Ayako Kashimada1, Setsuko Hasegawa1, Takeo Isagai2, Tsuyoshi Uchiyama3, Muneaki Matsuo4, Motoharu Kawai5, Masahide Goto6, Tomohiro Morio1, Yukiko K Hayashi7, Masatoshi Takagi8. 1. Department of Pediatrics, Developmental Biology, Tokyo Medical and Dental University, Tokyo, Japan. 2. Department of Pediatrics, Omuta City Hospital, Fukuoka, Japan. 3. Department of Neurology, Seirei Hamamatsu General Hospital, Shizuoka, Japan. 4. Department of Pediatrics, Saga University, Saga, Japan. 5. Department of Neurology, Graduate School of Medicine, Yamaguchi University, Yamaguchi, Japan. 6. Department of Pediatrics, Jichi Medical University, Tochigi, Japan. 7. Department of Pathophysiology, Tokyo Medical University, Tokyo, Japan. 8. Department of Pediatrics, Developmental Biology, Tokyo Medical and Dental University, Tokyo, Japan. Electronic address: m.takagi.ped@tmd.ac.jp.
Abstract
BACKGROUND AND OBJECTIVE: Marinesco-Sjögren syndrome (MSS) is an autosomal recessive infantile-onset disorder characterized by cataracts, cerebellar ataxia, and progressive myopathy caused by mutation of SIL1. In mice, a defect in SIL1 causes endoplasmic reticulum (ER) chaperone dysfunction, leading to unfolded protein accumulation and increased ER stress. However, ER stress and the unfolded protein response (UPR) have not been investigated in MSS patient-derived cells. METHODS: Lymphoblastoid cell lines (LCLs) were established from four MSS patients. Spontaneous and tunicamycin-induced ER stress and the UPR were investigated in MSS-LCLs. Expression of UPR markers was analyzed by western blotting. ER stress-induced apoptosis was analyzed by flow cytometry. The cytoprotective effects of ER stress modulators were also examined. RESULTS: MSS-LCLs exhibited increased spontaneous ER stress and were highly susceptible to ER stress-induced apoptosis. The inositol-requiring protein 1α (IRE1α)-X-box-binding protein 1 (XBP1) pathway was mainly upregulated in MSS-LCLs. Tauroursodeoxycholic acid (TUDCA) attenuated ER stress-induced apoptosis. CONCLUSION: MSS patient-derived cells exhibit increased ER stress, an activated UPR, and susceptibility to ER stress-induced death. TUDCA reduces ER stress-induced death of MSS patient-derived cells. The potential of TUDCA as a therapeutic agent for MSS could be explored further in preclinical studies.
BACKGROUND AND OBJECTIVE: Marinesco-Sjögren syndrome (MSS) is an autosomal recessive infantile-onset disorder characterized by cataracts, cerebellar ataxia, and progressive myopathy caused by mutation of SIL1. In mice, a defect in SIL1 causes endoplasmic reticulum (ER) chaperone dysfunction, leading to unfolded protein accumulation and increased ER stress. However, ER stress and the unfolded protein response (UPR) have not been investigated in MSS patient-derived cells. METHODS: Lymphoblastoid cell lines (LCLs) were established from four MSS patients. Spontaneous and tunicamycin-induced ER stress and the UPR were investigated in MSS-LCLs. Expression of UPR markers was analyzed by western blotting. ER stress-induced apoptosis was analyzed by flow cytometry. The cytoprotective effects of ER stress modulators were also examined. RESULTS: MSS-LCLs exhibited increased spontaneous ER stress and were highly susceptible to ER stress-induced apoptosis. The inositol-requiring protein 1α (IRE1α)-X-box-binding protein 1 (XBP1) pathway was mainly upregulated in MSS-LCLs. Tauroursodeoxycholic acid (TUDCA) attenuated ER stress-induced apoptosis. CONCLUSION: MSS patient-derived cells exhibit increased ER stress, an activated UPR, and susceptibility to ER stress-induced death. TUDCA reduces ER stress-induced death of MSS patient-derived cells. The potential of TUDCA as a therapeutic agent for MSS could be explored further in preclinical studies.