Apoptosis-associated tyrosine kinase and neuronal cell death.
Apoptosis-associated tyrosine kinase (AATYK) is up-regulated by phosphorylation in cultured cerebellar granule neurons (CGN) undergoing apoptosis upon switch to low KCl-containing medium. However, the underlying signaling pathways remain to be fully characterized. When CGN at culture day 7 were switched from 25 mM KCl (K25) to 5 mM (K5) medium, AATYK band migration on SDS-PAGE shifted to a more slowly migrating position expected for the hyperphosphorylated protein. The apoptosis-inducing agent C(2)-ceramide also caused a mobility shift of the AATYK protein. Exposing CGN (K25) to L-type voltage-dependent Ca(2+) channel antagonists shifted the AATYK band to the K5-induced position, while the Ca(2+) channel activator FPL-64176 had the contrary effect. FK-506, a calcineurin inhibitor caused AATYK hyperphosphorylation under high KCl conditions. CGN death in K5 medium is linked to inhibition of the PI 3-kinase/Akt survival pathway and concomitant activation of the pro-apoptotic downstream target glycogen synthase kinase-3 (GSK-3). GSK-3 inhibitors blocked the K5-induced mobility shift of AATYK. Moreover, CGN cultured from AATYK-deficient mice remained sensitive to death in K5 medium. Thus, AATYK activation may not be a physiologically relevant principal regulatory target of the GSK-3 death pathway in KCl-deprived CGN.
Hughes
Jane P
JP
Neurosciences Centre of Excellence for Drug Discovery, GlaxoSmithKline Research and Development Limited, New Frontiers Science Park, Harlow, UK.
Ward
Daniel R
DR
Facci
Laura
L
Richardson
Jill C
JC
Skaper
Stephen D
SD
D016229:Amyloid beta-Peptides / Q000378:metabolism; D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D020013:Calcium Signaling; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology / Q000201:enzymology; D003594:Cytoplasmic Granules / Q000201:enzymology; D004591:Electrophoresis, Polyacrylamide Gel; D051379:Mice; D009474:Neurons / Q000166:cytology* / Q000201:enzymology; D010766:Phosphorylation; D011188:Potassium / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D051381:Rats
D016229:Amyloid beta-Peptides; D011505:Protein-Tyrosine Kinases; D011188:Potassium