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van Vlimmeren AE, Voleti R, Chartier CA, Jiang Z, Karandur D, Humphries PA, Lo WL, Shah NH. The pathogenic T42A mutation in SHP2 rewires the interaction specificity of its N-terminal regulatory domain. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.07.10.548257. [PMID: 37502916 PMCID: PMC10369915 DOI: 10.1101/2023.07.10.548257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Mutations in the tyrosine phosphatase SHP2 are associated with a variety of human diseases. Most mutations in SHP2 increase its basal catalytic activity by disrupting auto-inhibitory interactions between its phosphatase domain and N-terminal SH2 (phosphotyrosine recognition) domain. By contrast, some disease-associated mutations located in the ligand-binding pockets of the N- or C-terminal SH2 domains do not increase basal activity and likely exert their pathogenicity through alternative mechanisms. We lack a molecular understanding of how these SH2 mutations impact SHP2 structure, activity, and signaling. Here, we characterize five SHP2 SH2 domain ligand-binding pocket mutants through a combination of high-throughput biochemical screens, biophysical and biochemical measurements, and molecular dynamics simulations. We show that, while some of these mutations alter binding affinity to phosphorylation sites, the T42A mutation in the N-SH2 domain is unique in that it also substantially alters ligand-binding specificity, despite being 8-10 Å from the specificity-determining region of the SH2 domain. This mutation exerts its effect on sequence specificity by remodeling the phosphotyrosine binding pocket, altering the mode of engagement of both the phosphotyrosine and surrounding residues on the ligand. The functional consequence of this altered specificity is that the T42A mutant has biased sensitivity toward a subset of activating ligands and enhances downstream signaling. Our study highlights an example of a nuanced mechanism of action for a disease-associated mutation, characterized by a change in protein-protein interaction specificity that alters enzyme activation.
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Affiliation(s)
- Anne E. van Vlimmeren
- Department of Chemistry, Columbia University, New York, NY 10027
- Department of Biological Sciences, Columbia University, New York, NY 10027
| | - Rashmi Voleti
- Department of Chemistry, Columbia University, New York, NY 10027
| | | | - Ziyuan Jiang
- Department of Chemistry, Columbia University, New York, NY 10027
| | - Deepti Karandur
- Department of Biochemistry, Vanderbilt University, Nashville, TN 37232
| | - Preston A. Humphries
- Division of Microbiology and Immunology, Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT 84112
| | - Wan-Lin Lo
- Division of Microbiology and Immunology, Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT 84112
| | - Neel H. Shah
- Department of Chemistry, Columbia University, New York, NY 10027
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Chen X, Ma J, Wang ZW, Wang Z. The E3 ubiquitin ligases regulate inflammation in cardiovascular diseases. Semin Cell Dev Biol 2024; 154:167-174. [PMID: 36872193 DOI: 10.1016/j.semcdb.2023.02.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 02/19/2023] [Accepted: 02/20/2023] [Indexed: 03/06/2023]
Abstract
Accumulating evidence has illustrated that the E3 ubiquitin ligases critically participate in the development and progression of cardiovascular diseases. Dysregulation of E3 ubiquitin ligases exacerbates cardiovascular diseases. Blockade or activation of E3 ubiquitin ligases mitigates cardiovascular performance. Therefore, in this review, we mainly introduced the critical role and underlying molecular mechanisms of E3 ubiquitin ligase NEDD4 family in governing the initiation and progression of cardiovascular diseases, including ITCH, WWP1, WWP2, Smurf1, Smurf2, Nedd4-1 and Nedd4-2. Moreover, the functions and molecular insights of other E3 ubiquitin ligases, such as F-box proteins, in cardiovascular disease development and malignant progression are described. Furthermore, we illustrate several compounds that alter the expression of E3 ubiquitin ligases to alleviate cardiovascular diseases. Therefore, modulation of E3 ubiquitin ligases could be a novel and promising strategy for improvement of therapeutic efficacy of deteriorative cardiovascular diseases.
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Affiliation(s)
- Xiao Chen
- Department of Cardiology, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang 325000, China
| | - Jia Ma
- Department of Biochemistry and Molecular Biology, School of Laboratory Medicine, Bengbu Medical College, Bengbu, Anhui, 233030, China
| | - Zhi-Wei Wang
- The Second Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang 325000, China.
| | - Zhiting Wang
- Department of Cardiology, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang 325000, China.
