title: Glucosamine protects nucleus pulposus cells and induces autophagy via the mTOR-dependent pathway.
abstract: Although glucosamine has been suggested to be effective in the treatment of osteoarthritis, its effect on disc degeneration remains unclear. We sought to explore whether glucosamine can activate autophagy in rat nucleus pulposus (NP) cells and protect cells treated with IL-1β or hydrogen peroxide (H2 O2 ). Autophagy in cells was examined by detecting for LC3, Beclin-1, m-TOR, and p70S6K, as well as by analyzing autophagosomes. To inhibit autophagy, 3-methyladenine (3-MA) was used. In the cells treated with IL-1β, the levels of Adamts-4, Mmp-13, aggrecan, and Col2a1 were analyzed by real-time PCR and immunofluorescence. Apoptosis was analyzed by TUNEL. Cell senescence under H2 O2 was revealed by SA-β-Gal staining. Glucosamine could activate autophagy in a dose-dependent manner within 24 h and inhibit the phosphorylation of m-TOR and p70S6K. Autophagy in IL-1β or H2 O2 -treated cells was increased by glucosamine. Glucosamine attenuated the decrease of aggrecan and prevented the apoptosis of the NP cells induced by IL-1β, whereas 3-MA partly reversed these effects. The percentage of SA-β-Gal-positive cells induced by H2 O2 treatment was decreased by glucosamine, accompanied by the decline of p70S6K phosphorylation. Glucosamine protects NP cells and up-regulates autophagy by inhibiting the m-TOR pathway, which might point a potential therapeutic agent for disc degeneration.
authors.affiliation: Department of Orthopedic Surgery, Zhongshan Hospital, Fudan University, 180 Fenglin Road, Shanghai, 200032, China.
authors.forename: LiBo
authors.initials: L
authors.lastname: Jiang
authors.forename: YongLong
authors.initials: Y
authors.lastname: Jin
authors.forename: HuiRen
authors.initials: H
authors.lastname: Wang
authors.forename: YunQi
authors.initials: Y
authors.lastname: Jiang
authors.forename: Jian
authors.initials: J
authors.lastname: Dong
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives* / Q000737:chemistry; D000818:Animals; D017209:Apoptosis; D001343:Autophagy; D002103:Cadaverine / Q000031:analogs & derivatives / Q000737:chemistry; D002470:Cell Survival; D016922:Cellular Senescence; D004305:Dose-Response Relationship, Drug; D005944:Glucosamine / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000737:chemistry; D053583:Interleukin-1beta / Q000737:chemistry; D007403:Intervertebral Disc / Q000187:drug effects*; D055959:Intervertebral Disc Degeneration / Q000517:prevention & control*; D008856:Microscopy, Fluorescence; D010766:Phosphorylation; D051381:Rats; D017207:Rats, Sprague-Dawley; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism*; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*
chemical_list: D053583:Interleukin-1beta; C025946:3-methyladenine; D006861:Hydrogen Peroxide; C546845:mTOR protein, rat; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D058570:TOR Serine-Threonine Kinases; C008542:monodansylcadaverine; D000225:Adenine; D002103:Cadaverine; D005944:Glucosamine
keywords: apoptosis; autophagy; glucosamine; mTOR; nucleus pulposus; senescence