title: Tougu Xiaotong capsule promotes chondrocyte autophagy by regulating the Atg12/LC3 conjugation systems.
abstract: We have previously reported that Tougu Xiaotong capsule (TXC) inhibits tidemark replication and cartilage degradation by regulating chondrocyte autophagy in vivo. Autophagy, a cell protective mechanism for maintaining cellular homeostasis, has been shown to be a constitutively active and protective process for chondrocyte survival. However, it remains unclear whether TXC promotes chondrocyte autophagy by regulating the autophagy-related (Atg)12/microtubule-associated protein 1 light chain 3 (LC3) conjugation systems. Thus, in the present study, we investigated the effects of TXC on primary chondrocytes treated with cobalt chloride (CoCl2). We found that CoCl2 induced a decrease in chondrocyte viability and the autophagosome formation of chondrocytes, indicating that CoCl2 induced autophagic death in a dose- and time-dependent manner. To determine the effects of TXC on CoCl2-exposed chondrocytes, we assessed cell viability by MTT assay. Our results revealed that TXC enhanced the viability of CoCl2-exposed chondrocytes. To gain insight into the mechanisms responsible for the enhancing effects of TXC on CoCl2-exposed chondrocytes, the expression of Atg genes was assessed in chondrocytes exposed to CoCl2 and treated with or without TXC. The results revealed that the expression of beclin 1, Atg3, Atg5, Atg7, Atg10, Atg12 and LC3 II/LC3 I in the chondrocytes treated with TXC increased, compared to that in the untreated chondrocytes. In addition, ultrastructural analysis indicated that treated chondrocytes contained more autophagosomes than the untreated cells, suggesting that TXC increased the formation of autophagosomes in the chondrocytes to clear the CoCl2-induced autophagic death. Therefore, these data suggest that TXC is a potential therapeutic agent for the reduction of cartilage degradation that occurs in osteoarthritis.
authors.affiliation: Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian 350122, P.R. China.
authors.forename: Xihai
authors.initials: X
authors.lastname: Li
authors.affiliation: Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian 350122, P.R. China.
authors.forename: Fayuan
authors.initials: F
authors.lastname: Liu
authors.affiliation: Research Base of Traditional Chinese Medicine Syndrome, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian 350122, P.R. China.
authors.forename: Wenna
authors.initials: W
authors.lastname: Liang
authors.affiliation: Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian 350122, P.R. China.
authors.forename: Hongzhi
authors.initials: H
authors.lastname: Ye
authors.affiliation: Fujian Key Laboratory of Integrative Medicine on Geriatrics, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian 350122, P.R. China.
authors.forename: Huiting
authors.initials: H
authors.lastname: Li
authors.affiliation: Fujian Key Laboratory of Integrative Medicine on Geriatrics, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian 350122, P.R. China.
authors.forename: Fangrong
authors.initials: F
authors.lastname: Yu
authors.affiliation: Fujian Key Laboratory of Integrative Medicine on Geriatrics, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian 350122, P.R. China.
authors.forename: Jiashou
authors.initials: J
authors.lastname: Chen
authors.affiliation: Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian 350122, P.R. China.
authors.forename: Wenlie
authors.initials: W
authors.lastname: Chen
authors.affiliation: Fujian Key Laboratory of Integrative Medicine on Geriatrics, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian 350122, P.R. China.
authors.forename: Ruhui
authors.initials: R
authors.lastname: Lin
authors.affiliation: Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian 350122, P.R. China.
authors.forename: Chunsong
authors.initials: C
authors.lastname: Zheng
authors.affiliation: Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian 350122, P.R. China.
authors.forename: Guangwen
authors.initials: G
authors.lastname: Wu
authors.affiliation: Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian 350122, P.R. China.
authors.forename: Huifeng
authors.initials: H
authors.lastname: Xu
authors.affiliation: Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian 350122, P.R. China.
authors.forename: Xianxiang
authors.initials: X
authors.lastname: Liu
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D001343:Autophagy / Q000187:drug effects*; D000071192:Autophagy-Related Protein 12; D002356:Cartilage / Q000187:drug effects / Q000378:metabolism; D002460:Cell Line; D019902:Chondrocytes / Q000187:drug effects / Q000378:metabolism; D003035:Cobalt / Q000633:toxicity; D004365:Drugs, Chinese Herbal / Q000008:administration & dosage*; D006801:Humans; D008869:Microtubule-Associated Proteins / Q000096:biosynthesis* / Q000378:metabolism; D010003:Osteoarthritis / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D010588:Phagosomes / Q000187:drug effects; D025841:Small Ubiquitin-Related Modifier Proteins / Q000096:biosynthesis* / Q000235:genetics
chemical_list: C466624:ATG12 protein, human; D000071192:Autophagy-Related Protein 12; D004365:Drugs, Chinese Herbal; C477012:MAP1LC3A protein, human; D008869:Microtubule-Associated Proteins; D025841:Small Ubiquitin-Related Modifier Proteins; C528129:tougu xiaotong; D003035:Cobalt; C018021:cobaltous chloride