Autophagy induction and CHOP under-expression promotes survival of fibroblasts from rheumatoid arthritis patients under endoplasmic reticulum stress

作者：Shin Yong Joo; Han Song Hee; Kim Do Sung; Lee Geum Hwa; Yoo Wan Hee; Kang Yong Mo; Choi Je Yong; Lee Yong Chul; Park Seoung Ju; Jeong Seul Ki; Kim Hyung Tae; Chae Soo Wan; Jeong Hyun Ja; Kim Hyung Ryong; Chae Han Jung^*

来源：Arthritis Research and Therapy, 2010, 12(1): R19.

DOI：10.1186/ar2921

Introduction: Synovial fibroblasts from rheumatoid arthritis show resistance to apoptotic stimuli, indicating they may be difficult to treat. To clearly understand these mechanisms of resistance, rheumatoid and osteoarthritis synovial fibroblasts (RASF and OASF) were exposed to endoplasmic reticulum (ER) stress such as thapsigargin, Ca(2+)-ATPase inhibitor.
Methods: Fibroblasts were assessed microscopically for cell viability by trypan blue exclusion and for autophagic cells by LC-3II formation. Caspase-3 activity was measured as aminomethyl-coumarin (AMC) liberated from AC-DEVD-AMC. Immunoblotting was performed to compare protein expression in OASF and RASF.
Results: ER stress caused cell death in OASF but not in RASF. Thapsigargin, a Ca(2+)-ATPase inhibitor, did not change the expression of GRP78, an ER chaperone in OASF and RASF, but induced another ER stress protein, CCAAT/enhancer binding protein (C/EBP) homologous protein (CHOP) differently, showing high levels in OASF and low levels in RASF. Thapsigargin increased the autophagy response in RASF, with autophagosome formation, beclin expression, and LC3-II conversion. Transfection with beclin siRNA inhibited autophagy and increased the susceptibility to ER stress-induced cell death. On the other hand, CHOP siRNA increased autophagy and improved cell survival, especially in RASF, indicating that CHOP is involved in regulation of autophagy and cell death, but that low expression of CHOP protects RASF from apoptosis.
Conclusions: Autophagy induction and CHOP under-expression increases cell resistance against ER stress-induced cell death in fibroblasts from rheumatoid arthritis patients.

• 出版日期2010