Phospholipase D1 corrects impaired βAPP trafficking and neurite outgrowth in familial Alzheimer's disease-linked presenilin-1 mutant neurons

Presenilins (PS1/PS2) regulate proteolysis of β-amyloid precursor protein (βAPP) and affect its intracellular trafficking. Here, we demonstrate that a PS1-interacting protein, phospholipase D1 (PLD1), affects intracellular trafficking of βAPP. Overexpression of PLD1 in PS1wt cells promotes generation of βAPP-containing vesicles from the trans-Golgi network. Conversely, inhibition of PLD1 activity by 1-butanol decreases βAPP trafficking in both wt and PS1-deficient cells. The subcellular localization of PLD1 is altered, and PLD enzymatic activity is reduced in cells expressing familial Alzheimer's disease (FAD) PS1 mutations compared with PS1wt cells. Overexpression of wt, but not catalytically inactive, PLD1 increases budding of βAPP-containing vesicles from the trans-Golgi network in FAD mutant cells. Surface delivery of βAPP is also increased by PLD1 in these cells. The impaired neurite outgrowth capacity in FAD mutant neurons was corrected by introducing PLD1 into these cells. The results indicate that PLD1 may represent a therapeutic target for rescuing compromised neuronal function in AD.