Regulatory role of Golgi brefeldin A resistance factor-1 in amyloid precursor protein trafficking, cleavage and Aβ formation.

β-amyloid peptide (Aβ) deposition derived from sequential cleavage of the amyloid precursor protein (APP) through the amyloidogenic pathway is an important characteristic feature of Alzheimer's disease (AD). During this process, cellular trafficking plays a crucial role. A large Sec7-domain containing ADP-ribosylation factor guanine nucleotide exchange factor (ARF-GEF), Golgi brefeldin A resistance factor 1 (GBF1) has been reported to initiate the ADP-ribosylation factor (Arf) activation cascade at trans-Golgi network, which plays a crucial function at the endoplasmic reticulum-Golgi interface. In this study, we investigated the role of GBF1 in APP transmembrane transport and Aβ formation. Using APP/PS1 (presenilin 1) overexpressing transgenic mice, we demonstrate that GBF1 has upregulated the expression of APP, indicating a role for GBF1 in APP physiological process. Knocking down of GBF1 using small interfering has significantly increased the intracellular but not the surface expression of APP. In contrast, overexpression of wild-type (WT) and guanine nucleotide exchange factor (GEF) in the activated form but not the GEF deficient mutation induced continuous activation of GBF1, which subsequently increased the surface level of APP. Interestingly, inhibition of GBF1 by c(BFA) also impaired APP trafficking and induced endoplasmic reticulum (ER) stress in SH-SY5Y cells. Our results thus for identified the role of GBF1 in APP trafficking and cleavage, and provide evidence for GBF1 as a possible therapeutic target in AD.