Targeting of neutral cholesterol ester hydrolase to the endoplasmic reticulum via its N-terminal sequence
Targeting of neutral cholesterol ester hydrolase to the endoplasmic reticulum via its N-terminal sequence
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DOI：
10.1194/jlr.m900201-jlr200
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发表时间：
2010-02-01
影响因子：
6.5
通讯作者：
Ishibashi, Shun
中科院分区：
文献类型：
--
作者：
Igarashi, Masaki;Osuga, Jun-ichi;Ishibashi, Shun
中性胆固醇酯水解酶（NCEH）占巨噬细胞泡沫细胞中nCEH活性的很大一部分，是动脉粥样硬化的标志，但其亚细胞定位和结构-功能关系尚不清楚。在这里，我们确定了亚细胞定位，糖基化，和nCEH活性的一系列NCEH突变体在巨噬细胞中表达。NCEH是一种单跨膜II型膜蛋白，包含三个结构域：N-末端结构域、催化结构域和脂质结合结构域。N-末端结构域作为II型信号锚序列，将NCEH募集到内质网（ER），其催化结构域位于腔内。NCEH的所有推定的N-连接糖基化位点（Asn（270）、Asn（367）和Asn（389））均被糖基化。Asn（270）的糖基化对于酶活性很重要，Asn（270）位于最靠近催化丝氨酸基序的位置。胆固醇负荷与乙酰-LDL孵育不改变ER定位的NCEH。总之，NCEH靶向巨噬细胞的ER，在那里它水解CE以递送胆固醇流出细胞。Igarashi，M.，J. Osuga，M. Isshiki，M. Sekiya，H. Okazaki，S. Takase，M. Takanashi，K. Ohta，M. Kumagai，M. Nishi，T.藤田河永井，T。Kadowaki和S.石桥中性胆固醇酯水解酶通过其N-末端序列靶向内质网。J. Lipid Res. 2010. 51：274 - 285。
Neutral cholesterol ester hydrolase (NCEH) accounts for a large part of the nCEH activity in macrophage foam cells, a hallmark of atherosclerosis, but its subcellular localization and structure-function relationship are unknown. Here, we determined subcellular localization, glycosylation, and nCEH activity of a series of NCEH mutants expressed in macrophages. NCEH is a single-membrane-spanning type II membrane protein comprising three domains: N-terminal, catalytic, and lipid-binding domains. The N-terminal domain serves as a type II signal anchor sequence to recruit NCEH to the endoplasmic reticulum (ER) with its catalytic domain within the lumen. All of the putative N-linked glycosylation sites (Asn(270), Asn(367), and Asn(389)) of NCEH are glycosylated. Glycosylation at Asn(270), which is located closest to the catalytic serine motif, is important for the enzymatic activity. Cholesterol loading by incubation with acetyl-LDL does not change the ER localization of NCEH. In conclusion, NCEH is targeted to the ER of macrophages, where it hydrolyzes CE to deliver cholesterol for efflux out of the cells.-Igarashi, M., J. Osuga, M. Isshiki, M. Sekiya, H. Okazaki, S. Takase, M. Takanashi, K. Ohta, M. Kumagai, M. Nishi, T. Fujita, R. Nagai, T. Kadowaki, and S. Ishibashi. Targeting of neutral cholesterol ester hydrolase to the endoplasmic reticulum via its N-terminal sequence. J. Lipid Res. 2010. 51: 274-285.