title: Cyclin D1, cdk4, and Bim are involved in thrombin-induced apoptosis in cultured cortical neurons.
abstract: Thrombin, a multifunctional serine protease, is neurotoxic in vitro and in vivo. Thrombin has been shown to be increased in Alzheimer's disease (AD) and other neuropathological conditions and could be a mediator of pathological neuronal cell death in the brain. The mechanisms of thrombin-induced neuronal cell death are incompletely understood. The objective of this study is to explore mechanisms that contribute to thrombin-induced neuronal apoptosis focusing on the role of cell cycle regulators and the pro-apoptotic protein Bim (Bcl-2-interacting mediator of cell death) in this process. Our data show that thrombin treatment of primary cerebral cortical cultures results in dose-dependent apoptotic cell death. Exposure of neuronal cultures to thrombin leads to induction of cell cycle proteins cyclin D1 and cyclin E, at both mRNA and protein levels. In addition, thrombin treatment causes the appearance of cyclin-dependent kinase 4 (cdk4) and expression of the pro-apoptotic protein Bim. Inhibition of cdk4 prevents both induction of Bim expression and thrombin-induced neuronal apoptosis. These data demonstrate that thrombin-induced apoptosis proceeds via cell cycle activation involving cdk4 resulting in induction of Bim. Thus, cell cycle proteins could be therapeutic targets in diseases such as AD where thrombin has been implicated.
authors.affiliation: Garrison Institute on Aging and Department of Neuropsychiatry and Behavioral Sciences, Texas Tech University Health Sciences Center, Lubbock, Texas 79430, USA.
authors.forename: Haripriya Vittal
authors.initials: HV
authors.lastname: Rao
authors.forename: Lakshmi
authors.initials: L
authors.lastname: Thirumangalakudi
authors.forename: Paula
authors.initials: P
authors.lastname: Desmond
authors.forename: Paula
authors.initials: P
authors.lastname: Grammas
mesh_terms: D000544:Alzheimer Disease / Q000378:metabolism / Q000503:physiopathology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D000072224:Bcl-2-Like Protein 11; D018797:Cell Cycle Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology; D019938:Cyclin D1 / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D051358:Cyclin-Dependent Kinase 4 / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D008565:Membrane Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D009410:Nerve Degeneration / Q000139:chemically induced / Q000378:metabolism / Q000503:physiopathology; D019636:Neurodegenerative Diseases / Q000378:metabolism / Q000503:physiopathology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D013917:Thrombin / Q000378:metabolism / Q000633:toxicity*
chemical_list: D051017:Apoptosis Regulatory Proteins; D000072224:Bcl-2-Like Protein 11; C000606778:Bcl2l11 protein, rat; D018797:Cell Cycle Proteins; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D019938:Cyclin D1; D051358:Cyclin-Dependent Kinase 4; D013917:Thrombin