Glrx, also known as glutaredoxin-1, is a cytosolic enzyme that catalyzes the reduction of S-glutathionylation, reversing the post-translational modification of protein-cysteine thiols by glutathione [4,5,6,7,8,10]. This process is crucial for maintaining protein thiols in a reduced state, regulating redox signaling, and protecting cysteines from irreversible oxidation [6]. Glrx is involved in multiple pathways such as those related to NF-κB signaling, actin polymerization, and Wnt5a/sFlt-1 pathway [7]. It plays a vital role in maintaining normal physiological functions, including hepatic lipid homeostasis, and is associated with various pathological conditions [6]. Genetic models like KO/CKO mouse models have been valuable in studying its function.

In acute lung injury mouse models, the expression of Grx1 (equivalent to Glrx) was decreased in the lungs. However, Grx1 KO and Grx1fl/flLysMcre mice showed significantly relieved acute lung injury induced by hyperoxia or LPS, indicating that Grx1-regulated S-glutathionylation in macrophages has a protective role [1]. In glioma, GLRX was highly enriched in higher-grade gliomas with specific genetic characteristics, and was closely related to the tumor immune process, immune checkpoints, and inflammatory factors, being specifically expressed in M0 macrophages. It was also an independent prognostic factor [2]. In gefitinib-resistant NSCLC cells, GLRX was upregulated, and its inhibition enhanced the effects of gefitinib in cell proliferation, apoptosis, and cell cycle arrest via the EGFR/FoxM1 signaling pathway [3]. In liver fibrosis models, Glrx depletion exacerbated liver fibrosis, while overexpression inhibited it. Pirfenidone, an anti-lung fibrosis drug, inhibited HSC activation and liver fibrosis in a GLRX-dependent manner, by deglutathionylating Smad3 [5]. In lung fibrosis, mice lacking Glrx were more susceptible to bleomycin-or AdTGFB1-induced pulmonary fibrosis, while transgenic overexpression of Glrx in the lung epithelium attenuated fibrosis. Direct administration of Glrx protein into airways reversed fibrosis [8]. In Parkinson's disease mouse models, low GLRX expression was observed in MPTP-induced mice, and GLRX overexpression alleviated motor dysfunction and dopamine neuron degeneration [9]. In ischemic limb neovascularization models, Glrx overexpression attenuated VEGF signaling in vitro and ischemic vascularization in vivo, while Glrx deletion improved in vivo limb revascularization, suggesting an anti-angiogenic role of endogenous Glrx [10].

In conclusion, Glrx is essential for maintaining redox homeostasis and protein function through regulating S-glutathionylation. The use of Glrx KO/CKO mouse models has significantly advanced our understanding of its role in various disease areas such as acute lung injury, glioma, NSCLC, liver fibrosis, lung fibrosis, Parkinson's disease, and ischemic limb neovascularization. These findings suggest that Glrx could be a potential therapeutic target for treating these diseases.

References:

1. Guo, Yuxian, Liu, Yaru, Zhao, Shihao, Ke, Yuehai, Zhang, Xue. 2021. Oxidative stress-induced FABP5 S-glutathionylation protects against acute lung injury by suppressing inflammation in macrophages. In Nature communications, 12, 7094. doi:10.1038/s41467-021-27428-9. https://pubmed.ncbi.nlm.nih.gov/34876574/

2. Chang, Yuanhao, Li, Guanzhang, Zhai, You, Zhang, Wei, Hu, Huimin. 2020. Redox Regulator GLRX Is Associated With Tumor Immunity in Glioma. In Frontiers in immunology, 11, 580934. doi:10.3389/fimmu.2020.580934. https://pubmed.ncbi.nlm.nih.gov/33329553/

3. Wang, Linlin, Liu, Jing, Liu, Jinguo, Bai, Chunxue, Song, Yuanlin. 2019. GLRX inhibition enhances the effects of geftinib in EGFR-TKI-resistant NSCLC cells through FoxM1 signaling pathway. In Journal of cancer research and clinical oncology, 145, 861-872. doi:10.1007/s00432-019-02845-y. https://pubmed.ncbi.nlm.nih.gov/30661098/

4. Corteselli, Elizabeth M, Sharafi, Mona, Hondal, Robert, Li, Jianing, Janssen-Heininger, Yvonne M W. 2023. Structural and functional fine mapping of cysteines in mammalian glutaredoxin reveal their differential oxidation susceptibility. In Nature communications, 14, 4550. doi:10.1038/s41467-023-39664-2. https://pubmed.ncbi.nlm.nih.gov/37507364/

5. Xi, Yue, Li, Yanping, Xu, Pengfei, Huang, Zhiying, Xie, Wen. 2021. The anti-fibrotic drug pirfenidone inhibits liver fibrosis by targeting the small oxidoreductase glutaredoxin-1. In Science advances, 7, eabg9241. doi:10.1126/sciadv.abg9241. https://pubmed.ncbi.nlm.nih.gov/34516906/

6. Matsui, Reiko, Ferran, Beatriz, Oh, Albin, Pimentel, David Richard, Bachschmid, Markus Michael. 2020. Redox Regulation via Glutaredoxin-1 and Protein S-Glutathionylation. In Antioxidants & redox signaling, 32, 677-700. doi:10.1089/ars.2019.7963. https://pubmed.ncbi.nlm.nih.gov/31813265/

7. Murdoch, Colin E, Bachschmid, Markus M, Matsui, Reiko. . Regulation of neovascularization by S-glutathionylation via the Wnt5a/sFlt-1 pathway. In Biochemical Society transactions, 42, 1665-70. doi:10.1042/BST20140213. https://pubmed.ncbi.nlm.nih.gov/25399587/

8. Anathy, Vikas, Lahue, Karolyn G, Chapman, David G, van der Vliet, Albert, Janssen-Heininger, Yvonne M W. 2018. Reducing protein oxidation reverses lung fibrosis. In Nature medicine, 24, 1128-1135. doi:10.1038/s41591-018-0090-y. https://pubmed.ncbi.nlm.nih.gov/29988126/

9. Gong, Xin, Huang, Mengyi, Chen, Lei. 2023. NRF1 mitigates motor dysfunction and dopamine neuron degeneration in mice with Parkinson's disease by promoting GLRX m6 A methylation through upregulation of METTL3 transcription. In CNS neuroscience & therapeutics, 30, e14441. doi:10.1111/cns.14441. https://pubmed.ncbi.nlm.nih.gov/37735974/

10. Matsui, Reiko, Watanabe, Yosuke, Murdoch, Colin E. 2017. Redox regulation of ischemic limb neovascularization - What we have learned from animal studies. In Redox biology, 12, 1011-1019. doi:10.1016/j.redox.2017.04.040. https://pubmed.ncbi.nlm.nih.gov/28505880/