Inhibition of GSK3β-mediated BACE1 expression reduces Alzheimer-associated phenotypes
Philip T.T. Ly, … , James Woodgett, Weihong Song
Philip T.T. Ly, … , James Woodgett, Weihong Song
Published December 3, 2012
Citation Information: J Clin Invest. 2013;123(1):224-235. https://doi.org/10.1172/JCI64516.
View: Text | PDF
Research Article Neuroscience

Inhibition of GSK3β-mediated BACE1 expression reduces Alzheimer-associated phenotypes

Abstract

Deposition of amyloid β protein (Aβ) to form neuritic plaques in the brain is the pathological hallmark of Alzheimer’s disease (AD). Aβ is generated from sequential cleavages of the β-amyloid precursor protein (APP) by the β- and γ-secretases, and β-site APP-cleaving enzyme 1 (BACE1) is the β-secretase essential for Aβ generation. Previous studies have indicated that glycogen synthase kinase 3 (GSK3) may play a role in APP processing by modulating γ-secretase activity, thereby facilitating Aβ production. There are two highly conserved isoforms of GSK3: GSK3α and GSK3β. We now report that specific inhibition of GSK3β, but not GSK3α, reduced BACE1-mediated cleavage of APP and Aβ production by decreasing BACE1 gene transcription and expression. The regulation of BACE1 gene expression by GSK3β was dependent on NF-κB signaling. Inhibition of GSK3 signaling markedly reduced Aβ deposition and neuritic plaque formation, and rescued memory deficits in the double transgenic AD model mice. These data provide evidence for regulation of BACE1 expression and AD pathogenesis by GSK3β and that inhibition of GSK3 signaling can reduce Aβ neuropathology and alleviate memory deficits in AD model mice. Our study suggests that interventions that specifically target the β-isoform of GSK3 may be a safe and effective approach for treating AD.

Authors

Philip T.T. Ly, Yili Wu, Haiyan Zou, Ruitao Wang, Weihui Zhou, Ayae Kinoshita, Mingming Zhang, Yi Yang, Fang Cai, James Woodgett, Weihong Song

×

Figure 2

GSK3β, but not GSK3α, regulates BACE1 gene expression and APP processing.

Options: View larger image (or click on image) Download as PowerPoint
GSK3β, but not GSK3α, regulates BACE1 gene expression and APP processing...
(A) SH-SY5Y human neuroblastoma cells were transfected with scrambled GSK3α or GSK3β isoform–specific siRNA. RNA was extracted, and semiquantitative RT-PCR was performed to measure endogenous human BACE1, GSK3A, GSK3B, and β-actin mRNA levels with specific primers recognizing the coding sequence of each gene. PCR products after 28 cycles were analyzed on 1.2% agarose gel. (B) Endogenous BACE1 mRNA was significantly reduced with GSK3β, but not GSK3α, isoform–specific knockdown. The values are expressed as mean ± SEM. n = 3; *P < 0.05, Student’s t test. (C) 20E2 cells were transfected with scrambled or GSK3α, or GSK3β isoform–specific siRNA while cotreated with L685,458 to block γ-secretase activity. Full-length APP and CTF fragments were detected with C20 antibody. GSK3α and GSK3β were detected using a monoclonal GSK3α/β antibody. GSK3α and GSK3β isoforms were selectively reduced by the isoform-specific siRNA. β-Actin served as an internal control and was detected using a monoclonal anti–β-actin antibody, AC-15. (D) GSK3β-specific knockdown significantly reduced C99 levels. GSK3α-specific knockdown did not have any significant effect. The values are expressed as mean ± SEM. n = 4; *P < 0.05, Student’s t test. (E) Tetracycline-regulated SHSY5Y cells were induced to express constitutively active S9A-GSK3β. Endogenous human BACE1 mRNA levels were assessed as described above. Tetracyline-induced S9A-GSK3β significantly increased BACE1 expression. (F) Quantification of the endogenous BACE1 mRNA level. Values are expressed as mean ± SEM. n = 4; *P < 0.05, Student’s t test.