title: Decreased Zn(2+) Influx Underlies the Protective Role of Hypoxia in Rat Nucleus Pulposus Cells.
abstract: Zn(2+) is an essential component of metalloproteinases, and is required for their activity in cartilage; however, the effect of Zn(2+) on nucleus pulposus (NP) cells has not been widely investigated. The aim of this paper was to investigate the effect of intracellular Zn(2+) concentration ([Zn(2+)]i) in hypoxia-induced regulation of metalloproteinases (MMPs) and extracellular matrix (ECM) production in NP cells. NP cells from Sprague-Dawley (SD) rats were cultured as monolayers or in alginate beads. [Zn(2+)]i was assayed by FluoZin-3 AM staining. Alcian Blue staining, immunochemistry, 1,9-dimethylmethylene blue (DMMB) assay, and real-time PCR were used to assay collagen II, proteoglycan, and COL2A1, MMP-13, and ADAMTS-5 mRNA expression. ZIP8, a main Zn(2+) transporter in chondrocytes, was assayed by immunochemistry and in Western blotting. Interleukin (IL)-1β- and ZnCl2-induced increases of [Zn(2+)]i were significantly inhibited by hypoxia. Hypoxia did not reverse a decline of ECM expression caused by IL-1β and ZnCl2 in monolayer cultures, but did significantly attenuate the decreases of proteoglycan, glycosaminoglycan (GAG), and COL2A1 mRNA expression following IL-1β and ZnCl2 treatment in alginate bead cultures. However, ZnCl2 inhibited the protective effect of hypoxia. Both an intracellular Zn(2+) chelator and hypoxia prevented the increase in MMP-13 mRNA expression. IL-1β and ZnCl2 treatment increased ZIP8 expression in NP cells, and hypoxia inhibited ZIP8 expression. In conclusion, decrease of Zn(2+) influx mediates the protective role of hypoxia on ECM and MMP-13 expression. Consequently, changes in intracellular Zn(2+) concentration maybe involved in intervertebral disc degeneration.
authors.affiliation: Department of Orthopedic Surgery, Zhongshan Hospital, Fudan University, 180 Fenglin Road, Shanghai, 200032, China.|Department of Orthopedic Surgery, Minhang Hospital, Fudan University, Shanghai, China.
authors.forename: Xiao-Fan
authors.initials: XF
authors.lastname: Yin
authors.affiliation: Department of Orthopedic Surgery, Zhongshan Hospital, Fudan University, 180 Fenglin Road, Shanghai, 200032, China.
authors.forename: Li-Bo
authors.initials: LB
authors.lastname: Jiang
authors.affiliation: Department of Orthopedic Surgery, Zhongshan Hospital, Fudan University, 180 Fenglin Road, Shanghai, 200032, China.
authors.forename: Yi-Qun
authors.initials: YQ
authors.lastname: Ma
authors.affiliation: Department of Orthopedic Surgery, Minhang Hospital, Fudan University, Shanghai, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Xu
authors.affiliation: Department of Orthopedic Surgery, Minhang Hospital, Fudan University, Shanghai, China.
authors.forename: Hui-Jie
authors.initials: HJ
authors.lastname: Gu
authors.affiliation: Department of Orthopedic Surgery, Minhang Hospital, Fudan University, Shanghai, China.
authors.forename: Xu-Hua
authors.initials: XH
authors.lastname: Wu
authors.affiliation: Department of Orthopedic Surgery, Zhongshan Hospital, Fudan University, 180 Fenglin Road, Shanghai, 200032, China. li.xilei@zs-hospital.sh.cn.
authors.forename: Xi-Lei
authors.initials: XL
authors.lastname: Li
authors.affiliation: Department of Orthopedic Surgery, Zhongshan Hospital, Fudan University, 180 Fenglin Road, Shanghai, 200032, China. dong.jian@zs-hospital.sh.cn.
authors.forename: Jian
authors.initials: J
authors.lastname: Dong
mesh_terms: D000818:Animals; D015687:Cell Hypoxia / Q000187:drug effects*; D002478:Cells, Cultured; D002712:Chlorides / Q000494:pharmacology; D019902:Chondrocytes / Q000187:drug effects* / Q000378:metabolism*; D005109:Extracellular Matrix / Q000187:drug effects; D053583:Interleukin-1beta / Q000494:pharmacology; D007403:Intervertebral Disc / Q000166:cytology*; D008297:Male; D045726:Metalloproteases / Q000378:metabolism; D011509:Proteoglycans / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D015032:Zinc / Q000378:metabolism* / Q000494:pharmacology*; D017967:Zinc Compounds / Q000494:pharmacology
chemical_list: D002712:Chlorides; D053583:Interleukin-1beta; D011509:Proteoglycans; D017967:Zinc Compounds; C016837:zinc chloride; D045726:Metalloproteases; D015032:Zinc
keywords: Extracellular matrix; Hypoxia; Metabolism; Nucleus pulposus cell; Zinc