Redox regulation of Cellular responses against cytokine stress

氧化应激如紫外线（UV）照射到哺乳动物细胞引发各种氧化应激反应，包括转录因子的激活。近年来，核因子κ B （nf - κ B）的活化受到硫氧还蛋白（TRX）的氧化还原（氧化还原）调控，而硫氧还蛋白是主要的内源性氧化还原调节分子之一，具有巯基还原活性。为了阐明TRX在细胞区室中参与NF-kappaB调控的位置，我们研究了UVB照射诱导TRX从细胞质转运到细胞核的细胞内定位。在体外二胺诱导交联研究中，我们发现TRX可以直接与NF-kappaB p50结合。与模拟转染相比，野生型TRX的过表达抑制了紫外线照射下nf - kappab结合位点荧光素酶活性的诱导。相反，核靶向TRX的过表达增强了荧光素酶的活性。因此，TRX似乎在调节NF-kappaB中起着双重和相反的作用，在细胞质中，它干扰IkappaB激酶的信号，阻断IkappaB的降解。然而，在细胞核中，TRX通过增强NF-kappaB结合DNA的能力来增强其转录活性。这种依赖trx的两步调控NP-kappaB复合体，可能是氧化还原敏感转录因子的一种新的激活机制。

Oxidative stresses such as ultraviolet (UV) irradiation to mammalian cells triggers variety of oxystress responses including activation of transcription factors. Recently, activation of nuclear factor-kappa B (NF-kappaB) has been shown to be under oxido-reduction (redox) regulation controlled by thioredoxin (TRX), which is one of major endogenous redox-regulating molecules with thiol reducing activity. In order to elucidate where in the cellular compartment TRX participates in NF-kappaB regulation, we investigated the intracellular localization of TRX UVB irradiation induced translocation of TRX from the cytoplasm into the nucleus. In in vitro diamide-induced crosslinking study, we showed that TRX can associate directly with NF-kappaB p50. Overexpression of wild-type TRX suppressed induction of luciferase activity under NF-kappaB-binding sites in response to UV irradiation compared to the mock transfectant. In contrast, overexpression of nuclear-targeted TRX enhanced the luciferase activity. Thus, TRX seems to play dual and opposing roles in the regulation of NF-kappaB, In the cytoplasm, it interferes with the signals to IkappaB kinases and block the degradation of IkappaB.In the nucleus, however, TRX enhances NF-kappaB transcriptional activities by enhancing its ability to bind DNA.This two step TRX-dependent regulation of NP-kappaB complex, may be a novel activation mechanism of redox-sensitive transcription factors.