title: Abnormal expression of the cell cycle regulators P16 and CDK4 in Alzheimer's disease.
abstract: In this study, we demonstrate that two important regulators of the cell cycle, cyclin-dependent kinase-4 and its inhibitor p16, are increased in the brains of cases of Alzheimer's disease patients compared with age-matched controls. Both proteins are increased in the pyramidal neurons of the hippocampus, including those neurons containing neurofibrillary tangles and granulovacuolar degeneration. As p16 is not normally found in terminally differentiated neurons, it seems paradoxical that it is increased in Alzheimer's disease unless it is responding to increases in cyclin-dependent kinase-4 or other cell cycle regulators. Induction of the latter, a protein that signals re-entry and progression through the cell cycle, may itself be the consequence of alpha response to a growth stimulus. Re-entry into the cell cycle is likely deleterious in terminally differentiated neurons and may contribute to the biochemical abnormalities, such as oxidative stress and hyperphosphorylated tau protein, as well as the neuronal degeneration characteristic of the pathology of Alzheimer's disease.
authors.affiliation: Bristol-Myers Squibb, Pharmaceutical Research Institute, Seattle, Washington, USA.
authors.forename: A
authors.initials: A
authors.lastname: McShea
authors.forename: P L
authors.initials: PL
authors.lastname: Harris
authors.forename: K R
authors.initials: KR
authors.lastname: Webster
authors.forename: A F
authors.initials: AF
authors.lastname: Wahl
authors.forename: M A
authors.initials: MA
authors.lastname: Smith
mesh_terms: D000544:Alzheimer Disease / Q000378:metabolism*; D001921:Brain / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D002453:Cell Cycle; D051358:Cyclin-Dependent Kinase 4; D019941:Cyclin-Dependent Kinase Inhibitor p16; D018844:Cyclin-Dependent Kinases / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D016874:Neurofibrillary Tangles / Q000378:metabolism; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D019941:Cyclin-Dependent Kinase Inhibitor p16; D004791:Enzyme Inhibitors; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins; C495900:CDK4 protein, human; D051358:Cyclin-Dependent Kinase 4; D018844:Cyclin-Dependent Kinases