Changes in NMDA receptor subunits and interacting PSD proteins in dorsolateral prefrontal and anterior cingulate cortex indicate abnormal regional expression in schizophrenia

Mol Psychiatry. 2006 Aug;11(8):737-47, 705. doi: 10.1038/sj.mp.4001844. Epub 2006 May 16.

Abstract

Abnormal expression of the N-methyl-D-Aspartate (NMDA) receptor and its interacting molecules of the postsynaptic density (PSD) are thought to be involved in the pathophysiology of schizophrenia. Frontal regions of neocortex including dorsolateral prefrontal (DLPFC) and anterior cingulate cortex (ACC) are essential for cognitive and behavioral functions that are affected in schizophrenia. In this study, we have measured protein expression of two alternatively spliced isoforms of the NR1 subunit (NR1C2 and NR1C2') as well as expression of the NR2A-D subunits of the NMDA receptor in DLPFC and ACC in post-mortem samples from elderly schizophrenic patients and a comparison group. We found significantly increased expression of NR1C2' but not of NR1C2 in ACC, suggesting altered NMDA receptor cell membrane expression in this cortical area. We did not find significant changes in the expression of either of the NR1 isoforms in DLPFC. We did not detect changes of any of the NR2 subunits studied in either cortical area. In addition, we studied expression of the NMDA-interacting PSD molecules NF-L, SAP102, PSD-95 and PSD-93 in ACC and DLPFC at both transcriptional and translational levels. We found significant changes in the expression of NF-L in DLPFC, and PSD-95 and PSD-93 in ACC; increased transcript expression was associated with decreased protein expression, suggesting abnormal translation and/or accelerated protein degradation of these molecules in schizophrenia. Our findings suggest abnormal regional processing of the NMDA receptor and its associated PSD molecules, possibly involving transcription, translation, trafficking and protein stability in cortical areas in schizophrenia.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Aged
  • Aged, 80 and over
  • Blotting, Western
  • Disks Large Homolog 4 Protein
  • Female
  • Gene Expression
  • Guanylate Kinases / genetics
  • Guanylate Kinases / metabolism
  • Gyrus Cinguli / physiology*
  • Humans
  • In Situ Hybridization
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / metabolism
  • Male
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism
  • Middle Aged
  • Nerve Tissue Proteins / genetics*
  • Nerve Tissue Proteins / metabolism*
  • Neurofilament Proteins / genetics
  • Neurofilament Proteins / metabolism
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism
  • Prefrontal Cortex / physiology*
  • Receptors, N-Methyl-D-Aspartate / genetics*
  • Receptors, N-Methyl-D-Aspartate / metabolism*
  • Schizophrenia / metabolism
  • Schizophrenia / physiopathology*
  • Transcription Factors / genetics
  • Transcription Factors / metabolism
  • Tumor Suppressor Proteins / genetics
  • Tumor Suppressor Proteins / metabolism

Substances

  • DLG3 protein, human
  • DLG4 protein, human
  • Disks Large Homolog 4 Protein
  • Intracellular Signaling Peptides and Proteins
  • Membrane Proteins
  • NR1 NMDA receptor
  • NR2A NMDA receptor
  • NR2B NMDA receptor
  • NR2C NMDA receptor
  • NR2D NMDA receptor
  • Nerve Tissue Proteins
  • Neurofilament Proteins
  • Nuclear Proteins
  • Receptors, N-Methyl-D-Aspartate
  • Transcription Factors
  • Tumor Suppressor Proteins
  • neurofilament protein L
  • postsynaptic density proteins
  • DLG2 protein, human
  • Guanylate Kinases