PHLPP1 gene deletion protects the brain from ischemic injury.
A recently discovered protein phosphatase PHLPP (PH domain Leucine-rich repeat Protein Phosphatase) has been shown to dephosphorylate Akt on its hydrophobic motif (Ser473) thereby decreasing Akt kinase activity. We generated PHLPP1 knockout (KO) mice and used them to explore the ability of enhanced in vivo Akt signaling to protect the brain against ischemic insult. Brains from KO mice subjected to middle cerebral artery occlusion (MCAO) for 2 hours showed significantly greater increases in Akt activity and less neurovascular damage after reperfusion than wild-type (WT) mice. Remarkably, infarct volume in the PHLPP1 KO was significantly reduced compared with WT (12.7±2.7% versus 22.9±3.1%) and this was prevented by Akt inhibition. Astrocytes from KO mice and neurons in which PHLPP1 was downregulated showed enhanced Akt activation and diminished cell death in response to oxygen-glucose deprivation. Thus, deletion of PHLPP1 can enhance Akt activation in neurons and astrocytes, and can significantly increase cell survival and diminish infarct size after MCAO. Inhibition of PHLPP could be a therapeutic approach to minimize damage after focal ischemia.
Department of Neurology, Cedars-Sinai Medical Center, Los Angeles, California, USA.
Bo
B
Chen
Jessica A
JA
Van Winkle
Patrick D
PD
Lyden
Joan H
JH
Brown
Nicole H
NH
Purcell
D000818:Animals; D001253:Astrocytes / Q000201:enzymology / Q000473:pathology; D020520:Brain Infarction / Q000201:enzymology* / Q000235:genetics / Q000473:pathology / Q000517:prevention & control; D001930:Brain Injuries / Q000201:enzymology* / Q000235:genetics / Q000473:pathology / Q000517:prevention & control; D004789:Enzyme Activation / Q000235:genetics; D017353:Gene Deletion; D005947:Glucose / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000201:enzymology / Q000473:pathology; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation / Q000235:genetics; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism; D015427:Reperfusion Injury / Q000201:enzymology* / Q000235:genetics / Q000473:pathology / Q000517:prevention & control; D015398:Signal Transduction / Q000235:genetics
D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D051057:Proto-Oncogene Proteins c-akt; C519282:PHLPP1 protein, mouse; D010749:Phosphoprotein Phosphatases; D005947:Glucose; D010100:Oxygen