title: Ginkgo biloba extract individually inhibits JNK activation and induces c-Jun degradation in human chondrocytes: potential therapeutics for osteoarthritis.
abstract: Osteoarthritis (OA) is a common joint disorder with varying degrees of inflammation. The ideal anti-OA drug should have immunomodulatory effects while at the same time having limited or no toxicity. We examined the anti-inflammatory effects of Ginkgo biloba extract (EGb) in interleukin-1 (IL-1)-stimulated human chondrocytes. Chondrocytes were prepared from cartilage specimens taken from patients with osteoarthritis who had received total hip or total knee replacement. The concentrations of chemokines and the degree of cell migration were determined by ELISA and chemotaxis assays, respectively. The activation of inducible nitric oxide synthase (iNOS), mitogen-activated protein kinases (MAPKs), activator protein-1 (AP-1), and nuclear factor-kappaB (NF-κB) was determined by immunoblotting, immunohistochemistry, and electrophoretic mobility shift assay. We found that EGb inhibited IL-1-induced production of chemokines, which in turn resulted in attenuation of THP-1 cell migration toward EGb-treated cell culture medium. EGb also suppressed IL-1-stimulated iNOS expression and release of nitric oxide (NO). The EGb-mediated suppression of the iNOS-NO pathway correlated with the attenuation of activator protein-1 (AP-1) but not nuclear factor-kappaB (NF-κB) DNA-binding activity. Of the mitogen-activated protein kinases (MAPKs), EGb inhibited only c-Jun N-terminal kinase (JNK). Unexpectedly, EGb selectively caused degradation of c-Jun protein. Further investigation revealed that EGb-mediated c-Jun degradation was preceded by ubiquitination of c-Jun and could be prevented by the proteosome inhibitor MG-132. The results imply that EGb protects against chondrocyte degeneration by inhibiting JNK activation and inducing ubiquitination-dependent c-Jun degradation. Although additional research is needed, our results suggest that EGb is a potential therapeutic agent for the treatment of OA.
authors.affiliation: Institute of Cellular and System Medicine, National Health Research Institute, Zhunan, Taiwan, R.O.C. ; Graduate Institute of Basic Medical Science, PhD Program of Aging, China Medical University, Taichung, Taiwan, R.O.C.
authors.forename: Ling-Jun
authors.initials: LJ
authors.lastname: Ho
authors.affiliation: Institute of Cellular and System Medicine, National Health Research Institute, Zhunan, Taiwan, R.O.C.
authors.forename: Li-Feng
authors.initials: LF
authors.lastname: Hung
authors.affiliation: Rheumatology/Immunology and Allergy, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, R.O.C.
authors.forename: Feng-Cheng
authors.initials: FC
authors.lastname: Liu
authors.affiliation: Rheumatology/Immunology and Allergy, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, R.O.C.
authors.forename: Tsung-Yun
authors.initials: TY
authors.lastname: Hou
authors.affiliation: Department of Orthopaedics, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, R.O.C.
authors.forename: Leou-Chyr
authors.initials: LC
authors.lastname: Lin
authors.affiliation: Institute of Cellular and System Medicine, National Health Research Institute, Zhunan, Taiwan, R.O.C.
authors.forename: Chuan-Yueh
authors.initials: CY
authors.lastname: Huang
authors.affiliation: Graduate Institute of Medical Science, National Defense Medical Center, Taipei, Taiwan, R.O.C. ; Division of Allergy, Immunology and Rheumatology, Department of Internal Medicine, Chang Gung Memorial Hospital, Chang Gung University, Tao-Yuan, Taiwan, R.O.C.
authors.forename: Jenn-Haung
authors.initials: JH
authors.lastname: Lai
mesh_terms: D019644:Arthroplasty, Replacement, Hip; D019645:Arthroplasty, Replacement, Knee; D002465:Cell Movement; D019902:Chondrocytes / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D005786:Gene Expression Regulation; D020441:Ginkgo biloba / Q000737:chemistry*; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D007976:Leupeptins / Q000494:pharmacology; D048670:MAP Kinase Kinase 4 / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D052247:Nitric Oxide Synthase Type II / Q000235:genetics / Q000378:metabolism; D010003:Osteoarthritis / Q000188:drug therapy / Q000235:genetics / Q000473:pathology / Q000601:surgery; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology*; D061251:Primary Cell Culture; D059748:Proteolysis / Q000187:drug effects; D015398:Signal Transduction; D018808:Transcription Factor AP-1 / Q000235:genetics / Q000378:metabolism; D054875:Ubiquitination
chemical_list: D007375:Interleukin-1; D007976:Leupeptins; D016328:NF-kappa B; D010936:Plant Extracts; D018808:Transcription Factor AP-1; D009569:Nitric Oxide; C496319:NOS2 protein, human; D052247:Nitric Oxide Synthase Type II; D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde