Cosmosiin Increases ADAM10 Expression via Mechanisms Involving 5'UTR and PI3K Signaling.

Zhuo Min,Bing-Lin Zhu,Jing-Si Zha,Xiao-Tong Hu,Ying Tang,Xiao-Juan Deng,Zhen Yan,Guo-Jun Chen,Yuan-Lin Ma

doi:10.3389/fnmol.2018.00198

Abstract

The α-secretase “a disintegrin and metalloproteinase domain-containing protein” (ADAM10) is involved in the processing of amyloid precursor protein (APP). Upregulation of ADAM10 precludes the generation of neurotoxic β-amyloid protein (Aβ) and represents a plausible therapeutic strategy for Alzheimer’s disease (AD). In this study, we explored compounds that can potentially promote the expression of ADAM10. Therefore, we performed high-throughput small-molecule screening in SH-SY5Y (human neuroblastoma) cells that stably express a luciferase reporter gene driven by the ADAM10 promoter, including a portion of its 5’-untranslated region (5’UTR). This has led to the discovery of cosmosiin (apigenin 7-O-β-glucoside). Here, we report that in human cell lines (SH-SY5Y and HEK293), cosmosiin proportionally increased the levels of the immature and mature forms of the ADAM10 protein without altering its mRNA level. This effect was attenuated by translation inhibitors or by deleting the 5’UTR of ADAM10, suggesting that a translational mechanism was responsible for the increased levels of ADAM10. Luciferase deletion assays revealed that the first 144 nucleotides of the 5’UTR were necessary for mediating the cosmosiin-induced enhancement of ADAM10 expression in SH-SY5Y cells. Cosmosiin failed to increase the levels of the ADAM10 protein in murine cells, which lack native expression of the ADAM10 transcript containing the identified 5’UTR element. The potential signaling pathway may involve phosphatidylinositide 3-kinase (PI3K) because pharmacological inhibition of PI3K attenuated the effect of cosmosiin on the expression of the ADAM10 protein. Finally, cosmosiin attenuated Aβ generation because the levels of Aβ40/42 in HEK-APP cells were significantly reduced after cosmosiin treatment. Collectively, we found that the first 144 nucleotides of the ADAM10 5’UTR, and PI3K signaling, are involved in cosmosiin-induced enhancement of the expression of ADAM10 protein. These results suggest that cosmosiin may be a potential therapeutic agent in the treatment of AD.

Highlights

a disintegrin and metalloproteinase domain-containing protein (ADAM10) belongs to the type I transmembrane protease family that plays an important role in various cellular functions including neurogenesis, angiogenesis, heart development and fertilization (Moss et al, 2007; Edwards et al, 2008; Pruessmeyer and Ludwig, 2009; Jouannet et al, 2016)
The ratio of m-ADAM10 to im-ADAM10 was not changed by cosmosiin (Figure 1A), suggesting that cosmosiin did not affect the maturation of ADAM10
Time-course experiments showed that the enhancement of ADAM10 protein levels started at 12 h and lasted for up to 48 h in SH-SY5Y cells treated with cosmosiin, while the ratio of m-ADAM10 / im-ADAM10 remained unchanged (Figure 1C)

Summary

Introduction

ADAM10 belongs to the type I transmembrane protease family that plays an important role in various cellular functions including neurogenesis, angiogenesis, heart development and fertilization (Moss et al, 2007; Edwards et al, 2008; Pruessmeyer and Ludwig, 2009; Jouannet et al, 2016). The amyloid precursor protein (APP) is one of the major targets of ADAM10 (Kuhn et al, 2010). Sequential proteolytic processing of APP by β-secretase 1 (BACE1) and γ-secretase generates the pathogenic β-amyloid protein (Aβ), which plays causative role in Alzheimer’s disease (AD; De Strooper et al, 2010). The α-secretase ADAM10 cleaves APP to form the soluble APPα (sAPPα) and α-COOH-terminal fragment (α-CTF), precluding the generation of Aβ (Postina, 2012). ADAM10 can decrease the Aβ load in mouse models of AD (Postina et al, 2004; Schroeder et al, 2009). Impaired ADAM10 trafficking generates a model of sporadic AD (Epis et al, 2010). Studies conducted with human AD patients show deficits in the expression of ADAM10 (Marcinkiewicz and Seidah, 2000). Upregulation of ADAM10 represents a promising therapeutic strategy for AD (Endres and Fahrenholz, 2010; Lichtenthaler, 2011)

Methods

Results

Conclusion