title: Cyclin-dependent kinase-5 prevents neuronal apoptosis through ERK-mediated upregulation of Bcl-2.
abstract: Cyclin-dependent kinase-5 (Cdk5) is required for neuronal survival, but its targets in the apoptotic pathways remain unknown. Here, we show that Cdk5 kinase activity prevents neuronal apoptosis through the upregulation of Bcl-2. Treatment of SH-SY5Y cells with retinoid acid (RA) and brain-derived neurotrophic factor (BDNF) generates differentiated neuron-like cells. DNA damage triggers apoptosis in the undifferentiated cells through mitochondrial pathway; however, RA/BDNF treatment results in Bcl-2 upregulation and inhibition of the mitochondrial pathway in the differentiated cells. RA/BDNF treatment activates Cdk5-mediated PI3K/Akt and ERK pathways. Inhibition of Cdk5 inhibits PI3K/Akt and ERK phosphorylation and Bcl-2 expression, and thus sensitizes the differentiated cells to DNA-damage. Inhibition of ERK, but not PI3K/Akt, abrogates Cdk5-medidated Bcl-2 upregulation and the protection of the differentiated cells. This study suggests that ERK-mediated Bcl-2 upregulation contributes to BDNF-induced Cdk5-mediated neuronal survival.
authors.affiliation: Department of Medicine and Laboratory Medicine & Pathology, University of Alberta, Edmonton, Canada.
authors.forename: C X
authors.initials: CX
authors.lastname: Wang
authors.forename: J H
authors.initials: JH
authors.lastname: Song
authors.forename: D K
authors.initials: DK
authors.lastname: Song
authors.forename: V W
authors.initials: VW
authors.lastname: Yong
authors.forename: A
authors.initials: A
authors.lastname: Shuaib
authors.forename: C
authors.initials: C
authors.lastname: Hao
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D019208:Brain-Derived Neurotrophic Factor / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D051360:Cyclin-Dependent Kinase 5 / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D005434:Flow Cytometry; D006801:Humans; D008954:Models, Biological; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D010957:Plasmids / Q000235:genetics; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects; D014162:Transfection; D014212:Tretinoin / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D019208:Brain-Derived Neurotrophic Factor; D019253:Proto-Oncogene Proteins c-bcl-2; D034741:RNA, Small Interfering; D014212:Tretinoin; D019869:Phosphatidylinositol 3-Kinases; D051360:Cyclin-Dependent Kinase 5; D051057:Proto-Oncogene Proteins c-akt; D048049:Extracellular Signal-Regulated MAP Kinases