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3
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Li Z, Pang Y, Hou L, Xing X, Yu F, Gao M, Wang J, Li X, Zhang L, Xiao Y. Exosomal OIP5-AS1 attenuates cerebral ischemia-reperfusion injury by negatively regulating TXNIP protein stability and inhibiting neuronal pyroptosis. Int Immunopharmacol 2024; 127:111310. [PMID: 38103409 DOI: 10.1016/j.intimp.2023.111310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 11/15/2023] [Accepted: 11/26/2023] [Indexed: 12/19/2023]
Abstract
BACKGROUND Cerebral ischemia-reperfusion injury (CIRI) can cause neuronal apoptosis and lead to irreversible brain injury. Numerous lncRNAs have been reported to play important roles in CIRI, but it is unclear whether these lncRNAs can function through exosomes. METHODS In this study, we utilized the middle cerebral artery occlusion/reperfusion (MCAO/R) animal model and the oxygen-glucose deprivation/ reoxygenation (OGD/R) cell model. RNA sequencing was performed to screen for differentially expressed lncRNAs in M2 microglia-derived exosomes (M2-Exos). RNA pull-down, RNA immunoprecipitation, co-immunoprecipitation and ubiquitination assays were used to explore the molecular mechanism of OIP5-AS1 in alleviating CIRI. RESULTS M2-Exos could alleviate nerve injury and pyroptosis after CIRI in vitro and in vivo. OIP5-AS1 was found to be significantly up-regulated in M2-Exos and down-regulated in OGD/R neurons, MCAO/R mice and ischemic stroke patients. In MCAO/R mice, OIP5-AS1 could reduce cerebral infarct size, cerebral edema and mNSS scores, and inhibit the expression levels of pyroptosis-related proteins in brain tissue. TXNIP was confirmed to be a reliable binding protein of OIP5-AS1. OIP5-AS1 overexpression significantly attenuated MCAO/R-induced upregulation of TXNIP at the protein level, but not at the mRNA level. OIP5-AS1 promoted the TXNIP degradation process and increased the ubiquitination of TXNIP. ITCH could bind to TXNIP. ITCH overexpression or knockdown did not alter the mRNA level of TXNIP, but negatively regulated TXNIP expression at the protein level. ITCH accelerated the degradation and ubiquitination of TXNIP, which could be attenuated by OIP5-AS1 knockdown. OIP5-AS1 could improve neuronal damage and inhibit neuronal pyroptosis through TXNIP. CONCLUSIONS M2-Exo-derived OIP5-AS1 can induce TXNIP ubiquitination and degradation by recruiting ITCH, negatively regulate TXNIP protein stability, inhibit neuronal pyroptosis, and attenuate CIRI.
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Affiliation(s)
- Zhongchen Li
- Department of Neurosurgery, Liaocheng People's Hospital, Liaocheng City, Shandong Province 252000, China; Department of Neurosurgery, Qilu Hospital of Shandong University, Jinan City, Shandong Province 250063, China
| | - Yuejiu Pang
- Department of Healthcare Neurology, Provincial Hospital Affiliated to Shandong First Medical University, Jinan City, Shandong Province 250021, China
| | - Lei Hou
- Department of Neurosurgery, Liaocheng People's Hospital, Liaocheng City, Shandong Province 252000, China
| | - Xiaohui Xing
- Department of Neurosurgery, Liaocheng People's Hospital, Liaocheng City, Shandong Province 252000, China
| | - Fuhua Yu
- Department of Neurosurgery, Liaocheng People's Hospital, Liaocheng City, Shandong Province 252000, China
| | - Mingxu Gao
- Department of Neurosurgery, Liaocheng People's Hospital, Liaocheng City, Shandong Province 252000, China
| | - Jiyue Wang
- Department of Neurosurgery, Liaocheng People's Hospital, Liaocheng City, Shandong Province 252000, China
| | - Xueyuan Li
- Department of Neurosurgery, Liaocheng People's Hospital, Liaocheng City, Shandong Province 252000, China.
| | - Liyong Zhang
- Department of Neurosurgery, Liaocheng People's Hospital, Liaocheng City, Shandong Province 252000, China.
| | - Yilei Xiao
- Department of Neurosurgery, Liaocheng People's Hospital, Liaocheng City, Shandong Province 252000, China.
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Jia W, Wang J, Wei C, Bian M, Bao S, Yu L. Synthesis and hypoglycemic activity of quinoxaline derivatives. Front Chem 2023; 11:1197124. [PMID: 37483267 PMCID: PMC10358274 DOI: 10.3389/fchem.2023.1197124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Accepted: 06/20/2023] [Indexed: 07/25/2023] Open
Abstract
In this study, a new series of quinoxalinone derivatives (5a-5p, 6a-6n) was designed and its hypoglycemic activity was evaluated. The results showed that compounds 5i and 6b exhibited stronger hypoglycemic effects than the lead compounds and were comparable to the positive control Pioglitazone. 5i and 6b may exert hypoglycemic effects by alleviating cellular OS and modulating the interactions among GLUT4, SGLT2, and GLUT1 proteins. The alleviating cellular OS of compound 6b was better than that of 5i, and 6b was found to bind better than 5i for most of the screening targets. In summary, compound 6b is a potential lead compound with hypoglycaemic activity.3.
