Molecular mechanism of ochratoxin A and ochratoxin A together with citrinin on human renal cells

赭曲霉毒素A和柠檬霉素是生长在食物和饲料上的霉菌的代谢物。它们经常一起出现在食品中，由于共同暴露而产生风险。我们可以证明，暴露于纳摩尔范围的OTA会导致Wnt1信号通路蛋白1 （WISP1）的RNA表达显著增加。除WISP1外，其他与纤维化或炎症相关的基因表达也升高。首先，实验表明，ota上调的WISP1-RNA不编码蛋白质，但可以结合抗纤维化miR-29b，从而干扰其调节功能。这个新的备选WISP1转录物也含有其他mirna的推测结合位点，它们与OTA毒性的关系仍有待确定。此外，其他ota调节基因的重要性仍有待确定。OTB是一个没有氯基团的OTA类似物，对WISP1-RNA的表达没有影响。因此，表征OTA分子的这个和其他官能团的作用是非常诱人的和机械相关的。通过交换氯与其他卤素和苯丙氨酸与其他氨基酸，我们能够确定这些组对细胞存活，纤维化事件和基因表达的影响。乙酸乙酯和柠檬酸可以一起在食品中找到。因此，对细胞命运的相互影响是可以想象的。单独一种物质（OTA或柠檬酸）的有害作用可能会因额外的压力而加剧，例如由自由基形成增加引起的压力。我们能够通过测量原代培养中人类肾细胞的细胞存活率、纤维化改变或基因表达失调，确定OTA和柠檬酸或OTA和其他内源性应激源共同暴露对自由基形成增加的影响。综上所述，有必要确定(i) WISP1-RNA（和其他OTA调节基因）的作用以及识别可能干扰OTA毒性的miRNAs，（ii）使用OTA类似物确定OTA分子功能基团的重要性，以及确定（iii）共同暴露于两种真菌毒素以及内源性细胞应激所产生的潜在风险。这些研究将主要使用原代培养的人肾细胞进行。

Ochratoxin A and citrinin are metabolites of mould fungi growing on food and feed. Often they are found together in foodstuff generating a risk due to co-exposure. We could show that exposure to OTA in the nanomolar range led to a marked increase of the RNA expression of WISP1 (Wnt1 signaling pathway protein 1). Besides WISP1 also the expression of other genes involved in fibrosis or inflammation was elevated. First experiments show that the OTA-upregulated WISP1-RNA does not code for a protein but can bind the anti-fibrotic miR-29b, thereby disturbing its regulatory function. This new alternative WISP1 transcript contains putative binding sites for other miRNAs also and their relatedness to OTA toxicity remains to be determined. Additionally, the importance of the other OTA-regulated genes remains to be deter-mined.OTB, an OTA analogon without the chloride moiety, has no effect on the alternative WISP1-RNA expression. Therefore, it is extremely tantalizing and mechanistically relevant to characterize the role of this and other functional groups of the OTA molecule. By exchanging the chloride against other halogens and the phenylalanine against other amino acids, we are able to determine the impact of these groups for cell survival, fibrotic events and gene expression.OTA and citrinin can be found together in foodstuff. Therefore, a mutual influence on cell fate is conceivable. The harmful effects of one substance (OTA or citrinin) alone may be aggravated by additional stress, as caused by e.g. increased radical formation. We are able to determine the effects of a co-exposure of OTA and citrinin or OTA and other endogenously generated stressors as increased radical formation by measuring cell survival, fibrotic alterations, or dysregulated gene expression in human renal cells in primary culture.In summary therefore, it is necessary to determine(i) the role of the WISP1-RNA (and the other OTA-regulated genes) as well as to identify miRNAs which may interfere in OTA toxicity,(ii) the importance of functional groups of the OTA molecule using OTA analoga and to determine(iii) the potential risk emanating from co-exposure to the two mycotoxins together with endogenously generated cell stress.These investigations will be done using human renal cells mostly in primary culture.