Inhibition of mitogen-activated protein kinase phosphatase-1 (MKP-1) increases experimental stroke injury.
OBJECTIVE
Activation of mitogen-activated protein kinases (MAPKs), particularly c-jun-N-terminal kinases (JNK) and p38 exacerbates stroke injury by provoking pro-apoptotic and pro-inflammatory cellular signaling. MAPK phosphatase-1 (MKP-1) restrains the over-activation of MAPKs via rapid de-phosphorylation of the MAPKs. We therefore examined the role of MKP-1 in stroke and studied its inhibitory effects on MAPKs after experimental stroke.


METHODS
Male mice were subjected to transient middle cerebral artery occlusion (MCAO). MKP-1 knockout (KO) mice and a MKP-1 pharmacological inhibitor were utilized. We utilized flow cytometry, immunohistochemistry (IHC), and Western blots analysis to explore MKP-1 signaling and its effects on apoptosis/inflammation in the brain and specifically in microglia after stroke.


RESULTS
MKP-1 was highly expressed in the nuclei of both neurons and microglia after stroke. MKP-1 genetic deletion exacerbated stroke outcome by increasing infarct, neurological deficits and hemorrhagic transformation. Additionally, delayed treatment of the MKP-1 pharmacological inhibitor worsened stroke outcome in wild type (WT) mice but had no effect in MKP-1 KO mice. Furthermore, MKP-1 deletion led to increased c-jun-N-terminal kinase (JNK) activation and microglial p38 activation after stroke. Finally, MKP-1 deletion or inhibition increased inflammatory and apoptotic response as evidenced by the increased levels of interleukin-6 (IL-6), tumor necrosis factor α (TNFα), ratio of p-c-jun/c-jun and cleaved caspase-3 following ischemia.


CONCLUSIONS
We have demonstrated that MKP-1 signaling is an endogenous protective mechanism in stroke. Our data imply that MKP-1 possesses anti-apoptotic and anti-inflammatory properties by simultaneously controlling the activities of JNK and microglial p38.
Department of Neuroscience, University of Connecticut Health Center, Farmington, CT, United States.
Lin
L
Liu
Department of Neuroscience, University of Connecticut Health Center, Farmington, CT, United States.
Sarah
S
Doran
Department of Neuroscience, University of Connecticut Health Center, Farmington, CT, United States.
Yan
Y
Xu
Department of Neuroscience, University of Connecticut Health Center, Farmington, CT, United States.
Bharti
B
Manwani
Department of Neuroscience, University of Connecticut Health Center, Farmington, CT, United States.
Rodney
R
Ritzel
Department of Neuroscience, University of Connecticut Health Center, Farmington, CT, United States.
Sharon
S
Benashski
Department of Neuroscience, University of Connecticut Health Center, Farmington, CT, United States.
Louise
L
McCullough
Department of Neuroscience, University of Connecticut Health Center, Farmington, CT, United States. Electronic address: junli@uchc.edu.
Jun
J
Li
D000818:Animals; D001930:Brain Injuries / Q000209:etiology / Q000517:prevention & control; D003514:Cyclohexylamines / Q000009:adverse effects; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D054638:Dual Specificity Phosphatase 1 / Q000172:deficiency* / Q000235:genetics; D004660:Encephalitis / Q000209:etiology*; D004789:Enzyme Activation / Q000187:drug effects / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000235:genetics*; D007192:Indenes / Q000009:adverse effects; D020244:Infarction, Middle Cerebral Artery / Q000150:complications* / Q000209:etiology* / Q000235:genetics; D048670:MAP Kinase Kinase 4 / Q000378:metabolism; D008297:Male; D018345:Mice, Knockout; D009460:Neurologic Examination; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
C543522:2-benzylidene-3-(cyclohexylamino)-2,3-dihydro-1H-inden-1-one; D003514:Cyclohexylamines; D004791:Enzyme Inhibitors; D007192:Indenes; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D054638:Dual Specificity Phosphatase 1
Cerebral ischemia; MAPK; MKP-1