FK506對於APP的蛋白質交互作用及代謝過程之影響

Abstract

過去對於AICD的研究發現某些伴隨蛋白（chaperone）可以和AICD產生交互作用。舉例來說，使用酵母菌雙雜交（yeast two-hybrid）篩選發現有PPIase活性之伴隨蛋白同時也是免疫親和素（immunophilin）的FKBP12可以和AICD產生交互作用。另一個PPIase—Pin1，也被報導參與amyloidogenic APP代謝過程。由此或許可以暗示FKBP12所扮演的角色。在這個研究中，truncated形式的FKBP12被用來確認和AICD間的交互作用，而結果顯示包含一些FKBP12結合區域的33-41片段可能對於FKBP12-AICD交互作用扮演著重要角色。在這個研究中，truncated形式的FKBP12被用來確認和AICD間的交互作用，而結果顯示包含一些FKBP12結合區域的33-41片段可能對於FKBP12-AICD交互作用扮演著重要角色。β-半乳醣苷酶試驗因而被用來檢視是否當免疫抑制藥物FK506或cyclosporin A的存在會影響FKBP12和AICD之間的交互作用。另外以FKBP12為標靶的另一種藥物—Rapamycin也以同樣的實驗來測試。實驗結果顯示未和FKBP12產生交互作用的cyclosporin A並不能阻斷FKBP12-AICD的交互作用，但是FK506和rapamycin可以。依據這個結果，我們認為FKBP12的疏水性binding pocket可能對於與AICD的交互作用而言是重要的。在HEK293T細胞株中過量表現APP和FKBP12顯示FKBP12可能可以改變C99和C83的量，而這結果可以被FK506反轉。這可能是FK506對於神經退化疾病的保護作用中的原因之一。

Past studies of AICD indicated that some chaperones can interact with AICD. For example, FKBP12, a chaperone and an immunophilin with PPIase activity, was found to interact with AICD by yeast two-hybrid screening. It was reported that Pin1, another PPIase, was involved in the amyloidogenic APP processing. This might hint the role of FKBP12. In this study, truncated forms of FKBP12 were checked for their ability to interact with AICD, and the results showed residues 33-41 containing several FK506 binding residues might play an important role in the FKBP12-AICD interaction. β-galactosidase assay was therefore used to see whether the presence of certain immunosuppresants such as FK506 or cyclosporin A affects the interaction between FKBP12 and AICD. Rapamycin, another compound targeting to FKBP12, was also tested using the same method. Our result indicate that cyclosporin A, which does not interact with FKBP12, could not block FKBP12-AICD interaction, but FK506 or rapamycin could. According to these results, we suggest that hydrophobic binding pockets of FKBP12 might be important for the interaction with AICD. Overexpression of APP and FKBP12 in HEK293T cell line showed that FKBP12 could alter the levels of C99 and C83, and this results could be reserved by FK506. This may be a point of protective activity of FKBP12 in neurodegeneration dissease.