title: Regulation of neuroprotective activity of myocyte-enhancer factor 2 by cAMP-protein kinase A signaling pathway in neuronal survival.
abstract: The transcription factor myocyte-enhancer factor 2 (MEF2) has been shown to be required for the survival of different types of neurons. However, the death- or survival-inducing second messenger pathways that regulate MEF2 activity remain to be fully elucidated. Membrane depolarization by KCl induces neuronal survival that is dependent upon MEF2-mediated gene transactivation. Here we report that membrane depolarizationinduced activation of MEF2 requires the cAMP-protein kinase A (PKA) pathway. Inhibition of the activity of cAMP-PKA pathway attenuates membrane depolarization-induced activation of MEF2 activity and neuronal survival, whereas enhancing the activity of this pathway prevents KCl withdrawal-induced inhibition of MEF2 and neuronal apoptosis. Moreover, PKA directly phosphorylates MEF2 at Thr-20 in vitro to increase MEF2 DNA binding activity. A mutation of Thr-20 to Ala renders MEF2 resistant to PKA phosphorylation in vitro and reduces its DNA binding activity. Transfection of this T20A mutant blocks survival and induces apoptosis in cultured cortical and cerebellar granule neurons. This study identifies the transcription factor MEF2 as a target of cAMP-PKA pathway and demonstrates that PKA phosphorylation of MEF2 is a key step in modulating its DNA binding activity and ability to promote neuronal survival.
authors.affiliation: Department of Medicine, Brown University Medical School and Rhode Island Hospital, Providence, Rhode Island 02903, USA.
authors.forename: Xuemin
authors.initials: X
authors.lastname: Wang
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Tang
authors.forename: Mingtao
authors.initials: M
authors.lastname: Li
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; D006690:Bisbenzimidazole / Q000494:pharmacology; D020169:Caspases / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D002470:Cell Survival; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000737:chemistry / Q000378:metabolism*; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism* / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008156:Luciferases / Q000378:metabolism; D064326:MEF2 Transcription Factors; D008969:Molecular Sequence Data; D009154:Mutation; D018006:Myogenic Regulatory Factors; D009474:Neurons / Q000378:metabolism*; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D051381:Rats; D015398:Signal Transduction; D013912:Threonine / Q000737:chemistry; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism* / Q000502:physiology*; D015533:Transcriptional Activation; D014162:Transfection
chemical_list: D004268:DNA-Binding Proteins; D064326:MEF2 Transcription Factors; D018006:Myogenic Regulatory Factors; D014157:Transcription Factors; D049452:Green Fluorescent Proteins; D013912:Threonine; D004247:DNA; D000242:Cyclic AMP; D008156:Luciferases; D017868:Cyclic AMP-Dependent Protein Kinases; D020169:Caspases; D006690:Bisbenzimidazole