PDF(Pubmed)
Abstract：
BACKGROUND: MG132, a proteasome inhibitor, is widely used to inhibit nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) activity by proteasome-mediated degradation of IκB. It has been marketed as a specific, reversible, cell-permeable and low-cost inhibitor. However, adverse effects of the compound have been reported in the literature. We recently discovered and characterised a point mutation in the acute phase protein serum amyloid A (SAA) in chickens, by overexpressing the protein in chicken hepatocellular carcinoma (LMH) cells. This serine to arginine exchange at amino acid position 90 (SAA.R90S) leads to intra- and extracellular accumulation of SAA, which is surprisingly counteracted by MG132 treatment, independent of SAA\'s intrinsic promoter.
RESULTS: To test, whether low proteasomal degradation of SAA.R90S is responsible for the observed intra- and extracellular SAA accumulation, we intended to inhibit the proteasome in SAA wild type (SAA.WT) overexpressing cells with MG132. However, we observed an unexpected drastic decrease in SAA protein expression at the transcript level. NF-κB gene expression was unchanged by MG132 at the measured time point.
CONCLUSIONS: The observed results demonstrate that MG132 inhibits SAA expression at the transcript level, independent of its endogenous promoter. Further, the data might indicate that NF-κB is not involved in the observed MG132-induced inhibition of SAA expression. We, consequently, question in this brief report whether MG132 should truly be categorised as a specific ubiquitin proteasome inhibitor and recommend the usage of alternative compounds.
RESULTS: To test, whether low proteasomal degradation of SAA.R90S is responsible for the observed intra- and extracellular SAA accumulation, we intended to inhibit the proteasome in SAA wild type (SAA.WT) overexpressing cells with MG132. However, we observed an unexpected drastic decrease in SAA protein expression at the transcript level. NF-κB gene expression was unchanged by MG132 at the measured time point.
CONCLUSIONS: The observed results demonstrate that MG132 inhibits SAA expression at the transcript level, independent of its endogenous promoter. Further, the data might indicate that NF-κB is not involved in the observed MG132-induced inhibition of SAA expression. We, consequently, question in this brief report whether MG132 should truly be categorised as a specific ubiquitin proteasome inhibitor and recommend the usage of alternative compounds.
摘要：
背景：MG132，一种蛋白酶体抑制剂，广泛用于通过蛋白酶体介导的IκB降解来抑制活化B细胞的核因子κ-轻链增强子（NF-κB）活性。它已经作为一个特定的，可逆,细胞通透性和低成本抑制剂。然而,该化合物的副作用已在文献中报道。我们最近在鸡的急性期蛋白血清淀粉样蛋白A（SAA）中发现并表征了点突变，通过在鸡肝细胞癌（LMH）细胞中过表达蛋白质。该丝氨酸在氨基酸位置90(SAA。R90S）导致SAA的细胞内和细胞外积累，令人惊讶的是MG132治疗抵消了这一点，独立于SAA的内在启动子。
结果：要测试，SAA是否低蛋白酶体降解。R90S负责观察到的细胞内和细胞外SAA积累，我们打算抑制SAA野生型的蛋白酶体(SAA。WT)过表达MG132的细胞。然而,我们观察到转录水平的SAA蛋白表达出乎意料地急剧下降。在测量的时间点,NF-κB基因表达通过MG132未改变。
结论：观察到的结果表明，MG132在转录水平上抑制SAA的表达，独立于其内源性启动子。Further,数据可能表明NF-κB不参与观察到的MG132诱导的SAA表达抑制。我们,因此,在这份简短报告中，问MG132是否应该真正归类为特定的泛素蛋白酶体抑制剂，并建议使用替代化合物。
结果：要测试，SAA是否低蛋白酶体降解。R90S负责观察到的细胞内和细胞外SAA积累，我们打算抑制SAA野生型的蛋白酶体(SAA。WT)过表达MG132的细胞。然而,我们观察到转录水平的SAA蛋白表达出乎意料地急剧下降。在测量的时间点,NF-κB基因表达通过MG132未改变。
结论：观察到的结果表明，MG132在转录水平上抑制SAA的表达，独立于其内源性启动子。Further,数据可能表明NF-κB不参与观察到的MG132诱导的SAA表达抑制。我们,因此,在这份简短报告中，问MG132是否应该真正归类为特定的泛素蛋白酶体抑制剂，并建议使用替代化合物。
