Abstract
It is well known that there is a cell-type-dependent apoptosis phenomenon in radiation induced apoptosis, like as the thymocytes and lymphocytes, which are known to be hypersensitive to radiation and exhibit interphase cell death. Contrary to those cell lines, many other human tumor cell lines which generally undergo necrotic cell death and show a delayed apoptosis following exposure to radiation. In order to identify the signaling regulators controlling apoptotic cell death, Jurkat (human leukemia) and HeLa S3 (human uncial carcinoma) were irradiated with 20 J/m2 of UV, after several hours post-incubation. Their cytosolic extracts were resolved with two dimensional gel electrophoresis (2DE). The different spots appeared in apoptotic and non-apoptotic cells in Jurkat and HeLa S3 cells cells were analyzed using a MALDI-TOF/TOF mass spectrometry. 12 proteins were identified, one of them was acidic ribosomal protein P2 (P2) which is known to be mainly located within the 60s ribosomal subunit and phosphorylated forms of P2 were detected in UV-irradiation Jurkat cells. Based on these observations, now we are trying to use in vitro and in vivo experiments to confirm the function relevance of the dephosphorylation of P2 in apoptosis sensitivity. All the data suggested that there is a regulator for the P2 phosphorylation and dephosphorylation and its function is associated with the activition of UV induced apoptosis.
