Effect of TiO2 Nanoparticles on the Expression of Chromatin Modifying Genes

Authors Whyte G., Runa S., Fan Y., Kemp M., Payne C.

TiO₂ nanoparticles (TiO₂ NPs) are ubiquitous in the modern world with applications ranging from providing the white color in powdered donuts to providing the UV protective properties in sunscreen. Because of our daily exposure, it is important to study the effects of TiO₂ NPs on cells. Previous research in the Payne and Kemp labs at Georgia Tech has shown that at sub-cytotoxic levels TiO₂ NPs induce an oxidative stress response in cells, detected as changes in peroxiredoxin gene activity. We next studied the effects of TiO₂ NPs on chromatin modifying genes. These genes regulate the control of genes activation or suppression. We first determined a sub-cytotoxic concentration of TiO₂ NPs using a mitochondrial enzyme activity. We then determined the changes in chromatin modifying gene activity by comparing the polymerase chain reaction (PCR) results between cells incubated for 24 hours with TiO₂ NPs and cells with no TiO₂ NP exposure. The results showed that with 24hr sub-cytotoxic exposure, TiO₂ NPs led to the upregulated activity chromatin modifying genes. Comparison between experiments showed that the specific genes upregulated were dependent on the age of the cell line (cell passage number). Moving forward, we will determine long-term epigenetic effects by studying the chromatin modifying genes of progeny cells from parent cells that were exposed to TiO₂ NPs.