T-2 toxin-induced apoptosis involving Fas,p53,Bcl-xL,Bcl-2,Bax and caspase-3 signaling pathways in human chondrocytes

Objective:To investigate the effects of T-2 toxin on expressions of Fas,p53,Bcl-xL,Bcl-2,Bax and caspase-3 on human chondrocytes.Methods:Human chondrocytes were treated with T-2 toxin(1～20 ng/ml)for 5 d.Fas,p53 and other apoptosis-related proteins such as Bax,Bcl-2,Bcl-xL,caspase-3 were determined by Western blot analysis and their mRNA expressions were determined by reverse transcriptase-polymerase chain reaction(RT-PCR).Results:Increases in Fas,p53 and the pro-apoptotic factor Bax protein and mRNA expressions and a decrease of the anti-apoptotic factor Bcl-xL were observed in a dose-dependent manner after exposures to 1～20 ng/ml T-2 toxin,while the expression of the anti-apoptotic factor Bcl-2 was unchanged.Meanwhile,T-2 toxin could also up-regulate the expressions of both pro-caspase-3 and caspase-3 in a dose-dependent manner.Conclusion:These data suggest a possible underlying molecular mechanism for T-2 toxin to induce the apoptosis sig- naling pathway in human chondrocytes by regulation of apoptosis-related proteins.

Increased Chondrocyte Apoptosis in Kashin-Beck Disease and Rats Induced by T-2 Toxin and Selenium Deficiency

Objective To investigate chondrocyte apoptosis and the expression of biochemical markers associated with apoptosis in Kashin-Beck disease（KBD） and in an established T-2 toxin-and selenium（Se） deficiency-induced rat model. Methods Cartilages were collected from the hand phalanges of five patients with KBD and five healthy children. Sprague-Dawley rats were administered a selenium-deficient diet for 4 weeks prior to T-2 toxin exposure. The apoptotic chondrocytes were observed by terminal deoxynucleotidyl transferase d UTP nick end labeling staining. Caspase-3, p53, Bcl-2, and Bax proteins in the cartilages were visualized by immunohistochemistry, their protein levels were determined by Western blotting, and m RNA levels were determined by real-time reverse transcription polymerase chain reaction. Results Increased chondrocyte apoptosis was observed in the cartilages of children with KBD. Increased apoptotic and caspase-3-stained cells were observed in the cartilages of rats fed with normal and Se-deficient diets plus T-2 toxin exposure compared to those in rats fed with normal and Se-deficient diets. Caspase-3, p53, and Bax proteins and m RNA levels were higher, whereas Bcl-2 levels were lower in rats fed with normal or Se-deficiency diets supplemented with T-2 toxin than the corresponding levels in rats fed with normal diet. Conclusion T-2 toxin under a selenium-deficient nutritional status induces chondrocyte death, which emphasizes the role of chondrocyte apoptosis in cartilage damage and progression of KBD.

一氧化氮和Fas在T-2毒素诱导的软骨细胞凋亡中的作用研究

目的探讨T-2毒素致软骨细胞凋亡与一氧化氮（NO）和Fas凋亡途径的关系。方法采用MTT法检测T-2毒素对软骨细胞存活率的影响；Annexin V／PI法和电镜观察研究T-2毒素致人软骨细胞凋亡的作用；用Griess重氮化法，测定T-2毒素作用于软骨细胞培养上清液中NO含量；Western Blotting检测T-2毒素对人软骨细胞表达一氧化氮合酶（iNOS）和Fas蛋白的影响。统计分析T-2毒素诱导人软骨细胞凋亡与其分泌NO、iNOS和Fas蛋白的相关性。结果T-2毒素在浓度为1～2000ng／mL的范围内，对软骨细胞存活率的作用呈较典型的浓度依赖关系和时间依赖关系，而且随着作用时间的延长，浓度依赖关系更为明显；T-2毒素可引起软骨细胞发生凋亡的典型电镜形态改变，并使早期凋亡率和晚期凋亡率明显增加，在一定范围内呈浓度依赖性；T-2毒素刺激软骨细胞分泌NO和表达iNOS蛋白；T-2毒素使凋亡相关蛋白Fas表达增多；软骨细胞分泌NO和表达iNOS蛋白和Fas蛋白量与T-2毒素诱导人软骨细胞凋亡率均有正相关性。结论T-2毒索引起的软骨细胞凋亡与T-2毒素刺激软骨细胞分泌NO和表达iNOS蛋白增多有关，并与凋亡相关蛋白Fas表达增多有关。