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Chronic LiCl pretreatment suppresses thrombin‐stimulated intracellular calcium mobilization through TRPC 3 in astroglioma cells
Author(s) -
Uemura Takuji,
Green Marty,
Warsh Jerry J
Publication year - 2016
Publication title -
bipolar disorders
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.285
H-Index - 129
eISSN - 1399-5618
pISSN - 1398-5647
DOI - 10.1111/bdi.12447
Subject(s) - trpc , chemistry , trpc5 , microbiology and biotechnology , transient receptor potential channel , receptor , biology , biochemistry
Objectives Transient receptor potential canonical type 3 ( TRPC 3) channels are activated in B lymphoblast cell lines from patients with bipolar disorder ( BD ), and its expression is reduced by chronic lithium treatment, implicating TRPC 3 in the intracellular calcium (Ca 2+ ) dyshomeostasis of BD . Thrombin, via a protease‐activated receptor, moderates Ca 2+ signaling and TRPC 3 in astrocytes, and also cell proliferation. We examined whether lithium pretreatment attenuates thrombin‐stimulated TRPC 3 expression and function in astrocytes, and levels of the calcium‐binding peptide, S100B, which is expressed mainly in these cells. Methods Human astroglioma, U‐87 MG, cells were pretreated with 1 mmol L −1 LiCl for 1 day (acute), 3 days (subacute), and 7 days (chronic). To examine the role of TRPC 3, genetically stable knockdown TRPC 3 cells ( TRPC 3 Low cells) were constructed using U‐87 MG cells. Thrombin (2.0 U/mL)‐stimulated Ca 2+ mobilization was measured by ratiometric fluorimetry. Changes in TRPC 3 and S100B expression levels were determined by quantitative reverse transcription‐polymerase chain reaction and immunoblotting, respectively. Cell proliferation was also measured using the WST ‐8 assay. Results In this cell model, thrombin‐stimulated Ca 2+ mobilization, and both TRPC 3 and S100B expression were suppressed by chronic LiCl pretreatment and the knockdown of TRPC 3. Additionally, cell proliferation was attenuated in TRPC 3 Low cells, compared with the negative control vector‐transfected cell. Conclusions The reduced Ca 2+ mobilization and S100B expression levels following chronic LiCl pretreatment and in TRPC 3 Low cells support the notion that TRPC 3 modulates S100B expression and is the target of the LiCl effect. Downregulation of TRPC 3 may be an important mechanism by which lithium ameliorates pathophysiological intracellular Ca 2+ disturbances as observed in BD , accounting, in part, for its mood‐stabilizing effects.