Tracking N-acetyllactosamine on cell-surface glycans in vivo.
Tracking N-acetyllactosamine on cell-surface glycans in vivo.
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DOI：
10.1002/anie.201100265
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发表时间：
2011-04-26
影响因子：
16.6
通讯作者：
Wu, Peng
中科院分区：
文献类型：
--
作者：
Zheng, Tianqing;Jiang, Hao;Gros, Marilyn;del Amo, David Soriano;Sundaram, Subha;Lauvau, Gregoire;Marlow, Florence;Liu, Yi;Stanley, Pamela;Wu, Peng
糖糖是细胞产生的多聚糖的总和，是细胞S生理的动态指标。[1]糖糖的变化反映了细胞S的发育阶段和细胞的转化状态。最近，通过用叠氮或烷基网络标记的单糖前体处理细胞或生物体，利用生物正交化学报告策略，体内的糖链成像已经成为可能。[2，3]修饰的单糖，当被细胞摄取时，在细胞质中被激活，形成核苷酸糖，糖基转移酶的底物，在内质网和高尔基体中产生复杂的糖链。一旦结合到细胞表面的糖偶联物中，生物正交化学标记允许与用于显影的荧光探针、[2]或用于浓缩和糖链分析的亲和探针进行共价结合。[4]这种方法已成功地用于检测和成像粘蛋白O连接的多聚糖、[2]唾液酸化和岩藻糖化的多聚糖、[5]和胞质O-GlcN酰化蛋白(GlcNAc=N-乙酰氨基葡萄糖)。[2]然而，这种方法只跟踪单糖，并且通常在大量的多聚糖上发现每个单糖。不能通过用非天然单糖劫持它们的生物合成途径来唯一地标记特定组成的蛋白质(图1a)。在这里，我们报道了一种快速和高度特异的化学酶方法，用于标记含有普遍存在的二糖-N-乙酰乳糖胺(LacNAc，Galβ1，4GlcNAc)的细胞表面糖链-生物物理探针用于成像或糖组分分析。LacNAc广泛分布于大多数脊椎动物、包膜病毒、某些病原菌和人类寄生虫中。[6]它是复杂和混合N-聚糖以及一些类型的O-聚糖和糖脂的通用成分。[6]在反式高尔基体中，支链的N-和O-聚糖被β(1，4)-半乳糖基转移酶修饰以产生LacNAc双糖，该双糖可被β(1，3)-N-乙酰氨基葡萄糖转移酶进一步延长，最终形成可变长度的LacNAc的线形均聚物，称为聚-LacNAc。糖基转移酶和供体底物，即UDP-GlcNAc和UDP-Gal(UDP=尿苷二磷酸)的可用性和定位影响高尔基体中聚-LacNAc的生物合成和延伸。[7]末端LacNAc可以由末端半乳糖上的α连接的唾液酸、半乳糖或岩藻糖封顶，或者在内部N-乙酰氨基葡萄糖残基上岩藻糖化，以产生Lewis X(Galβ1，4-(Fucα1，3)GlcNAc，Lex)和sialyl Lewis X(Siaα2，3Galβ1，4-(Fucα1，3)cNAc，SLex)。[8]β(1，4)-半乳糖基转移酶-1是β(1，4)-半乳糖基转移酶中的一种，可将半乳糖基转移酶添加到GlcNAc中形成LacNAc。[8]此外，在某些恶性组织中，细胞表面LacNAc水平升高。例如，对正常粘膜和人类结直肠癌的免疫组织化学分析表明，细胞表面LacNAc的水平与结直肠癌密切相关。[9]LacNAc二糖在正常粘膜中几乎检测不到，但在人类结直肠癌中显著增加。因此，含有LacNAc的多糖是分子成像的有吸引力的靶点，也是癌症的潜在生物标记物。
The glycome, the totality of glycans produced by a cell, is a dynamic indicator of the cell s physiology.[1] Changes in the glycome reflect a cell s developmental stage and the transformation state of a cell. Recently, imaging of glycans in vivo has been enabled using a bioorthogonal chemical reporter strategy by treating cells or organisms with azide-or alkynetagged monosaccharide precursors.[2, 3] The modified monosaccharides, when taken up by cells, are activated in the cytoplasm to form nucleotide sugars, substrates of glycosyltransferases that generate complex glycans in the endoplasmic reticulum and Golgi. Once incorporated into cell-surface glycoconjugates, the bioorthogonal chemical tags allow covalent conjugation with fluorescent probes for visualization,[2] or with affinity probes for enrichment and glycomic analysis.[4] This approach has been successfully used for the detection and imaging of mucin O-linked glycans,[2] sialylated [2] and fucosylated glycans,[5] and cytosolic O-GlcNAcylated proteins (GlcNAc= N-acetylglucosamine).[2] However, only monosaccharides are tracked by this strategy, and each monosaccharide is usually found on a plethora of glycans.