Chen Yixiong, Cen Kai, Lu Yuzhen, Zhang Siwei, Shang Yanfang, Wang Chengshu
CAS Key Laboratory of Insect Developmental and Evolutionary Biology, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China.
CAS Key Laboratory of Insect Developmental and Evolutionary Biology, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China.
Fungal Biol. 2018 Jun;122(6):410-419. doi: 10.1016/j.funbio.2017.07.001. Epub 2017 Jul 13.
Nitrogen starvation can induce cellular triacylglycerol (TAG) accumulation in different organisms with an unclear mechanism. In this study, we performed nutrient starvation and lipid droplet (LD) proteomics analyses of the filamentous fungus Metarhizium robertsii. Our results indicated that nitrogen starvation activated cell autophagic activity but inhibited the internalization of LDs into vacuoles for degradation. LD proteomic analyses identified an array of differentially accumulated proteins including autophagy-related (ATG) proteins, heat shock proteins, TAG metabolic and phospholipid biosynthetic enzymes when the fungus was grown in different nutrient conditions. In contrast to the highly activated MrATG8, the ATG proteins involved in vacuolar LD internalization were down-regulated after nitrogen starvation. Cellular TAG contents were increased in different ATG-gene null mutants of M. robertsii. In addition, TAG increase could be due to the up-regulation of TAG biogenesis along with the down-regulation of TAG catabolic enzymes in fungal cells after nitrogen deprivation. The data of this study benefit our understanding of the mechanism of nitrogen starvation induced TAG increase in different cells.
氮饥饿可诱导不同生物体中细胞三酰甘油（TAG）积累，但其机制尚不清楚。在本研究中，我们对丝状真菌罗伯茨绿僵菌进行了营养饥饿和脂滴（LD）蛋白质组学分析。我们的结果表明，氮饥饿激活了细胞自噬活性，但抑制了脂滴向液泡的内化以进行降解。脂滴蛋白质组学分析确定了一系列差异积累的蛋白质，包括自噬相关（ATG）蛋白、热休克蛋白、TAG代谢和磷脂生物合成酶，这些蛋白质是在真菌处于不同营养条件下生长时发现的。与高度活化的MrATG8相反，参与液泡脂滴内化的ATG蛋白在氮饥饿后下调。罗伯茨绿僵菌不同ATG基因缺失突变体中的细胞TAG含量增加。此外，TAG增加可能是由于氮剥夺后真菌细胞中TAG生物合成上调以及TAG分解代谢酶下调所致。本研究的数据有助于我们理解氮饥饿诱导不同细胞中TAG增加的机制。
