Nuclear localisation of wild type and mutant galectin-3 in transfected cells
Nuclear localisation of wild type and mutant galectin-3 in transfected cells
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DOI：
10.1016/s0248-4900(00)88763-8
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发表时间：
2000-01-01
影响因子：
2.7
通讯作者：
Hughes, RC
中科院分区：
文献类型：
--
作者：
Gaudin, JC;Mehul, B;Hughes, RC
半乳糖凝集素-3是碳水化合物结合蛋白家族的成员，通常存在于细胞的细胞质中。然而，半乳糖凝集素3也可以在某些条件下位于细胞核中，尽管它缺乏任何已知的核定位信号，并且蛋白质被隔离在细胞核中的机制是未知的。在这里，我们描述了Cos-7细胞或兔平滑肌lib-l细胞转染的cDNA编码仓鼠半乳糖凝集素-3螯合的蛋白质在细胞核中，而未转染的BHK细胞表达的内源性仓鼠凝集素或转染的BHK细胞过表达的蛋白质，不。用编码含有N-末端或内部缺失的仓鼠半乳糖凝集素-3的突变体的cDNA转染的Cos-7细胞或兔平滑肌Rb-1细胞的共聚焦免疫荧光显微镜显示，核定位不需要蛋白质的前103个氨基酸残基。残基104-110的进一步缺失显著地防止了在细胞核中的螯合。然而，序列A（104）PTGALT（110）本身对于核定位不是必须的，并且可以被其他不相关的序列取代。在核表达中被阻断的截短的半乳糖凝集素-3蛋白保留碳水化合物结合活性，使得半乳糖凝集素-3的严重N-末端截短诱导错误折叠导致聚集和细胞质螯合以及对核运输的附带影响的可能性较小。这些研究表明，半乳糖凝集素-3的核输入和保留是CRD结构域的性质，并且独立于N-末端结构域，其他人已经表明包含各种核组分的结合结构域。2000年（C）Elsevier SAS科学与医学版。
Galectin-3, a member of a family of carbohydrate-binding proteins, is present generally in the cytoplasm of cells. However, galectin 3 can also be located in nuclei under certain conditions although it lacks any known nuclear localisation signal and the mechanism by which the protein is sequestered in nuclei is unknown. Here we describe that Cos-7 cells or rabbit smooth muscle lib-l cells transfected with cDNA encoding hamster galectin-3 sequester the protein in nuclei whereas untransfected BHK cells expressing the endogenous hamster lectin or transfected BHK cells over-expressing the protein, do not. Confocal immunofluorescence microscopy of Cos-7 cells or rabbit smooth muscle Rb-l cells transfected with cDNAs encoding mutants of hamster galectin-3 containing N-terminal or internal deletions shows that nuclear localisation does not require the first 103 amino acid residues of the protein. Further deletion of residues 104-110 dramatically prevents sequestration in nuclei. However, the sequence A(104)PTGALT(110) by itself is not obligatory for nuclear localisation and can be substituted by other unrelated sequences. A truncated galectin-3 protein, that is blocked in nuclear expression, retains carbohydrate-binding activity, making less likely the possibility that severe N-terminal truncations of galectin-3 induce mis-folding leading to aggregation and cytoplasmic sequestration and an incidental effect on nuclear trafficking. These studies indicate that nuclear import and retention of galectin-3 is a property of the CRD domain and is independent of N-terminal domains that others have shown to contain binding domains for various nuclear components. 2000 (C) Editions scientifiques et medicales Elsevier SAS.