Glial-derived neurotrophic factor (GDNF) prevents ethanol-induced apoptosis and JUN kinase phosphorylation.
Ethanol exposure during neural development leads to substantial neuronal loss in multiple brain regions. Our previous research indicated that exogenous glial-derived neurotrophic factor (GDNF) attenuated ethanol-induced cerebellar Purkinje cell loss. Additionally, ethanol decreased GDNF release suggesting that ethanol disrupts GDNF-signaling pathways. The present experiments utilized a homogeneous GDNF-responsive neuroblastoma cell line (SK-N-SH) to test the hypothesis that exogenous GDNF could attenuate ethanol-induced cell loss by suppressing cytotoxic signaling pathways and cell suicide. We measured two independently regulated markers of apoptosis, DNA fragmentation and the externalization of phosphatidylserine to the outer cell membrane leaflet. Ethanol induced a dose-related increase in both apoptosis and necrosis. Lower concentrations of ethanol (34 and 68 mM) specifically increased DNA fragmentation, while all concentrations (up to 137 mM) increased phosphatidylserine translocation, suggesting that ethanol induction of apoptosis is not a unitary process. Furthermore, only higher concentrations of ethanol (103 and 137 mM) induced necrosis. Additionally, ethanol specifically induced phosphorylation of c-jun N-terminal-kinase (JNK), a mitogen-activated protein (MAP) kinase selectively associated with apoptosis. In contrast, ethanol did not alter the phosphorylation of another MAP kinase, the extracellular signal-regulated kinases (ERK) that mediate cell survival. Thus, ethanol activated specific intracellular cell death-associated pathways and induced cell death. GDNF, in turn, prevented both ethanol-induced apoptosis and the activation of the death-associated JNK cascade. Therefore, GDNF may regulate multiple pathways to prevent ethanol-induced cell loss.
McAlhany
R E
RE
Texas A&M University Health Science Center, College Station, TX 77843-1114, USA.
West
J R
JR
Miranda
R C
RC
D017304:Annexin A5 / Q000032:analysis; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D002462:Cell Membrane / Q000737:chemistry / Q000201:enzymology; D002470:Cell Survival / Q000502:physiology; D002492:Central Nervous System Depressants / Q000494:pharmacology*; D053938:DNA Fragmentation; D000431:Ethanol / Q000494:pharmacology*; D063647:Fetal Alcohol Spectrum Disorders / Q000188:drug therapy / Q000201:enzymology; D051100:Glial Cell Line-Derived Neurotrophic Factor; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009336:Necrosis; D009414:Nerve Growth Factors; D009419:Nerve Tissue Proteins / Q000494:pharmacology*; D009447:Neuroblastoma; D018696:Neuroprotective Agents / Q000494:pharmacology*; D010718:Phosphatidylserines / Q000378:metabolism; D010766:Phosphorylation; D014407:Tumor Cells, Cultured / Q000166:cytology / Q000187:drug effects / Q000201:enzymology
D017304:Annexin A5; D002492:Central Nervous System Depressants; C495039:GDNF protein, human; D051100:Glial Cell Line-Derived Neurotrophic Factor; D009414:Nerve Growth Factors; D009419:Nerve Tissue Proteins; D018696:Neuroprotective Agents; D010718:Phosphatidylserines; D000431:Ethanol; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases