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Profiling transcriptomes of human SH-SY5Y neuroblastoma cells exposed to maleic acid

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ABSTRACT

Background: Maleic acid is a multi-functional chemical widely used in the field of industrial chemistry for producing food additives and food contact materials. As maleic acid may contaminate food by the release from food packages or intentional addition, it raises the concern about the effects of excessive dietary exposure to maleic acid on human health. However, the influence of maleic acid on human health has not been thoroughly studied. In silico toxicogenomics approaches have found the association between maleic acid and nervous system disease in human. The aim of this study is to experimentally explore the effects of maleic acid on human neuronal cells.

Methods: A microarray-based transcriptome profiling was performed to offer a better understanding of the effects of maleic acid on human health. Gene expression profiles of human neuroblastoma SH-SY5Y cells exposed to three concentrations of maleic acid (10, 50, and 100 μM) for 24 h were analyzed. Genes which were differentially expressed in dose-dependent manners were identified and further analyzed with an enrichment analysis. The expression profile of selected genes related to the inferred functional changes was validated using quantitative polymerase chain reaction (qPCR). Specific fluorescence probes were applied to observe the inferred functional changes in maleic acid-treated neuronal cells.

Results: A total of 316 differentially expressed genes (141 upregulated and 175 downregulated) were identified in response to the treatment of maleic acid. The enrichment analysis showed that DNA binding and metal ion binding were the significant molecular functions (MFs) of the neuronal cells affected by maleic acid. Maleic acid exposure decreased the expression of genes associated with calcium and thiol levels of the cells in a dose-dependent manner. The levels of intracellular calcium and thiol levels were also affected by maleic acid dose-dependent.

Discussion: The exposure to maleic acid is found to decrease the cellular calcium and thiol levels in human neuronal cells at both transcriptional and functional levels. This study reported the first transcriptomic profiling of human neuronal cells treated with maleic acid. It is also the first experimental validation of chemical effects predicted by in silico toxicogenomics approaches. The proposed approach may be useful in understanding the potential effects of other poorly characterized chemicals on human health.

No MeSH data available.


The hierarchical tree of enriched GO terms associated with molecular functions.
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fig-2: The hierarchical tree of enriched GO terms associated with molecular functions.

Mentions: The analysis of enriched GO terms was conducted for the 243 differential expressed genes to identify affected functions associated with maleic acid. As shown in Table 1, there were 12 significantly enriched GO terms (corrected p-value <0.05), including eight MFs, two CCs, and two BPs. The enriched MF GO terms were visually analyzed as shown in Fig. 2. Two main branches with hierarchy levels higher than binding (GO:005488) were identified. Metal ion binding (GO:0046872), cation binding (GO:0043169), and ion binding (GO:0043167) are located at the same branch, whereas DNA binding (GO:003677), nucleic acid binding (GO:0003676), heterocyclic compound binding (GO:1901363), and organic cyclic compound binding (GO:0097159) are located at the other branch. Both branches of GO terms of metal ion binding and DNA binding were consistent with our previous analysis from ChemDIS system (Lin, Wang & Tung, 2014; Tung, 2015). The calcium binding (GO:0005509), a direct descendant of the enriched term of metal ion binding (GO:0046872), was inferred to be associated with maleic acid. The enriched GO term of DNA binding (GO:0003677) is related to nucleotide binding (GO:0000166) that was inferred to be associated with maleic acid from ChemDIS (Lin, Wang & Tung, 2014; Tung, 2015). The enriched pathways are hematopoietic cell lineage (KEGG ID:hsa04640) and generic transcription pathway (Reactome ID: 212436), and there are no enriched DO and DOLite terms from the analysis. For validating the enrichment analysis in this study, the same gene set was applied to analyze enriched terms using the comparative toxicogenomics (CTD) database. As expected, except for the analysis of enriched disease terms, ChemDIS and CTD generated similar enriched GO and pathway terms as shown in Table S2. ChemDIS and CTD utilizing different disease ontologies could generate different results of enriched diseases (Tung, 2015).


