Ogata Fernando Toshio, Batista Wagner Luiz, Sartori Adriano, Gesteira Tarsis Ferreira, Masutani Hiroshi, Arai Roberto Jun, Yodoi Junji, Stern Arnold, Monteiro Hugo Pequeno
Departamento de Bioquímica/Biologia Molecular and Center for Cellular and Molecular Therapy - CTCMol - Universidade Federal de São Paulo, São Paulo, Brazil.
Departamento de Ciências Biológicas, Universidade Federal de São Paulo, Campus Diadema, São Paulo, Brazil.
PLoS One. 2013 Dec 20;8(12):e84588. doi: 10.1371/journal.pone.0084588. eCollection 2013.
Thioredoxin (TRX-1) is a multifunctional protein that controls the redox status of other proteins. TRX-1 can be found in the extracellular milieu, cytoplasm and nucleus, and it has distinct functions in each environment. Previously, we studied the intracellular localization of TRX-1 and its relationship with the activation of the p21Ras-ERK1/2 MAP Kinases signaling pathway. In situations where this pathway was activated by stress conditions evoked by a nitrosothiol, S-nitroso-N-acetylpenicillamine (SNAP), TRX-1 accumulated in the nuclear compartment due to nitrosylation of p21Ras and activation of downstream ERK1/2 MAP kinases. Presently, we demonstrate that ERK1/2 MAP Kinases activation and spatial distribution within cells trigger TRX-1 nuclear translocation through down-regulation of the physiological inhibitor of TRX-1, Thioredoxin Interacting Protein (TXNIP). Once activated by the oxidants, SNAP and H₂O₂, the ERK1/2 MAP kinases migrate to the nucleus. This is correlated with down-regulation of TXNIP. In the presence of the MEK inhibitors (PD98059 or UO126), or in cells transfected with the Protein Enriched in Astrocytes (PEA-15), a cytoplasmic anchor of ERK1/2 MAP kinases, TRX-1 nuclear migration and TXNIP down-regulation are no longer observed in cells exposed to oxidants. On the other hand, over-expression of TXNIP abolishes nuclear migration of TRX-1 under nitrosative/oxidative stress conditions, whereas gene silencing of TXNIP facilitates nuclear migration even in the absence of stress conditions. Studies based on the TXNIP promoter support this regulation. In conclusion, changes in TRX-1 compartmentalization under nitrosative/oxidative stress conditions are dependent on the expression levels of TXNIP, which are regulated by cellular compartmentalization and activation of the ERK1/2 MAP kinases.
硫氧还蛋白（TRX-1）是一种多功能蛋白质，可控制其他蛋白质的氧化还原状态。TRX-1存在于细胞外环境、细胞质和细胞核中，且在每个环境中都具有独特的功能。此前，我们研究了TRX-1的细胞内定位及其与p21Ras-ERK1/2丝裂原活化蛋白激酶信号通路激活的关系。在亚硝基硫醇S-亚硝基-N-乙酰青霉胺（SNAP）引发的应激条件激活该通路的情况下，由于p21Ras的亚硝基化和下游ERK1/2丝裂原活化蛋白激酶的激活，TRX-1在核区室中积累。目前，我们证明ERK1/2丝裂原活化蛋白激酶在细胞内的激活和空间分布通过下调TRX-1的生理抑制剂硫氧还蛋白相互作用蛋白（TXNIP）触发TRX-1的核转位。一旦被氧化剂SNAP和H₂O₂激活，ERK1/2丝裂原活化蛋白激酶就会迁移到细胞核。这与TXNIP的下调相关。在存在MEK抑制剂（PD98059或UO126）的情况下，或在用富含星形胶质细胞的蛋白质（PEA-15，ERK1/2丝裂原活化蛋白激酶的细胞质锚定物）转染的细胞中，在暴露于氧化剂的细胞中不再观察到TRX-1的核迁移和TXNIP的下调。另一方面，TXNIP的过表达消除了亚硝化/氧化应激条件下TRX-1的核迁移，而TXNIP的基因沉默即使在没有应激条件的情况下也促进核迁移。基于TXNIP启动子的研究支持这种调节。总之，亚硝化/氧化应激条件下TRX-1区室化的变化取决于TXNIP的表达水平，而TXNIP的表达水平受细胞区室化和ERK1/2丝裂原活化蛋白激酶激活的调节。
