Osmotic stress interferes with DNA damage response and H2AX phosphorylation in human keratinocytes. Osmostress_Keratinocytes

The human skin and in particular its outermost layer, the epidermis, protects the body from potentially harmful substances, radiation as well as excessive water loss. However, the interference between the various stress responses of the epidermal keratinocytes, which often occur simultaneously, is largely unknown. The focus of this study is to mechanistically investigate the interference between osmotic stress and DNA damage response. Gene expression analysis of osmotically stressed keratinocytes revealed, in addition to the already well-described regulation of diverse gene sets such as cellular processes like transcription, translation, and metabolic pathways (e.g. KEGG Citrate Cycle, Reactome G2/M Checkpoints), an influence on the transcription of genes also related to the UV induced DNA damage response. A gene network regulating the H2AX phosphorylation was identified to be regulated by osmotic stress. To mechanistically analyze and test the interference between osmotic stress and DNA damage response, which can be triggered by UV stress on the one hand and oxidative stress on the other hand, in more detail, primary human keratinocytes were cultured under osmotic stress conditions and subsequently exposed to UV light and H2O2, respectively. γH2AX measurements revealed lower γH2AX levels in cells previously cultured under osmotic stress conditions.