Epigenetic Regulation of Glutamic Acid Decarboxylase 67 in a Hippocampal Circuit

Cereb Cortex. 2017 Nov 1;27(11):5284-5293. doi: 10.1093/cercor/bhw307.

Abstract

GABAergic dysfunction in hippocampus, a key feature of schizophrenia (SZ), may contribute to cognitive impairment in this disorder. In stratum oriens (SO) of sector CA3/2 of the human hippocampus, a network of genes involved in the regulation of glutamic acid decarboxylase GAD67 has been identified. Several of the genes in this network including epigenetic factors histone deacetylase 1 (HDAC1) and death-associated protein 6 (DAXX), the GABAergic enzyme GAD65 as well as the kainate receptor (KAR) subunits GluR6 and 7 show significant changes in expression in this area in SZ. We have tested whether HDAC1 and DAXX regulate GAD67, GAD65, or GluR in the intact rodent hippocampus. Stereotaxic injections of lentiviral vectors bearing shRNAi sequences for HDAC1 and DAXX were delivered into the SO of CA3/2, followed by laser microdissection of individual transduced GABA neurons. Quantitative PCR (QPCR) analyses demonstrated that inhibition of HDAC1 and DAXX increased expression of GAD67, GAD65, and GluR6 mRNA. Inhibition of DAXX, but not HDAC1 resulted in a significant increase in GluR7 mRNA. Our data support the hypothesis that HDAC1 and DAXX play a central role in coordinating the expression of genes in the GAD67 regulatory pathway in the SO of CA3/2.

Keywords: DAXX; GABA dysfunction; GluR6; GluR7; HDAC1; molecular mechanism.

MeSH terms

  • Adaptor Proteins, Signal Transducing / antagonists & inhibitors
  • Adaptor Proteins, Signal Transducing / metabolism*
  • Animals
  • CA2 Region, Hippocampal / cytology
  • CA2 Region, Hippocampal / metabolism*
  • CA3 Region, Hippocampal / cytology
  • CA3 Region, Hippocampal / metabolism*
  • Cell Line
  • Epigenesis, Genetic*
  • GABAergic Neurons / cytology
  • GABAergic Neurons / metabolism
  • Glutamate Decarboxylase / metabolism*
  • Histone Deacetylase 1 / antagonists & inhibitors
  • Histone Deacetylase 1 / metabolism*
  • Male
  • Molecular Chaperones
  • Neural Pathways / cytology
  • Neural Pathways / metabolism
  • Nuclear Proteins / antagonists & inhibitors
  • Nuclear Proteins / metabolism*
  • RNA, Messenger / metabolism
  • Rats, Sprague-Dawley
  • Receptors, Glutamate / metabolism

Substances

  • Adaptor Proteins, Signal Transducing
  • Daxx protein, rat
  • Molecular Chaperones
  • Nuclear Proteins
  • RNA, Messenger
  • Receptors, Glutamate
  • Hdac1 protein, rat
  • Histone Deacetylase 1
  • Glutamate Decarboxylase
  • glutamate decarboxylase 1
  • glutamate decarboxylase 2