Cochlin (human) (LCCL domain) (rec.)

Cochlin is an extracellular matrix protein expressed in the cochlea and vestibule of the inner ear. Mutations in the cochlin gene are linked to the autosomal-dominant DFNA9 syndrome, a disorder characterized by hearing loss. Cochlin is also expressed in follicular dendritic cells of the spleen and the lymph nodes. The N-terminus of cochlin contains a LCCL domain also present in Factor C, a serine protease of the horseshoe crab Limulus, involved in activating the coagulation cascade in response to LPS. A recent study showed that in response to inflammation, LPS or bacterial infection, cochlin is cleaved by the proteases aggrecanases and secreted into blood circulation. The secreted cochlin (LCCL domain) seems to have a role in local cytokine production, recruitment of immune effector cells and bacterial clearance. Cochlin is secreted as two forms p8 and p18, whereas p18 being the glycosylated form of p8.