CD44 antigen

CD44 antigen is a cell-surface receptor that mediates cell-cell interactions, adhesion, and migration by engaging extracellular matrix components including hyaluronan, collagen, and growth factors (UniProt: P16070). It assembles signaling complexes containing receptor kinases and membrane proteases that coordinate pathways promoting calcium mobilization and cytoskeleton reorganization, and activates downstream signaling upon ligand binding to promote immune cell activation. The protein participates broadly in T-lymphocyte homing, hematopoiesis, inflammation, and bacterial infection response.

CD44 is expressed across tissues and functions as a platform for signal transduction in multiple physiological contexts (UniProt: P16070). No specific disease associations are documented in UniProt's curated disease field for this entry.

CD44 shows increased expression in Alzheimer's disease brain tissue. Proteomics analysis of human post-mortem AD brain compared to age-matched controls detected CD44 as upregulated (mean log2 fold-change: 1.64) across subcellular fractions using TMT-labeled tandem mass spectrometry (Chaparral AD proteomics). This elevation may reflect altered neuroinflammatory responses or changes in cell adhesion dynamics characteristic of AD pathology.