title: Calcium channel genes associated with bipolar disorder modulate lithium's amplification of circadian rhythms.
abstract: Bipolar disorder (BD) is associated with mood episodes and low amplitude circadian rhythms. Previously, we demonstrated that fibroblasts grown from BD patients show weaker amplification of circadian rhythms by lithium compared to control cells. Since calcium signals impact upon the circadian clock, and L-type calcium channels (LTCC) have emerged as genetic risk factors for BD, we examined whether loss of function in LTCCs accounts for the attenuated response to lithium in BD cells. We used fluorescent dyes to measure Ca(2+) changes in BD and control fibroblasts after lithium treatment, and bioluminescent reporters to measure Per2::luc rhythms in fibroblasts from BD patients, human controls, and mice while pharmacologically or genetically manipulating calcium channels. Longitudinal expression of LTCC genes (CACNA1C, CACNA1D and CACNB3) was then measured over 12-24 h in BD and control cells. Our results indicate that independently of LTCCs, lithium stimulated intracellular Ca(2+) less effectively in BD vs. control fibroblasts. In longitudinal studies, pharmacological inhibition of LTCCs or knockdown of CACNA1A, CACNA1C, CACNA1D and CACNB3 altered circadian rhythm amplitude. Diltiazem and knockdown of CACNA1C or CACNA1D eliminated lithium's ability to amplify rhythms. Knockdown of CACNA1A or CACNB3 altered baseline rhythms, but did not affect rhythm amplification by lithium. In human fibroblasts, CACNA1C genotype predicted the amplitude response to lithium, and the expression profiles of CACNA1C, CACNA1D and CACNB3 were altered in BD vs.
  
  
  METHODS
  We conclude that in cells from BD patients, calcium signaling is abnormal, and that LTCCs underlie the failure of lithium to amplify circadian rhythms.
authors.affiliation: Research and Psychiatry Service, Veterans Affairs, San Diego, USA; Department of Psychiatry and Center for Circadian Biology, University of California, San Diego, USA. Electronic address: mmccarthy@ucsd.edu.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: McCarthy
authors.affiliation: Department of Psychiatry and Center for Circadian Biology, University of California, San Diego, USA.
authors.forename: Melissa J
authors.initials: MJ
authors.lastname: Le Roux
authors.affiliation: Research and Psychiatry Service, Veterans Affairs, San Diego, USA.
authors.forename: Heather
authors.initials: H
authors.lastname: Wei
authors.affiliation: Department of Psychiatry and Center for Circadian Biology, University of California, San Diego, USA.
authors.forename: Stephen
authors.initials: S
authors.lastname: Beesley
authors.affiliation: Research and Psychiatry Service, Veterans Affairs, San Diego, USA; Department of Psychiatry and Center for Circadian Biology, University of California, San Diego, USA.
authors.forename: John R
authors.initials: JR
authors.lastname: Kelsoe
authors.affiliation: Research and Psychiatry Service, Veterans Affairs, San Diego, USA; Department of Psychiatry and Center for Circadian Biology, University of California, San Diego, USA.
authors.forename: David K
authors.initials: DK
authors.lastname: Welsh
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D001714:Bipolar Disorder / Q000235:genetics / Q000473:pathology; D001896:Boron Compounds / Q000494:pharmacology; D056926:CLOCK Proteins / Q000235:genetics / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000235:genetics* / Q000378:metabolism; D020746:Calcium Channels, L-Type / Q000235:genetics* / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects*; D002478:Cells, Cultured; D002940:Circadian Rhythm / Q000187:drug effects* / Q000235:genetics*; D005260:Female; D005347:Fibroblasts; D006801:Humans; D008094:Lithium / Q000494:pharmacology / Q000627:therapeutic use*; D008297:Male; D051379:Mice; D008875:Middle Aged; D041681:NIH 3T3 Cells; D056950:Period Circadian Proteins / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D014700:Verapamil / Q000494:pharmacology; D055815:Young Adult; D020864:Calcium Channels, N-Type
chemical_list: D001896:Boron Compounds; D056926:CLOCK Proteins; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D020746:Calcium Channels, L-Type; D008094:Lithium; D056950:Period Circadian Proteins; D034741:RNA, Small Interfering; D014700:Verapamil; C105656:CACNA1A protein, human; D020864:Calcium Channels, N-Type; C472073:CACNA1D protein, human; C421902:PER2 protein, human; C109986:2-aminoethoxydiphenyl borate
keywords: Bipolar disorder; Calcium; Cells; Circadian rhythms; Gene; Lithium