Fission Yeast Ing Family Proteins Png1p In The Dna Damage Response Function Of The Process

ING (INhibitor of Growth) tumor suppressor proteins are very important tumor inhibitors in species ranging from yeast to humans, and function in the process of cell apoptosis, senescence, cell cycle regulation, DNA damage response, cell proliferation, tumor growth, hormone signaling, gene transcription, chromatin remodeling and genome integrity. There are many studies about how ING family proteins function in the DNA damage response pathway. However, the molecular mechnism is so complicated that the blueprint of how ING family proteins function in the DNA damage signaling is still not very clear.There are two homolog proteins in fission yeast, Png1p and Png2p. Until now, there is no report about how ING family proteins function in the DNA damage pathway in fission yeast. Phylogenic assay indicates although Png1p and Png2p belong to the same ING family, but they located at different branch. Here, we knock out PNG1 and PNG2 respectively. The functional analysis reveals that Png1p and Png2p have different functions in the process of cell growth and DNA damage reponse.Cell growth and flow cytometry assay show PNG1 is not only required for normal cell growth, but also for DNA damage response.△png1 mutants get an intra-S-phase cell cycle arrest under DNA-damage induced conditions and are sensitive to DNA damage agents. Yeast-two-hybrid assay, Pull-down assay, Co-IP and fluorescent location assay indicate Png1p is collaborated with the fission yeast histone acetyltransferase Mst1p, but they might not have direct interaction。TSA rescue and western blot assay show Png1p is required for histone H4 acetylation at K5,K8,K12. The decrease of histone H4 acetylation at K5,K8,K12 leads to the down-regulation of many genes'expression, including DNA repair related genes (such as RAD22, ASF1, SPT3), chromatin remodeling related genes(such as SNF5), cell cycle related genes (such as CDC20, CDC22, ENG1, AGN1).Further study shows over-expression of the DNA damage repair central gene RAD22 can recuse the DNA damage sensitivity in the△png1 cells, respectively. So, PNG1 might function in the DNA damage response pathway through RAD22. The DREB transcription factors, which specifically interact with C-repeat/DRE (A/GCCGAC), play an important role in plant abiotic stress tolerance by controlling the expression of many cold or/and drought-inducible genes in an ABA-independent pathway. In our study, we have isolated three novel rice DREB genes, OsDREB1E, OsDREB1G, and OsDREB2B, which are homologous to Arabidopsis DREB genes. The yeast one-hybrid assay indicated that OsDREB1E, OsDREB1G, and OsDREB2B can specifically bind to the C-repeat/DRE element. To elucidate the function of respective OsDREB genes, we have stably introduced these to rice by agrobacterium-mediated transformation. Transgenic rice plants analysis revealed that over-expression of OsDREB1G and OsDREB2B in rice significantly improved their tolerance to water deficit stress, while over-expression of OsDREB1E could only slightly improved the tolerance to water deficit stress, suggesting that the OsDREBs might participate in the stress response pathway in different manners.