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GAD1 alternative transcripts and DNA methylation in human prefrontal cortex and hippocampus in brain development, schizophrenia

Molecular Psychiatry volume 23, pages 1496–1505 (2018)Cite this article

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Abstract

Genetic variations and adverse environmental events in utero or shortly after birth can lead to abnormal brain development and increased risk of schizophrenia. γ-Aminobutyric acid (GABA), the major inhibitory neurotransmitter in the mammalian brain, plays a vital role in normal brain development. GABA synthesis is controlled by enzymes derived from two glutamic acid decarboxylase (GAD) genes, GAD1 and GAD2, both of which produce transcript isoforms. While the full-length GAD1 transcript (GAD67) has been implicated in the neuropathology of schizophrenia, the transcript structure of GAD1 in the human brain has not been fully characterized. In this study, with the use of RNA sequencing and PCR technologies, we report the discovery of 10 novel transcripts of GAD1 in the human brain. Expression levels of four novel GAD1 transcripts (8A, 8B, I80 and I86) showed a lifespan trajectory expression pattern that is anticorrelated with the expression of the full-length GAD1 transcript. In addition, methylation levels of two CpG loci within the putative GAD1 promoter were significantly associated with the schizophrenia-risk SNP rs3749034 and with the expression of GAD25 in dorsolateral prefrontal cortex (DLPFC). Moreover, schizophrenia patients who had completed suicide and/or were positive for nicotine exposure had significantly higher full-length GAD1 expression in the DLPFC. Alternative splicing of GAD1 and epigenetic state appear to play roles in the developmental profile of GAD1 expression and may contribute to GABA dysfunction in the PFC and hippocampus of patients with schizophrenia.

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References

  1. LoTurco JJ, Owens DF, Heath MJ, Davis MB, Kriegstein AR . GABA and glutamate depolarize cortical progenitor cells and inhibit DNA synthesis. Neuron 1995; 15: 1287–1298.

    Article  CAS  PubMed  Google Scholar 

  2. Marty S, Berninger B, Carroll P, Thoenen H . GABAergic stimulation regulates the phenotype of hippocampal interneurons through the regulation of brain-derived neurotrophic factor. Neuron 1996; 16: 565–570.

    Article  CAS  PubMed  Google Scholar 

  3. Behar TN, Schaffner AE, Scott CA, Greene CL, Barker JL . GABA receptor antagonists modulate postmitotic cell migration in slice cultures of embryonic rat cortex. Cereb Cortex 2000; 10: 899–909.

    Article  CAS  PubMed  Google Scholar 

  4. Varju P, Katarova Z, Madarász E, Szabó G . Sequential induction of embryonic and adult forms of glutamic acid decarboxylase during in vitro-induced neurogenesis in cloned neuroectodermal cell-line, NE-7C2. J Neurochem 2002; 80: 605–615.

    Article  CAS  PubMed  Google Scholar 

  5. Erlander MG, Tillakaratne NJ, Feldblum S, Patel N, Tobin AJ . Two genes encode distinct glutamate decarboxylases. Neuron 1991; 7: 91–100.

    Article  CAS  PubMed  Google Scholar 

  6. Bu DF, Erlander MG, Hitz BC, Tillakaratne NJ, Kaufman DL, Wagner-McPherson CB et al. Two human glutamate decarboxylases, 65-kDa GAD and 67-kDa GAD, are each encoded by a single gene. Proc Natl Acad Sci USA 1992; 89: 2115–2119.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  7. Asada H, Kawamura Y, Maruyama K, Kume H, Ding RG, Kanbara N et al. Cleft palate and decreased brain gamma-aminobutyric acid in mice lacking the 67-kDa isoform of glutamic acid decarboxylase. Proc Natl Acad Sci USA 1997; 94: 6496–6499.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  8. Condie BG, Bain G, Gottlieb DI, Capecchi MR . Cleft palate in mice with a targeted mutation in the gamma-aminobutyric acid-producing enzyme glutamic acid decarboxylase 67. Proc Natl Acad Sci USA 1997; 94: 11451–11455.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  9. Mason GF, Martin DL, Martin SB, Manor D, Sibson NR, Patel A et al. Decrease in GABA synthesis rate in rat cortex following GABA-transaminase inhibition correlates with the decrease in GAD(67) protein. Brain Res 2001; 914: 81–91.

    Article  CAS  PubMed  Google Scholar 

  10. Akbarian S, Kim JJ, Potkin SG, Hagman JO, Tafazzoli A, Bunney WE et al. Gene expression for glutamic acid decarboxylase is reduced without loss of neurons in prefrontal cortex of schizophrenics. Arch Gen Psychiatry 1995; 52: 258–266.

