Thiol oxidation by 2,2′-dithiodipyridine induced calcium mobilization in MG63 human osteosarcoma cells

Soong Yu Kuo, Bang Ping Jiann, Yih Chau Lu, Hong Tai Chang, Wei Chung Chen, Jong Khing Huang, Chung Ren Jan*

*Corresponding author for this work

Research output: Contribution to journalJournal Article peer-review

16 Scopus citations

Abstract

2,2′-dithiodipyridine (2,2′-DTDP), a reactive disulphide that mobilizes Ca2+ in muscle, induced an increase in cytoplasmic free Ca2+concentrations ([Ca2+]i) in MG63 human osteosarcoma cells loaded with the Ca2+-sensitive dye fura-2. 2,2′-DTDP acted in a concentration-independent manner with an EC50 of 50 μM. The Ca2+ signal comprised an initial spike and a prolonged increase. Removing extracellular Ca2+ did not alter the Ca2+ signal, suggesting that the Ca2+ signal was due to store Ca2+ release. In Ca2+-free medium, the 2,2′-DTDP-induced [Ca2+]i increase was not changed by depleting store Ca2+ with 50 μM bredfeldin A (a Golgi apparatus permeabilizer), 2 μM carbonylcyanide m-chlorophenylhydrazone (CCCP, a mitochondrial uncoupler), 1 μM thapsigargin (an endoplasmic reticulum Ca2+pump inhibitor) or 5 μM ryanodine. Conversely, 2,2′-DTDP pretreatment abolished CCCP and thapsigargin-induced [Ca2+]i increases. 2,2′-DTDP-induced Ca2+ signals in Ca2+-containing medium were not affected by modulation of protein kinase C activity or suppression of phospholipase C activity. However, 2,2′-DTDP-induced Ca2+ release was inhibited by a thiol-selective reducing reagent, dithiothreitol (5-25 μM) in a concentration-dependent manner. Collectively, this study shows that 2,2′-DTDP induced [Ca2+]i increases in human osteosarcoma cells via releasing store Ca2+from multiple stores in a manner independent of protein kinase C or phospholipase C activity. The 2,2′-DTDP-induced store Ca2+ release appeared to be dependent on oxidation of membranes.

Original languageEnglish
Pages (from-to)1733-1743
Number of pages11
JournalLife Sciences
Volume72
Issue number15
DOIs
StatePublished - 28 02 2003
Externally publishedYes

Keywords

  • 2,2′-dithiodipyridine
  • Ca stores
  • Free radicals
  • Fura-2
  • Osteosarcoma cells
  • Reactive oxygen species

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