Orai1-STIM1 formed store-operated Ca2+ channels (SOCs) as the molecular components needed for Pb2+ entry in living cells

Yu Fen Chang, Hsiao Chuan Teng, Sha Yen Cheng, Chin Tien Wang, Shi Hwa Chiou, Lung Sen Kao, Fu Jen Kao, Arthur Chiou, De Ming Yang*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

Heavy metal lead (Pb2+) is a pollutant and causes severe toxicity when present in human tissues especially the nervous system. Recent reviews have suggested that Pb2+ can target Ca2+-related proteins within neurons and that Ca2+ channels might be a candidate for Pb2+ entry. This study's main aim was to identify the functional entry pathway of Pb2+ into living cells. We firstly characterized the endogenous expression of Orai1 and STIM1 mRNA together with the level of thapsigargin (TG) stimulated capacitative Ca2+ entry in PC12 and HeLa cells; this was done by RT-PCR and time-lapse Ca2+ imaging microscopy, respectively. Our data supported Orai1 and STIM1 as contributing to store-operated Ca2+ channel (SOC) basal activity. Secondly, using the indo-1 quenching method with the SOC blocker 2-APB, we observed that Pb2+ was able to enter cells directly through unactivated SOCs without TG pretreatment. Thirdly, we further demonstrated that co-expression of Orai1 and STIM1 differentially enhanced SOC functional activity (4-fold with PC12 and 5-fold with HeLa cells) and Pb2+ entry (5- to 7-fold with PC12 and 2-fold with HeLa cells). Furthermore, after a 1 h of Pb2+ exposure, the depolarization- and histamine-induced Ca2+ responses were significantly decreased in both PC12 and HeLa cells in a dose-dependent manner. This result indicated that the decreased Ca2+ responses were, in part, due to Pb2+ entry. In summary, our results suggest that SOCs are responsible for Pb2+ permeation and that the Orai1-STIM1 protein complex formed by functional SOCs is one of the molecular components involved in Pb2+ entry.

Original languageEnglish
Pages (from-to)430-439
Number of pages10
JournalToxicology and Applied Pharmacology
Volume227
Issue number3
DOIs
StatePublished - 15 Mar 2008

Keywords

  • HeLa cells
  • Indo-1
  • Orai1
  • Pb
  • PC12 cells
  • STIM1
  • Store-operated Ca channels

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