    Article  CAS  PubMed  Google Scholar 

  11. Volk D, Austin M, Pierri J, Sampson A, Lewis D . GABA transporter-1 mRNA in the prefrontal cortex in schizophrenia: decreased expression in a subset of neurons. Am J Psychiatry 2001; 158: 256–265.

    Article  CAS  PubMed  Google Scholar 

  12. Hashimoto T, Volk DW, Eggan SM, Mirnics K, Pierri JN, Sun Z et al. Gene expression deficits in a subclass of GABA neurons in the prefrontal cortex of subjects with schizophrenia. J Neurosci 2003; 23: 6315–6326.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  13. Curley AA, Arion D, Volk DW, Asafu-Adjei JK, Sampson AR, Fish KN et al. Cortical deficits of glutamic acid decarboxylase 67 expression in schizophrenia: clinical, protein, and cell type-specific features. Am J Psychiatry 2011; 168: 921–929.

    Article  PubMed  PubMed Central  Google Scholar 

  14. Addington AM, Gornick M, Duckworth J, Sporn A, Gogtay N, Bobb A et al. GAD1 (2q31.1), which encodes glutamic acid decarboxylase (GAD67), is associated with childhood-onset schizophrenia and cortical gray matter volume loss. Mol Psychiatry 2005; 10: 581–588.

    Article  CAS  PubMed  Google Scholar 

  15. Straub RE, Lipska BK, Egan MF, Goldberg TE, Callicott JH, Mayhew MB et al. Allelic variation in GAD1 (GAD67) is associated with schizophrenia and influences cortical function and gene expression. Mol Psychiatry 2007; 12: 854–869.

    Article  CAS  PubMed  Google Scholar 

  16. Zhao X, Qin S, Shi Y, Zhang A, Zhang J, Bian L et al. Systematic study of association of four GABAergic genes: glutamic acid decarboxylase 1 gene, glutamic acid decarboxylase 2 gene, GABA(B) receptor 1 gene and GABA(A) receptor subunit beta2 gene, with schizophrenia using a universal DNA microarray. Schizophr Res 2007; 93: 374–384.

    Article  PubMed  Google Scholar 

  17. Du J, Duan S, Wang H, Chen W, Zhao X, Zhang A et al. Comprehensive analysis of polymorphisms throughout GAD1 gene: a family-based association study in schizophrenia. J Neural Transm Vienna Austria 1996 2008; 115: 513–519.

    CAS  Google Scholar 

  18. Kundakovic M, Chen Y, Costa E, Grayson DR . DNA methyltransferase inhibitors coordinately induce expression of the human reelin and glutamic acid decarboxylase 67 genes. Mol Pharmacol 2007; 71: 644–653.

    Article  CAS  PubMed  Google Scholar 

  19. Veldic M, Caruncho HJ, Liu WS, Davis J, Satta R, Grayson DR et al. DNA-methyltransferase 1 mRNA is selectively overexpressed in telencephalic GABAergic interneurons of schizophrenia brains. Proc Natl Acad Sci USA 2004; 101: 348–353.

    Article  CAS  PubMed  Google Scholar 

  20. Veldic M, Guidotti A, Maloku E, Davis JM, Costa E . In psychosis, cortical interneurons overexpress DNA-methyltransferase 1. Proc Natl Acad Sci USA 2005; 102: 2152–2157.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  21. Ruzicka WB, Subburaju S, Benes FM . Circuit- and diagnosis-specific DNA methylation changes at γ-aminobutyric acid–related genes in postmortem human hippocampus in schizophrenia and bipolar disorder. JAMA Psychiatry 2015; 72: 541–551.

    Article  PubMed  PubMed Central  Google Scholar 

  22. Subburaju S, Coleman AJ, Cunningham MG, Ruzicka WB, Benes FM . Epigenetic regulation of glutamic acid decarboxylase 67 in a hippocampal circuit. Cereb Cortex 2016; e-pub ahead of print 12 October 2016.