[6] Higher-order glycans, such as disaccharides or trisaccharides, of specific composition cannot be uniquely labeled by hijacking their biosynthetic pathways with nonnatural monosaccharides (Figure 1a). Herein, we report a rapid and highly specific chemoenzymatic method for labeling cell-surface glycans bearing a ubiquitous disaccharide—N-acetyllactosamine (LacNAc, Galβ1, 4GlcNAc)—with biophysical probes for imaging or glycomic analysis. LacNAc is widely distributed in most vertebrates, enveloped viruses, certain pathogenic bacteria, and human parasites.[6] It is a universal component of complex and hybrid N-glycans as well as a few types of O-glycans and glycolipids.[6] Branched N-and O-glycans are modified in the trans Golgi by β (1, 4)-galactosyltransferases to generate the LacNAc disaccharide, which can be further elongated by β (1, 3)-N-acetylglucosaminyltransferases to ultimately form linear homopolymers of LacNAc of variable length, known as poly-LacNAc. The availability and localization of glycosyltransferases and donor substrates, that is, UDP-GlcNAc and UDP-Gal (UDP= uridine diphosphate), influences the biosynthesis and elongation of poly-LacNAc in the Golgi apparatus.[7]Terminal LacNAc may be capped by α-linked sialic acid, galactose or fucose added to the terminal galactose, or fucosylated on the internal N-acetylglucosamine residue to generate glycan epitopes such as Lewis X (Galβ1, 4-(Fucα1, 3) GlcNAc, LeX) and sialyl Lewis X (Siaα2, 3Galβ1, 4-(Fucα1, 3) GlcNAc, sLeX). Many of these modifications are developmentally regulated.[8] Mice with homozygous knockout of β (1, 4)-galactosyltransferase-1, one of the β (1, 4)-galactosyltransferases that adds Gal to GlcNAc to form LacNAc, exhibit growth retardation and a markedly shortened life span.[8] Furthermore, cell-surface LacNAc levels are elevated in certain malignant tissues. For example, immunohistochemical analysis of normal mucosa and carcinomas of the human colorectum revealed a strong correlation between the level of cell-surface LacNAc and colorectal cancer.[9] LacNAc disaccharides are barely detectable in normal mucosa, but are markedly increased in carcinomas of the human colorectum. Thus, glycans with LacNAc constitute attractive targets for molecular imaging and potential biomarkers for cancer.
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影响因子：
46.2
作者：
Jewett JC;Bertozzi CR
通讯作者：
Bertozzi CR
影响因子：
64.5
作者：
Lau, Ken S.;Partridge, Emily A.;Dennis, James W.
通讯作者：
Dennis, James W.
DOI：
10.1073/pnas.0811481106
发表时间：
2009-01-06
影响因子：
11.1
作者：
Laughlin, Scott T.;Bertozzi, Carolyn R.
通讯作者：
Bertozzi, Carolyn R.
影响因子：
4.8
作者：
Oelmann, S;Stanley, P;Gerardy-Schahn, R
通讯作者：
Gerardy-Schahn, R
DOI：
10.1074/jbc.m109.068353
发表时间：
2010-02-19
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
North SJ;Huang HH;Sundaram S;Jang-Lee J;Etienne AT;Trollope A;Chalabi S;Dell A;Stanley P;Haslam SM
通讯作者：
Haslam SM