Lacritin (LACRT)

Lacritin is a 12.3 kDa glycoprotein encoded in humans by the LACRT gene. Lacritin is a secreted protein found in tears and saliva. Lacritin also promotes tear secretion and proliferation of some epithelial cells.

Lacritin is thus a prosecretory mitogen. Most lacritin is produced by the lacrimal gland. Some lacritin is produced by the meibomian gland, and also by epithelial cells of the conjunctiva and cornea. Together these epithelia comprise much of the lacrimal functional unit (LFU). Dry eye is the most common disease of the LFU. Preliminary studies with small trials suggest that lacritin may be differentially downregulated in dry eye. Topical lacritin promotes tearing in rabbit preclinical studies. Lacritin cell targeting is dependent on the cell surface heparan sulfate proteoglycan syndecan-1 (SDC1).