title: Cdk5-mediated inhibition of the protective effects of transcription factor MEF2 in neurotoxicity-induced apoptosis.
abstract: Neurotoxic insults deregulate Cdk5 activity, which leads to neuronal apoptosis and may contribute to neurodegeneration. The biological activity of Cdk5 has been ascribed to its phosphorylation of cytoplasmic substrates. However, its roles in the nucleus remain unknown. Here we investigate the mechanism by which Cdk5 promotes neuronal apoptosis. We have identified the prosurvival transcription factor MEF2 as a direct nuclear target of Cdk5. Cdk5 phosphorylates MEF2 at a distinct serine in its transactivation domain to inhibit MEF2 activity. Neurotoxicity enhances nuclear Cdk5 activity, leading to Cdk5-dependent phosphorylation and inhibition of MEF2 function in neurons. MEF2 mutants resistant to Cdk5 phosphorylation restore MEF2 activity and protect primary neurons from Cdk5 and neurotoxin-induced apoptosis. Our studies reveal a nuclear pathway by which neurotoxin/Cdk5 induces neuronal apoptosis through inhibiting prosurvival nuclear machinery.
authors.affiliation: The Liver Research Center, Department of Medicine, Rhode Island Hospital, Brown University School of Medicine, Providence, Rhode Island 02903, USA.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Gong
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Tang
authors.forename: Marcus
authors.initials: M
authors.lastname: Wiedmann
authors.forename: Xuemin
authors.initials: X
authors.lastname: Wang
authors.forename: Junmin
authors.initials: J
authors.lastname: Peng
authors.forename: Dong
authors.initials: D
authors.lastname: Zheng
authors.forename: Leslie A C
authors.initials: LA
authors.lastname: Blair
authors.forename: John
authors.initials: J
authors.lastname: Marshall
authors.forename: Zixu
authors.initials: Z
authors.lastname: Mao
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D002467:Cell Nucleus / Q000201:enzymology; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology; D051360:Cyclin-Dependent Kinase 5; D018844:Cyclin-Dependent Kinases / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005260:Female; D018698:Glutamic Acid / Q000494:pharmacology; D066298:In Vitro Techniques; D064326:MEF2 Transcription Factors; D008969:Molecular Sequence Data; D018006:Myogenic Regulatory Factors; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D009474:Neurons / Q000166:cytology* / Q000201:enzymology*; D009498:Neurotoxins / Q000494:pharmacology; D018384:Oxidative Stress / Q000502:physiology; D010766:Phosphorylation; D011247:Pregnancy; D011817:Rabbits; D051381:Rats; D020318:Rats, Long-Evans; D013379:Substrate Specificity; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation / Q000502:physiology
chemical_list: D004268:DNA-Binding Proteins; D064326:MEF2 Transcription Factors; D018006:Myogenic Regulatory Factors; D009419:Nerve Tissue Proteins; D009498:Neurotoxins; D014157:Transcription Factors; C089495:neuronal Cdk5 activator (p25-p35); D018698:Glutamic Acid; D051360:Cyclin-Dependent Kinase 5; C495907:Cdk5 protein, rat; D018844:Cyclin-Dependent Kinases