Analysis Of The Effects Of Heavy Metals On MRNA Modifications In HEK293T Cells

Hexavalent chromium[Cr???]compounds that are generated during industrial processes are widely recognized as highly toxic and carcinogenic environmental pollutants.It has been reported that exposure to Cr???can produce some chromium intermediates and reactive oxygen species?ROS?,which can subsequently cause DNA damages,genetic instability,and eventually leads to the elevated risk of various diseases including cancers.In recent years,it has been proposed that epigenetic-based mechanisms may involve in the toxic heavy metals-induced cytotoxicity and mutagenicity besides the genetic-based mechanisms.There are almost twenty kinds of RNA modifications reported to exist in mRNA,which can regulate the biological functions of mRNA and play important roles in the occurrence of many disease.However,whether Cr???could impose its cytotoxic effect through dysregulating the mRNA epigenetic modifications remains poorly defined.In this study,we utilized liquid chromatography-electrospray ionization tandem-mass spectrometry?LC-ESI-MS/MS?combined with biological research method to explore the effects of Cr???exposure on mRNA modifications of HEK293T cells,expecting to clarify the Cr???-induced cytotoxicity from the view of RNA epigenetics.The specific contents are as follows:1.We systematically quantified the change in contents of 14 kinds of nucleoside modifications in mRNA of HEK293T cell upon 1?M and 5?M K₂Cr O₄?Potassium dichromate?exposure.We found Cr???exposure can induce an obvious decrease of inosine in mRNA,suggesting that Cr???could interrupt A-to-I RNA editing in mRNA,which may eventually lead to the cytotoxicity and mutagenicity.In addition,the increased activity of Caspase 3 protein demonstrated that Cr???exposure can induce cell apoptosis.2.We subsequently argued the cause to reduce the level of inosine in mRNA,we observed that the expression level of the adenosine deaminase acting on RNA?ADAR1?was significantly decreased upon Cr???exposure,which may contribute to the decrease of inosine in HEK293T cells.In summary,this study focused on the effects of Cr???exposure upon HEK293T mRNA modifications.We declared a new mechanism that heavy metals can dysregulate RNA modifications to perform cytotoxicity and carcinogenicity.Our study provides a molecular basis for the therapy of heavy metal induced disease.