The Metalloprotease ‘A Disintegrin and Metalloprotease 10’ (ADAM10) undergoes rapid, post-lysis autocatalytic degradation

The transmembrane protein ‘a disintegrin and metalloprotease 10’ (ADAM10) has key physiological functions, e.g. during embryonic development and in the brain. During transit through the secretory pathway, immature ADAM10 (proADAM10) is converted to its proteolytically active, mature form (mADAM10). Increasing or decreasing the abundance/activity of mADAM10 is considered a therapeutic approach for diseases, such as Alzheimer’s disease and cancer. Yet, biochemical detection and characterization of mADAM10 has been difficult. In contrast, proADAM10 is readily detected, e.g. in immunoblots, suggesting that mADAM10 is only a minor fraction of total cellular ADAM10. Here, we demonstrate that mADAM10, but not proADAM10 unexpectedly undergoes rapid, time-dependent degradation upon biochemical cell lysis in different cell lines and in primary neurons, preventing the detection of the majority of mADAM10 in immunoblots. This degradation required the catalytic activity of ADAM10, was efficiently prevented by adding active-site inhibitors to the lysis buffer and did not affect proADAM10, suggesting that ADAM10 degradation occurred in an intramolecular and autoproteolytic manner. Inhibition of post-lysis autoproteolysis demonstrated efficient cellular ADAM10 maturation with higher levels of mADAM10 than of proADAM10. Moreover, a cycloheximide chase experiment revealed that mADAM10 is a long-lived protein with a half-life of around 12 hours. In summary, this study demonstrates that mADAM10 autoproteolysis must be blocked to allow proper detection of the mature mADAM10, which is essential for the correct interpretation of biochemical and cellular studies of ADAM10.