Cholesterol glucosylation is catalyzed by transglucosylation reaction of β-glucosidase 1
Cholesterol glucosylation is catalyzed by transglucosylation reaction of β-glucosidase 1
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DOI：
10.1016/j.bbrc.2013.10.145
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发表时间：
2013-11-29
影响因子：
3.1
通讯作者：
Murakami-Murofushi, Kimiko
中科院分区：
文献类型：
--
作者：
Akiyama, Hisako;Kobayashi, Susumu;Murakami-Murofushi, Kimiko
胆固醇葡萄糖苷 (β-ChIGIc) 是胆固醇的单葡萄糖基化衍生物，参与热休克反应的调节。 beta-ChIGIc 会因热休克而迅速诱导，激活热休克转录因子 1 (HSF1)，导致人成纤维细胞中热休克蛋白 70 (HSP70) 的表达。负责 β-ChIGIc 形成的酶的鉴定和生化特征对于全面了解热激后导致 HSP70 诱导的分子机制非常重要。最近，我们证明动物组织和人类成纤维细胞中的 β-ChIGIc 合成不依赖于 UDP-葡萄糖，而是依赖于葡萄糖神经酰胺 (GlcCer)。在这项研究中，我们研究了葡萄糖脑苷脂酶（一种 GIcCer 降解糖苷酶）充当 β-ChIGIc 合成酶的可能性。 β-葡萄糖苷酶（GBA1，溶酶体酸性β-葡萄糖脑苷酶）的过度表达导致人成纤维细胞中胆固醇葡萄糖基化活性的增加。使用 GBA1 活性严重缺陷的 2 型戈谢病患者产生的细胞系，我们发现细胞中胆固醇糖基化活性非常低，而 GBA1 的过度表达挽救了该活性。此外，纯化的重组 GBA1 具有 conduritol B-环氧化物敏感性胆固醇糖基化活性。 GBA1对胆固醇糖基化的最适pH和温度分别约为5.3和43℃。在测试的含有饱和脂肪酸（C8:0至C18:0）的GlcCer中，短链C8:0-GlcCer是胆固醇糖基化活性最有效的供体。与含有相同链长的饱和脂肪酸的GlcCer相比，含有单不饱和脂肪酸的GlcCer是更优选的胆固醇糖基化底物。这些结果首次证明了 GBA1 作为 β-ChIGIc 合成酶的新功能。因此，我们的结果也揭示了哺乳动物糖脂代谢的新途径。 (C) 2013 Elsevier Inc. 保留所有权利。
Cholesteryl glucoside (beta-ChIGIc), a monoglucosylated derivative of cholesterol, is involved in the regulation of heat shock responses. beta-ChIGIc, which is rapidly induced in response to heat shock, activates heat shock transcription factor 1 (HSF1) leading to the expression of heat shock protein 70 (HSP70) in human fibroblasts. Identification and biochemical characterization of the enzyme responsible for beta-ChIGIc formation is important for a complete understanding of the molecular mechanisms leading to HSP70-induction following heat shock. Recently, we demonstrated that beta-ChIGIc synthesis is not dependent on UDP-Glucose but glucosylceramide (GlcCer) in animal tissue and human fibroblasts. In this study, we examined the possibility of glucocerebrosidase, a GIcCer-degrading glycosidase, acting as beta-ChIGIc-synthesizing enzyme. Overexpression of beta-glucosidase (GBA1, lysosomal acid beta-glucocerebrosidase) led to an increase in cholesterol glucosylation activity in human fibroblasts. Using a cell line generated from type 2 Gaucher disease patients with severe defects in GBA1 activity, we found that cholesterol glucosylation activity was very low in the cells and the overexpression of GBA1 rescued the activity. In addition, purified recombinant GBA1 exhibits conduritol B-epoxide-sensitive cholesterol glucosylation activity. The optimum pH and temperature for cholesterol glucosylation by GBA1 were at about 5.3 and 43 C, respectively. Short chain C8:0-GIcCer was the most effective donor for cholesterol glucosylation activity among GIcCer containing saturated fatty acid (C8:0 to C18:0) tested. GlcCer containing mono-unsaturated fatty acid was more preferred substrate for cholesterol glucosylation when compared with GIcCer containing same chain length of saturated fatty acid. These results demonstrate, for the first time, a novel function of GBA1 as a beta-ChIGIc-synthesizing enzyme. Therefore, our results also reveal a new pathway for glycolipid metabolism in mammals. (C) 2013 Elsevier Inc. All rights reserved.