Altered mTOR Signaling in Senescent Retinal Pigment Epithelium

被引:49
作者
Chen, Yan [1 ]
Wang, Jian [1 ]
Cai, Jiyang [1 ]
Sternberg, Paul [1 ]
机构
[1] Vanderbilt Univ, Med Ctr, Vanderbilt Eye Inst, Nashville, TN 37232 USA
基金
美国国家卫生研究院;
关键词
BETA-GALACTOSIDASE ACTIVITY; LIFE-SPAN EXTENSION; MAMMALIAN TARGET; REPLICATIVE SENESCENCE; AUTOPHAGY GENES; S6; KINASE; RAPAMYCIN; PHOSPHORYLATION; PATHWAY; COMPLEX;
D O I
10.1167/iovs.10-5280
中图分类号
R77 [眼科学];
学科分类号
100212 ;
摘要
PURPOSE. Mammalian target of rapamycin (mTOR)-mediated pathways play central roles in regulating aging. The purpose of the present study was to characterize the mTOR cascade in human retinal pigment epithelial (RPE) cells and to investigate its potential roles in controlling RPE senescence. METHODS. Expression of major components of the mTOR signaling networks was evaluated by Western blot analyses. Formations of the two signaling complexes of mTOR, mTORC1, and mTORC2 were determined by coimmunoprecipitation. The activation of mTORC1 was monitored by measuring the phosphorylation status of the downstream substrate protein S6. Senescence of the cultured human RPE cells was assessed by measuring both the senescence associated-beta-galactosidase (SA-beta-Gal) activity and the expression level of p16, a cyclin-dependent kinase inhibitor. RESULTS. Human RPE cells contained functional mTORC1 and mTORC2 signaling complexes. The assembly and activity of mTORC1 were regulated by upstream nutrient and growth factor signals. The sensitivity of mTORC1 to extracellular nutrient stimuli increased in RPE cells that had developed in vitro senescence. Suppression of the mTORC1 by rapamycin prevented the appearance of senescence markers in the RPE. CONCLUSIONS. The mTOR pathway presented age-associated changes in human RPE cells, and downregulation of mTORC1 could delay the aging process of the RPE. (Invest Ophthalmol Vis Sci. 2010;51:5314-5319) DOI:10.1167/iovs.10-5280
引用
收藏
页码:5314 / 5319
页数:6
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