Resveratrol-induced autophagy is dependent on IP3Rs and on cytosolic Ca2+
Resveratrol-induced autophagy is dependent on IP3Rs and on cytosolic Ca2+
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DOI：
10.1016/j.bbamcr.2017.02.013
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发表时间：
2017-06-01
影响因子：
5.1
通讯作者：
Bultynck, Geert
中科院分区：
文献类型：
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作者：
Luyten, Tomas;Welkenhuyzen, Kirsten;Bultynck, Geert
先前的工作表明，细胞内Ca 2+信号和肌醇1，4，5-三磷酸（IP 3）受体（IP 3R）是必不可少的，以增加自噬通量响应mTOR抑制，诱导营养饥饿或雷帕霉素治疗。在这里，我们研究了白藜芦醇诱导的自噬是否也需要IP（3）Rs和Ca 2+信号转导，白藜芦醇是一种多酚类植物化学物质，据报道以非经典的方式触发自噬。白藜芦醇以时间依赖性方式增强HeLa细胞的自噬通量。重要的是，白藜芦醇（80 μ M，2小时）诱导的自噬在10 μ M BAPTA-AM，细胞内钙离子螯合剂的存在下被完全废除。为了阐明IP 3R在这一过程中的作用，我们采用了最近建立的缺乏所有三种IP 3R亚型的HEK 3 KO细胞。与HEK 293 wt细胞和HEK 3 KO细胞重新表达IP（3）R1相反，暴露于白藜芦醇的HEK 3 KO细胞中的自噬反应严重受损。这些改变的自噬反应不能归因于mTOR/p70 S6 K通路的改变，因为白藜芦醇诱导的S6磷酸化抑制不能通过螯合胞质Ca 2+或敲除IP（3）Rs而消除。最后，我们研究了白藜芦醇本身是否诱导Ca 2+释放。在透化HeLa细胞中，白藜芦醇既不影响肌浆网和内质网Ca 2 + ATP酶（SERCA）的活性，也不影响IP 3诱导的Ca 2+释放，也不影响ER的基础Ca 2+泄漏。此外，延长（4小时）治疗与100 M白藜芦醇不影响随后的IP 3诱导的Ca 2+释放。然而，在完整的HeLa细胞中，尽管白藜芦醇本身并不引起胞浆Ca 2+信号，但无论IP（3）Rs的存在与否，它都能急剧降低ER Ca 2 +-库含量，从而抑制激动剂诱导的Ca 2+信号。总之，这些结果表明，IP（3）Rs和胞质Ca 2+信号传导对于驱动自噬通量至关重要，不仅响应于mTOR抑制，而且响应于非经典自噬诱导剂如白藜芦醇。本文是由Claus Heizmann、Joachim Krebs和Jacques Haiech编辑的题为：ECS会议的特刊的一部分。(C)2017爱思唯尔B. V.保留所有权利。
Previous work revealed that intracellular Ca2+ signals and the inositol 1,4,5-trisphosphate (IP3) receptors (IP3R) are essential to increase autophagic flux in response to mTOR inhibition, induced by either nutrient starvation or rapamycin treatment. Here, we investigated whether autophagy induced by resveratrol, a polyphenolic phytochemical reported to trigger autophagy in a non-canonical way, also requires IP(3)Rs and Ca2+ signaling. Resveratrol augmented autophagic flux in a time-dependent manner in HeLa cells. Importantly, autophagy induced by resveratrol (80 mu M, 2 h) was completely abolished in the presence of 10 mu M BAPTA-AM, an intracellular Ca2+-chelating agent. To elucidate the IP3R's role in this process, we employed the recently established HEK 3KO cells lacking all three IP3R isoforms. In contrast to the HEK293 wt cells and to HEK 3KO cells re-expressing IP(3)R1, autophagic responses in HEK 3KO cells exposed to resveratrol were severely impaired. These altered autophagic responses could not be attributed to alterations in the mTOR/p70S6K pathway, since resveratrol-induced inhibition of S6 phosphorylation was not abrogated by chelating cytosolic Ca2+ or by knocking out IP(3)Rs. Finally, we investigated whether resveratrol by itself induced Ca2+ release. In permeabilized HeLa cells, resveratrol neither affected the sarco- and endoplasmic reticulum Ca2+ ATPase (SERCA) activity nor the IP3-induced Ca2+ release nor the basal Ca2+ leak from the ER. Also, prolonged (4 h) treatment with 100 M resveratrol did not affect subsequent IP3-induced Ca2+ release. However, in intact HeLa cells, although resveratrol did not elicit cytosolic Ca2+ signals by itself, it acutely decreased the ER Ca2+-store content irrespective of the presence or absence of IP(3)Rs, leading to a dampened agonist-induced Ca2+ signaling. In conclusion, these results reveal that IP(3)Rs and cytosolic Ca2+ signaling are fundamentally important for driving autophagic flux, not only in response to mTOR inhibition but also in response to non-canonical autophagy inducers like resveratrol. This article is part of a Special Issue entitled: ECS Meeting edited by Claus Heizmann, Joachim Krebs and Jacques Haiech. (C) 2017 Elsevier B.V. All rights reserved.