TBP Dynamics In The Process Of Genome Reprogramming In Reconstructed Embryos Produced By Nuclear Transfer

Embryos produced by somatic nuclear transfer could reattain developmtntal potential,when correct epigenetic reprogramming completed. A epigenetic modification mark special for somatoblast would be erased during this reprogramming.The attempt was made to better understand TBP dynamics in living reconstructed embryos via NIH3T3 cells which express EGFP-TBP as the donors and Mil-phase mouse oocytes which enucleared as the receptors. The results showed that:TBP was distributed over whole karyplasm and associated with chromatin throughout mitosis. TBP is one of the chromatin-associated proteins.In living NIH3T3 cells, interphase chromatin had quite larger quantity of TBP than that on metaphase chromosomes. The relative fluorescence intensity of metaphase chromosomes was 16% of that of interphase. However, some of TBP remained on metaphase chrosomoses.When EGFP-TBP expression cells NIH3T3 were transferred into MII phase enucleared mouse oocytes and the reconstructed embryos fusion two hours later, the chromatin condensed into chromosomes, but it was different from metaphase chromosmes during mitosis which had rudimental TBP, the fluorescence of EGFP on embryos nuclei dramatically disappeared.During this period,epigenetic reprogramming of the reconstructed embryos genome occurred. TBP was erased as a kind of potential epigenetic cell mark.In conclusion, TBP remained on metaphase chrosomoses during mitosis induced chromatin remodeling, which could be regarded as a memory mark for the daughter cells. The erasion of the mark likely was crucial in the process of the genome epigenetic reprogramming.