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Affiliation(s)
| | | | | | - Ming Bian
- *Correspondence: Ming Bian, ; Shuyin Bao, ; Lijun Yu,
| | - Shuyin Bao
- *Correspondence: Ming Bian, ; Shuyin Bao, ; Lijun Yu,
| | - Lijun Yu
- *Correspondence: Ming Bian, ; Shuyin Bao, ; Lijun Yu,
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Marasco M, Kirkpatrick J, Carlomagno T, Hub JS, Anselmi M. Experiment-guided molecular simulations define a heterogeneous structural ensemble for the PTPN11 tandem SH2 domains. Chem Sci 2023; 14:5743-5755. [PMID: 37265738 PMCID: PMC10231330 DOI: 10.1039/d3sc00746d] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 05/04/2023] [Indexed: 06/03/2023] Open
Abstract
SHP2 plays an important role in regulating cellular processes, and its pathogenic mutations cause developmental disorders and are linked to cancer. SHP2 is a multidomain protein, comprising two SH2 domains arranged in tandem, a catalytic PTP domain, and a disordered C-terminal tail. SHP2 is activated upon binding two linked phosphopeptides to its SH2 domains, and the peptide orientation and spacing between binding sites are critical for enzymatic activation. For decades, the tandem SH2 has been extensively studied to identify the relative orientation of the two SH2 domains that most effectively binds effectors. So far, neither crystallography nor experiments in solution have provided conclusive results. Using experiment-guided molecular simulations, we determine the heterogeneous structural ensemble of the tandem SH2 in solution in agreement with experimental data from small-angle X-ray scattering and NMR residual dipolar couplings. In the solution ensemble, N-SH2 adopts different orientations and positions relative to C-SH2. We suggest that the intrinsic structural plasticity of the tandem SH2 allows SHP2 to respond to external stimuli and is essential for its functional activity.
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Affiliation(s)
- Michelangelo Marasco
- Molecular Pharmacology Program, Memorial Sloan Kettering Cancer Center New York NY USA
| | - John Kirkpatrick
- School of Biosciences, University of Birmingham Edgbaston B15 2TT Birmingham UK
| | - Teresa Carlomagno
- School of Biosciences, University of Birmingham Edgbaston B15 2TT Birmingham UK
- Institute of Cancer and Genomic Sciences, University of Birmingham Edgbaston B15 2TT Birmingham UK
| | - Jochen S Hub
- Theoretical Physics and Center for Biophysics, Saarland University 66123 Saarbrücken Germany
| | - Massimiliano Anselmi
- Theoretical Physics and Center for Biophysics, Saarland University 66123 Saarbrücken Germany
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Qualls-Histed SJ, Nielsen CP, MacGurn JA. Lysosomal trafficking of the glucose transporter GLUT1 requires sequential regulation by TXNIP and ubiquitin. iScience 2023; 26:106150. [PMID: 36890792 PMCID: PMC9986520 DOI: 10.1016/j.isci.2023.106150] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 12/04/2022] [Accepted: 02/02/2023] [Indexed: 02/08/2023] Open
Abstract
Glucose transporters are gatekeepers of cellular glucose metabolism. Understanding how their activity is regulated can provide insight into mechanisms of glucose homeostasis and diseases arising from dysregulation of glucose transport. Glucose stimulates endocytosis of the human glucose transporter GLUT1, but several important questions remain surrounding the intracellular trafficking itinerary of GLUT1. Here, we report that increased glucose availability triggers lysosomal trafficking of GLUT1 in HeLa cells, with a subpopulation of GLUT1 routed through ESCRT-associated late endosomes. This itinerary requires the arrestin-like protein TXNIP, which interacts with both clathrin and E3 ubiquitin ligases to promote GLUT1 lysosomal trafficking. We also find that glucose stimulates GLUT1 ubiquitylation, which promotes its lysosomal trafficking. Our results suggest that excess glucose first triggers TXNIP-mediated endocytosis of GLUT1 and, subsequently, ubiquitylation to promote lysosomal trafficking. Our findings underscore how complex coordination of multiple regulators is required for fine-tuning of GLUT1 stability at the cell surface.
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Affiliation(s)
- Susan J. Qualls-Histed
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37240 USA
| | - Casey P. Nielsen
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37240 USA
| | - Jason A. MacGurn
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37240 USA
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7
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Anselmi M, Hub JS. Revealing Allostery in PTPN11 SH2 Domains from MD Simulations. Methods Mol Biol 2023; 2705:59-75. [PMID: 37668969 DOI: 10.1007/978-1-0716-3393-9_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/06/2023]
Abstract
Src-homology 2 (SH2) domains are protein interaction domains that bind to specific peptide motifs containing phosphotyrosine. SHP2, a tyrosine phosphatase encoded by PTPN11 gene, which has been emerged as positive or negative modulator in multiple signaling pathways, contains two SH2 domains, respectively, called N-SH2 and C-SH2. These domains play a relevant role in regulating SHP2 activity, either by recognizing its binding partners or by blocking its catalytic site. Considering the multiple functions that these domains carry out in SHP2, N-SH2 and C-SH2 represent an interesting case of study. In this chapter, we present a methodology that permits, by means of the principal component analysis (PCA), to study and to rationalize the structures adopted by the SH2 domains, in terms of the conformations of their binding sites. The structures can be distinguished, grouped, classified, and reported in a diagram. This approach permits to identify the accessible conformations of the SH2 domains in different binding conditions and to eventually reveal allosteric interactions. The method further reveals that the conformation dynamics of N-SH2 and C-SH2 strongly differ, which likely reflects their distinct functional roles.
