Maeda Tomoji, Marutani Toshihiro, Zou Kun, Araki Wataru, Tanabe Chiaki, Yagishita Naoko, Yamano Yoshihisa, Amano Tetsuya, Michikawa Makoto, Nakajima Toshihiro, Komano Hiroto
Department of Neuroscience, School of Pharmacy, Iwate Medical University, Morioka, Japan.
FEBS J. 2009 Oct;276(20):5832-40. doi: 10.1111/j.1742-4658.2009.07264.x. Epub 2009 Sep 2.
The presenilin complex, consisting of presenilin, nicastrin, anterior pharynx defective-1 and presenilin enhancer-2, constitutes gamma-secretase, which is required for the generation of amyloid beta-protein. In this article, we show that Synoviolin (also called Hrd1), which is an E3 ubiquitin ligase implicated in endoplasmic reticulum-associated degradation, is involved in the degradation of endogenous immature nicastrin, and affects amyloid beta-protein generation. It was found that the level of immature nicastrin was dramatically increased in synoviolin-null cells as a result of the inhibition of degradation, but the accumulation of endogenous presenilin, anterior pharynx defective-1 and presenilin enhancer-2 was not changed. This was abolished by the transfection of exogenous Synoviolin. Moreover, nicastrin was co-immunoprecipitated with Synoviolin, strongly suggesting that nicastrin is the substrate of Synoviolin. Interestingly, amyloid beta-protein generation was increased by the overexpression of Synoviolin, although the nicastrin level was decreased. Thus, Synoviolin-mediated ubiquitination is involved in the degradation of immature nicastrin, and probably regulates amyloid beta-protein generation. Structured digital abstract: * MINT-7255352: Synoviolin (uniprotkb:Q9DBY1) physically interacts (MI:0915) with NCT (uniprotkb:P57716) by anti tag coimmunoprecipitation (MI:0007) * MINT-7255377: Ubiquitin (uniprotkb:P62991) physically interacts (MI:0915) with NCT (uniprotkb:P57716) by anti bait coimmunoprecipitation (MI:0006) * MINT-7255363: NCT (uniprotkb:P57716) physically interacts (MI:0915) with Synoviolin (uniprotkb:Q9DBY1) by anti bait coimmunoprecipitation (MI:0006).
早老素复合物由早老素、尼卡斯特林、咽前缺陷蛋白-1和早老素增强子-2组成，构成γ-分泌酶，这是生成淀粉样β蛋白所必需的。在本文中，我们表明，滑膜素（也称为Hrd1）作为一种参与内质网相关降解的E3泛素连接酶，参与内源性未成熟尼卡斯特林的降解，并影响淀粉样β蛋白的生成。研究发现，由于降解受到抑制，未成熟尼卡斯特林的水平在滑膜素缺失的细胞中显著升高，但内源性早老素、咽前缺陷蛋白-1和早老素增强子-2的积累没有变化。转染外源性滑膜素可消除这种现象。此外，尼卡斯特林与滑膜素共免疫沉淀，强烈表明尼卡斯特林是滑膜素的底物。有趣的是，尽管尼卡斯特林水平降低，但滑膜素的过表达增加了淀粉样β蛋白的生成。因此，滑膜素介导的泛素化参与未成熟尼卡斯特林的降解，并可能调节淀粉样β蛋白的生成。结构化数字摘要：*MINT-7255352：滑膜素（uniprotkb:Q9DBY1）通过抗标签共免疫沉淀（MI:0007）与NCT（uniprotkb:P57716）发生物理相互作用（MI:0915）*MINT-7255377：泛素（uniprotkb:P62991）通过抗诱饵共免疫沉淀（MI:0006）与NCT（uniprotkb:P57716）发生物理相互作用（MI:0915）*MINT-7255363：NCT（uniprotkb:P57716）通过抗诱饵共免疫沉淀（MI:0006）与滑膜素（uniprotkb:Q9DBY1）发生物理相互作用（MI:0915）。
