Role of vicinal protein thiols in radiation and cytotoxic responses
Role of vicinal protein thiols in radiation and cytotoxic responses
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DOI：
10.1667/rr3505.1
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发表时间：
2006-03-01
影响因子：
3.4
通讯作者：
Mieyal, JJ
中科院分区：
文献类型：
--
作者：
Biaglow, JE;Ayene, IS;Mieyal, JJ
谷胱甘肽(GSH)和最近发现的蛋白质硫醇(P-SH)在细胞辐射反应中起主要作用。然而，邻近的硫醇蛋白对几种主要酶的功能是重要的，对细胞对辐射的反应的影响还没有明确的描述。在这里，我们研究了耗竭GSH和蛋白质邻近硫醇(HS-P-SH)和P-SH对细胞毒性和辐射反应的影响。我们用羟乙基二硫化物(HEDS，β-巯基乙醇-二硫化物)单独或联合苯砷(PAO)改变P-SH、HS-P-SH和GSH。HEDS是硫氧还蛋白还原酶的直接底物，也是谷氧还蛋白(硫醇转移酶)的间接底物，不改变细胞中邻近硫醇的蛋白质。然而，与邻近的硫醇形成共价加合物的PAO阻止了HEDS的生物还原；在HEDS和PAO存在的情况下，K1细胞GSH出现了伴随的但尚未解释的下降。G6PD(+)(K1)和G6PD(-)(E89)细胞经L-丁硫氨酸亚磺胺(L-BSO)作用72h后，G6PD(+)(K1)和G6PD(-)(E89)细胞毒作用增强。然而，存活的E89细胞的辐射致死率是K1细胞的10,000倍。本文还研究了L-BSO与谷胱甘肽-S转移酶底物二甲基甲基甲酸二甲酯联用对谷胱甘肽快速耗竭的影响。在此条件下，PAO对E89细胞的放射增敏作用是K1细胞的1000多倍。改变反应的潜在机制可能与抑制硫氧还蛋白还原酶和谷氧还蛋白有关。这两种酶都是参与DNA合成、蛋白质动态平衡和细胞生存的关键酶。随着谷胱甘肽的去除，邻近的硫醇似乎在决定细胞存活率和放射敏感性方面起着关键作用。降低P-SH，清除GSH和邻近的硫醇对K1和E89细胞有极强的毒性。我们得出结论，辐射敏感性和细胞存活依赖于邻近的硫醇和GSH。在前一种情况和后一种情况下，蛋白质硫醇也很重要。(C)2006年，由辐射研究学会提供。
Glutathione (GSH) and more recently protein thiols (P-SH) have been found to play a major role in cellular radiation response. However, the effects of protein vicinal thiols, which are important for the functions of several major enzymes, on cellular responses to radiation have not been clearly delineated. Here we investigated the effects of depleting GSH and protein vicinal thiols (HS-P-SH) and P-SH on cell toxicity and radiation response. We used hydroxyethyldisulfide (HEDS, beta-mercaptoethanol-disulfide) alone and in combination with phenylarsine oxide (PAO) to alter P-SH, HS-P-SH and GSH. HEDS, a direct substrate for thioredoxin reductase and an indirect substrate for glutaredoxin (thioltransferase), did not alter protein vicinal thiols in cells. However, PAO, which specifically forms a covalent adduct with vicinal thiols, blocked bioreduction of HEDS; there was a concomitant and yet unexplained decrease in K1 cell GSH in the presence of HEDS and PAO. G6PD(+) (K1) and G6PD(-) (E89) cells treated with L-buthionine sulfoximine (L-BSO) for 72 h to deplete GSH followed by PAO showed an increased cytotoxic response. However, the surviving E89 cells showed a 10,000-fold greater radiation lethality than the K1 cells. The effects of rapid depletion of GSH by a combination Of L-BSO and dimethyfomarate (DMF), a glutathione-S-transferase substrate, were also investigated. Under these conditions, PAO radiosensitized the E89 cells more than 1000-fold over the K1 cells. The potential mechanisms for the altered response may be related to the inhibition of thioredoxin reductase and glutaredoxin. Both are key enzymes involved in DNA synthesis, protein homeostasis and cell survival. With GSH removed, vicinal thiols appear to play a critical role in determining cell survival and radiosensitivity. Decreasing P-SH and removing GSH and vicinal thiols is extremely toxic to K1 and E89 cells. We conclude that radiation sensitivity and cell survival are dependent on vicinal thiol and GSH. In the former and latter cases, the protein thiols are also important. (C) 2006 by Radiation Research Society.