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Affiliation(s)
- Massimiliano Anselmi
- Theoretical Physics and Center for Biophysics, Saarland University, Saarbrücken, Germany.
| | - Jochen S Hub
- Theoretical Physics and Center for Biophysics, Saarland University, Saarbrücken, Germany
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8
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Sun Q, Wang BB, Wei W, Huang GC, Liu LL, Chen WW, Wang J, Zhao XY, Lu L, Fang R, Zhu CY, Chu XY. ITCH facilitates proteasomal degradation of TXNIP in hypoxia- induced lung cancer cells. Thorac Cancer 2022; 13:2235-2247. [PMID: 35811256 PMCID: PMC9346185 DOI: 10.1111/1759-7714.14552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 06/06/2022] [Accepted: 06/09/2022] [Indexed: 11/30/2022] Open
Abstract
Background Lung cancer (LC) is one of the most common cancers and a leading cause of cancer‐related deaths worldwide. In many pathological conditions, particularly in the tumor microenvironment, cells and tissues frequently exist in a hypoxic state. Here, we evaluated Itchy E3 ubiquitin protein ligase (ITCH) expression in LC cells following hypoxia treatment. Methods LC cell lines were treated with hypoxic condition. Cell migration, invasion, inflammation, reactive oxygen species (ROS) production, and apoptosis of LC cells were determined by wound healing assay, Transwell invasive assay, ELISA, DCFH‐DA staining, and flow cytometry, respectively. qPCR and WB were used to determine the expression of ITCH and TXNIP. Co‐IP was performed to assess the interaction between ITCH and TXNIP. Results ITCH expression was downregulated in LC cells under hypoxic conditions. Next, LC cells were subjected to hypoxic conditions and changes in cell viability and metastasis were determined. Hypoxic conditions resulted in increased migration and invasion abilities of LC cells. Intracellular reactive oxygen species (ROS) production, inflammation, and apoptosis were also promoted by hypoxia. We found that ITCH overexpression led to the proteasomal degradation of thioredoxin‐interacting protein (TXNIP), whereas the expression of the ITCH C830A mutant did not affect TXNIP levels in LC cells. The gain‐of‐function experiment demonstrated that migration, invasion, ROS generation, inflammation, and apoptosis of hypoxia‐conditioned LC cells were ameliorated by ITCH overexpression, whereas the ITCH C830A mutant did not cause any changes in these phenotypes. Furthermore, the contribution of TXNIP knockdown and ITCH overexpression to the hypoxia‐induced features in LC cells with ITCH C830A was found to be similar. Conclusion Our results suggest a novel mechanism underlying the changes in ITCH‐mediated malignant phenotypes of hypoxia‐conditioned LC cells via TXNIP.
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Affiliation(s)
- Qian Sun
- Department of Medical Oncology, Jinling Hospital, Nanjing, China
| | - Bi-Bo Wang
- Department of Medical Oncology, Jinling Hospital, Nanjing, China
| | - Wei Wei
- Department of Cardiothoracic Surgery, Jinling Hospital, Nanjing, China
| | - Gui-Chun Huang
- Department of Medical Oncology, Jinling Hospital, Medical School of Nanjing University, Nanjing, China
| | - Lei-Lei Liu
- Department of Pathology, Jinling Hospital, Nanjing, China
| | - Wei-Wei Chen
- Department of Medical Oncology, Jinling Hospital, Nanjing, China
| | - Jing Wang
- Department of Medical Oncology, Jinling Hospital, Nanjing, China
| | - Xiao-Yue Zhao
- Department of Medical Oncology, Jinling Hospital, Nanjing, China
| | - Lu Lu
- Department of Medical Oncology, Jinling Hospital, Nanjing, China
| | - Rong Fang
- Department of Medical Oncology, Jinling Hospital, Nanjing, China
| | - Chun-Yan Zhu
- Department of Medical Oncology, Jinling Hospital, Nanjing, China
| | - Xiao-Yuan Chu
- Department of Medical Oncology, Jinling Hospital, Nanjing, China
