Altered functional protein networks in the prefrontal cortex and amygdala of victims of suicide

PLoS One. 2012;7(12):e50532. doi: 10.1371/journal.pone.0050532. Epub 2012 Dec 6.

Abstract

Probing molecular brain mechanisms related to increased suicide risk is an important issue in biological psychiatry research. Gene expression studies on post mortem brains indicate extensive changes prior to a successful suicide attempt; however, proteomic studies are scarce. Thus, we performed a DIGE proteomic analysis of post mortem tissue samples from the prefrontal cortex and amygdala of suicide victims to identify protein changes and biomarker candidates of suicide. Among our matched spots we found 46 and 16 significant differences in the prefrontal cortex and amygdala, respectively; by using the industry standard t test and 1.3 fold change as cut off for significance. Because of the risk of false discoveries (FDR) in these data, we also made FDR adjustment by calculating the q-values for all the t tests performed and by using 0.06 and 0.4 as alpha thresholds we reduced the number of significant spots to 27 and 9 respectively. From these we identified 59 proteins in the cortex and 11 proteins in the amygdala. These proteins are related to biological functions and structures such as metabolism, the redox system, the cytoskeleton, synaptic function, and proteolysis. Thirteen of these proteins (CBR1, DPYSL2, EFHD2, FKBP4, GFAP, GLUL, HSPA8, NEFL, NEFM, PGAM1, PRDX6, SELENBP1 and VIM,) have already been suggested to be biomarkers of psychiatric disorders at protein or genome level. We also pointed out 9 proteins that changed in both the amygdala and the cortex, and from these, GFAP, INA, NEFL, NEFM and TUBA1 are interacting cytoskeletal proteins that have a functional connection to glutamate, GABA, and serotonin receptors. Moreover, ACTB, CTSD and GFAP displayed opposite changes in the two examined brain structures that might be a suitable characteristic for brain imaging studies. The opposite changes of ACTB, CTSD and GFAP in the two brain structures were validated by western blot analysis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Amygdala / metabolism*
  • Autopsy
  • Biomarkers / metabolism
  • Brain / metabolism
  • Brain / pathology
  • Brain Mapping / methods
  • Cytoskeleton / metabolism
  • Databases, Factual
  • False Positive Reactions
  • Glial Fibrillary Acidic Protein / metabolism
  • Humans
  • Male
  • Middle Aged
  • Models, Statistical
  • Peptides / chemistry
  • Prefrontal Cortex / metabolism*
  • Protein Isoforms
  • Proteomics / methods
  • Reproducibility of Results
  • Suicide*

Substances

  • Biomarkers
  • Glial Fibrillary Acidic Protein
  • Peptides
  • Protein Isoforms

Grants and funding

This work was supported by the FP-7 Health EC project 201 159 (Memoload), the Social Renewal Operational Programme (TÁMOP-4.2.2/08/1) to G. Juhász, K.F. Medzihradszky and B. Penke; the Economic Competitiveness Operational Programme (GVOP-3.2.1.-2004-04-0309) to G. Juhász, the Social Renewal Operational Programme (TÁMOP 4.2.1./B-09/1/KMR-2010-0003) to G. Juhász, A. Czurkó and K.A. Kékesi and NKTH EGISPSYCH grant to B. Penke, G. Juhász and A. Czurkó. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.