α-2,3唾液酸化可区分角膜缘和角膜上皮细胞表型。

Alpha-2,3 sialylation differentiate the limbal and corneal epithelial cell phenotypes.

作者信息

Wolosin J M, Wang Y

机构信息

Department of Ophthalmology, Mount Sinai Medical Center, New York, NY 10026-6574, USA.

出版信息

Invest Ophthalmol Vis Sci. 1995 Oct;36(11):2277-86.

PMID:7558722

Abstract

PURPOSE

The initial differentiation event for the corneal epithelial cell lineage occurs as the limbally localized stem cells yield, through mitosis, the highly proliferative, transiently amplifying corneal peripheral cells. This differentiation is characterized by the expression of tissue-specific cytokeratins, as well as the loss of alpha-enolase and pigmentation. All these are intracellular events. The aim of this study was to identify and characterize, through lectin analysis, changes in cell surface properties associated with differentiation.

METHODS

Cryostat sections of the limbo-corneal area from freshly dissected pigmented rabbit corneas were stained with fluorescent lectins.

RESULTS

Peanut lectin (PNA; binds to Ser/Threo-GalNAc-beta-1,3-Gal, if the Gal residue is not sialylated) stained the plasma membrane of all layers of the conjunctiva and limbus but was excluded from corneal cell membranes. Maakia amurensis agglutinin (MAA; binds to sialic acid attached to galactose through alpha-2,3 bonds in either N-glycans or O-glycans) stained exclusively corneal cell plasma membrane. After complete tissue desialylation, all corneal plasma membranes became PNA positive with equal stain intensity across both sides of the limbo-corneal margin. The binding of the agglutinins from Limax flavus (binds unselectively to sialic acid) and Sambucus nigra (binds to sialic acid attached through alpha-2,6 bonds) to the basement membrane displayed a large increase at the corneal side of limbo-corneal demarcation.

CONCLUSIONS

Limbal (stem) cells express on the cell surface unsialylated galactose residues that are recognized by PNA and that lack any sialic acid bound through alpha-2,3 bonds. The initial differentiation involves sialylation of these residues and the concurrent appearance of alpha-2,3 sialic acid residues, suggesting expression or activation of alpha-2-3 sialytransferase. Changes in basement membrane composition, charge, or both may underpin this expression.

摘要

目的

角膜上皮细胞谱系的初始分化事件发生于位于角膜缘的干细胞通过有丝分裂产生高度增殖的、短暂扩增的角膜周边细胞之时。这种分化的特征在于组织特异性细胞角蛋白的表达，以及α-烯醇化酶的丧失和色素沉着的消失。所有这些都是细胞内事件。本研究的目的是通过凝集素分析鉴定和表征与分化相关的细胞表面特性的变化。

方法

用荧光凝集素对刚解剖的有色兔角膜的角膜缘区域的冰冻切片进行染色。

结果

花生凝集素（PNA；如果半乳糖残基未被唾液酸化，则与丝氨酸/苏氨酸 - N - 乙酰半乳糖胺 - β - 1,3 - 半乳糖结合）对结膜和角膜缘所有层的质膜进行染色，但不与角膜细胞膜结合。黑果腺肋花楸凝集素（MAA；与通过α - 2,3键连接到半乳糖上的唾液酸结合，存在于N - 聚糖或O - 聚糖中）仅对角膜细胞质膜进行染色。在完全组织去唾液酸化后，所有角膜质膜均变为PNA阳性，在角膜缘 - 角膜边缘两侧具有相同的染色强度。黄蛞蝓凝集素（无选择性地与唾液酸结合）和接骨木凝集素（与通过α - 2,6键连接的唾液酸结合）与基底膜的结合在角膜缘 - 角膜分界的角膜侧显著增加。