It has been reported that the main function of tau protein is to stabilize microtubules and promote the movement of organelles through the axon in neurons. In Alzheimer’s disease, tau protein is the major constituent of the paired helical filament, and it undergoes post-translational modifications including hyperphosphorylation and truncation. Whether other functions of tau protein are involved in Alzheimer’s disease is less clear. We used SH-SY5Y human neuroblastoma cells as an in vitro model to further study the functions of tau protein. We detected phosphorylated tau protein as small dense dots in the cell nucleus, which strongly colocalize with intranuclear speckle structures that were also labelled with an antibody to SC35, a protein involved in nuclear RNA splicing. We have shown further that tau protein, phosphorylated at the sites recognized by pT231, TG-3, and AD2 antibodies, is closely associated with cell division. Different functions may be characteristic of phosphorylation at specific sites. Our findings suggest that the presence of tau protein is involved in separation of sister chromatids in anaphase, and that tau protein also participates in maintaining the integrity of the DNA (pT231, prophase) and chromosomes during cell division (TG-3).
Authors want to express their gratitude to Dr. P. Davies (Albert Einstein College of Medicine, Bronx, NY, USA); Lester I. Binder † (North Western, Chicago, IL, USA) for the generous gift of mAbs (TG-3, Alz-50) and (Tau-1, Tau-5, Tau-7), respectively; Tec. Amparo Viramontes Pintos for the handling of the brain tissue; M. en C. Samadhi Moreno-Campuzano for her technical assistance; M en C.J. Iván Gálvan for his support in confocal microscopy, and the confocal microscopy unit of Laboratorio Nacional de Servicios Experimentales (LaNSE), CINVESTAV. We also want to express our gratitude to the Mexican families who donated brains of loved ones affected with Alzheimer’s disease, and made our research possible. This work is dedicated to the memory of Professor Dr. José Raúl Mena López †. This work was financially supported by CONACyT grants, No. 142293 (to R.M.), 266492 (I.V-F), 239516 (J.S) and the Mancera-Reséndiz family.
- Alzheimer’s disease
- cell cycle
- phospho-tau protein