Targeted Multiplexed Selected Reaction Monitoring Analysis Evaluates Protein Expression Changes of Molecular Risk Factors for Major Psychiatric Disorders

Abstract

Background:Extensive research efforts have generated genomic, transcriptomic, proteomic, and functional data hoping to elucidate psychiatric pathophysiology. Selected reaction monitoring, a recently developed targeted proteomic mass spectrometric approach, has made it possible to evaluate previous findings and hypotheses with high sensitivity, reproducibility, and quantitative accuracy.Methods:Here, we have developed a labelled multiplexed selected reaction monitoring assay, comprising 56 proteins previously implicated in the aetiology of major psychiatric disorders, including cell type markers or targets and effectors of known psychopharmacological interventions. We analyzed postmortem anterior prefrontal cortex (Brodmann area 10) tissue of patients diagnosed with schizophrenia (n=22), bipolar disorder (n=23), and major depressive disorder with (n=11) and without (n=11) psychotic features compared with healthy controls (n=22).Results:Results agreed with several previous studies, with the finding of alterations of Wnt-signalling and glutamate receptor abundance predominately in bipolar disorder and abnormalities in energy metabolism across the neuropsychiatric disease spectrum. Calcium signalling was predominantly affected in schizophrenia and affective psychosis. Interestingly, we were able to show a decrease of all 4 tested oligodendrocyte specific proteins (MOG, MBP, MYPR, CNPase) in bipolar disorder and to a lesser extent in schizophrenia and affective psychosis. Finally, we provide new evidence linking ankyrin 3 specifically to affective psychosis and the 22q11.2 deletion syndrome-associated protein septin 5 to schizophrenia.Conclusions:Our study highlights the potential of selected reaction monitoring to evaluate the protein abundance levels of candidate markers of neuropsychiatric spectrum disorders, providing a high throughput multiplex platform for validation of putative disease markers and drug targets.

Proteomic systems evaluation of the molecular validity of preclinical psychosis models compared to schizophrenia brain pathology

“…Once such candidate biomarkers have been identified, SRM can be applied to analyze protein abundance levels of these markers in tissue in a quantitative manner. We have previously reported on this in a study of anterior prefrontal cortex tissue from patients with SCZ, bipolar disorder and major depressive disorder, in which the expression levels were quantified for a panel of 56 proteins suggested to be associated with various functional aspects of these disorders, including for example alterations in cellular energy metabolism and dysfunction of neuronal differentiation (Wesseling et al, 2015a). It is interesting to note that despite precautions of introducing a speciesspecific bias (e.g.…”

Microglial Gene Expression Alterations in the Brains of Patients with Psychiatric Disorders

“…Patients with bipolar disorder and major depressive disorder had significant reductions in the TNFR2 mRNA expression in the dorsolateral prefrontal cortex without a reduction in the anterior cingulate cortex levels [67]. Additionally, microgliaspecific actin-binding protein coronin-1a (CORO1A) [71] was decreased in the anterior prefrontal cortices of patients with major depressive disorder [72].…”

“…In addition to the molecules related to M1 and M2 microglia, S100A8-and S100A9-positive microglia are observed in brain samples following cerebral infarction and other neurological disorders [72,73]. S100A8 and S100A9 belong to the macrophagerelated protein-100 family of calcium binding proteins, which inhibit pro-inflammatory functions [61][62][63].…”

Altered apolipoprotein C expression in association with cognition impairments and hippocampus volume in schizophrenia and bipolar disorder

“…Tryptic digested proteins were quantified using Waters Xevo Triple quadrupole coupled to a nanoAcquity UPLC system (Waters Corporation, UK) and operated in the multiple reaction monitoring (MRM) mode as described previously (Wesseling, Gottschalk, & Bahn, 2014). The LC buffer system was as follows: mobile phase A, 0.1% formic acid and mobile phase B, 0.1% formic acid in acetonitrile.…”

“…Briefly, unique peptides and fragment ions for each targeted proteins were selected as described previously (Wesseling et al, 2014). The peptides were then quantified along with spiked stable-isotope-labeled internal standards of the same sequence.…”