Glutamine Produces Ammonium to Tune Lysosomal pH and Regulate Lysosomal Function.
Glutamine Produces Ammonium to Tune Lysosomal pH and Regulate Lysosomal Function.
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谷氨酰胺是细胞中最丰富的氨基酸之一。在线粒体中，谷氨酰胺酶1和2 （GLS1/2）将谷氨酰胺水解为谷氨酸，谷氨酸是多种代谢物的前体。在这里，我们发现在gls1 /2介导的谷氨酰胺水解过程中产生的铵调节溶酶体pH，进而调节溶酶体降解。在原代人皮肤成纤维细胞BJ细胞和小鼠胚胎成纤维细胞中，总氨基酸缺失1小时可增加溶酶体降解能力，表现为脂化微管相关蛋白1A/1B轻链3B （LC3-II）、几种自噬受体和内吞DQ-BSA的周转率增加。从培养基中去除谷氨酰胺而不去除任何其他氨基酸，可增强溶酶体降解，类似于总氨基酸饥饿。常规培养基中谷氨酰胺的存在使溶酶体pH升高了0.5个pH单位，谷氨酰胺的去除引起溶酶体酸化。GLS1/2敲除、GLS1拮抗剂或铵清除剂在谷氨酰胺存在下降低溶酶体pH。在氨基酸饥饿的早期，谷氨酰胺或NH4Cl的添加阻止了溶酶体降解的增加，并限制了mTORC1功能的扩展。我们的研究结果表明，谷氨酰胺通过产生铵来调节溶酶体的pH值，从而调节溶酶体的降解以满足细胞活动的需要。在氨基酸饥饿的早期阶段，谷氨酰胺依赖机制允许更有效地利用内部储备和内吞噬蛋白来延长mTORC1的激活，这样正常的合成代谢就不会因为氨基酸供应的短暂中断而容易中断。
Glutamine is one of the most abundant amino acids in the cell. In mitochondria, glutaminases 1 and 2 (GLS1/2) hydrolyze glutamine to glutamate, which serves as the precursor of multiple metabolites. Here, we show that ammonium generated during GLS1/2-mediated glutaminolysis regulates lysosomal pH and in turn lysosomal degradation. In primary human skin fibroblasts BJ cells and mouse embryonic fibroblasts, deprivation of total amino acids for 1 h increased lysosomal degradation capacity as shown by the increased turnover of lipidated microtubule-associated proteins 1A/1B light chain 3B (LC3-II), several autophagic receptors, and endocytosed DQ-BSA. Removal of glutamine but not any other amino acids from the culture medium enhanced lysosomal degradation similarly as total amino acid starvation. The presence of glutamine in regular culture media increased lysosomal pH by >0.5 pH unit and the removal of glutamine caused lysosomal acidification. GLS1/2 knockdown, GLS1 antagonist, or ammonium scavengers reduced lysosomal pH in the presence of glutamine. The addition of glutamine or NH4Cl prevented the increase in lysosomal degradation and curtailed the extension of mTORC1 function during the early time period of amino acid starvation. Our findings suggest that glutamine tunes lysosomal pH by producing ammonium, which regulates lysosomal degradation to meet the demands of cellular activities. During the early stage of amino acid starvation, the glutamine-dependent mechanism allows more efficient use of internal reserves and endocytosed proteins to extend mTORC1 activation such that the normal anabolism is not easily interrupted by a brief disruption of the amino acid supply.
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影响因子：
16
作者：
Ganley IG;Wong PM;Gammoh N;Jiang X
通讯作者：
Jiang X
DOI：
10.1016/0304-4165(82)90113-1
发表时间：
1982-01-01
期刊：
BIOCHIMICA ET BIOPHYSICA ACTA
影响因子：
--
作者：
BATES, PJ;COETZEE, GA;VANDERWESTHUYZEN, DR
通讯作者：
VANDERWESTHUYZEN, DR
DOI：
10.1126/science.1236566
发表时间：
2013-07-26
期刊：
Science (New York, N.Y.)
影响因子：
--
作者：
Kang SA;Pacold ME;Cervantes CL;Lim D;Lou HJ;Ottina K;Gray NS;Turk BE;Yaffe MB;Sabatini DM
通讯作者：
Sabatini DM
影响因子：
64.5
作者：
Cang C;Zhou Y;Navarro B;Seo YJ;Aranda K;Shi L;Battaglia-Hsu S;Nissim I;Clapham DE;Ren D
通讯作者：
Ren D
DOI：
10.1126/science.1259472
发表时间：
2015-01-09
期刊：
Science (New York, N.Y.)
影响因子：
--
作者：
Jewell JL;Kim YC;Russell RC;Yu FX;Park HW;Plouffe SW;Tagliabracci VS;Guan KL
通讯作者：
Guan KL