MUC1 splice variants in human ocular surface tissues: Possible differences between dry eye patients and normal controls
MUC1 splice variants in human ocular surface tissues: Possible differences between dry eye patients and normal controls
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DOI：
10.1016/j.exer.2006.01.031
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发表时间：
2006-09-01
影响因子：
3.4
通讯作者：
Young, William W., Jr.
中科院分区：
文献类型：
--
作者：
Imbert, Yoannis;Darling, Douglas S.;Young, William W., Jr.
粘蛋白是高度糖基化的蛋白质，其对于维持健康的上皮表面（包括眼表面）至关重要。粘蛋白作为润滑剂、保护剂和信号转导介质。跨膜粘蛋白MUC 1上的大多数O-糖基化位点位于含有可变数目串联重复序列（VNTR）的高度多态性核心区。MUC 1等位基因可分为含有小（30-45）或大（60-90）重复数目的大小类别。尽管在其他组织中发现了至少12种MUC 1剪接变体，但在人眼表组织中没有报道剪接变体。我们已经使用RT-PCR来鉴定MUC 1剪接变体，然后通过测序来确认。我们在此报告了在人角膜、结膜和泪腺的一些样本中存在MUC 1/B，其特征在于外显子1和2之间的典型剪接，MUC 1/A是一种转录物，保留内含子1的3'端的27个碱基，并预测在串联重复区的MUC 1序列上游添加9个氨基酸。角膜和结膜都含有MUC 1/SEC剪接变体，该变体缺乏跨膜结构域，因此导致MUC 1的可溶性分泌形式。角膜和结膜也含有MUC 1/Y和MUC 1/Z（X）变体，它们缺乏串联重复区。角膜、结膜和泪腺也含有以前未描述的MUC 1变体转录物，称为MUC 1/YI，其保留第一内含子的5'端99 bp和3'端27 bp，导致移码和过早终止密码子。该转录物被预测在信号肽酶切割后产生新的27个氨基酸的肽。刷检细胞学样本的分析显示，在结膜上皮中表达MUC 1/A变体的干眼症患者的百分比低于正常对照供体。Western blotting证实MUC 1/A与含有大尺寸串联重复序列的等位基因相关。因此，我们提出，干眼病易感性的一个因素可能是结膜上皮中MUC 1 VNTR的长度，这是基于较长的VNTR提供更好的润滑和更大的眼表面抗炎症保护的原理。(c)2006爱思唯尔有限公司版权所有。
Mucins are highly glycosylated proteins that are vital to the maintenance of healthy epithelial surfaces including the ocular surface. Mucins act as lubricants, protectants, and mediators of signal transduction. The majority of the O-glycosylation sites on the transmembrane mucin MUC1 are found in a highly polymorphic core region containing a variable number of tandem repeats (VNTR). MUC1 alleles can be divided into size classes that contain small (30-45) or large (60-90) numbers of repeats. Although at least 12 splice variants of MUC1 have been found in other tissues, no splice variants have been reported in human ocular surface tissues. We have used RT-PCR to identify MUC1 splice variants that were then confirmed by sequencing. We here report the presence in some samples of human cornea, conjunctiva, and lacrimal gland of MUC1/B which features canonical splicing between exons 1 and 2 and MUC1/A, a transcript that retains 27 by from the 3' end of intron 1 and is predicted to add 9 amino acids to the MUC1 sequence upstream of the tandem repeat region. Cornea and conjunctiva both contain the MUC1/SEC splice variant that lacks the transmembrane domain and, therefore, results in a soluble, secreted form of MUC1. Cornea and conjunctiva also contain MUC1/Y and MUC1/Z(X) variants that lack the tandem repeat region. Cornea, conjunctiva, and lacrimal gland also contain a previously undescribed MUC1 variant transcript, termed MUC1/YI, that retains 99 by from the 5' end and 27 by from the 3' end of the first intron, resulting in a frame shift and premature stop codon. This transcript is predicted to produce a novel 27 amino acid peptide after signal peptidase cleavage. Analysis of brush cytology samples revealed that the percentage of dry eye patients expressing the MUC1/A variant in the conjunctival epithelium is lower than in normal control donors. Western blotting confirmed that MUC1/A is associated with alleles containing the large size class of tandem repeats. Therefore, we propose that one factor in susceptibility to dry eye disease may be the lengths of the MUC1 VNTR in conjunctival epithelium based on the rationale that longer VNTR provide better lubrication and greater protection of the ocular surface against inflammation. (c) 2006 Elsevier Ltd. All rights reserved.