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Wedegaertner H, Pan WA, Gonzalez CC, Gonzalez DJ, Trejo J. The α-Arrestin ARRDC3 Is an Emerging Multifunctional Adaptor Protein in Cancer. Antioxid Redox Signal 2022; 36:1066-1079. [PMID: 34465145 PMCID: PMC9127825 DOI: 10.1089/ars.2021.0193] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Significance: Adaptor proteins control the spatiotemporal dynamics of cellular signaling. Dysregulation of adaptor protein function can cause aberrant cell signaling and promote cancer. The arrestin family of adaptor proteins are known to regulate signaling by the superfamily of G protein-coupled receptors (GPCRs). The GPCRs are highly druggable and implicated in cancer progression. However, the molecular mechanisms responsible for arrestin dysregulation and the impact on GPCR function in cancer have yet to be fully elucidated. Recent Advances: A new family of mammalian arrestins, termed the α-arrestins, was recently discovered. The α-arrestin, arrestin domain-containing protein 3 (ARRDC3), in particular, has been identified as a tumor suppressor and is reported to control cellular signaling of GPCRs in cancer. Critical Issues: Compared with the extensively studied mammalian β-arrestins, there is limited information regarding the regulatory mechanisms that control α-arrestin activation and function. Here, we discuss the molecular mechanisms that regulate ARRDC3, which include post-translational modifications such as phosphorylation and ubiquitination. We also provide evidence that ARRDC3 can interact with a wide array of proteins that control diverse biological functions. Future Directions: ARRDC3 interacts with numerous proteins and is likely to display diverse functions in cancer, metabolic disease, and other syndromes. Thus, understanding the regulatory mechanisms of ARRDC3 activity in various cellular contexts is critically important. Recent studies suggest that α-arrestins may be regulated through post-translational modification, which is known to impact adaptor protein function. However, additional studies are needed to determine how these regulatory mechanisms affect ARRDC3 tumor suppressor function. Antioxid. Redox Signal. 36, 1066-1079.
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Affiliation(s)
- Helen Wedegaertner
- Department of Pharmacology, School of Medicine, University of California, San Diego, La Jolla, California, USA.,Biomedical Sciences Graduate Program, University of California, San Diego, La Jolla, California, USA
| | - Wen-An Pan
- Department of Pharmacology, School of Medicine, University of California, San Diego, La Jolla, California, USA
| | - Carlos C Gonzalez
- Department of Pharmacology, School of Medicine, University of California, San Diego, La Jolla, California, USA
| | - David J Gonzalez
- Department of Pharmacology, School of Medicine, University of California, San Diego, La Jolla, California, USA.,Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California, USA
| | - JoAnn Trejo
- Department of Pharmacology, School of Medicine, University of California, San Diego, La Jolla, California, USA
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10
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Basnet R, Bahadur T, Basnet BB, Khadka S. Overview on thioredoxin-interacting protein (TXNIP): a potential target for diabetes intervention. Curr Drug Targets 2022; 23:761-767. [PMID: 35240955 DOI: 10.2174/1389450123666220303092324] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 11/25/2021] [Accepted: 12/31/2021] [Indexed: 11/22/2022]
Abstract
BACKGROUND Diabetes mellitus (DM) is a common metabolic disorder characterized by a persistent increment of blood glucose. Type 2 DM is characterized by insulin resistance and β-cell dysfunction. Thioredoxin-interacting protein (TXNIP) is among the factors that control the production and loss of pancreatic β-cells. OBJECTIVE Recent studies have shown that high glucose can significantly up-regulate the expression of the TXNIP. Overexpression of TXNIP in β-cells not only induced apoptosis but also decreased the production of insulin. At the same time, TXNIP deficiency protected the apoptosis of β-cells, leading to increased insulin production. Therefore, finding small molecules that can modulate TXNIP expression and downstream signalling pathways is essential. Thus, the inhibition of TXNIP has beneficial effects on the cardiovascular system and other tissues such as the heart and the kidney in DM. Therefore, DM treatment must target small TXNIP activity, inhibit expression, and promote endogenous cell mass and insulin production. CONCLUSION This review briefly describes the effect mechanism, regulatory mechanism, and crystal structure of TXNIP. In addition, we highlight how TXNIP signalling networks contribute to diabetes and interact with drugs that inhibit the development often and its complexes. Finally, the current status and prospects of TXNIP targeted therapy are also discussed.
