title: Inhibition of MLK3-MKK4/7-JNK1/2 pathway by Akt1 in exogenous estrogen-induced neuroprotection against transient global cerebral ischemia by a non-genomic mechanism in male rats.
abstract: Numerous studies have demonstrated the neuroprotective effects of estrogen in experimental cerebral ischemia. To investigate molecular mechanisms of estrogen neuroprotection in global ischemia, immunoblotting, immunohistochemistry and Nissel-staining analysis were used. Our results showed that chronic pretreatment with beta-estradiol 3-benzoate (E2) enhanced Akt1 activation and reduced the activation of mixed-lineage kinase 3 (MLK3), mitogen-activated protein kinase kinase 4/7 (MKK4/7), and c-Jun N-terminal kinase 1/2 (JNK1/2) in the hippocampal CA1 subfield during reperfusion after 15 min of global ischemia. In addition, E2 reduced downstream JNK nuclear and non-nuclear components, c-Jun and Bcl-2 phosphorylation and Fas ligand protein expression induced by ischemia/reperfusion. Administration of phosphoinositide 3-kinase (PI3K) inhibitor LY 294,002 prevented both activation of Akt1 and inhibition of MLK3, MKK4/7 and JNK1/2. The interaction between ERalpha and the p85 subunit of PI3K was also examined. E2 and antiestrogen ICI 182,780 promoted and prevented this interaction, respectively. Furthermore, ICI 182,780 blocked both the activation of Akt1 and the inhibition of MLK3, MKK4/7 and JNK1/2. Photomicrographs of cresyl violet-stained brain sections showed that E2 reduced CA1 neuron loss after 5 days of reperfusion, which was abolished by ICI 182,780 and LY 294,002. Our data indicate that in response to estrogen, ERalpha interacts with PI3K to activate Akt1, which may inhibit the MLK3-MKK4/7-JNK1/2 pathway to protect hippocampal CA1 neurons against global cerebral ischemia in male rats.
authors.affiliation: Research Center for Biochemistry and Molecular Biology, Jiangsu Key Laboratory for Brain Disease Bioinformation, Xuzhou Medical College, Xuzhou, China.
authors.forename: Ran
authors.initials: R
authors.lastname: Wang
authors.forename: Quan-Guang
authors.initials: QG
authors.lastname: Zhang
authors.forename: Dong
authors.initials: D
authors.lastname: Han
authors.forename: Jing
authors.initials: J
authors.lastname: Xu
authors.forename: Qian
authors.initials: Q
authors.lastname: Lü
authors.forename: Guang-Yi
authors.initials: GY
authors.lastname: Zhang
mesh_terms: D000818:Animals; D015153:Blotting, Western / Q000379:methods; D002867:Chromones / Q000494:pharmacology; D004195:Disease Models, Animal; D004347:Drug Interactions; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004958:Estradiol / Q000031:analogs & derivatives / Q000494:pharmacology; D004965:Estrogen Antagonists / Q000494:pharmacology; D004967:Estrogens / Q000008:administration & dosage*; D000077267:Fulvestrant; D006624:Hippocampus / Q000187:drug effects / Q000201:enzymology; D007150:Immunohistochemistry / Q000379:methods; D047468:Immunoprecipitation / Q000379:methods; D002546:Ischemic Attack, Transient / Q000473:pathology / Q000517:prevention & control*; D048688:MAP Kinase Kinase 7 / Q000378:metabolism; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism; D008297:Male; D048055:Mitogen-Activated Protein Kinase 8 / Q000378:metabolism; D009025:Morpholines / Q000494:pharmacology; D018696:Neuroprotective Agents / Q000008:administration & dosage*; D051057:Proto-Oncogene Proteins c-akt / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012694:Serine / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D000097767:Mitogen-Activated Protein Kinase Kinase Kinase 11
chemical_list: D002867:Chromones; D004791:Enzyme Inhibitors; D004958:Estradiol; D004965:Estrogen Antagonists; D004967:Estrogens; D000077267:Fulvestrant; D048688:MAP Kinase Kinase 7; D020930:MAP Kinase Kinase Kinases; D048055:Mitogen-Activated Protein Kinase 8; D009025:Morpholines; D018696:Neuroprotective Agents; D051057:Proto-Oncogene Proteins c-akt; D012694:Serine; D000097767:Mitogen-Activated Protein Kinase Kinase Kinase 11; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C494920:Akt1 protein, rat