The metalloprotease ADAM10 is required for notch1 S2 cleavage.
van Tetering G, van Diest P, Verlaan I, van der Wall E, Kopan R, Vooijs M.
JBC Papers in Press published on September 2, 2009 as doi:10.1074/jbc.M109.006775
Notch signaling is controlled by ligand binding which unfolds a negative control region to induce proteolytic cleavage of the receptor. First, a membrane proximal cleavage is executed by a metalloprotease, removing the extracellular domain. This allows gamma-secretase to execute a second cleavage within the Notch transmembrane domain which releases the intracellular domain to enter the nucleus. Here we show that the ADAM10 metalloprotease Kuzbanian, but not ADAM17/TACE, plays an essential role in executing ligand induced extracellular cleavage at site 2 (S2) in cells and localize this step to the plasma membrane. Importantly, genetic or pharmacological inhibition of metalloproteases still allowed extracellular cleavage of Notch, indicating the presence of unknown proteases with the ability to cleave at S2. Gain of function mutations identified in human cancers and in model organisms that map to the negative control region alleviate the requirement for ligand binding for extracellular cleavage to occur. Since cancer-causing Notch1 mutations also depend on (rate-limiting) S2 proteolysis, the identity of these alternative proteases have important implications for understanding Notch activation in normal and cancer cells.