  23. Subburaju S, Coleman AJ, Ruzicka WB, Benes FM . Toward dissecting the etiology of schizophrenia: HDAC1 and DAXX regulate GAD67 expression in an in vitro hippocampal GABA neuron model. Transl Psychiatry 2016; 6: e723.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  24. Bond RW, Wyborski RJ, Gottlieb DI . Developmentally regulated expression of an exon containing a stop codon in the gene for glutamic acid decarboxylase. Proc Natl Acad Sci USA 1990; 87: 8771–8775.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  25. Szabo G, Katarova Z, Greenspan R . Distinct protein forms are produced from alternatively spliced bicistronic glutamic acid decarboxylase mRNAs during development. Mol Cell Biol 1994; 14: 7535–7545.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  26. Liu H, Zhang Y, Li S, Yan Y, Li Y . Dynamic regulation of glutamate decarboxylase 67 gene expression by alternative promoters and splicing during rat testis maturation. Mol Biol Rep 2010; 37: 3111–3119.

    Article  CAS  PubMed  Google Scholar 

  27. Popp A, Urbach A, Witte OW, Frahm C . Adult and embryonic GAD transcripts are spatiotemporally regulated during postnatal development in the rat brain. PLoS ONE 2009; 4: e4371.

    Article  PubMed  PubMed Central  Google Scholar 

  28. Lynex CN, Carr IM, Leek JP, Achuthan R, Mitchell S, Maher ER et al. Homozygosity for a missense mutation in the 67 kDa isoform of glutamate decarboxylase in a family with autosomal recessive spastic cerebral palsy: parallels with Stiff-Person syndrome and other movement disorders. BMC Neurol 2004; 4: 20.

    Article  PubMed  PubMed Central  Google Scholar 

  29. Hyde TM, Lipska BK, Ali T, Mathew SV, Law AJ, Metitiri OE et al. Expression of GABA signaling molecules KCC2, NKCC1, and GAD1 in cortical development and schizophrenia. J Neurosci 2011; 31: 11088–11095.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  30. Li M, Jaffe AE, Straub RE, Tao R, Shin JH, Wang Y et al. A human-specific AS3MT isoform and BORCS7 are molecular risk factors in the 10q24.32 schizophrenia-associated locus. Nat Med 2016; 22: 649–656.

    Article  CAS  PubMed  Google Scholar 

  31. Jaffe AE, Gao Y, Deep-Soboslay A, Tao R, Hyde TM, Weinberger DR et al. Mapping DNA methylation across development, genotype and schizophrenia in the human frontal cortex. Nat Neurosci 2016; 19: 40–47.

    Article  CAS  PubMed  Google Scholar 

  32. Aryee MJ, Jaffe AE, Corrada-Bravo H, Ladd-Acosta C, Feinberg AP, Hansen KD et al. Minfi: a flexible and comprehensive Bioconductor package for the analysis of Infinium DNA methylation microarrays. Bioinforma Oxf Engl 2014; 30: 1363–1369.

    Article  CAS  Google Scholar 

  33. Chessler SD, Lernmark A . Alternative splicing of GAD67 results in the synthesis of a third form of glutamic-acid decarboxylase in human islets and other non-neural tissues. J Biol Chem 2000; 275: 5188–5192.

    Article  CAS  PubMed  Google Scholar 

  34. Trifonov S, Yamashita Y, Kase M, Maruyama M, Sugimoto T . Glutamic acid decarboxylase 1 alternative splicing isoforms: characterization, expression and quantification in the mouse brain. BMC Neurosci 2014; 15: 114.

    Article  PubMed  PubMed Central  Google Scholar 

  35. Krizbai IA, Katarova Z, Szabó G, Párducz A, Wolff JR . Modulation of the truncated GAD25 by estrogen in the olfactory bulb of adult rats. Neuroreport 2000; 11: 791–794.

    Article  CAS  PubMed  Google Scholar 

  36. Szabó G, Kartarova Z, Hoertnagl B, Somogyi R, Sperk G . Differential regulation of adult and embryonic glutamate decarboxylases in rat dentate granule cells after kainate-induced limbic seizures. Neuroscience 2000; 100: 287–295.

    Article  PubMed  Google Scholar 

  37. Lu K-T, Wu C-Y, Cheng N-C, Wo Y-YP, Yang J-T, Yen H-H et al. Inhibition of the Na+–K+–2Cl−-cotransporter in choroid plexus attenuates traumatic brain injury-induced brain edema and neuronal damage. Eur J Pharmacol 2006; 548: 99–105.

    Article  CAS  PubMed  Google Scholar 

  38. Boulenguez P, Liabeuf S, Bos R, Bras H, Jean-Xavier C, Brocard C et al. Down-regulation of the potassium-chloride cotransporter KCC2 contributes to spasticity after spinal cord injury. Nat Med 2010; 16: 302–307.

    Article  CAS  PubMed  Google Scholar 

  39. Sullivan CR, Funk AJ, Shan D, Haroutunian V, McCullumsmith RE . Decreased chloride channel expression in the dorsolateral prefrontal cortex in schizophrenia. PLoS ONE 2015; 10: e0123158.

