MCPIP1抑制NF-κB活性之分子機制探討

Study of the molecular mechanisms of MCPIP1 impairs NF-κB activity

柯韋廷(Wei-Ting Ke)

指導教授 ： 梁有志

臺北醫學大學/醫學科技學院/醫學檢驗暨生物技術學系/碩士(2011年)

https://doi.org/10.6831/TMU.2011.00063

摘要

人類週邊血液中加入單核球趨化蛋白-1後，會使單核球誘發出MCP-1-induced protein 1 (MCPIP1) 蛋白，為一種新發現的CCCH類型zinc finger蛋白，因此具有轉錄因子的特性。MCPIP1也被許多前發炎調節分子，像單核球趨化蛋白-1、介白素-1β、腫瘤壞死因子α以及脂多醣體，快速的誘發出來。目前已知MCPIP1具有抑制NF-κB報告基因活性的能力，在發炎反應中也扮演重要的角色，可以負向調控巨噬細胞的活化，但其分子機制尚未清楚。本研究使用野生型與突變型的MCPIP1細胞來探討抑制腫瘤壞死因子α誘發NF-κB活化的能力。結果發現，野生型MCPIP1可藉由減少腫瘤壞死因子α誘發IκB的磷酸化、IκB的降解、NF-κB轉移到細胞核以及NF-κB的DNA結合能力，但是突變型MCPIP1則無此效果。除此之外，本研究也發現MCPIP1可以大量的抑制IKK的激酶活性。近期的研究發現，特殊的importin分子可以幫助NF-κB轉移到細胞核中。我們的研究發現，野生型MCPIP1會降低importin α3與importin α4的mRNA與蛋白質表現量，但是突變型MCPIP1並無此效果。由以上的實驗結果推測，在腫瘤壞死因子α誘發的細胞中，MCPIP1可能會藉由抑制IKK的活性和減少importin α3與importin α4的表現，來減少NF-κB的活化。

關鍵字

MCPIP1 ； NF-κB ； 腫瘤壞死因子α

並列摘要

MCP-1-induced protein 1 (MCPIP1), a novel CCCH-zinc finger-containing protein, was identified in monocyte chemotactic protein-1 (MCP-1)-activated monocytes, and induced also by other proinflammatory mediators, such as interleukin-1β, tumor necrosis factor α (TNFα), and lipopolysaccharide. MCPIP1 has been known to inhibit NF-κB reporter activity and may play an important role in feedback inhibition of inflammation, but the underlying molecular mechanisms are not yet understood. In this study, both wild type and mutant MCPIP1 cells were used to investigate the inhibitory effects of TNFα-induced NF-κB activation. Our results indicated the wild type but not mutant MCPIP1 could impair TNFα-induced IκB phosphorylation, IκB degradation, NF-κB nuclear translocation, and NF-κB DNA binding activity. In addition, we found wild type MCPIP1 dramatically inhibited IKK kinase activity. It is well know that particular importin molecules are need for helping NF-κB transfer to the nucleus. We found the wild type but not mutant MCPIP1 decreased the mRNA and protein levels of importin α3 and importin α4. These results suggest that MCPIP1 might impair NF-κB activation through both inhibition of IKK activity and decrease of importin α3 and importin α4 expression in TNFα-treated cells.

並列關鍵字

MCPIP1 ； NF-κB ； TNFα

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