title: Sam68 is cleaved by caspases under apoptotic cell death induced by ionizing radiation.
abstract: The RNA-binding protein Sam68, a mitotic substrate of tyrosine kinases, has been reported to participate in the cell cycle, apoptosis, and signaling. In particular, overexpression of Sam68 protein is known to suppress cell growth and cell cycle progression in NIH3T3 cells. Although Sam68 is involved in many cellular activities, the function of Sam68, especially in response to apoptotic stimulation, is not well understood. In this study, we found that Sam68 protein is cleaved in immune cells undergoing apoptosis induced by γ-radiation. Moreover, we found that Sam68 cleavage was induced by apoptotic stimuli containing γ-radiation in a caspase-dependent manner. In particular, we showed that activated casepase-3, 7, 8 and 9 can directly cleave Sam68 protein through in vitro protease cleavage assay. Finally, we found that the knockdown of Sam68 attenuated γ-radiation-induced cell death and growth suppression. Conclusively, the cleavage of Sam68 is a new indicator for the cell damaging effects of ionizing radiation.
authors: KHNP Radiation Health Institute, Korea Hydro & Nuclear Power Co. Ltd, Seoul, Korea.
authors: Seong-Jun
authors: SJ
authors: Cho
authors: KHNP Radiation Health Institute, Korea Hydro & Nuclear Power Co. Ltd, Seoul, Korea.
authors: Moo Hyun
authors: MH
authors: Choi
authors: KHNP Radiation Health Institute, Korea Hydro & Nuclear Power Co. Ltd, Seoul, Korea.
authors: Seon Young
authors: SY
authors: Nam
authors: KHNP Radiation Health Institute, Korea Hydro & Nuclear Power Co. Ltd, Seoul, Korea.
authors: Ji Young
authors: JY
authors: Kim
authors: KHNP Radiation Health Institute, Korea Hydro & Nuclear Power Co. Ltd, Seoul, Korea.
authors: Cha Soon
authors: CS
authors: Kim
authors: College of Pharmacy, Sungkyunkwan University, Suwon City, Kyunggi-do, Korea kwangheey@khnp.co.kr snpyo@skku.edu.
authors: Suhkneung
authors: S
authors: Pyo
authors: KHNP Radiation Health Institute, Korea Hydro & Nuclear Power Co. Ltd, Seoul, Korea kwangheey@khnp.co.kr snpyo@skku.edu.
authors: Kwang Hee
authors: KH
authors: Yang
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D017209:Apoptosis / Q000502:physiology* / Q000528:radiation effects; D015415:Biomarkers / Q000378:metabolism; D020169:Caspases / Q000378:metabolism*; D002460:Cell Line; D049109:Cell Proliferation / Q000502:physiology* / Q000528:radiation effects; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004307:Dose-Response Relationship, Radiation; D004789:Enzyme Activation / Q000502:physiology / Q000528:radiation effects; D005720:Gamma Rays; D006801:Humans; D019169:Jurkat Cells; D016601:RNA-Binding Proteins / Q000378:metabolism*; D011829:Radiation Dosage
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D015415:Biomarkers; D004268:DNA-Binding Proteins; C489559:KHDRBS1 protein, human; D016601:RNA-Binding Proteins; D020169:Caspases
keywords: Sam68; apoptosis; caspase; cleavage; ionizing radiation