Protein S100-A4

S100-A4 is a small calcium-binding protein (101 amino acids) that regulates multiple cellular processes including cell motility, angiogenesis, differentiation, and apoptosis (UniProt: P26447). It enhances cell invasiveness and chemotaxis by promoting non-muscle myosin IIA filament dynamics and serves as an extracellular chemoattractant for T-lymphocytes through CCR5 and CXCR3 signaling pathways.

S100-A4 is expressed across various tissues and participates in both intracellular and extracellular signaling, with roles in cytokine production and immune cell recruitment. It also modulates the pro-apoptotic function of TP53 through direct nuclear binding (UniProt: P26447).

In Alzheimer's disease, S100-A4 is significantly upregulated in post-mortem AD brain tissue compared to age-matched controls, with a mean log2 fold-change of 0.97 (Chaparral AD proteomics). This elevation was detected across subcellular fractions in TMT-labeled proteomics analysis, suggesting potential involvement in AD-associated neuroinflammatory or cellular stress response pathways.