Tunicamycin Mixture

Tunicamycin (TCM or TM) [1] [2] is an antibiotic. It can block the reaction between UDP-N-acetylglucosamine and dolichol phosphate in the first step of glycoprotein synthesis and thus inhibit the synthesis of all N-linked glycoproteins, finally cause endoplasmic reticulum (ER) stress [3]. In Bacillus subtilis cells, the IC50 for TCM to inhibit the formation of dolichyl pyrophosphoryl N-acetylglucosamine (Dol-p-p-GlcNAc) is 0.03 μg/ml [2].

The ER stress response is a potent, evolutionarily conserved response to cellular metabolic stress and misfolded proteins. ER stress is induced by disruption of ER functions, such as transport to the Golgi complex or protein glycosylation, or by disturbances in the ER lumen environment, such as redox status or altered calcium homeostasis [3].

In RAW264.7 cells, tunicamycin significantly reduced LPS-induced nitrite release/production and attenuated the expression of mRNAs and hence proteins of COX-2 and iNOS. In addition, tunicamycin at a concentration of 0.5 μg/ml did not have any effect on cell survival/proliferation, but at 48h tunicamycin provided protection against activation-induced macrophage cell death. In a concentration-dependent manner, tunicamycin reduced COX-2 and iNOS protein expressions in response to LPS and induced a concurrent increase in 78-kDa glucose-regulated protein (GRP78), an ER chaperone [3].

In the small intestine of wild-type mice, tunicamycin elevated expression levels of suppressed 1370 probes and 1291 probes by >2 fold. In the small intestine of Nrf 2 (-/-) mice, tunicamycin inhibited 2024 probes and induced 3471 probes by >2 fold. Compared with results of small intestine samples, in wild-type mice liver, less well-defined genes were either suppressed (943) or elevated (750) >2 fold by tunicamycin; whereas in Nrf2 (-/-) mice liver, 3170 genes were inhibited or 39 well-defined genes were induced [1].

Tunicamycin（TCM或TM）[1] [2]是一种抗生素。它可以阻止UDP-N-乙酰葡萄糖胺和多立克醇磷酸在糖蛋白合成的第一步中的反应，从而抑制所有N-连接的糖蛋白的合成，并最终导致内质网（ER）应激[3]。在枯草杆菌细胞中，TCM抑制多立克基焦磷酸N-乙酰葡萄糖胺(Dol-p-p-GlcNAc)形成的IC50为0.03μg/ml [2]。

内质网应激反应是一种强大的、进化上保守的细胞代谢应激和蛋白质错折的反应。内质网功能受到破坏，如运输到高尔基复合体或蛋白质糖基化，或者在内质网腔环境中出现干扰，如氧化还原状态或钙离子稳态改变等都会引起内质网应激。

在RAW264.7细胞中，tunicamycin显著降低了LPS诱导的亚硝酸盐释放/产生，并减弱了COX-2和iNOS mRNA及其蛋白质表达。此外，浓度为0.5μg/ml的tunicamycin对细胞存活/增殖没有任何影响，但48小时后可保护免受激活引起的巨噬细胞死亡。以浓度依赖性方式，tunicamycin降低了LPS诱导的COX-2和iNOS蛋白表达，并同时增加78-kDa糖调节蛋白（GRP78），一种内质网伴侣蛋白[3]。

在野生型小鼠的小肠中，tunicamycin提高了1370个探针和1291个探针的表达水平超过2倍。在Nrf 2 (-/-)小鼠的小肠中，tunicamycin抑制了2024个探针并诱导3471个探针超过2倍。与小肠样本结果相比，在野生型小鼠的肝脏中，被tunicamycin抑制或提高超过2倍的基因不太明确（943和750）；而在Nrf2(-/-) 小鼠的肝脏中，则有3170个基因被抑制或39个明确定义基因被诱导[1]。

Reference:
[1].  Sujit Nair, Changjiang Xu, Guoxiang Shen, et al. Toxicogenomics of Endoplasmic Reticulum stress inducer Tunicamycin in the Small Intestine and Liver of Nrf2 Knockout and C57BL/6J Mice. Toxicol Lett., 2007, 168(1):21-39.
[2].  Masatoshi Inukai, Fujio Isono and Akira Takatsuki. Selective Inhibition of the Bacterial Translocase Reaction in Peptidoglycan Synthesis by Mureidomycins. Antimicrobial Agents and Chemotherapy, 1993, 37(5): 980-983.
[3].  Song-YiKim, Ji-SunHwang and Inn-OcHan. Tunicamycin inhibits Toll-like receptor-activated inflammation in RAW264.7 cells by suppression of NF-κB and c-Junactivity via a mechanism that is independent of ER-stress and N-glycosylation. European Journal of Pharmacology, 2013, 721: 294-300.