Int J Mol Sci 2026 Jul 15;2714:. doi: 10.3390/ijms27146292.

Proteomic Profiling of Density-Gradient Fractions Reveals Candidate Cell Surface Markers in Subpopulations of Starfish Asterias rubens Coelomocytes and Coelomic Epithelial Cells.

???displayArticle.abstract???
Cell surface markers are essential for lineage tracing and for understanding cellular mechanisms of regeneration, yet they remain largely unavailable for echinoderms. Using the starfish Asterias rubens as a model for physiological coelomocyte renewal, we combined Percoll density-gradient fractionation with label-free LC-MALDI proteomics to identify candidate surface proteins that distinguish subpopulations of coelomocytes and coelomic epithelium (CE) cells. However, LC-MALDI is prone to signal variability, sample depletion and nonlinear response. To address the quantitative limitations of LC-MALDI, we implemented a chi-square test with an empirically derived probability density function, which we validated on control mixtures, achieving high precision. Four fractions enriched in distinct cell types were analyzed: coelomocyte fractions 1 (roundish cells) and 4 (large agranulocytes that form cell nets) and CE fractions 1 (type 2 small CE cells) and 4 (ciliated cells), together with a weakly attached CE subpopulation enriched in small putative progenitor cells. LC-MALDI identified 714 protein groups, of which 160 showed significant differential abundance across fractions. Functional enrichment revealed actin cytoskeleton and integrin signaling in coelomocytes, and catenin-related terms in CE-W. Among the 101 predicted membrane proteins, 31 candidate cell surface markers were selected. These include integrins α8β1 and α9β1, three-finger proteins, scavenger receptors, and low-density lipoprotein receptor-related proteins, as well as metallopeptidases. This work provides the first proteome-scale set of candidate surface markers for starfish cell subpopulations, enabling future lineage-tracing studies to resolve the origin of coelomocytes from the coelomic epithelium.

???displayArticle.pubmedLink??? 42511633
???displayArticle.pmcLink??? PMC13409769
???displayArticle.link??? Int J Mol Sci