title: TRPC1 is involved in Ca²⁺ influx and cytotoxicity following Pb²⁺ exposure in human embryonic kidney cells.
abstract: Lead (Pb(2+)) is a divalent heavy metal ion which causes severe damage to almost all life forms and is therefore considered a notorious toxicant. Exposure to Pb(2+) is associated with poor cognitive development in children at relatively low levels that previously were thought to be safe. The mechanism through which Pb(2+) enters cells, however, is unclear. Previous studies have showed that Ca(2+) release-activated Ca(2+) protein 1 (Orai1), a component of store-operated Ca(2+) channels (SOCs), contributes to Pb(2+) cellular entry. Canonical transient receptor potential (TRPC1) channel 1 is a transient receptor potential (TRP) channel which is sometimes referred to as a SOC. The present study was designed to investigate the role of TRPC1 in Pb(2+) entry and toxicity in human embryonic kidney cells (HEK293). Additionally, changes in intracellular Ca(2+) concentration were determined through Fluo-4 and Mag-fluo-4 fluorescent Ca(2+) imaging. Following Pb(2+) exposure, there was a dose-dependent decrease in cell viability. Overexpression of TRPC1 increased Pb(2+)-induced cell death, while knockdown of this channel attenuated cell death. There was increased entry of Pb(2+), as measured by inductively coupled plasma mass spectrometry (ICP-MS), following overexpression of TRPC1. Conversely, knockdown of TRPC1 led to a decrease in Pb(2+) influx. Down-regulation of STIM1 by RNA interference attenuated the Pb(2+) influx, and transfection with a mutant STIM1, which could not gate TRPC1, had a similar effect. Co-transfection of mutant STIM1 and mutant TRPC1, which restore the electrostatic interaction between STIM1 and TRPC1, resumed Pb(2+) entry in HEK293 cells. Down-regulation of TRPC1 by RNA interference decreased Ca(2+) influx whilst its overexpression increased Ca(2+) entry in HEK293 cells. These results suggest that TRPC1 is involved in the cytotoxicity and entry of Pb(2+) through molecular interactions with STIM1 and subsequent Ca(2+) influx in HEK293 cells.
authors: Department of Occupational Health and Occupational Medicine, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, Guangdong Province 510515, China.
authors: Hongmei
authors: H
authors: Zhang
authors: Department of Occupational Health and Occupational Medicine, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, Guangdong Province 510515, China.
authors: Wenjun
authors: W
authors: Li
authors: Department of Occupational Health and Occupational Medicine, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, Guangdong Province 510515, China; Jiangxi Science & Technology Research Center for Work Safety, Nanchang, Jiangxi Province, 330030, China.
authors: Yong
authors: Y
authors: Xue
authors: Department of Occupational Health and Occupational Medicine, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, Guangdong Province 510515, China. Electronic address: feizoudean@hotmail.com.
authors: Fei
authors: F
authors: Zou
mesh_terms: D000111:Acetylcysteine; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects*; D057809:HEK293 Cells; D006801:Humans; D007202:Indicators and Reagents; D007854:Lead / Q000378:metabolism; D007855:Lead Poisoning / Q000378:metabolism* / Q000473:pathology; D013058:Mass Spectrometry; D008565:Membrane Proteins / Q000378:metabolism; D009363:Neoplasm Proteins / Q000378:metabolism; D000071737:Stromal Interaction Molecule 1; D050052:TRPC Cation Channels / Q000502:physiology*; D014162:Transfection
chemical_list: D007202:Indicators and Reagents; D008565:Membrane Proteins; D009363:Neoplasm Proteins; C103530:STIM1 protein, human; D000071737:Stromal Interaction Molecule 1; D050052:TRPC Cation Channels; C096351:transient receptor potential cation channel, subfamily C, member 1; D007854:Lead; D002118:Calcium; D000111:Acetylcysteine
keywords: HEK293 cells; Inductively coupled plasma mass spectrometry (ICP-MS); Pb(2+); STIM1; TRPC1