A Preliminary Study On Fission Yeast Dnt1Participating In Spindle Assembly Checkpoint Silencing

Every mitosis, replicated chromosomes must be accurately segregated into each daughter cell. Cells have a series of checkpoints to supervise the process, to ensure accurate genome replication, repair in time and correctly. When kinetocore failure to attach correctly to the spindle or sense enquality tension from the opposite poles before anaphase onset, the spindle checkpoint activate. Cells delay anaphase onset until all chromosomes are correctly attached in a bipolar fashion to the mitotic spindle. Then the spindle checkpoint silence and the cell cycle continues.In the fission yeast, Dntl mainly locate in the nucleolus, and it also position on the spindle and spindle pole body at anaphase. Current study found that Dntl inhibitted cytokinesis through interacting with checkpoint protein Dmal and suppressing its E3ubiquitin ligase function. Besides Dntl reduced Weel protein level to regulate G2/M transformation.In this paper we use the nda3-KM311cdcl3-gfp arkl-as3silencing assay. Cells were arrested at18℃for6h and shifted to permissive temperature of30℃. Through caculating the percentage of Cdc13-GFP localization on SPB of every10min for50mins, we indentified that Dntl was required for the spindle checkpoint silencing for the first time. And Dntl regulating SAC silencing was dependent on the essential checkpoint protein Mad2, Mad3and Bubl; It cooperated with Dis2and Bub3to regulate SAC silencing in distinct pathway.Through the study on the orientation of cell biology and biochemistry analysis, we found that Dntl participating in the spindle checkpoint silencing was achieved by two pathways. dntl△mutant delayed Plol recruitment to the SPBs when the spindle checkpoint was activated, and this process was partly dependent on Dmal. On the other hand, dntl△mutant promoted MCC and APC to connect longer so as to suppress the activity of APC, causing the spindle checkpoint silencing deficiency. But the current study did not determine the relationship between this two pathways, and the intermediate mechanism was not clear.In conclusion, we first discovered that Dntl participated in the spindle assembly checkpoint silencing. In addition, we explored the possible mechanism of Dntl regulating checkpoint silencing preliminary, and this provided an important theoretical basis for the future research.