Src-YAP activity in mesenchymal stem cells under oxidative stress and its relation with apoptosis

One of the reasons for the post-transplantation loss of mesenchymal stem cells (MSCs), which are used in the treatment of many diseases with their immunomodulatory and regenerative properties, is oxidative stress-induced cell death. Therefore, investigating and elucidating the cellular signaling responses occurring in MSCs under oxidative stress will contribute to the development of future treatments. In the thesis study, it was aimed to examine the changes in Src-YAP activity in MSCs under oxidative stress caused by H2O2 and to correlate this with apoptosis through Bax excretion and pYAPY357-p73 interaction. For this purpose, the H2O2 concentration was determined as 300 μM by WST-1 analysis to induce oxidative stress in MSCs isolated from lipo-aspirate and characterized. It was determined by flow cytometry that intracellular ROS levels increased after H2O2 applications for 15, 30, 60, and 120 minutes. In Western blot analyses, it was determined that Src phosphorylation increased, followed by an increase in YAP and phosphorylations. In Western blot and immunofluorescence analyses, it was determined that the nucleus-cytoplasm distribution of YAP and its phosphorylations changed after H2O2 application. It was determined that the Bax/Bcl-2 ratio increased after H2O2 application. In the immunoprecipitation analysis, the pYAPY357 protein band was detected in the samples precipitated with p73 in the nuclear extract. In line with the stated purpose, this thesis is the first study to detect the Src-YAP relationship in MSCs under oxidative stress, and it is unique in that it shows that pYAPY357 increases and is localized in the nucleus. The interaction of pYAPY357 and p73 in MSCs was also shown for the first time in this study.