Exposure to Cobalt Causes Transcriptomic and Proteomic Changes in Two Rat Liver Derived Cell Lines

Abstract

Cobalt is a transition group metal present in trace amounts in the human diet, but in larger doses it can be acutely toxic or cause adverse health effects in chronic exposures. Its use in many industrial processes and alloys worldwide presents opportunities for occupational exposures, including military personnel. While the toxic effects of cobalt have been widely studied, the exact mechanisms of toxicity remain unclear. In order to further elucidate these mechanisms and identify potential biomarkers of exposure or effect, we exposed two rat liver-derived cell lines, H4-II-E-C3 and MH1C1, to two concentrations of cobalt chloride. We examined changes in gene expression using DNA microarrays in both cell lines and examined changes in cytoplasmic protein abundance in MH1C1 cells using mass spectrometry. We chose to closely examine differentially expressed genes and proteins changing in abundance in both cell lines in order to remove cell line specific effects. We identified enriched pathways, networks, and biological functions using commercial bioinformatic tools and manual annotation. Many of the genes, proteins, and pathways modulated by exposure to cobalt appear to be due to an induction of a hypoxic-like response and oxidative stress. Genes that may be differentially expressed due to a hypoxic-like response are involved in Hif-1α signaling, glycolysis, gluconeogenesis, and other energy metabolism related processes. Gene expression changes linked to oxidative stress are also known to be involved in the NRF2-mediated response, protein degradation, and glutathione production. Using microarray and mass spectrometry analysis, we were able to identify modulated genes and proteins, further elucidate the mechanisms of toxicity of cobalt, and identify biomarkers of exposure and effect in vitro, thus providing targets for focused in vivo studies.

Cobalt-Induced Ototoxicity in Rat Postnatal Cochlear Organotypic Cultures

“…Similarly, the minimum Cd concentrations required to induce mild toxicity in the rat cochlea was around 100 lM, much higher than that seen in vivo (Liu et al 2014). Another study reported using concentrations of Co up to 310 lM to examine biomarker gene changes induced by Co in H4-II-E-C3, a rat hepatoma cell line (Permenter et al 2013). One factor that is likely to account for in vivo versus in vitro differences toxicity is the duration of Co exposure.…”

“…Based on its toxicity and long-term stability in the environment as well as its high probability score, a study by the Department of Defense rated CoCl 2 as having the highest toxicity potential among a subclass of 36 pure elements and metal compounds used in industry including toxic compounds such as arsenic, lead oxide, mercuric nitrate, mercury, and cadmium (Sutto 2011;Permenter et al 2013). The LD50 value for soluble Co salts has been estimated to be & Jerome A.…”

Distinct regulatory mechanisms of the human ferritin gene by hypoxia and hypoxia mimetic cobalt chloride at the transcriptional and post-transcriptional levels

“…3). The recent report of gene expression analyses in rat liver cell lines by microarray and mass spectrometry approaches suggested that cobalt chloride modulates expression of gene sets primarily regulated by hypoxia and oxidative stress (39). Our results are consistent with this report and provide direct evidence for upregulation of Nrf2-regulated gene expression (Fig.…”

The epigenetic regulation of HIF-1α by SIRT1 in MPP + treated SH-SY5Y cells

“…Its downstream target genes, pathways and proteins can regulate the cell response due to a hypoxia-like stimulation [20]. HIF-1 is composed of the HIF-1α and HIF-1 β subunits; the latter is constitutively expressed in the nucleus, whereas HIF-1α is regulated by the environment [21–23].…”