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Affiliation(s)
- Rajesh Basnet
- State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, China
| | - Til Bahadur
- Fujian Medical University, Fuzhou, Fujian, China
| | - Buddha Bahadur Basnet
- Faculty of Science, Nepal Academy of Science and Technology, Government of Nepal, Lalitpur, Nepal
| | - Sandhya Khadka
- Department of Pharmacy, Hope International College, Purbanchal University, Lalitpur, Nepal
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11
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Potjewyd FM, Axtman AD. Exploration of Aberrant E3 Ligases Implicated in Alzheimer's Disease and Development of Chemical Tools to Modulate Their Function. Front Cell Neurosci 2021; 15:768655. [PMID: 34867205 PMCID: PMC8637409 DOI: 10.3389/fncel.2021.768655] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 10/28/2021] [Indexed: 11/24/2022] Open
Abstract
The Ubiquitin Proteasome System (UPS) is responsible for the degradation of misfolded or aggregated proteins via a multistep ATP-dependent proteolytic mechanism. This process involves a cascade of ubiquitin (Ub) transfer steps from E1 to E2 to E3 ligase. The E3 ligase transfers Ub to a targeted protein that is brought to the proteasome for degradation. The inability of the UPS to remove misfolded or aggregated proteins due to UPS dysfunction is commonly observed in neurodegenerative diseases, such as Alzheimer's disease (AD). UPS dysfunction in AD drives disease pathology and is associated with the common hallmarks such as amyloid-β (Aβ) accumulation and tau hyperphosphorylation, among others. E3 ligases are key members of the UPS machinery and dysfunction or changes in their expression can propagate other aberrant processes that accelerate AD pathology. The upregulation or downregulation of expression or activity of E3 ligases responsible for these processes results in changes in protein levels of E3 ligase substrates, many of which represent key proteins that propagate AD. A powerful way to better characterize UPS dysfunction in AD and the role of individual E3 ligases is via the use of high-quality chemical tools that bind and modulate specific E3 ligases. Furthermore, through combining gene editing with recent advances in 3D cell culture, in vitro modeling of AD in a dish has become more relevant and possible. These cell-based models of AD allow for study of specific pathways and mechanisms as well as characterization of the role E3 ligases play in driving AD. In this review, we outline the key mechanisms of UPS dysregulation linked to E3 ligases in AD and highlight the currently available chemical modulators. We present several key approaches for E3 ligase ligand discovery being employed with respect to distinct classes of E3 ligases. Where possible, specific examples of the use of cultured neurons to delineate E3 ligase biology have been captured. Finally, utilizing the available ligands for E3 ligases in the design of proteolysis targeting chimeras (PROTACs) to degrade aberrant proteins is a novel strategy for AD, and we explore the prospects of PROTACs as AD therapeutics.
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12
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Zhu QQ, Lai MC, Chen TC, Wang X, Tian L, Li DL, Wu ZH, Wang XH, He YY, He YY, Shang T, Xiang YL, Zhang HK. LncRNA SNHG15 relieves hyperglycemia-induced endothelial dysfunction via increased ubiquitination of thioredoxin-interacting protein. J Transl Med 2021; 101:1142-1152. [PMID: 34103662 DOI: 10.1038/s41374-021-00614-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 04/06/2021] [Accepted: 04/26/2021] [Indexed: 11/09/2022] Open
Abstract
Numerous studies have revealed that hyperglycemia is a pivotal driver of diabetic vascular complications. However, the mechanisms of hyperglycemia-induced endothelial dysfunction in diabetes remain incompletely understood. This study aims to expound on the underlying mechanism of the endothelial dysfunction induced by hyperglycemia from the perspective of long non-coding RNAs (lncRNA). In this study, a downregulation of SNHG15 was observed in the ischemic hind limb of diabetic mice and high glucose (HG)-treated HUVECs. Functionally, the overexpression of SNHG15 promoted cell proliferation, migration, and tube formation, and suppressed cell apoptosis in HG-treated HUVECs. Mechanistically, SNHG15 reduced thioredoxin-interacting protein (TXNIP) expression by enhancing ITCH-mediated ubiquitination of TXNIP. TXNIP overexpression abrogated the protective effect of lncRNA SNHG15 overexpression on HG-induced endothelial dysfunction. The following experiment further confirmed that SNHG15 overexpression promoted angiogenesis of the ischemic hind limb in diabetic mice. In conclusion, SNHG15 is a novel protector for hyperglycemia-induced endothelial dysfunction via decreasing TXNIP expression.
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Affiliation(s)
- Qian-Qian Zhu
- Department of Vascular Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Ming-Chun Lai
- Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Tian-Chi Chen
- Department of Vascular Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Xun Wang
- Department of Vascular Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Lu Tian
- Department of Vascular Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Dong-Lin Li
- Department of Vascular Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China.
| | - Zi-Heng Wu
- Department of Vascular Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Xiao-Hui Wang
- Department of Vascular Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Yun-Yun He
- Department of Vascular Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Yang-Yan He
- Department of Vascular Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Tao Shang
- Department of Vascular Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Yi-Lang Xiang
- Department of Vascular Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Hong-Kun Zhang
- Department of Vascular Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China.
