Li Feng-Jun, Xu Zhi-Shen, Soo Andy D S, Lun Zhao-Rong, He Cynthia Y
a Department of Biological Sciences , National University of Singapore , Singapore.
b State Key Laboratory of Biocontrol, School of Life Sciences, and Key Laboratory of Tropical Diseases and Control of the Ministry of Education , Zhongshan Medical School, Sun Yat-Sen University , Guangzhou , China.
Autophagy. 2017 Apr 3;13(4):715-729. doi: 10.1080/15548627.2017.1280218. Epub 2017 Jan 25.
Autophagy is a catabolic cellular process required to maintain protein synthesis, energy production and other essential activities in starved cells. While the exact nutrient sensor(s) is yet to be identified, deprivation of amino acids, glucose, growth factor and other nutrients can serve as metabolic stimuli to initiate autophagy in higher eukaryotes. In the early-branching unicellular parasite Trypanosoma brucei, which can proliferate as procyclic form (PCF) in the tsetse fly or as bloodstream form (BSF) in animal hosts, autophagy is robustly triggered by amino acid deficiency but not by glucose depletion. Taking advantage of the clearly defined adenosine triphosphate (ATP) production pathways in T. brucei, we have shown that autophagic activity depends on the levels of cellular ATP production, using either glucose or proline as a carbon source. While autophagosome formation positively correlates with cellular ATP levels; perturbation of ATP production by removing carbon sources or genetic silencing of enzymes involved in ATP generation pathways, also inhibited autophagy. This obligate energy dependence and the lack of glucose starvation-induced autophagy in T. brucei may reflect an adaptation to its specialized, parasitic life style.
自噬是一种分解代谢的细胞过程,对于维持饥饿细胞中的蛋白质合成、能量产生及其他基本活动是必需的。虽然确切的营养传感器尚未确定,但氨基酸、葡萄糖、生长因子及其他营养物质的缺乏可作为代谢刺激,在高等真核生物中启动自噬。在早期分支的单细胞寄生虫布氏锥虫中,它可以在采采蝇中以原循环形式(PCF)增殖,或在动物宿主中以血流形式(BSF)增殖,氨基酸缺乏可强烈触发自噬,而葡萄糖耗尽则不会。利用布氏锥虫中明确界定的三磷酸腺苷(ATP)产生途径,我们已经表明,自噬活性取决于细胞ATP产生水平,使用葡萄糖或脯氨酸作为碳源。虽然自噬体形成与细胞ATP水平呈正相关;通过去除碳源或对参与ATP生成途径的酶进行基因沉默来干扰ATP产生,也会抑制自噬。布氏锥虫这种对能量的绝对依赖性以及缺乏葡萄糖饥饿诱导的自噬,可能反映了其对特殊寄生生活方式的一种适应。