Secretome

The secretome is the collection of proteins and other molecules secreted by a cell, tissue, or organism into the extracellular space and body fluids. It includes proteins released through the classical secretory pathway, as well as those secreted via non-classical routes that lack a signal peptide. In many studies, the secretome also encompasses cargo carried by extracellular vesicles, such as exosomes and microvesicles.

Secreted components include cytokines, chemokines, growth factors, enzymes, hormones, extracellular matrix proteins, soluble receptors, and vesicle-associated proteins. Through these mediators, the secretome drives intercellular communication, tissue remodeling, immune responses, development, and tissue homeostasis. Abnormal secretome signaling has been linked to diseases such as cancer, fibrosis, and inflammatory conditions.

Investigations of the secretome commonly employ proteomic and secretome profiling approaches, often using mass spectrometry. Culturing cells in serum-free or defined media helps reduce background from serum proteins. Secreted proteins may be enriched by concentration methods or affinity capture, and bioinformatic prediction distinguishes classical secreted proteins with signal peptides from non-classical secreted proteins.

Challenges in secretome analysis include contamination from lysed cells, variability with cell type and condition, and the dynamic, context-dependent nature of secretion. Nevertheless, secretome data are used in biomarker discovery, understanding disease mechanisms, and identifying potential therapeutic targets.