Regulation of IL-10, IL-21 and IL-22 gene expression by the Basic Region of c-Maf in Th17 cells
|Keywords:||第十七型輔助性T細胞;介白素十;介白素二十一;介白素二十二;c-Maf;IL-10;IL-21;IL-22;Th17 cells||Issue Date:||2012||Abstract:||
c-Maf 除了在第二型輔助性T細胞 (Th2)中扮演調控介白素4 (IL-4) 的角色外，也可以在第十七型輔助性T 細胞 (Th17) 中直接調控介白素10 (IL-10) 和介白素21 (IL-21)。此外，最近c-Maf也被發現可以做為轉換生長因子 (TGF-β) 的下游，抑制介白素22 (IL-22) 的表現。作為轉錄因子，c-Maf 的鹼性區域 (basic region) 在辨認轉錄因子c-Maf DNA 結合位( MARE site) 扮演重要角色。許多鹼性區域的突變已被證實和人類先天性白內障有關。既然鹼性區域在DNA結合上不可或缺，我們想要探討這些在先天性白內障中被發現的突變 (K294R, R296S 和Y298F) 是否會影響c-Maf對細胞激素的調控。
我們利用逆轉濾過性病毒轉染 (retroviral transduction) 的方式送入野生型 (WT) c-Maf 或是突變型的c-Maf，藉由ELISA及real-time PCR的方式觀察其對細胞激素的影響。我們發現所有的突變都會降低介白素10和介白素21的表現。接著探討其中的機制，我們發現R296S和Y298F突變c-Maf 進入細胞核的能力會受到影響，且所有的突變型c-Maf 蛋白質都比野生型蛋白質不穩定，這些可能都是造成介白素10和介白素21表現降低的原因。
In addition to act as IL-4 activator in Th2 cells, c-Maf has been demonstrated to activate IL-10 and IL-21 directly in Th17 cells. Recently, c-Maf has also been discovered to be the downstream of TGF-β,and inhibit IL-22 production. As a transcription factor, the basic region of c-Maf plays a significant role in recognizing the MARE site, Maf recognition element. Several mutations in the basic region of c-Maf have been reported to cause congenital cataracts in human. Since the basic region of c-Maf play an important role in the DNA-binding, we plan to investigate whether the mutants in c-Maf basic region, including K294R, R296S and Y298F, affect their transactivation abilities on cytokine gene expression.
Retroviral transduction was performed to express the WT or mutant c- Mafs in the IL-6-skewing CD4+ T cells, and the cytokine expression was assayed by ELISA and real-time PCR. We observed that the IL-10 and IL-21 production were impaired in c-Maf BR mutants. In further investigation of the mechanism involved, we discovered that the cellular distribution of all mutants was changed. In addition, all mutant proteins were less stable than WT c-Maf. These phenomena may contribute partially to the reduction of cytokine production of c-Maf BR mutants.
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