Glucose-regulated protein 75 (Grp75), also known as mortalin/mthsp70/PBP74, is a member of the heat-shock protein 70 (HSP70) family. Grp75 is known to protect cells from stress-induced injury. Previous studies have shown that the expression of Grp75 is upregulated by a low dose of ionizing radiation (IR). To evaluate the protective role of Grp75 on cell proliferation in response to IR, Grp75 was over-expressed in a rat adrenal pheochromocytoma cell line (PC12). It was revealed that Grp75 overexpression desensitized PC12 cells to IR-mediated cell injury. In addition, the expression of topoisomerase II alpha (Topo II alpha) was downregulated in PC12 cells following gamma-ray IR. The effect of Grp75 overexpression on Topo II alpha expression was examined. It was revealed that Grp75 overexpression reversed the inhibitory effect of IR on Topo ha expression. In conclusion, the data indicated that Grp75 overexpression attenuates IR-induced injury in PC12 cells by maintaining the expression of Topo II alpha.
[1]Fudan Univ, Shanghai Med Coll, Dept Cellular & Genet Med, Shanghai 200032, Peoples R China.
[2]Fudan Univ, Shanghai Med Coll, Expt Teaching Ctr, Shanghai 200032, Peoples R China.
[3]Shanghai Univ Tradit Chinese Med, Dept Biol, Shanghai, Peoples R China.
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