c-Maf在調控小鼠IL-21基因所扮演的角色

Abstract

c-Maf是一個b-Zip家族的轉錄因子，根據之前的文獻報導，c-Maf在Th2細胞中對IL-4基因調控是一個必要的存在。而最近的文獻則是報導 c-Maf與 IL-21在Th17細胞中的關係。這篇文獻發現在c-Maf KO小鼠中，IL-21的基因表現是有缺陷的，也就是說，c-Maf很有可能是調控IL-21基因表現的一個上游分子。由於c-Maf本身是一個轉錄分子，因此我們假設c-Maf會調控IL-21基因表現。為了確定c-Maf調控IL-21基因是經由直接接觸IL-21 gene locus或是透過與其它不明轉錄蛋白作用再影響到IL-21基因表現，我們利用電腦軟體在IL-21 promoter的基因序列中找尋MARE。我們在-1.3kb中總共找到兩個half MARE和兩個V-MARE。為了確定c-Maf會藉由哪一個MARE影響IL-21的表現，我們建構了具有點突變或是截短的promoter片段的pGL3質體，再利用這些質體進行Luciferase assay。我們的研究結果指出c-Maf最有與位在-192 ~ -205 kb的V-MARE作用，進而影響IL-21基因表現。除了以上的實驗，我們也去測試SUMOylation會不會讓c-Maf對IL-21基因表現造成影響。在這方面，我們的結論是：c-Maf的轉錄能力在調控IL-21基因系統中，不受到SUMOylation的影響。

c-Maf is a b-Zip transcription factor, which was found to be an essential role in regulating IL-4 expression in Th2 cells. Recent study has investigated the relationship between c-Maf and IL-21 gene expression in Th17 cells. Their study uncovered shortage of IL-21 production in c-Maf KO mice, which implied that c-Maf might be an upstream molecule of IL-21. Since c-Maf itself is a transcription factor, we hypothesized that c-Maf should regulate IL-21 gene expression. To identify whether c-Maf regulates IL-21 expression by directly or indirectly binding on IL-21 promoter, we went to investigate MARE sequence on IL-21 promoter. We found two half MARE and two V-MARE in -1.3kb upstream region. We constructed several point mutatated and truncated promoter fragments onto pGL3 Basic vector, and performed luciferase assay. Our results pointed out that the putative c-Maf binding site should be V-MARE locating -192 ~ -205kb. On the other hand, the SUMOylation effect of c-Maf on IL-21 gene expression was tested. We concluded that c-Maf transactivation ability on IL-21 gene expression was not affected by SUMOylation.