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13
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Xu C, Li XF, Gao LL, Ding ZR, Huang XP, Li YY, Xie DZ. Molecular characterization of thioredoxin-interacting protein (TXNIP) from Megalobrama amblycephala and its potential roles in high glucose-induced inflammatory response. Int J Biol Macromol 2021; 188:460-472. [PMID: 34391784 DOI: 10.1016/j.ijbiomac.2021.08.064] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Accepted: 08/08/2021] [Indexed: 12/17/2022]
Abstract
This study aimed to characterize the full-length cDNA of thioredoxin-interacting protein (TXNIP) from Megalobrama amblycephala, and investigate its roles in high glucose (HC)-induced inflammatory response. The cDNA obtained covered 2706-bp with an open reading frame of 1203-bp encoding 400 amino acids, compared to Cyprinus carpio, it showed 89.96% homology. The highest expression of txnip was observed in head kidney followed by spleen and liver. After a 12-week feeding trial, high-carbohydrate diet remarkably increased txnip expression in liver and white muscle. Glucose administration resulted in a remarkably increased liver txnip expression, which peaked at 1 h. Thereafter, the expression decreased remarkably to the basal value at 12 h. However, insulin injection resulted in a significant decrease in txnip expression with minimum values attained at 2 h. Subsequently, it gradually increased to the normal values. Moreover, in the in-vitro study, over-expression of txnip along with remarkably increased il-1β and il-6 expression in hepatocytes, and its knockdown led to remarkably reduced il-1β expression. Furthermore, metformin treatment remarkably increased the cell viability and trx expression of hepatocytes under high glucose, while the opposite was true for ROS levels, LDH activity, the ALT/AST ratio, Txnip protein content and the transcriptions of txnip, tnfα and il-1β.
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Affiliation(s)
- Chao Xu
- College of Marine Sciences of South China Agricultural University & Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, China
| | - Xiang-Fei Li
- Key Laboratory of Aquatic Nutrition and Feed Science of Jiangsu Province, College of Animal Science and Technology, Nanjing Agricultural University, No.1 Weigang Road, Nanjing 210095, China
| | - Liu-Ling Gao
- College of Marine Sciences of South China Agricultural University & Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, China
| | - Zhi-Rong Ding
- College of Marine Sciences of South China Agricultural University & Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, China
| | - Xiao-Ping Huang
- College of Marine Sciences of South China Agricultural University & Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, China
| | - Yuan-You Li
- College of Marine Sciences of South China Agricultural University & Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, China.
| | - Di-Zhi Xie
- College of Marine Sciences of South China Agricultural University & Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, China.
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14
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Cao X, He W, Pang Y, Cao Y, Qin A. Redox-dependent and independent effects of thioredoxin interacting protein. Biol Chem 2021; 401:1215-1231. [PMID: 32845855 DOI: 10.1515/hsz-2020-0181] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 08/13/2020] [Indexed: 12/12/2022]
Abstract
Thioredoxin interacting protein (TXNIP) is an important physiological inhibitor of the thioredoxin (TXN) redox system in cells. Regulation of TXNIP expression and/or activity not only plays an important role in redox regulation but also exerts redox-independent physiological effects that exhibit direct pathophysiological consequences including elevated inflammatory response, aberrant glucose metabolism, cellular senescence and apoptosis, cellular immunity, and tumorigenesis. This review provides a brief overview of the current knowledge concerning the redox-dependent and independent roles of TXNIP and its relevance to various disease states. The implications for the therapeutic targeting of TXNIP will also be discussed.
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Affiliation(s)
- Xiankun Cao
- Department of Orthopaedic Surgery, Shanghai Key Laboratory of Orthopedic Implants, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, No. 639, Zhizaoju Road, Shanghai, 200011,People's Republic of China
| | - Wenxin He
- Department of Orthopaedic Surgery, Shanghai Key Laboratory of Orthopedic Implants, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, No. 639, Zhizaoju Road, Shanghai, 200011,People's Republic of China
| | - Yichuan Pang
- Department of Oral Surgery, Shanghai Key Laboratory of Stomatology, National Clinical Research Center of Stomatology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011,People's Republic of China
| | - Yu Cao
- Department of Orthopaedics and Institute of Precision Medicine, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, No. 639, Zhizaoju Road, Shanghai, 200011,People's Republic of China
| | - An Qin
- Department of Orthopaedic Surgery, Shanghai Key Laboratory of Orthopedic Implants, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, No. 639, Zhizaoju Road, Shanghai, 200011,People's Republic of China
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15
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Ishida T, Ciulli A. E3 Ligase Ligands for PROTACs: How They Were Found and How to Discover New Ones. SLAS DISCOVERY : ADVANCING LIFE SCIENCES R & D 2021; 26:484-502. [PMID: 33143537 PMCID: PMC8013866 DOI: 10.1177/2472555220965528] [Citation(s) in RCA: 121] [Impact Index Per Article: 40.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 09/14/2020] [Accepted: 09/21/2020] [Indexed: 12/19/2022]
Abstract
Bifunctional degrader molecules, also called proteolysis-targeting chimeras (PROTACs), are a new modality of chemical tools and potential therapeutics to understand and treat human disease. A required PROTAC component is a ligand binding to an E3 ubiquitin ligase, which is then joined to another ligand binding to a protein to be degraded via the ubiquitin-proteasome system. The advent of nonpeptidic small-molecule E3 ligase ligands, notably for von Hippel-Lindau (VHL) and cereblon (CRBN), revolutionized the field and ushered in the design of drug-like PROTACs with potent and selective degradation activity. A first wave of PROTAC drugs are now undergoing clinical development in cancer, and the field is seeking to extend the repertoire of chemistries that allow hijacking new E3 ligases to improve the scope of targeted protein degradation.Here, we briefly review how traditional E3 ligase ligands were discovered, and then outline approaches and ligands that have been recently used to discover new E3 ligases for PROTACs. We will then take an outlook at current and future strategies undertaken that invoke either target-based screening or phenotypic-based approaches, including the use of DNA-encoded libraries (DELs), display technologies and cyclic peptides, smaller molecular glue degraders, and covalent warhead ligands. These approaches are ripe for expanding the chemical space of PROTACs and usher in the advent of other emerging bifunctional modalities of proximity-based pharmacology.