Profiling transcriptomes of human SH-SY5Y neuroblastoma cells exposed to maleic acid
The hierarchical tree of enriched GO terms associated with molecular functions.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5384566&req=5

fig-2: The hierarchical tree of enriched GO terms associated with molecular functions.
Mentions: The analysis of enriched GO terms was conducted for the 243 differential expressed genes to identify affected functions associated with maleic acid. As shown in Table 1, there were 12 significantly enriched GO terms (corrected p-value <0.05), including eight MFs, two CCs, and two BPs. The enriched MF GO terms were visually analyzed as shown in Fig. 2. Two main branches with hierarchy levels higher than binding (GO:005488) were identified. Metal ion binding (GO:0046872), cation binding (GO:0043169), and ion binding (GO:0043167) are located at the same branch, whereas DNA binding (GO:003677), nucleic acid binding (GO:0003676), heterocyclic compound binding (GO:1901363), and organic cyclic compound binding (GO:0097159) are located at the other branch. Both branches of GO terms of metal ion binding and DNA binding were consistent with our previous analysis from ChemDIS system (Lin, Wang & Tung, 2014; Tung, 2015). The calcium binding (GO:0005509), a direct descendant of the enriched term of metal ion binding (GO:0046872), was inferred to be associated with maleic acid. The enriched GO term of DNA binding (GO:0003677) is related to nucleotide binding (GO:0000166) that was inferred to be associated with maleic acid from ChemDIS (Lin, Wang & Tung, 2014; Tung, 2015). The enriched pathways are hematopoietic cell lineage (KEGG ID:hsa04640) and generic transcription pathway (Reactome ID: 212436), and there are no enriched DO and DOLite terms from the analysis. For validating the enrichment analysis in this study, the same gene set was applied to analyze enriched terms using the comparative toxicogenomics (CTD) database. As expected, except for the analysis of enriched disease terms, ChemDIS and CTD generated similar enriched GO and pathway terms as shown in Table S2. ChemDIS and CTD utilizing different disease ontologies could generate different results of enriched diseases (Tung, 2015).

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Background: Maleic acid is a multi-functional chemical widely used in the field of industrial chemistry for producing food additives and food contact materials. As maleic acid may contaminate food by the release from food packages or intentional addition, it raises the concern about the effects of excessive dietary exposure to maleic acid on human health. However, the influence of maleic acid on human health has not been thoroughly studied. In silico toxicogenomics approaches have found the association between maleic acid and nervous system disease in human. The aim of this study is to experimentally explore the effects of maleic acid on human neuronal cells.

Methods: A microarray-based transcriptome profiling was performed to offer a better understanding of the effects of maleic acid on human health. Gene expression profiles of human neuroblastoma SH-SY5Y cells exposed to three concentrations of maleic acid (10, 50, and 100 &mu;M) for 24 h were analyzed. Genes which were differentially expressed in dose-dependent manners were identified and further analyzed with an enrichment analysis. The expression profile of selected genes related to the inferred functional changes was validated using quantitative polymerase chain reaction (qPCR). Specific fluorescence probes were applied to observe the inferred functional changes in maleic acid-treated neuronal cells.

Results: A total of 316 differentially expressed genes (141 upregulated and 175 downregulated) were identified in response to the treatment of maleic acid. The enrichment analysis showed that DNA binding and metal ion binding were the significant molecular functions (MFs) of the neuronal cells affected by maleic acid. Maleic acid exposure decreased the expression of genes associated with calcium and thiol levels of the cells in a dose-dependent manner. The levels of intracellular calcium and thiol levels were also affected by maleic acid dose-dependent.

Discussion: The exposure to maleic acid is found to decrease the cellular calcium and thiol levels in human neuronal cells at both transcriptional and functional levels. This study reported the first transcriptomic profiling of human neuronal cells treated with maleic acid. It is also the first experimental validation of chemical effects predicted by in silico toxicogenomics approaches. The proposed approach may be useful in understanding the potential effects of other poorly characterized chemicals on human health.

No MeSH data available.