Transcriptome Analysis Reveals Distinct Responses to Physiologic versus Toxic Manganese Exposure in Human Neuroblastoma Cells

We report the application of RNA-Seq analysis to determine the transcriptional responses to Mn dose, ranging from physiological to toxicological levels in human SH-SY5Y neuroblastoma cells. We find that Mn dose showed widespread effects in abundance of protein coding genes for metabolism of reactive oxygen species, energy sensing, glycolysis, protein homeostasis including the unfolded protein response and transcriptional regulation. Adaptive responses at physiological Mn concentration-10 µM Mn for 5 h, a concentration that did not result in cell death after 24 h increased abundance of differentially expressed genes (DEGs) in the protein secretion pathway that function in protein trafficking and cellular homeostasis.These include BET1 (Golgi vesicular membrane trafficking protein), ADAM10 (ADAM metallopeptidase domain 10) and ARFGAP3 (ADP-ribosylation factor GTPase activating protein 3). In contrast, 5 h exposure to 100 µM Mn, a concentration that caused cell death after 24 h, increased abundance of DEGs for components of the mitochondrial oxidative phosphorylation pathway. In conclusion, this study provides a framework for Mn dose dependent exposure in a human in vitro cell culture model and provides a testable hypothesis for in vivo studies. Importantly, the transcriptome responses at toxic Mn dose demonstrated patterns observed with neurological diseases and suggest that differential functions of the secretory pathway and mitochondria could provide a basis to improve detection and management of adverse environmental and occupational Mn exposures. Overall design: Examination of transcriptomic responses to Mn dose (0,1,5,10,50,100 µM MnCl2 for 5 h) in human SH-SY5Y neuroblastoma cells with three biological replicates per Mn treatment using Illumina HiSeq 2500.

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Fernandes J, Chandler JD, Lili LN, Uppal K, Hu X, Hao L, Go YM, Jones DP