Neuronal pentraxin 1 induction in hypoxic-ischemic neuronal death is regulated via a glycogen synthase kinase-3α/β dependent mechanism.
Intracellular signaling pathways that regulate the production of lethal proteins in central neurons are not fully characterized. Previously, we reported induction of a novel neuronal protein neuronal pentraxin 1 (NP1) in neonatal brain injury following hypoxia-ischemia (HI); however, how NP1 is induced in hypoxic-ischemic neuronal death remains elusive. Here, we have elucidated the intracellular signaling regulation of NP1 induction in neuronal death. Primary cortical neurons showed a hypoxic-ischemia time-dependent increase in cell death and that NP1 induction preceded the actual neuronal death. NP1 gene silencing by NP1-specific siRNA significantly reduced neuronal death. The specificity of NP1 induction in neuronal death was further confirmed by using NP1 (-/-) null primary cortical neurons. Declines in phospho-Akt (i.e. deactivation) were observed concurrent with decreased phosphorylation of its downstream substrate GSK-3α/β (at Ser21/Ser9) (i.e. activation) and increased GSK-3α and GSK-3β kinase activities, which occurred prior to NP1 induction. Expression of a dominant-negative inhibitor of Akt (Akt-kd) blocked phosphorylation of GSK-3α/β and subsequently enhanced NP1 induction. Whereas, overexpression of constitutively activated Akt (Akt-myr) or wild-type Akt (wtAkt) increased GSK-α/β phosphorylation and attenuated NP1 induction. Transfection of neurons with GSK-3α siRNA completely blocked NP1 induction and cell death. Similarly, overexpression of the GSK-3β inhibitor Frat1 or the kinase mutant GSK-3βKM, but not the wild-type GSK-3βWT, blocked NP1 induction and rescued neurons from death. Our findings clearly implicate both GSK-3α- and GSK-3β-dependent mechanism of NP1 induction and point to a novel mechanism in the regulation of hypoxic-ischemic neuronal death.
The Hugo W. Moser Research Institute at Kennedy Krieger, Baltimore, MD 21205, USA.
Juliet C
JC
Russell
Koji
K
Kishimoto
Cliona
C
O'Driscoll
Mir Ahamed
MA
Hossain
D000818:Animals; D002097:C-Reactive Protein / Q000235:genetics / Q000378:metabolism*; D018929:Cell Culture Techniques; D016923:Cell Death; D015687:Cell Hypoxia; D002470:Cell Survival; D002478:Cells, Cultured; D004789:Enzyme Activation; D055785:Gene Knockdown Techniques; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D020925:Hypoxia-Ischemia, Brain / Q000378:metabolism / Q000473:pathology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism* / Q000473:pathology; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D034622:RNA Interference; D051381:Rats; D011916:Rats, Inbred F344; D000099153:Pentraxins
D002097:C-Reactive Protein; D038362:Glycogen Synthase Kinase 3; D000071679:Glycogen Synthase Kinase 3 beta; D009419:Nerve Tissue Proteins; D051057:Proto-Oncogene Proteins c-akt; D000099153:Pentraxins; C000605507:Gsk3b protein, mouse; C000605508:Gsk3b protein, rat; C448021:glycogen synthase kinase 3 alpha