Le Bivic A, Garcia M, Rodriguez-Boulan E
Biologie de la Différenciation Cellulaire, Unité de Recherche associée 179, Faculté des Sciences de Luminy, Marseille, France.
J Biol Chem. 1993 Apr 5;268(10):6909-16.
gp114 is a major sialoglycoprotein expressed on the apical membrane of Madin-Darby canine kidney (MDCK) II cells. We investigated its distribution in two lectin-resistant mutant cell lines derived from MDCKII cells, MDCKII-RCAr and MDCKII-ConAr cells. gp114 was present on the apical membrane of MDCKII-ConAr cells but was predominantly basolateral in MDCKII-RCAr cells. No change of polarity was observed for several apical and basolateral markers in this cell line. Reversal of polarity of gp114 mainly resulted from a modification of its intracellular sorting. gp114 showed altered endocytosis in MDCKII-RCAr cells. In MDCKII cells gp114 was slowly endocytosed, whereas in MDCKII-RCAr cells endocytosis of gp114 was highly increased. Using mannosidase I and II inhibitors we found that N-glycosylation only slightly affects gp114 sorting and endocytosis. Our results suggest that gp114 or an associated component in MDCK-RCAr fails to express apical information or that a mutation creates a basolateral sorting signal which could be related to endocytic signals.
gp114是一种主要的唾液酸糖蛋白，表达于麦氏犬肾（MDCK）II细胞的顶端膜上。我们研究了它在源自MDCKII细胞的两种凝集素抗性突变细胞系，即MDCKII-RCAr和MDCKII-ConAr细胞中的分布情况。gp114存在于MDCKII-ConAr细胞的顶端膜上，但在MDCKII-RCAr细胞中主要位于基底外侧。在该细胞系中，几种顶端和基底外侧标记物的极性未观察到变化。gp114极性的反转主要是由于其细胞内分选的改变。gp114在MDCKII-RCAr细胞中显示出内吞作用的改变。在MDCKII细胞中，gp114被缓慢内吞，而在MDCKII-RCAr细胞中，gp114的内吞作用高度增加。使用甘露糖苷酶I和II抑制剂，我们发现N-糖基化仅轻微影响gp114的分选和内吞作用。我们的结果表明，MDCK-RCAr中的gp114或相关成分未能表达顶端信息，或者一个突变产生了一个与内吞信号相关的基底外侧分选信号。
