Brain Proteomics

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proteins common to both cohorts, the importance of extended granin family

proteins was highlighted [65]. Moreover, recently different workflow applica-

tions have greatly improved the protein profile in CSF. Despite the disadvan-

tages of biofluid proteomics, such as low measurement sensitivity and limited

proteome depth, 1400 CSF proteins were identified in a single analysis with

very small amounts of CSF samples. Thus, with the high protein count and

reproducibility in the study, a workflow is presented showing that MS-based

proteomics is a powerful technology for biomarker discovery in biofluids [18].

Additionally, intense efforts have been directed towards plasma, serum

exosome, urine, saliva, tears, and organelle proteomics in the hope of finding

specific biomarkers [66–71]. Chitinase-3-like protein 1 (CHI3L1) and thymosin

beta-4 (TMSB4X) were most significantly altered in the plasma proteome,

while 14 targetable proteins were reported in the serum exosome, including

Apolipoprotein J, pigment epithelium-derived factor (PEDF), and gelsolin

[66, 67]. In the study investigating the salivary proteome, it was hypothesized

that there may be protein markers reflected in saliva before the onset of motor

symptoms in PD. In the light of the findings, it was reported that a decrease

in the levels of proteins playing a role in inflammatory processes, exosome

formation and adipose tissue formation, and it was suggested that the inflam-

mation associated with PD pathology may be reflected in the saliva profile

[69]. The protein profile results of tears, which are rarely investigated in pro-

teomic studies, are also very interesting. In addition to the results supporting

dry eye syndrome-like pathology in PD, it has been revealed that there are

irregularities in proteins that play a role in lipid metabolism, oxidative stress,

vesicle secretion and immune response, specific to PD [70].

Organelle proteomics studies, which provide more specific data, also pro-

vide important information about the pathogenesis of PD. A new strategy for

Mitochondrial Degradoma has been developed in which the N-terminal pep-

tides are enriched by the dimethylation-TAILS approach after isolating the

mitochondrial subcellular fraction In the study showing the effects of changing

dopamine homeostasis on the mitochondrial N-terminome using this strategy,

it was reported that neprilysin may be a candidate for mitochondrial protease

indicating mitochondrial dysfunction [71].

10.6.3

Schizophrenia

Schizophrenia is a serious neuropsychiatric disease that negatively affects so-

cial life. Since its diagnosis is based on the subjective evaluation of clinical

symptoms, it can be confused with different types of diseases such as bipolar

disorder. Although genomic studies reveal some rare mutations in schizophre-

nia, there are significant deficiencies in the diagnosis and classification of

the disease [72]. Although fewer reports have been stated on schizophrenia

compared to Alzheimer’s and Parkinson’s, proteomic studies provide impor-

tant contributions to the molecular pathogenesis, diagnosis, and treatment of