Presenilin-1 uses phospholipase D1 as a negative regulator of β-amyloid formation

Presenilin (PS1/PS2) is a major component of γ-secretase, the activity that mediates proteolysis of β-amyloid precursor protein to generate β-amyloid (Aβ). Here we demonstrate that PS1, through its loop region, binds to phospholipase D1 (PLD1), thereby recruiting it to the Golgi/trans-Golgi network. Overexpression of wild-type PLD1 reduces Aβ generation. Conversely, down-regulation of endogenous PLD1 by small hairpin RNA elevates Aβ production. The Aβ-lowering effect of PLD1 is independent of its ability to promote vesicular budding of β-amyloid precursor protein. The data indicate that overexpression of PLD1 decreases, and down-regulation of PLD1 increases, the catalytic activity, and the association of the subunits, of γ-secretase.