Transglutaminase type 2-dependent selective recruitment of proteins into exosomes under stressful cellular conditions
Transglutaminase type 2-dependent selective recruitment of proteins into exosomes under stressful cellular conditions
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DOI：
10.1016/j.bbamcr.2016.05.005
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发表时间：
2016-08-01
影响因子：
5.1
通讯作者：
Piacentini, Mauro
中科院分区：
文献类型：
--
作者：
Diaz-Hidalgo, Laura;Altuntas, Sara;Piacentini, Mauro
许多研究揭示了外泌体在细胞间通讯中的作用，越来越多的证据表明这些囊泡在癌症和神经退行性疾病的进展和发病机制中具有重要功能。然而，外泌体的生物发生过程仍不清楚。组织转氨酶（TG2）是一种多功能酶，具有不同的亚细胞定位。特别是，在应激条件下，细胞外基质中也检测到该酶，但TG 2释放到细胞外的机制需要进一步研究。因此，本研究的目的是确定外泌体是否可能是TG2到达细胞外空间的载体，以及TG2是否可能参与外泌体的生物发生。为了解决这个问题，我们分离并表征了在应激条件下（即蛋白酶体损伤或表达含有84个多聚谷氨酰胺重复序列的亨廷顿蛋白（mHtt）的突变形式）源自表达或不表达TG2的细胞的外泌体。我们的研究结果表明，TG2只存在于蛋白酶体阻断，其中TG2与TSG101和阿利克斯，两个关键蛋白参与外泌体生物发生相互作用的条件。有趣的是，我们发现TG2有利于组装包括mHtt、阿利克斯、TSG101和BAG3的蛋白质复合物，BAG3是参与mHtt清除的共分子伴侣。该复合物的形成通过mHtt和BAG3在仅来源于TG2熟练细胞的外泌体中的选择性募集来实现。总的来说，我们的数据表明，TG 2是外泌体的生物发生中的重要参与者，在应激细胞条件下控制其货物的选择性。此外，这些囊泡代表了细胞在蛋白质稳态受损的情况下将TG 2释放到细胞外空间的方式。(C)2016由Elsevier B.V.出版
Numerous studies are revealing a role of exosomes in intercellular communication, and growing evidence indicates an important function for these vesicles in the progression and pathogenesis of cancer and neurodegenerative diseases. However, the biogenesis process of exosomes is still unclear. Tissue transglutaminase (TG2) is a multifunctional enzyme with different subcellular localizations. Particularly, under stressful conditions, the enzyme has been also detected in the extracellular matrix, but the mechanism(s) by which TG2 is released outside the cells requires further investigation. Therefore, the goal of the present study was to determine whether exosomes might be a vehicle for TG2 to reach the extracellular space, and whether TG2 could be involved in exosomes biogenesis. To address this issue, we isolated and characterized exosomes derived from cells either expressing or not TG2, under stressful conditions (i.e. proteasome impairment or expressing a mutated form of huntingtin (mHtt) containing 84 polyglutamine repeats). Our results show that TG2 is present in the exosomes only upon proteasome blockade, a condition in which TG2 interacts with TSG101 and ALIX, two key proteins involved in exosome biogenesis. Interestingly, we found that TG2 favours the assembly of a protein complex including mHtt, ALIX, TSG101 and BAG3, a co-chaperone involved in the clearance of mHtt. The formation of this complex is paralleled by the selective recruitment of mHtt and BAG3 in the exosomes derived from TG2 proficient cells only. Overall, our data indicate that TG2 is an important player in the biogenesis of exosomes controlling the selectivity of their cargo under stressful cellular conditions. In addition, these vesicles represent the way by which cells can release TG2 into the extracellular space under proteostasis impairment. (C) 2016 Published by Elsevier B.V.