探討在T淋巴細胞中酪胺酸磷酸化之c-Maf對於細胞激素基因的結合機轉

Abstract

轉錄因子c-Maf在第二型輔助T淋巴球(Th2)中特別調控介白素4 (IL-4)，最近的研究指出c-Maf亦能分別在第十七型輔助T淋巴球(Th17)中調控介白素21 (IL-21)及在第一型調節性T淋巴球 (type 1 regulatory T cell) 中調控介白素10 (IL-10)的表現，然而對於c-Maf的磷酸化如何調控介白素的相關研究尚未清楚。根據實驗室之前的實驗結果，發現活體外c-Maf的磷酸化可以調節IL-4的表現，而且c-Maf被磷酸化的位點也被界定。因此，在我的研究，從小鼠分離出primary CD4 T細胞，並大量表現野生型(WT)或是無法磷酸化的c-Maf，進而利用染色質沉澱技術(chromatin immunoprecipitation analysis) 探討在c-Maf的酪胺酸磷酸化的有無是否會改變結合到DNA的能力，進而影響IL-4及IL-21的表現量。結果發現酪胺酸能被磷酸化的WT c-Maf相較於不具有酪胺酸磷酸化能力的突變型c-Maf對於Il4 啟動子有較強的DNA結合能力，然而對於Il21啟動子則沒有影響。造成在這兩者不同影響的機制則是需要進一步的研究。

c-Maf, is known as a Th2 specific transcription factor that could transactivate IL-4 gene expression. Recent studies have shown that c-Maf could transactivate Il21 and Il10 in Th17 cells and type 1 regulatory T cells (Tr1), respectively. However, the function of the tyrosine phosphorylated c-Maf remains unknown. Previous studies in our lab have shown that the phosphorylation of c-Maf could regulate the IL-4 production in vitro. Furthermore, the tyrosine residues of c-Maf could be phosphorylated have been identified. Thus, in my research, I study whether the tyrosine phosphorylated c-Maf could affect the IL-4 and IL-21 production through its DNA binding to the respective promoters. The binding abilities of Il4 and Il21 promoters by tyrosine-phospho-deficient c-Maf and WT c-Maf in primary T cells were analyzed by chromatin immunoprecipitation (ChIP) analysis. The results demonstrated that the tyrosine phosphorylation of c-Maf could enhance its DNA binding to the Il4, but not Il21, promoters in vivo.