PB0368 - Proteomics demonstrate differences in protein lifespan regulation in platelets from adult and pediatric donors

Background: Differences between platelet functioning in adults and children have been reported previously. Such differences include hyper-responsiveness to stimulation for children platelets or different pattern for granule secretion. However, the possible origin of these differences was not determined.

Aims: Here we aim to determine differences in functionality in platelets from adult and pediatric donors by means of proteomics and continuous flow cytometry.

Methods: Platelet proteomics and analysis of functional responses were performed for two cohorts of healthy donors: 4 adults (23.5±2.6 years) and 4 children (13.0±3.6 years). Conventional platelet responses to stimulation with ADP, PAR1AP or collagen related peptide (CRP) were measured by continues and end-point flow cytometry. For proteomics analysis washed platelets were used. Platelet protein lysates were analysed using LC-Orbitrap MS. The analysis of raw data was performed by MaxQuant software. The resulting relative abundances analysis was performed in Python 3.7. In addition, a UniProt-based and Gene Ontology (GO) – based study was conducted.

Results: Differences in functional responses between adult and pediatric platelets were shown both for resting state and after stimulation. We performed label-free quantitative proteomics to detect protein abundances. We selected age-specific proteins that have significant >2-fold difference in copy number between adult and pediatric groups. It appears that selected proteins are more abundant in children donors, than adult. GO-based analysis showed high levels of ribosome-related proteins (P08865, P06730, P22626) along with proteosome subunits (P60900, P49720, P25788, P25789) and proteins related to the intracellular vesicle transport (Q9NRW1, Q9H0U4, O75396, etc.).

Conclusion(s): Preliminary results suggest, that the vesicle trafficking and proteosome proteins differ the most between the groups. This may indicate specific regulation of protein content by platelets due to total high initial concentration of proteins. All parts of this study were supported by the Russian Science Foundation grant 21-74-20087.