title: Mitochondrial DNA-dependent effects of valproate on mitochondrial calcium levels in transmitochondrial cybrids.
abstract: Calcium plays important roles in various cellular processes. Using transmitochondrial hybrid cells (cybrids) carrying fluorescent calcium indicators, we previously found two mitochondrial DNA (mtDNA) polymorphism sites, 8701 and 10398, that alter intracellular calcium signalling and mitochondrial pH. The 10398A polymorphism is reportedly associated with bipolar disorder, Parkinson's disease, Alzheimer's disease, and cancer, whereas 10398G is associated with longevity. In bipolar disorder, elevation of intracellular calcium levels in the platelets and lymphocytes is a well-replicated finding. Thus, we examined whether two mood stabilizers, lithium and valproate, affect the intracellular calcium signalling in cybrids with these mtDNA polymorphisms. After cybrids with 8701A/10398A and 8701G/10398G (three cell lines for each) derived from healthy controls were pretreated with lithium (0.75 mm or 1.5 mm) or valproate (0.6 mm or 1.2 mm) for 7 d, they were stimulated by 10 mum histamine. Valproate decreased mitochondrial calcium levels, compared with untreated cybrids, only in cybrids with 8701A/10398A. Moreover, valproate decreased cytosolic calcium levels at plateau after stimulation in cybrids with 8701A/10398A. These finding suggest that valproate may stabilize intracellular calcium only in cells with high mitochondrial calcium levels.
authors.affiliation: Laboratory for Molecular Dynamics of Mental Disorders, Brain Science Institute, Wako, Japan.
authors.forename: An-A
authors.initials: AA
authors.lastname: Kazuno
authors.forename: Kae
authors.initials: K
authors.lastname: Munakata
authors.forename: Nobumasa
authors.initials: N
authors.lastname: Kato
authors.forename: Tadafumi
authors.initials: T
authors.lastname: Kato
mesh_terms: D000328:Adult; D018692:Antimanic Agents / Q000494:pharmacology*; D002118:Calcium / Q000097:blood*; D020013:Calcium Signaling / Q000187:drug effects; D002460:Cell Line; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D004272:DNA, Mitochondrial / Q000235:genetics*; D005260:Female; D006632:Histamine / Q000494:pharmacology; D006801:Humans; D006822:Hybrid Cells; D018021:Lithium Chloride / Q000494:pharmacology; D008297:Male; D008928:Mitochondria / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D014635:Valproic Acid / Q000494:pharmacology*
chemical_list: D018692:Antimanic Agents; D004272:DNA, Mitochondrial; D014635:Valproic Acid; D006632:Histamine; D018021:Lithium Chloride; D002118:Calcium