ACTIVITY-DEPENDENT MOBILIZATION OF THE ADHESION MOLECULE POLYSIALIC NCAM TO THE CELL-SURFACE OF NEURONS AND ENDOCRINE-CELLS
ACTIVITY-DEPENDENT MOBILIZATION OF THE ADHESION MOLECULE POLYSIALIC NCAM TO THE CELL-SURFACE OF NEURONS AND ENDOCRINE-CELLS
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DOI：
10.1002/j.1460-2075.1994.tb06862.x
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发表时间：
1994-11-15
期刊：
影响因子：
11.4
通讯作者：
PRALONG, WF
中科院分区：
文献类型：
--
作者：
KISS, JZ;WANG, C;PRALONG, WF
神经细胞黏附分子(NCAM)上的α-2，8-连接唾液酸聚合物(PSA)是细胞表面相互作用的重要调节因子。我们研究了在不同细胞活动条件下，PSA-NCAM在培养的皮质神经元和分泌胰岛素的β细胞表面的移位。内尿氨酸酶N是一种特异性切割PSA链的酶，用来从质膜上去除先前存在的PSA，并通过免疫细胞化学监测该分子的重新表达。点状IPSA免疫染色在1h内在68%的神经元表面恢复，这种恢复几乎完全被河豚毒素所阻止，提示自发电活动是必需的。在河豚毒素存在的情况下，K+去极化(50 MM)可使PSA表面染色恢复，这一作用需要细胞外钙离子的存在。在刺激胰岛素分泌的条件下，观察到PSA-NCAM迅速重新分布到β细胞表面。抑制Ca~(2+)通道使PSA-NCAM的表达和胰岛素分泌均降低至对照、非刺激水平。最后，对一个胰岛素分泌细胞系进行亚细胞分离，结果表明分泌囊泡部分高度富含PSA-NCAM。这些结果表明，PSA-NCAM可以通过调控的胞吐作用转移到细胞表面。综上所述，我们的结果提供了前所未有的证据，将细胞活性和PSA-NCAM的表达联系起来，并提出了一种快速调节细胞表面相互作用的机制。
The alpha-2,8-linked sialic acid polymer (PSA) on the neural cell adhesion molecule (NCAM) is an important regulator of cell surface interactions. We have examined the translocation of PSA-NCAM to the surface of cultured cortical neurons and insulin secreting beta cells under different conditions of cell activity. Endoneuraminidase N, an enzyme that specifically cleaves PSA chains, was used to remove pre-existing PSA from the plasma membrane and the re-expression of the molecule was monitored by immunocytochemistry. Punctate IPSA immunostaining was restored on the surface of 68% of neurons within 1 h. This recovery was almost completely prevented by tetrodotoxin, suggesting that spontaneous electrical activity is required. K+ depolarization (50 mM) allowed recovery of PSA surface staining in the presence of tetrodotoxin and this effect required the presence of extracellular Ca2+. Rapid redistribution of PSA-NCAM to the surface of beta cells was observed under conditions that stimulate insulin secretion. Ca2+ channel inhibition decreased both PSA-NCAM expression and insulin secretion to control, non-stimulated levels. Finally, subcellular fractionation of an insulin-secreting cell line showed that the secretory vesicle fraction is highly enriched in PSA-NCAM. These results suggest that PSA-NCAM can be translocated to the cell surface via regulated exocytosis. Taken together, our results provide unprecedented evidence linking cell activity and PSA-NCAM, expression, and suggest a mechanism for rapid modulation of cell surface interactions.