The Steroid Hormone 20-Hydroxyecdysone Regulates the Conjugation of Autophagy-Related Proteins 12 and 5 in a Concentration and Time-Dependent Manner to Promote Insect Midgut Programmed Cell Death.
The Steroid Hormone 20-Hydroxyecdysone Regulates the Conjugation of Autophagy-Related Proteins 12 and 5 in a Concentration and Time-Dependent Manner to Promote Insect Midgut Programmed Cell Death.
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类固醇激素 20-羟基蜕皮酮以浓度和时间依赖性方式调节自噬相关蛋白 12 和 5 的结合，促进昆虫中肠程序性细胞死亡
DOI：
10.3389/fendo.2018.00028
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发表时间：
2018
影响因子：
5.2
通讯作者：
Zhao XF
中科院分区：
文献类型：
--
作者：
Li YB;Yang T;Wang JX;Zhao XF
自噬需要自噬相关蛋白12（ATG 12）通过共价连接与自噬相关蛋白5（ATG 5）缀合。然而，调节ATG 12-ATG 5缀合的信号尚不清楚。鳞翅目昆虫幼虫中肠在甾体激素20-羟基蜕皮激素（20 E）的调控下，在幼虫向蛹的转化过程中依次进行自噬和凋亡，为研究甾体激素对ATG 12-ATG 5结合的调控提供了一个模型。在本研究中，使用鳞翅目昆虫Helicoverpa armigera作为模型，我们报告了20 E以浓度和时间依赖性的方式调节ATG 12-ATG 5的结合。ATG 12-ATG 5共轭物丰富的表皮，中肠，和脂肪体从幼虫到蛹的变态过程中，然而，ATG 12-ATG 5共轭物的水平在化蛹时下降。在低浓度（2-5 µM）下，在短时间内（1-48 h），20 E促进了ATG 12-ATG 5的结合;然而，在10 µM和72 h时，20 E抑制了ATG 12-ATG 5的结合。ATG 12定位于变态期的幼虫中肠。在幼虫中敲低ATG 12导致死亡，延迟化蛹，推迟中肠程序性细胞死亡（PCD）的过程，并抑制ATG 8（也称为LC 3-I）转化为LC 3-II和caspase-3的切割;因此，在幼虫中敲低ATG 12阻断自噬和凋亡。在H.棉铃虫表皮细胞系细胞也抑制20 E诱导的自噬体形成和caspase-3激活。结果表明，20 E以浓度和时间依赖的方式在ATG 12-ATG 5偶联过程中起关键作用，ATG 12在昆虫中肠PCD过程中是自噬和凋亡所必需的。
Autophagy requires the conjugation of autophagy-related protein 12 (ATG12) to autophagy-related protein 5 (ATG5) through covalent attachment. However, the signals regulating ATG12–ATG5 conjugation are unclear. The larval midgut of lepidopteran insects performs autophagy and apoptosis sequentially during the transition of larvae to pupae under regulation by the steroid hormone 20-hydroxyecdysone (20E), thus representing a model to study steroid hormone regulation of ATG12–ATG5 conjugation. In the present study, using the lepidopteran insect Helicoverpa armigera as a model, we report that 20E regulates the conjugation of ATG12–ATG5 in a concentration and time-dependent manner. The ATG12–ATG5 conjugate was abundant in the epidermis, midgut, and fat body during metamorphosis from the larvae to the pupae; however, the ATG12–ATG5 conjugate level decreased at the time of pupation. At low concentrations (2–5 µM) over a short time course (1–48 h), 20E promoted the conjugation of ATG12–ATG5; however, at 10 µM and 72 h, 20E repressed the conjugation of ATG12–ATG5. ATG12 was localized in the larval midgut during metamorphosis. Knockdown of ATG12 in larvae caused death with delayed pupation, postponed the process of midgut programmed cell death (PCD), and repressed ATG8 (also called LC3-I) transformation to LC3-II and the cleavage of caspase-3; therefore, knockdown of ATG12 in larvae blocked both autophagy and apoptosis. Knockdown of ATG12 in H. armigera epidermis cell line cells also repressed 20E-induced autophagosome formation and caspase-3 activation. The results suggested that 20E plays key role in the regulation of ATG12–ATG5 conjugation in a concentration and time-dependent manner for autophagy or apoptosis, and that ATG12 is necessary by both autophagy and apoptosis during insect midgut PCD.