Microarray analysis on human neuroblastoma cells exposed to aluminum, β(1-42)-amyloid or the β(1-42)-amyloid aluminum complex

Abstract

Background: A typical pathological feature of Alzheimer's disease (AD) is the appearance in the brain of senile plaques made up of β-amyloid (Aβ) and neurofibrillary tangles. AD is also associated with an abnormal accumulation of some metal ions, and we have recently shown that one of these, aluminum (Al), plays a relevant role in affecting Aβ aggregation and neurotoxicity.

Methodology: In this study, employing a microarray analysis of 35,129 genes, we investigated the effects induced by the exposure to the Aβ(1-42)-Al (Aβ-Al) complex on the gene expression profile of the neuronal-like cell line, SH-SY5Y.

Principal findings: The microarray assay indicated that, compared to Aβ or Al alone, exposure to Aβ-Al complex produced selective changes in gene expression. Some of the genes selectively over or underexpressed are directly related to AD. A further evaluation performed with Ingenuity Pathway analysis revealed that these genes are nodes of networks and pathways that are involved in the modulation of Ca(2+) homeostasis as well as in the regulation of glutamatergic transmission and synaptic plasticity.

Conclusions and significance: Aβ-Al appears to be largely involved in the molecular machinery that regulates neuronal as well as synaptic dysfunction and loss. Aβ-Al seems critical in modulating key AD-related pathways such as glutamatergic transmission, Ca(2+) homeostasis, oxidative stress, inflammation, and neuronal apoptosis.

Figure 1. Biological functions associated with genes selectively changed by the exposure to the Aβ-Al complex.

Bar charts show key biological functions associated with genes found to be selectively either overexpressed (A) or downexpressed (B) in SH-SY5Y cells exposed to Aβ-Al.

Figure 2. Top networks generated by IPA associated with genes selectively overexpressed by the exposure to the Aβ-Al complex.

Genes in red show increased expression in SH-SY5Y cells exposed to Aβ-Al when compared with untreated SH-SY5Y cells. Arrows indicate that a molecule acts on another while lines indicate that a molecule binds to another. Small histograms indicate changes in gene expression.

Figure 3. Top networks generated by IPA associated with genes selectively downexpressed by the exposure to the Aβ-Al complex.

Genes in green show decreased expression in SH-SY5Y cells exposed to Aβ-Al when compared with untreated SY5Y cells. Arrows indicate that a molecule acts on another while lines indicate that a molecule binds to another. Small histograms indicate changes in gene expression.

Figure 4. IPA-generated pathways associated with genes selectively over or downexpressed upon exposure to Aβ-Al: modulation of glutamatergic transmission and synaptic plasticity.

IPA-generated pathways as resulting from the analysis of gene changes in SH-SY5Y cells exposed to the Aβ-Al when compared with untreated SH-SY5Y cells. Overexpressed genes are depicted in red, downexpressed genes are in green while genes in white are the ones inferred by IPA.

Figure 5. IPA-generated pathways associated with genes selectively over or downexpressed upon exposure to Aβ-Al: modulation of Ca²⁺ homeostasis.

IPA-generated pathways as resulting from the analysis of gene changes in SH-SY5Y cells exposed to the Aβ-Al when compared with untreated SH-SY5Y cells. Overexpressed genes are depicted in red, downexpressed genes are in green while genes in white are the ones inferred by IPA.

Figure 6. Summary of genes, biological functions, and pathways associated with gene expression changes triggered by the exposure to the Aβ-Al complex in SH-SY5Y cells.