The association of 14-3-3gamma and actin plays a role in cell division and apoptosis in astrocytes.
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.
Chen
Xiao Qian
XQ
Department of Biology, Hong Kong University of Science and Technology, Hong Kong, China.
Yu
Albert Cheung Hoi
AC
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*
D048948:14-3-3 Proteins; D000199:Actins; D014446:Tyrosine 3-Monooxygenase