title: Mitochondrial-related gene expression changes are sensitive to agonal-pH state: implications for brain disorders.
abstract: Mitochondrial defects in gene expression have been implicated in the pathophysiology of bipolar disorder and schizophrenia. We have now contrasted control brains with low pH versus high pH and showed that 28% of genes in mitochondrial-related pathways meet criteria for differential expression. A majority of genes in the mitochondrial, chaperone and proteasome pathways of nuclear DNA-encoded gene expression were decreased with decreased brain pH, whereas a majority of genes in the apoptotic and reactive oxygen stress pathways showed an increased gene expression with a decreased brain pH. There was a significant increase in mitochondrial DNA copy number and mitochondrial DNA gene expression with increased agonal duration. To minimize effects of agonal-pH state on mood disorder comparisons, two classic approaches were used, removing all subjects with low pH and agonal factors from analysis, or grouping low and high pH as a separate variable. Three groups of potential candidate genes emerged that may be mood disorder related: (a) genes that showed no sensitivity to pH but were differentially expressed in bipolar disorder or major depressive disorder; (b) genes that were altered by agonal-pH in one direction but altered in mood disorder in the opposite direction to agonal-pH and (c) genes with agonal-pH sensitivity that displayed the same direction of changes in mood disorder. Genes from these categories such as NR4A1 and HSPA2 were confirmed with Q-PCR. The interpretation of postmortem brain studies involving broad mitochondrial gene expression and related pathway alterations must be monitored against the strong effect of agonal-pH state. Genes with the least sensitivity to agonal-pH could present a starting point for candidate gene search in neuropsychiatric disorders.
authors.affiliation: Department of Psychiatry, University of California, Irvine, USA. mvawter@uci.edu
authors.forename: M P
authors.initials: MP
authors.lastname: Vawter
authors.forename: H
authors.initials: H
authors.lastname: Tomita
authors.forename: F
authors.initials: F
authors.lastname: Meng
authors.forename: B
authors.initials: B
authors.lastname: Bolstad
authors.forename: J
authors.initials: J
authors.lastname: Li
authors.forename: S
authors.initials: S
authors.lastname: Evans
authors.forename: P
authors.initials: P
authors.lastname: Choudary
authors.forename: M
authors.initials: M
authors.lastname: Atz
authors.forename: L
authors.initials: L
authors.lastname: Shao
authors.forename: C
authors.initials: C
authors.lastname: Neal
authors.forename: D M
authors.initials: DM
authors.lastname: Walsh
authors.forename: M
authors.initials: M
authors.lastname: Burmeister
authors.forename: T
authors.initials: T
authors.lastname: Speed
authors.forename: R
authors.initials: R
authors.lastname: Myers
authors.forename: E G
authors.initials: EG
authors.lastname: Jones
authors.forename: S J
authors.initials: SJ
authors.lastname: Watson
authors.forename: H
authors.initials: H
authors.lastname: Akil
authors.forename: W E
authors.initials: WE
authors.lastname: Bunney
mesh_terms: D000928:Antidepressive Agents / Q000494:pharmacology; D017209:Apoptosis / Q000235:genetics; D001714:Bipolar Disorder / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D001921:Brain / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D002531:Cerebellum / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D004272:DNA, Mitochondrial / Q000235:genetics / Q000378:metabolism; D003643:Death; D003866:Depressive Disorder / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D005260:Female; D018628:Gene Dosage; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D006179:Gyrus Cinguli / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D017403:In Situ Hybridization; D008094:Lithium / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D018832:Molecular Chaperones / Q000096:biosynthesis / Q000235:genetics; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000235:genetics*; D009419:Nerve Tissue Proteins / Q000096:biosynthesis / Q000235:genetics*; D020411:Oligonucleotide Array Sequence Analysis; D018384:Oxidative Stress / Q000235:genetics; D016133:Polymerase Chain Reaction; D011180:Postmortem Changes; D017397:Prefrontal Cortex / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D017367:Selective Serotonin Reuptake Inhibitors / Q000494:pharmacology; D013997:Time Factors
chemical_list: D000928:Antidepressive Agents; D004272:DNA, Mitochondrial; D008094:Lithium; D018832:Molecular Chaperones; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D046988:Proteasome Endopeptidase Complex; D012333:RNA, Messenger; D017367:Selective Serotonin Reuptake Inhibitors; C087940:LRPPRC protein, human