Exosome release is regulated by a calcium-dependent mechanism in K562 cells
Exosome release is regulated by a calcium-dependent mechanism in K562 cells
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DOI：
10.1074/jbc.m301642200
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发表时间：
2003-05-30
影响因子：
4.8
通讯作者：
Colombo, MI
中科院分区：
文献类型：
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作者：
Savina, A;Furl치n, M;Colombo, MI
多泡体（MVB）是一种内吞结构，含有由内体膜出芽进入腔室形成的小泡。MVB与质膜的融合导致称为外泌体的小内囊泡的分泌。K562细胞是释放外泌体的造血细胞系。莫能菌素（MON）的应用产生了大的MVB，用荧光脂质标记。外泌体释放显着增强MON治疗，Na+/H+交换，诱导细胞内钙（Ca 2+）的变化。为了探索MON对外泌体释放的影响是通过增加Ca 2+引起的可能性，我们使用了钙离子载体和细胞内Ca 2+的螯合剂。我们的结果表明，增加细胞内Ca 2+会刺激外泌体分泌。此外，MON刺激的外泌体释放被1，2-双（2-氨基苯氧基）乙烷-N，N，N '，N'-四乙酸乙酰氧基甲酯（BAPTA-AM）完全消除，这意味着在该过程中需要Ca 2+。我们已经观察到，在MON的存在下产生的大的MVB积累的Ca 2+，通过与Fluo 3-AM标记确定，这表明腔内Ca 2+可能在分泌过程中发挥关键作用。有趣的是，我们的研究结果表明，转铁蛋白（Tf）刺激外泌体的释放在一个Ca 2+依赖的方式，表明Tf可能是一种生理刺激外泌体释放在K562细胞。
Multivesicular bodies (MVBs) are endocytic structures that contain small vesicles formed by the budding of an endosomal membrane into the lumen of the compartment. Fusion of MVBs with the plasma membrane results in secretion of the small internal vesicles termed exosomes. K562 cells are a hematopoietic cell line that releases exosomes. The application of monensin (MON) generated large MVBs that were labeled with a fluorescent lipid. Exosome release was markedly enhanced by MON treatment, a Na+/H+ exchanger that induces changes in intracellular calcium (Ca2+). To explore the possibility that the effect of MON on exosome release was caused via an increase in Ca2+, we have used a calcium ionophore and a chelator of intracellular Ca2+. Our results indicate that increasing intracellular Ca2+ stimulates exosome secretion. Furthermore, MON-stimulated exosome release was completely eliminated by 1,2-bis(2-aminophenoxy) ethane-N,N,N',N'-tetraacetic acid acetoxymethyl ester (BAPTA-AM), implying a requirement for Ca2+ in this process. We have observed that the large MVBs generated in the presence of MON accumulated Ca2+ as determined by labeling with Fluo3-AM, suggesting that intralumenal Ca2+ might play a critical role in the secretory process. Interestingly, our results indicate that transferrin (Tf) stimulated exosome release in a Ca2+-dependent manner, suggesting that Tf might be a physiological stimulus for exosome release in K562 cells.