DRAM-3 modulates autophagy and promotes cell survival in the absence of glucose.
DRAM-3 modulates autophagy and promotes cell survival in the absence of glucose.
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DOI：
10.1038/cdd.2015.26
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发表时间：
2015-10
影响因子：
12.4
通讯作者：
Ryan KM
中科院分区：
文献类型：
--
作者：
Mrschtik M;O'Prey J;Lao LY;Long JS;Beaumatin F;Strachan D;O'Prey M;Skommer J;Ryan KM
巨噬是一种将细胞质成分传递给溶酶体降解的膜运输过程。该过程在基本条件下作为一种机制来周转受损或错误折叠的蛋白质和细胞器。因此，它在保持细胞完整性和活力方面起着重要作用。除了这一基本功能外，巨噬也可以被调节以应对各种形式的细胞应激，并且巨噬的速率和数量可以被调整以促进特定情况下的适当细胞反应。巨噬机制受一组进化保守的自噬相关蛋白（ATG）和其他几种自噬调节因子的调控，这些自噬调节因子要么具有组织限制性表达，要么在特定环境下起作用。我们在此报告了一种新的自噬调节剂的特性，我们将其命名为DRAM-3，因为它与损伤调节的自噬调节剂（DRAM-1）具有显著的同源性。DRAM-3在正常组织和肿瘤细胞中广泛表达，但与DRAM-1不同的是，DRAM-3不受p53或dna损伤剂的诱导。免疫荧光研究显示，dam -3定位于溶酶体/自溶酶体、核内体和质膜，但不定位于内质网、吞噬细胞、自噬体或高尔基体，表明与dam -1定位和与巨噬相关的细胞器有显著重叠。在这方面，我们进一步表明，在基础条件下，表达DRAM-3导致自噬体的积累，并增强自噬通量。反过来，CRISPR/ cas9介导的对DRAM-3的破坏会损害自噬通量，证实了DRAM-3是巨噬的调节剂。由于巨噬在饥饿条件下具有细胞保护作用，我们也测试了DRAM-3是否能促进营养剥夺下的生存。这表明，在缺乏葡萄糖的情况下，DRAM-3可以抑制细胞死亡，促进细胞的长期克隆性存活。然而，有趣的是，这种效应与巨噬无关。综上所述，这些发现构成了dam -3在饥饿条件下作为巨噬和细胞存活调节剂的主要特征。
Macroautophagy is a membrane-trafficking process that delivers cytoplasmic constituents to lysosomes for degradation. The process operates under basal conditions as a mechanism to turnover damaged or misfolded proteins and organelles. As a result, it has a major role in preserving cellular integrity and viability. In addition to this basal function, macroautophagy can also be modulated in response to various forms of cellular stress, and the rate and cargoes of macroautophagy can be tailored to facilitate appropriate cellular responses in particular situations. The macroautophagy machinery is regulated by a group of evolutionarily conserved autophagy-related (ATG) proteins and by several other autophagy regulators, which either have tissue-restricted expression or operate in specific contexts. We report here the characterization of a novel autophagy regulator that we have termed DRAM-3 due to its significant homology to damage-regulated autophagy modulator (DRAM-1). DRAM-3 is expressed in a broad spectrum of normal tissues and tumor cells, but different from DRAM-1, DRAM-3 is not induced by p53 or DNA-damaging agents. Immunofluorescence studies revealed that DRAM-3 localizes to lysosomes/autolysosomes, endosomes and the plasma membrane, but not the endoplasmic reticulum, phagophores, autophagosomes or Golgi, indicating significant overlap with DRAM-1 localization and with organelles associated with macroautophagy. In this regard, we further proceed to show that DRAM-3 expression causes accumulation of autophagosomes under basal conditions and enhances autophagic flux. Reciprocally, CRISPR/Cas9-mediated disruption of DRAM-3 impairs autophagic flux confirming that DRAM-3 is a modulator of macroautophagy. As macroautophagy can be cytoprotective under starvation conditions, we also tested whether DRAM-3 could promote survival on nutrient deprivation. This revealed that DRAM-3 can repress cell death and promote long-term clonogenic survival of cells grown in the absence of glucose. Interestingly, however, this effect is macroautophagy-independent. In summary, these findings constitute the primary characterization of DRAM-3 as a modulator of both macroautophagy and cell survival under starvation conditions.