Rescue of auditory hair cells from aminoglycoside toxicity by Clostridium difficile toxin B, an inhibitor of the small GTPases Rho/Rac/Cdc42
Rescue of auditory hair cells from aminoglycoside toxicity by Clostridium difficile toxin B, an inhibitor of the small GTPases Rho/Rac/Cdc42
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DOI：
10.1016/s0378-5955(02)00514-2
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发表时间：
2002-10-01
期刊：
影响因子：
2.8
通讯作者：
Ryan, AF
中科院分区：
文献类型：
--
作者：
Bodmer, D;Brors, D;Ryan, AF
毛细胞（HCs）是耳蜗中最脆弱的部分，它们的损伤是引起感音神经性听力损失的最常见原因。了解导致hcc死亡的细胞内事件是制定保护策略的关键。最近，研究表明c- jun - n末端激酶（JNK）通路在hc中对氨基糖苷的反应被激活（J. Neurosci. 20(2000) 43）。我们在体外研究了氨基糖苷毒性中导致JNK活化的上游事件。小gtpase Rac和Cdc42是其他细胞类型中众所周知的JNK上游激活因子。艰难梭菌毒素B单糖基化Rho GTP酶亚家族的所有成员（Rho， Rac和Cdc42亚型），并通过位阻干扰抑制GTP结合（Nature 341(1989) 209）。将5个大鼠基底部Corti外植体器官保存在组织培养中，用艰难梭菌毒素B处理12 h，然后用毒素B加庆大霉素处理72 h。与单独用庆大霉素处理相比，HC死亡明显减少。在使用的最高浓度下，单独的毒素B对hc没有影响。利用phospho-c-Jun抗体，我们观察到对照外植体的背景免疫反应性，庆大霉素处理的外植体外毛细胞核染色强烈，庆大霉素和艰难梭菌毒素b处理的外植体免疫染色较弱。我们得出结论，Rho家族小gtpase作为JNK信号通路的上游激活剂在氨基糖苷毒性信号传导中发挥作用。(C) 2002 Elsevier Science B.V.版权所有
The hair cells (HCs) are the most vulnerable elements in the cochlea and damage to them is the most common cause of sensorineural hearing loss. Understanding the intracellular events that lead to the death of HCs is a key to developing protective strategies. Recently, it has been shown that the c-Jun-N-terminal kinase (JNK) pathway is activated in HCs in response to aminoglycosides (J. Neurosci. 20 (2000) 43). We have studied the upstream events leading to JNK activation in aminoglycoside toxicity in vitro. The small GTPases Rac and Cdc42 are well known upstream activators of JNK in other cell types. Clostridium difficile toxin B monoglucosylates all members of the Rho GTPase subfamily (Rho, Rac and Cdc42 isoforms) and inhibits GTP binding by steric interference (Nature 341 (1989) 209). Organ of Corti explants from p5 rat basal turns were maintained in tissue culture and treated with C difficile toxin B for 12 h. They were then treated with toxin B plus gentamicin for 72 h. Significantly less HC death was observed compared to with gentamicin alone. Toxin B alone had no effect on HCs at the highest concentration used. Using antibodies against phospho-c-Jun, we observed background immunoreactivity in control explants, strong staining of outer hair cell nuclei in gentamicin treated explants, and weaker immunostaining in explants treated with gentamicin and C. difficile toxin B. We conclude that Rho family small GTPases play a role in aminoglycoside toxicity signaling as upstream activators of the JNK signaling pathway. (C) 2002 Elsevier Science B.V. All rights reserved.