BIOSYNTHETIC PROCESSING OF NEU DIFFERENTIATION FACTOR - GLYCOSYLATION, TRAFFICKING, AND REGULATED CLEAVAGE FROM THE CELL-SURFACE
BIOSYNTHETIC PROCESSING OF NEU DIFFERENTIATION FACTOR - GLYCOSYLATION, TRAFFICKING, AND REGULATED CLEAVAGE FROM THE CELL-SURFACE
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DOI：
10.1074/jbc.270.32.19188
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发表时间：
1995-08-11
影响因子：
4.8
通讯作者：
HU, S
中科院分区：
文献类型：
--
作者：
BURGESS, TL;ROSS, SL;HU, S
Neu分化因子(NDF)，又称hereglin，在结构上与表皮生长因子家族的生长因子家族有关；它刺激neu/HER-2癌基因的酪氨酸磷酸化，并导致某些人乳腺癌细胞系的分化，单个基因的选择性剪接导致多种NDF/hereglin的异构体，以及神经元同源物，命名为ARIA(乙酰胆碱受体诱导活性)和GGF(胶质生长因子)；至少15个结构变体已知。除了两个以外，所有的NDF/hereglin cDNA都被预测为编码可溶性NDF的跨膜糖基化前体。在这篇报道中，我们研究了稳定表达单个NDF亚型的中国仓鼠卵巢细胞和表达至少六种不同NDF亚型的天然细胞系大鼠1-EJ中不同NDF亚型的生物合成过程。我们发现NDF的前体经历了典型的糖基化和贩运。一部分分子在细胞内被蛋白水解性切割，导致可溶的、成熟的NDF结构性分泌到培养液中，然而，新合成的NDF前体分子中的很大一部分逃脱了细胞内的切割，并被运输到转基因细胞和天然细胞的细胞表面，在那里它们作为全长的跨膜蛋白存在。最后，我们证明了这些全长的跨膜NDF分子可以经历佛波酯调节的从膜上切割，将可溶性生长因子释放到介质中。
neu differentiation factor (NDF), also known as heregulin, is structurally related to the epidermal growth factor family of growth factors; it stimulates tyrosine phosphorylation of the neu/HER-2 oncogene and causes differentiation of certain human breast cancer cell lines, Alternative splicing of a single gene gives rise to multiple isoforms of NDF/heregulin, as well as the neuronal homologues, designated ARIA (acetylcholine receptor inducing activity) and GGF (glial growth factor); at least 15 structural variants are known. All but two of the NDF/heregulin cDNAs are predicted to encode transmembrane, glycosylated precursors of soluble NDF.In this report we characterized the biosynthetic processing of different NDF isoforms in stably transfected Chinese hamster ovary cells expressing individual NDF isoforms, and in the native cell line Rat 1-EJ, which expresses at least six different NDF isoforms. We found that the precursors for NDF undergo typical glycosyIation and trafficking. A portion of the molecules are proteolyticafly cleaved intracellularly leading to the constitutive secretion of soluble, mature NDF into the culture media, However, a significant portion of the newly synthesized NDF precursor molecules escape intracellufar cleavage and are transported to the cell surface of both transfected and native cells, where they reside as fulllength, transmembrane proteins. Finally we show that these full-length, transmembrane NDF molecules can undergo phorbol ester regulated cleavage from the membrane, releasing the soluble growth factor into the medium.