    Article  PubMed  PubMed Central  Google Scholar 

  40. Weinberger DR . Implications of normal brain development for the pathogenesis of schizophrenia. Arch Gen Psychiatry 1987; 44: 660–669.

    Article  CAS  PubMed  Google Scholar 

  41. Chen Y, Dong E, Grayson DR . Analysis of the GAD1 promoter: trans-acting factors and DNA methylation converge on the 5’ untranslated region. Neuropharmacology 2011; 60: 1075–1087.

    Article  CAS  PubMed  Google Scholar 

  42. Davis KN, Tao R, Li C, Gao Y, Gondré-Lewis MC, Lipska BK et al. GAD2 alternative transcripts in the human prefrontal cortex, and in schizophrenia and affective disorders. PLoS ONE 2016; 11: e0148558.

    Article  PubMed  PubMed Central  Google Scholar 

  43. Gos T, Günther K, Bielau H, Dobrowolny H, Mawrin C, Trübner K et al. Suicide and depression in the quantitative analysis of glutamic acid decarboxylase-Immunoreactive neuropil. J Affect Disord 2009; 113: 45–55.

    Article  CAS  PubMed  Google Scholar 

  44. Li D, Yang X, Ge Z, Hao Y, Wang Q, Liu F et al. Cigarette smoking and risk of completed suicide: a meta-analysis of prospective cohort studies. J Psychiatr Res 2012; 46: 1257–1266.

    Article  PubMed  Google Scholar 

  45. Mäkikyrö TH, Hakko HH, Timonen MJ, Lappalainen JA, Ilomäki RS, Marttunen MJ et al. Smoking and suicidality among adolescent psychiatric patients. J Adolesc Health 2004; 34: 250–253.

    Article  PubMed  Google Scholar 

  46. Benes FM . Nicotinic receptors and functional regulation of GABA cell microcircuitry in bipolar disorder and schizophrenia. In: Geyer MA, Gross G (eds). Novel Antischizophrenia Treatments. Springer: Berlin, Heidelberg, 2012, pp 401–417.

    Chapter  Google Scholar 

  47. Jow F, Chiu D, Lim H-K, Novak T, Lin S . Production of GABA by cultured hippocampal glial cells. Neurochem Int 2004; 45: 273–283.

    Article  CAS  PubMed  Google Scholar 

  48. Lee M, Schwab C, McGeer PL . Astrocytes are GABAergic cells that modulate microglial activity. Glia 2011; 59: 152–165.

    Article  PubMed  Google Scholar 

  49. Skene NG, Grant SGN . Identification of vulnerable cell types in major brain disorders using single cell transcriptomes and expression weighted cell type enrichment. Front Neurosci 2016; 10: 16.

    Article  PubMed  PubMed Central  Google Scholar 

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Acknowledgements

We thank Amy Deep-Soboslay, MEd of Lieber Institute for Brain Development for the efforts in clinical diagnosis and demographic characterization. MC Gondré-Lewis is supported by NIH/NIAAA grant number R01AA021262.

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Author notes

  1. R Tao and K N Davis: These authors contributed equally to this work.

Authors and Affiliations

  1. The Lieber Institute for Brain Development, Johns Hopkins University Medical Campus, Baltimore, MD, USA

    R Tao, K N Davis, C Li, J H Shin, Y Gao, A E Jaffe, D R Weinberger, J E Kleinman & T M Hyde

  2. Department of Anatomy, Developmental Neuropsychopharmacology Laboratory, Howard University College of Medicine, Washington, DC, USA

    K N Davis & M C Gondré-Lewis

  3. Department of Mental Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA

    A E Jaffe

  4. Department of Psychiatry and Behavior Sciences, Johns Hopkins School of Medicine, Baltimore, MD, USA

    D R Weinberger, J E Kleinman & T M Hyde

  5. Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA

    D R Weinberger & T M Hyde

  6. Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA

    D R Weinberger

  7. Department of Psychiatry & Behavioral Sciences, Howard University College of Medicine, Washington, DC, USA

    M C Gondré-Lewis

  8. McKusick Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA

    D R Weinberger

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Correspondence to T M Hyde.

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Tao, R., Davis, K., Li, C. et al. GAD1 alternative transcripts and DNA methylation in human prefrontal cortex and hippocampus in brain development, schizophrenia. Mol Psychiatry 23, 1496–1505 (2018). https://doi.org/10.1038/mp.2017.105

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