growth factors and PI3Ks induce neuroprotection and cell growth by adding a new branch to the signaling network downstream of GSK-3ß, which, ultimately, leads to the induction of the cystine/glutamate antiporter system xc-. Importantly, the induction of this pathway by neuronal activity and in epileptic hippocampi points to a potential role in epilepsy. Conclusion: PI3K-regulated system xc- activity is not only involved in the stress resistance of neuronal cells and in cell growth by increasing the cysteine supply and glutathione synthesis, but also plays a role in the pathophysiology of tumor- and non-tumor-associated epilepsy by up-regulating extracellular cerebral glutamate.
UR - http://www.scopus.com/inward/record.url?scp=84901610814&partnerID=8YFLogxK
U2 - 10.1089/ars.2013.5455
DO - 10.1089/ars.2013.5455
M3 - Article
C2 - 24219064
AN - SCOPUS:84901610814
SN - 1523-0864
VL - 20
SP - 2907
EP - 2922
JO - Antioxidants & Redox Signaling
JF - Antioxidants & Redox Signaling
IS - 18
ER -