Biosynthesis and function of LFA-3 in human mutant cells deficient in phosphatidylinositol-anchored proteins.
Biosynthesis and function of LFA-3 in human mutant cells deficient in phosphatidylinositol-anchored proteins.
复制标题
DOI：
10.4049/jimmunol.141.12.4283
复制
发表时间：
1988-12
影响因子：
4.4
通讯作者：
N. Hollander;P. Selvaraj;T. Springer
中科院分区：
文献类型：
--
作者：
N. Hollander;P. Selvaraj;T. Springer
缺乏磷脂酰肌醇(PI)锚定蛋白表达的突变体来自人B淋巴母细胞系JY。与野生型细胞不同，野生型细胞既表达跨膜型LFA-3糖蛋白，又表达PI连接形式的LFA-3糖蛋白，突变细胞只表达跨膜型LFA-3。突变细胞的LFA-3中未掺入乙醇胺，表明锚定部分完全缺失。阻断PI锚定形式的正常生物合成导致两个中间体的积累，这两个中间体可能具有完整和截断的多肽链。突变细胞分泌不附着在细胞膜上的截短型LFA-3到培养上清中。以JY细胞系为CTL靶点，研究了两种形式LFA-3之间黏附功能的可能划分。野生型和突变型JY细胞与CTL形成偶联物，随后以相似的程度裂解。此外，野生型和突变型JY细胞对CTL增殖的刺激作用相同。抗体阻断实验表明，CD2/LFA-3通路在野生型和突变型细胞与CTL相互作用中起主导作用。由于E只表达PI连接的LFA-3形式，而这种形式是已知的介导细胞黏附的形式，目前的结果表明，两种不同的膜锚定LFA-3形式都能够介导黏附。两种形式的LFA-3之间可能的信号功能划分正在调查中。
Mutants that lack expression of phosphatidylinositol (PI)-anchored proteins were derived from the human B lymphoblastoid JY cell line. It was demonstrated that unlike wild-type cells, which normally express both a transmembrane and a PI-linked form of LFA-3 glycoprotein, the mutant cells expressed only the transmembrane form of LFA-3. [3H]Ethanolamine was not incorporated into LFA-3 of mutant cells, indicating that the anchor moiety was entirely missing. Blockade of normal biosynthesis of the PI-anchored form led to accumulation of two intermediates that may have intact and truncated polypeptide chains. The truncated LFA-3, which was not attached to the cell membrane, was secreted by mutant cells into culture supernatants. A possible division of adhesion function between the two forms of LFA-3 was studied by using the JY cell lines as targets for CTL. Wild-type and mutant JY cells formed conjugates with CTL and were subsequently lysed to a similar extent. In addition, wild-type and mutant JY cells stimulated CTL proliferation to the same extent. Antibody-blocking experiments demonstrated a predominant role for the CD2/LFA-3 pathway in interaction of both wild-type and mutant cells with CTL. Because E exclusively express only the PI-linked LFA-3 form, and this form is known to mediate cell adhesion, the present results indicate that the two distinct membrane-anchored LFA-3 forms are each capable of mediating adhesion. A possible division of signaling functions between the two forms of LFA-3 is under investigation.