Expanding the cerebrospinal fluid endopeptidome

Area of Science:

• Neuroscience
• Proteomics
• Biochemistry

Background:

• Neurodegenerative disorders require reliable biomarkers for diagnosis and monitoring.
• Cerebrospinal fluid (CSF) proteomic and peptidomic analysis is a promising avenue for biomarker identification.

Purpose of the Study:

• To create an extensive inventory of the human CSF endopeptidome.
• To establish a foundation for future targeted biomarker studies in neurodegenerative diseases.

Main Methods:

• Off-line sample prefractionation using high-pH reversed-phase high-performance liquid chromatography (RP HPLC).
• Low-pH nano-liquid chromatography-mass spectrometry (LC-MS) analysis.
• Comparison of different software programs and scoring algorithms for peptide identification.

Main Results:

• Identification of 18,031 endogenous peptides at a 1% false discovery rate (FDR), a 10-fold increase in known CSF peptides.
• Peptides originated from 2,053 proteins, with over 60 linked to neurodegeneration.
• Specific findings include tau protein peptides (some spanning diagnostic marker Threonine-181), amyloid precursor protein peptides (including those within amyloid-beta 1-40/42 sequences), and apolipoprotein E peptides differentiating isoforms.

Conclusions:

• The study significantly expands the catalog of endogenous CSF peptides.
• This comprehensive CSF peptidome dataset is valuable for identifying novel biomarkers for neurodegenerative disorders.
• The identified peptides offer potential for improved diagnosis, disease monitoring, and understanding of disease mechanisms.