Regulation of ADAM10 activity through microdomain-dependent intracellular calcium changes.

A disintegrin and metalloproteinases (ADAMs) are transmembrane proteases that cleave other proteins close to the surface in a process called shedding. The prominent member ADAM10 has been linked to several pathologies such as Alzheimer's disease, bacterial infection, cancer development and metastasis. Although the regulation of the ADAM10 activity by calcium influx and calmodulin inhibition has been reported, the spatiotemporal regulation of Ca²⁺-dependent ADAM10 activation and the required source of Ca²⁺ ions have not been thoroughly studied. In the present study, we observed the rapid Ca²⁺-dependent activation of ADAM10 in A549 lung carcinoma cells upon stimulation with ionomycin. The calmodulin-inhibitors trifluoperazine and ophiobolin A mediated delayed activation of ADAM10, which apparently did not depend on intracellular Ca²⁺ in the case of trifluoperazine. Furthermore, the surface translocation and release of ADAM10 in extracellular vesicles exhibited different kinetics and were only partially linked to catalytic activation. Finally, ADAM10 activation was observed after the entry of Ca²⁺ through certain channels, such as canonical members of transient receptor potential (TRP) channels. Therefore, the opening of particular channels for Ca²⁺ entry points and subsequent Ca²⁺ flux as well as the temporal aspects of the consequent increase in Ca²⁺ levels, must be considered for future therapeutic options involving the increasing or decreasing ADAM10 activity.