The Role of the Anti-Amyloidogenic Secretase ADAM10 in Shedding the APP-like Proteins

: ADAM10 (A disintegrin and metalloproteinase 10) has been demonstrated as an enzyme with protective properties in Alzheimer's disease: in mouse models it not only lowered generation of toxic A-beta peptides and formation of senile plaques but also alleviated learning deficits and enhanced synaptic density. This is due to cleavage of the amyloid precursor protein (APP) within its A-beta stretch and to the release of the extracellular domain of APP with neuroprotective function. Aside from cleaving APP, ADAM10 has been linked to over 40 putative substrates at least in cell culture. These substrates are connected with important cellular functions such as cell migration, stress response and transport. For this contribution we focussed on ADAM10 acting on the APP-like proteins since for some of their representatives - in particular APLP2 and APP-L - a shedding by ADAM10 has been demonstrated in vivo. In addition, the importance of these proteins, especially of APLP2, has been repeatedly shown by intense analysis of double and triple transgenic mice which lack APP in combination with one or both APLPs: several phenotypes such as defects in migration of neuroblasts, in formation of synapses and synaptic transmission have been reported. However, the specific contribution of either the uncleaved full-length proteins or their extracellular domains secreted upon ADAM10 activity has not been elucidated. In this review, we report on recent findings concerning shedding of APP-like proteins and resulting functional consequences.