Abstract
Dysregulation of the disintegrin-metalloproteinase ADAM10 may contribute to the development of diseases including tumorigenesis and Alzheimer’s disease. The mechanisms underlying ADAM10 sheddase activation are incompletely understood. Here, we show that transient exposure of the negatively charged phospholipid phosphatidylserine (PS) is necessarily required. The soluble PS headgroup was found to act as competitive inhibitor of substrate cleavage. Overexpression of the Ca2+-dependent phospholipid scramblase Anoctamin-6 (ANO6) led to increased PS externalization and substrate release. Transfection with a constitutively active form of ANO6 resulted in maximum sheddase activity in the absence of any stimulus. Calcium-dependent ADAM10 activation could not be induced in lymphocytes of patients with Scott syndrome harbouring a missense mutation in ANO6. A putative PS-binding motif was identified in the conserved stalk region. Replacement of this motif resulted in strong reduction of sheddase activity. In conjunction with the recently described 3D structure of the ADAM10 extracellular domain, a model is advanced to explain how surface-exposed PS triggers ADAM10 sheddase function.
Highlights
Disintegrin-like metalloproteases (ADAMs) control many important cellular functions through the release of membraneanchored molecules from the cell surface (Reiss and Saftig, 2009; Saftig and Reiss, 2011)
Induction of calcium influx e.g. by ionomycin (IO) is the classical pathway leading to PS externalization (Suzuki et al, 2010) and to ADAM10 activation (Maretzky et al, 2015)
BTC shedding was significantly inhibited by broadspectrum metalloprotease inhibitor TAPI-1, the preferential ADAM10 inhibitor GI254023X (GI) (Ludwig et al, 2005), and dosedependently reduced by OPS (Figure 1A)
Summary
Disintegrin-like metalloproteases (ADAMs) control many important cellular functions through the release of membraneanchored molecules from the cell surface (Reiss and Saftig, 2009; Saftig and Reiss, 2011). ADAM10 is the major sheddase of cell adhesion molecules including neuronal (N)-cadherin (Reiss et al, 2005), epithelial (E)-cadherin
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