Research On The Function Of TET1Protein During Somatic Cell Reprogramming

Research on the function of TET protein during somatic cell reprogrammingTET protein (Ten Eleven Translocation, TET), an oxidative enzyme, was first published in2009. It has the ability to convert5mC into5hmC in genome DNA, which is related to DNAdemethylation. And then it is followed by a great trend in the field of investigating epigenetics onDNA level. And for the past few years, with the development of technology in generating theinduced Pluripotent Stem Cells (iPSCs), somatic cell reprogramming technique has been paidmore and more attention in the field of epigenetics.The iPSCs generating technique is to transfect the four core factors (Oct4, Sox2, Klf4,c-Myc) that are discovered by Yamanaka into somatic cells, and then the somatic cells can goback to the original pluripotent state. With the continued research on the mechanism ofreprogramming, the efficiency of this process was gradually enhanced. Combined application ofsmall molecule compounds and transcription factors is now common-use way in this field toperform the reprogramming. For example, Vitamin C that is also called ascorbic acid, a kind ofsmall molecule compounds, can significantly promote the reprogramming efficiently. And theestablishment of the high-efficiency reprogramming technique also provides a new platform forthe scientists who are working on transcriptional factors and signal pathway in the cell-fatedetermination research.It has been proven that the level of TET1expression and hmC are quite low in MEFs whileare relatively high in mESCs. So we guess TET1may participate in the process of somatic cellreprogramming. In order to illuminate the biological function of TET family during somatic cellreprogramming, my thesis is mainly about discovering the role TET1plays in this process basedon the reprogramming technique and the mouse model. We choose two methods to investigatethe TET1protein, one way is to perform the reprogramming with TET1-null MEFs and the wildtype MEFs to see if TET1is a key factor or not, which is also called loss-of-function experiment.The other is to over express the short version of TET1, TET1CD containing the catalytic domain,during reprogramming to identify TET1function, which is also called gain-of-functionexperiment. At last, according to the analysis of the data we get from our work, we found that TET1function during reprogramming was modulated by Vc. In the absence of vitamin C, TET1promotes somatic cell reprogramming independent of MET. TET1deficiency enhancesreprogramming, and its overexpression impairs reprogramming in the context of vitamin C.What is more, TET1regulates hmC formation at loci related to MET in a vitamin C-dependentfashion, blocking the MET and then inhibiting the reprogramming.