Function evaluation of the interaction between PTK2 and p68 helicase during genotoxic stress in cardiac myocytes

Abstract

Protein tyrosine kinase 2 (PTK2) is a member of the non-receptor tyrosine kinase family crucial for the regulation of distinct cellular functions, such as cell migration and proliferation. In addition to its canonical roles in cytoplasmic signaling mediated by integrins and growth factor receptors, PTK2 acts in the nucleus, where it interacts with transcription factors and regulates processes such as survival, differentiation, and hypertrophic growth. Studies with emphasis on signaling activated by chemotherapeutics agents in cardiac myocytes have demonstrated the relevance of PTK2 for cell survival and resistance to genotoxic stress. However, targets regulated by PTK2 during this stress remain poorly explored. Data from Co-Immunoprecipitation experiments and Super-Resolution Structured Illumination Microscopy (SR-SIM) revealed a new interaction between PTK2 and the RNA helicase p68/DDX5 in distinct nuclear foci, in H9c2 myocytes treated with the chemotherapy drug doxorubicin (dox). While p68 acts as a transcriptional cofactor of p53 and µ-catenin, this project will investigate whether the PTK2/p68 interaction can modulate the co-activation of these transcription factors to impact the expression of p21 and AKT genes, an essential event for cell survival control during genotoxic stress. We will also investigate whether the interaction with PTK2 impacts post-translational modifications of p68 in cardiac myocytes. Furthermore, SR-SIM images will be analyzed to verify if the post-translational helicase modifications are related to nuclear foci where an intense colocalization of PTK2 and p68 was observed in dox-treated cells. The data generated by the present study will improve the understanding of the signaling activated by genotoxic agents in cardiomyocytes, with a possible impact to human health. (AU)