Functional evaluation of the interaction between PTK2 and p68 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 antineoplastic chemotherapeutics in cardiac myocytes have demonstrated the importance of PTK2 for cell survival and resistance to genotoxic stress. However, targets regulated by PTK2 during this stress remain underexplored. Data from Co-Immunoprecipitation experiments and Super-Resolution Structured Illumination Microscopy (SR-SIM) demonstrated PTK2 interaction and localization at nuclear foci with p68 RNA helicase, in H9c2 myocytes treated with the chemotherapeutic doxorubicin (doxo). While p68 acts as a transcriptional cofactor of p53 and µ-catenin, this project will investigate if the PTK2 modulates the interaction of p68 with these transcription factors, in order to impact the expression of p21 and AKT genes, essential for the control of cell survival in genotoxic stress. We will also investigate whether the interaction with PTK2 impacts phosphorylation of p68 in cardiac myocytes. Furthermore, SR-SIM images will be analyzed to verify if the post-translational helicase modifications are related to nuclear focis where there is an intense colocalization of PTK2 and p68 in doxo-treated cells. The data generated by the present study may contribute to the understanding of the signaling activated by genotoxic agents, with a possible impact to human health.