Jiang Haibo, Xiong Siqi, Xia Xiaobo
Department of Ophthalmology, Xiangya Hospital, Central South University, 87 Xiangya Road, Changsha, Hunan 410078 P.R. China.
Cell Biosci. 2014 Dec 4;4(1):75. doi: 10.1186/2045-3701-4-75. eCollection 2014.
Rhodopsin mutations are associated with the autosomal dominant form of retinitis pigmentosa. T17M mutation in rhodopsin predisposes cells to endoplasmic reticulum (ER) stress and induces cell death. This study aimed to examine whether chemical chaperone 4-phenylbutyrate prevents ER stress induced by rhodopsin T17M.
ARPE-19 cells were transfected with myc-tagged wild-type (WT) and T17M rhodopsin constructs. Turnover of WT and T17M rhodopsin was measured by cycloheximide chase analysis. The activity of ubiquitin-proteasome system was evaluated by GFPU reporter. We found that T17M rhodopsin was misfolded, ubiqutinated and eliminated by ER-associated degradation pathway (ERAD) in ARPE-19 cells. Accumulated T17M rhodopsin induced unfolded protein response, but had no effect on the activity of ubiquitin proteasome system. Moreover, chemical chaperone 4-phenylbutyrate facilitated the turnover of T17M rhodopsin and prevented apoptosis and ER stress induced by T17M rhodopsin.
Chemical chaperone could attenuate UPR signaling and ER stress induced by T17M rhodopsin and has potential therapeutic significance for retinitis pigmentosa.
视紫红质突变与常染色体显性遗传性视网膜色素变性相关。视紫红质中的T17M突变使细胞易发生内质网（ER）应激并诱导细胞死亡。本研究旨在检测化学伴侣4-苯基丁酸是否能预防视紫红质T17M诱导的内质网应激。
用带有myc标签的野生型（WT）和T17M视紫红质构建体转染ARPE-19细胞。通过放线菌酮追踪分析检测WT和T17M视紫红质的转换。用GFPU报告基因评估泛素-蛋白酶体系统的活性。我们发现T17M视紫红质在ARPE-19细胞中错误折叠、泛素化并通过内质网相关降解途径（ERAD）被清除。积累的T17M视紫红质诱导未折叠蛋白反应，但对泛素蛋白酶体系统的活性没有影响。此外，化学伴侣4-苯基丁酸促进了T17M视紫红质的转换，并预防了T17M视紫红质诱导的细胞凋亡和内质网应激。
化学伴侣可减轻T17M视紫红质诱导的未折叠蛋白反应信号和内质网应激，对视网膜色素变性具有潜在的治疗意义。
