title: Cyclin E marks quiescent neural stem cells and caspase-3-positive newborn cells during adult hippocampal neurogenesis in mice.
abstract: Cyclin E is a key regulator of progression through the G1-phase of the cell cycle. Recently, a cell cycle-independent role for cyclin E in the adult mouse central nervous system has been suggested. In the present study, we examined expression of cyclin E in the mouse hippocampal dentate gyrus (DG), a region of neurogenesis in adulthood, using immunofluorescence. In the adult DG, cyclin E-immunoreactive (cyclin E+) cells was limited to postmitotic cells. In the subgranular zone, cyclin E was detected in the vertical process of radial glia-like cells, which were marked by the neural stem cell markers nestin and GFAP. Cyclin E was also detected in the nucleus of cells, which were labeled with stage-specific neuronal cell markers, including Pax6, Sox2, NeuroD, doublecortin, and NeuN. The densities of cyclin E+ cells in the DG reduced and increased with age and running, respectively. Furthermore, the majority of cyclin E+ cells co-expressed active caspase-3, a marker of apoptosis. Together, the results indicate that cyclin E is expressed in the process of quiescent neural stem cells and in the nucleus of active caspase-3+ cells during neuronal cell differentiation, suggesting that cyclin E has a Cdk-independent function, which might be important for the mechanisms regulating adult hippocampal neurogenesis.
authors.affiliation: Department of Anatomy, Aichi-Gakuin University School of Dentistry, 1-100 Kusumoto-cho, Chikusa-ku, Nagoya 464-8650, Japan. Electronic address: yayoi@dpc.agu.ac.jp.
authors.forename: Yayoi
authors.initials: Y
authors.lastname: Ikeda
authors.affiliation: Section of Molecular Craniofacial Embryology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo 113-8510, Japan. Electronic address: mikeda.emb@tmd.ac.jp.
authors.forename: Masa-Aki
authors.initials: MA
authors.lastname: Ikeda
mesh_terms: D000375:Aging / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis; D015415:Biomarkers / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism*; D002454:Cell Differentiation; D019070:Cell Lineage; D002467:Cell Nucleus / Q000378:metabolism; D049109:Cell Proliferation; D019927:Cyclin E / Q000378:metabolism*; D004622:Embryo, Mammalian; D006624:Hippocampus / Q000166:cytology* / Q000378:metabolism; D008297:Male; D008810:Mice, Inbred C57BL; D058953:Neural Stem Cells / Q000166:cytology* / Q000378:metabolism; D055495:Neurogenesis; D009457:Neuroglia / Q000378:metabolism; D009474:Neurons / Q000166:cytology* / Q000378:metabolism; D012420:Running
chemical_list: D015415:Biomarkers; D019927:Cyclin E; D053148:Caspase 3
keywords: Cyclin E; Dentate gyrus; Neural stem cells; Postmitotic neurons; Radial glia; Subgranular zone