細胞分裂期の中心体形成における protein phosphatase 6結合分子AGN-1の関与

抄録

We cloned AGN-1 that interacted with protein phosphatase 6 as a molecule highly expressed in nephritic rat kidney. Our previous studies revealed that in neuronal cells (Neuro2a cells), AGN-1 was co-localized with U1snRNP and splicing factor SC35 participating in the synthesis of tau alternative splicing variants, 4R-tau and 3R-tau. Our studies also showed that AGN-1 was found in centrosome of renal tubular cells, H4IIE cells, during cell division. In this study, to address a biological role of AGN-1 in the centrosome during cell division, we investigated an interaction of AGN-1 protein with gamma-tubulin, which localizes in the centrosome and the effect of AGN-1 knock-down on the centrosome formation during cell division. Immunocytochemical staining resulted in co-localization of AGN-1 and gamma-tubulin in the centrosome of serum-stimulated Neuro2a and IMCD3 (renal collecting duct) cells, as well as H4IIE cells. Immunoreactivity of AGN-1 and gamma-tubulin was observed in the centrosome fraction of all the cells types prepared by a sucrose gradient centrifugation. In addition, AGN-1-siRNA treatment showed the decrease in the number of the gamma-tubulin positive centrosome in the serum-stimulated cells. These results suggest that AGN-1 protein interacts with gamma-tubulin in the centrosome and plays a role in the centrosome formation during cell division.