Extracellular glycoprotein lacritin (LACRT)

Lacritin is a secreted extracellular glycoprotein (molecular weight ~12–14 kDa) encoded by the LACRT gene, mainly present in the tear film and produced by the lacrimal gland, with additional expression in the meibomian gland and ocular surface epithelia. Its functions include stimulating tear secretion, promoting cell proliferation and survival, supporting regeneration and healing of the corneal epithelium and nerves, and protecting against stress and inflammation. Lacritin binds the heparan sulfate proteoglycan syndecan-1 (after cleavage by heparanase) and signals through mitogenic and cell survival pathways, potentially involving a G-protein-coupled receptor. Splice variants and C-terminal proteolytic fragments of lacritin exist, with unique functional properties. Topical bioactive lacritin peptides (such as Lacripep) are being studied as novel treatments for dry eye disease, where endogenous lacritin is pathologically reduced. As a biotherapeutic, lacritin’s restoration may help address ocular surface instability, provide bactericidal activity, and serve as a clinical biomarker of tear function and epithelial health

Other names

LacritinLACRTLACRITINextracellular glycoprotein lacritinLACRT; historically also referred by splice variants names such as lacritin-blacritin-c

Lacritin (or its C-terminal peptides such as Lacripep) binds to the surface heparan sulfate proteoglycan syndecan-1 (SDC1), after heparanase cleavage exposes the core protein, facilitating cell targeting. Stimulates tear secretion via a G-protein-coupled receptor signaling pathway (candidate GPCR under study), activating downstream pathways such as NFAT and mTOR for proliferation, and AKT/FOXO3 for stress survival and autophagy. Restores epithelial and neural health through direct mitogenic and regenerative signaling.