Presenilin-1 is indirectly implicated in Notch1 cleavage

It has been previously demonstrated that the Notch1 signalling pathway is impaired in presenilin-1 null cells. This observation suggests a role for presenilin-1 in the Notch1 developmental pathway, possibly through physical interaction. Here, we show that presenilin-1 and Notch1 do not interact directly with each other but are associated in the cell. These findings raise the possibility that the gamma-secretase cleavage occurs via a presenilin complex in association with a putative co-factor specific for the molecule that is being cleaved (e.g. Notch1, (beta-amyloid precursor protein, E-cadherin and ErbB-4, all of which are gamma-secretase substrates).