Functional Analysis Of OsMSIL In Rice Epigenetic Regulation

MSI1-like(MSIL) proteins are eukaryote-specific proteins composed of a tandem repeat of WD40 domian. They are reported to play pleiotropic roles in chromatin assembly, DNA damage repair, and regulation of nutrient/stress-sensing signaling pathways. MSIL proteins have been discovered in diverse eukaryotes from yeasts to humans. Their functions are well studied in animals, yeast and Arabidopsis, but in rice(Oryza sativa), the function of MSIL proteins remains unknown. In this study, Os MSI1, one of the MSIL proteins, was identified in the epigenetic regulation of rice development. Yeast-two-hybrid and pull-down assays were to detect the proteins associated with Os MSI1 and other MSIL proteins. The major results are as follows.1. Full-length c DNA of Os MSI1, Os MSI2, Os MSI3 and Os FAS2 and Os MSI1, Os MSI3 and Os FAS2 proteins fused with GST tag were obtained.2. The over-expression of Os MSI1 and the RNAi of Os MSI3 transgenic plants have no abivious phenotypes. Reduction of Os MSI1 dramatically affected development, and the transgenic plants displayed seimi-dwarf and delayed heading date compared to wild type plants.3. Histological analyses showed that cell sizes in mature tissue of Os MSI1 RNAi plants stem were smaller and cell numbers in intercalary meristem was less than that in wild type plants. Whereas expression of GA and BR hormore-related genes showed no obviously altered in Os MSI1 RNAi lines compared to wild type.4. We obtained the specific antibody of Os MSI1.5. Yeast-two-hybrid screening and Pull-down confirmed that Os MSI1 interacted with Os DDM1 b and SDG711. Os MSI2, Os FAS2 and FSM were also found to participatin the CAF-1 complex in rice.6. Os MSI1 RNAi plants affected the overall level of H3K27me3 and H3K27me2 but DNA methylation of transposon analysis showed no change.