title: The association of 14-3-3gamma and actin plays a role in cell division and apoptosis in astrocytes.
abstract: The 14-3-3 protein family plays critical regulatory roles in signaling pathways in cell division and apoptosis. 14-3-3gamma is mainly expressed in brain. Using primary cultures of cerebral cortical astrocytes, we investigated the relationships between 14-3-3gamma proteins and actin in astrocytes in cell division and under ischemia. Our results showed that endogenous 14-3-3gamma proteins in immature astrocytes appeared filamentous and co-localized with filamentous actin (F-actin). During certain stages of mitosis, 14-3-3gamma proteins first aggregated and then formed a ring-like structure that surrounded the daughter nuclei and enclosed the F-actin. In 4-week-old cultures of astrocytes, 14-3-3gamma proteins appeared as punctate aggregates in the cytoplasm. Under ischemia, 14-3-3gamma proteins formed filamentous structures and were closely associated with F-actin in surviving astrocytes. However, in apoptotic astrocytes, the intensity of immunostaining of 14-3-3gamma proteins in the cytoplasm decreased. The proteins aggregated around the nucleus and dissociated from the actin filaments. Reciprocal co-immunoprecipitations demonstrated that endogenous 14-3-3gamma proteins bound to detergent-soluble actin and the level of binding increased after 4h of ischemia. As actin is a critical structural protein heavily involved in cell division and apoptotic death, our findings suggest that 14-3-3gamma proteins play a role in cytoskeletal function during the process of cell division and apoptosis in astrocytes in association with actin.
authors.affiliation: Department of Biology, Hong Kong University of Science and Technology, Hong Kong, China.
authors.forename: Xiao Qian
authors.initials: XQ
authors.lastname: Chen
authors.forename: Albert Cheung Hoi
authors.initials: AC
authors.lastname: Yu
mesh_terms: D048948:14-3-3 Proteins; D008841:Actin Cytoskeleton / Q000648:ultrastructure; D000199:Actins / Q000032:analysis / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis; D001253:Astrocytes / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure*; D002455:Cell Division; D015687:Cell Hypoxia; D002478:Cells, Cultured; D051379:Mice; D008813:Mice, Inbred ICR; D008938:Mitosis; D014446:Tyrosine 3-Monooxygenase / Q000032:analysis / Q000378:metabolism / Q000502:physiology*
chemical_list: D048948:14-3-3 Proteins; D000199:Actins; D014446:Tyrosine 3-Monooxygenase