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Novel Cadmium Responsive MicroRNAs in Daphnia pulex
Shuai Chen1, Garrett J McKinney2, Krista M Nichols1,3
1Department of Forestry and Natural Resources, Purdue University , West Lafayette, Indiana, 47907 United States.
Abstract:
Daphnia pulex is a widely used toxicological model and is known for its sensitivity to cadmium (Cd). Recent research suggests that microRNAs (miRNAs) play a critical role in animal responses to heavy metals. To investigate the functions of D. pulex miRNAs under Cd exposure, we analyzed the miRNA profiles of D. pulex after 48 h using miRNA microarrays and validated our findings by q-PCR. miRNA dpu-let-7 was identified as a stably expressed gene and used as a reference. We identified 22 and 21 differentially expressed miRNAs under low (20 μg/L CdCl2) and high-exposure (40 μg/L CdCl2) concentrations compared to controls, respectively. Cellular functions of predicted miRNA target Cd-responsive genes included oxidative stress, ion transport, mitochondrial damage, and DNA repair. An insulin-related network was also identified in relation to several Cd-responsive miRNAs. The expression of three predicted target genes for miR-71 and miR-210 were evaluated, and expression of two of them (SCN2A and SLC31A1) was negatively correlated with the expression of their regulator miRNAs. We show miR-210 is hypoxia-responsive in D. pulex and propose Cd and hypoxia induce miR-210 via a same HIF1α modulated pathway. Collectively, this research advances our understanding on the role of miRNAs in response to heavy-metal exposure.
Insights
This study reveals how microRNAs (miRNAs) in Daphnia pulex respond to cadmium (Cd) exposure, identifying specific miRNAs and affected cellular processes like oxidative stress and ion transport, crucial for understanding heavy metal toxicity.
Area of Science:
- Environmental Toxicology
- Molecular Biology
- Genomics
Background:
- Daphnia pulex is a key model organism for toxicology studies.
- MicroRNAs (miRNAs) are increasingly recognized for their role in heavy metal stress responses.
- Cadmium (Cd) is a toxic heavy metal with significant environmental impact.
Purpose of the Study:
- To investigate the differential expression of miRNAs in Daphnia pulex upon cadmium exposure.
- To identify cellular functions and molecular pathways regulated by Cd-responsive miRNAs.
- To elucidate the role of specific miRNAs, such as miR-210, in cadmium toxicity.
Main Methods:
- miRNA microarray analysis to profile miRNA expression in Daphnia pulex exposed to varying CdCl2 concentrations.
- Quantitative PCR (q-PCR) for validation of miRNA expression.
- Bioinformatic analysis to predict miRNA targets and associated cellular functions.
- Evaluation of target gene expression and correlation with miRNA levels.
Main Results:
- Identified 22 and 21 differentially expressed miRNAs under low and high Cd exposure, respectively.
- Predicted targets of these miRNAs are involved in oxidative stress, ion transport, mitochondrial damage, and DNA repair.
- miR-210 was found to be hypoxia-responsive, suggesting a shared regulatory pathway (HIF1α) for Cd and hypoxia.
- Negative correlation observed between miR-71/miR-210 and their target genes (SCN2A, SLC31A1).
Conclusions:
- MicroRNAs play a significant role in the toxicological response of Daphnia pulex to cadmium.
- Cadmium exposure alters miRNA profiles, impacting key cellular processes.
- miR-210 is a potential mediator of both cadmium and hypoxia stress in Daphnia pulex.
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