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Affiliation(s)
- Tasuku Ishida
- Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee, UK
| | - Alessio Ciulli
- Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee, UK
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16
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Mathieu NA, Levin RH, Spratt DE. Exploring the Roles of HERC2 and the NEDD4L HECT E3 Ubiquitin Ligase Subfamily in p53 Signaling and the DNA Damage Response. Front Oncol 2021; 11:659049. [PMID: 33869064 PMCID: PMC8044464 DOI: 10.3389/fonc.2021.659049] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 03/16/2021] [Indexed: 12/27/2022] Open
Abstract
Cellular homeostasis is governed by the precise expression of genes that control the translation, localization, and termination of proteins. Oftentimes, environmental and biological factors can introduce mutations into the genetic framework of cells during their growth and division, and these genetic abnormalities can result in malignant transformations caused by protein malfunction. For example, p53 is a prominent tumor suppressor protein that is capable of undergoing more than 300 posttranslational modifications (PTMs) and is involved with controlling apoptotic signaling, transcription, and the DNA damage response (DDR). In this review, we focus on the molecular mechanisms and interactions that occur between p53, the HECT E3 ubiquitin ligases WWP1, SMURF1, HECW1 and HERC2, and other oncogenic proteins in the cell to explore how irregular HECT-p53 interactions can induce tumorigenesis.
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Affiliation(s)
- Nicholas A Mathieu
- Gustaf H. Carlson School of Chemistry and Biochemistry, Clark University, Worcester, MA, United States
| | - Rafael H Levin
- Gustaf H. Carlson School of Chemistry and Biochemistry, Clark University, Worcester, MA, United States
| | - Donald E Spratt
- Gustaf H. Carlson School of Chemistry and Biochemistry, Clark University, Worcester, MA, United States
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17
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Zhu QQ, Lai MC, Chen TC, Wang X, Tian L, Li DL, Wu ZH, Wang XH, He YY, He YY, Shang T, Xiang YL, Zhang HK. LncRNA SNHG15 relieves hyperglycemia-induced endothelial dysfunction via increasing ubiquitination of thioredoxin-interacting protein. Life Sci 2021:119255. [PMID: 33636173 DOI: 10.1016/j.lfs.2021.119255] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 01/11/2021] [Accepted: 01/27/2021] [Indexed: 02/07/2023]
Abstract
OBJECTIVE Numerous evidence indicates that hyperglycemia is a pivotal driver of the vascular complications of diabetes. However, the mechanisms of hyperglycemia-induced endothelial dysfunction in diabetes remain incompletely understood. This study aims to expound on the underlying mechanism of the endothelial dysfunction induced by hyperglycemia from the perspective of long non-coding RNAs (lncRNA). MATERIALS AND METHODS Cell proliferation, migration, apoptosis, and tube formation were measured by cell counting kit-8 assay, transwell assay, flow cytometry, and tube formation assay, respectively. RNA pull-down and RNA-binding protein immunoprecipitation were used to detect the interaction between lncRNA SNHG15 and thioredoxin-interacting protein (TXNIP). Co-immunoprecipitation was used to detect the ubiquitination level of TXNIP and the interaction between TXNIP and E3 ubiquitin ligase ITCH. RESULTS A downregulation of SNHG15 was observed in the ischemic hind limb of diabetic mice and high glucose (HG)-treated HUVECs. Functionally, the overexpression of SNHG15 promoted cell proliferation, migration, and tube formation, and suppressed cell apoptosis in HG-treated HUVECs. Mechanically, SNHG15 reduced TXNIP expression by enhancing ITCH-mediated ubiquitination of TXNIP. TXNIP overexpression abrogated the protective effect of LncRNA SNHG15 overexpression on HG-induced endothelial dysfunction. The following experiment further confirmed that SNHG15 overexpression promoted angiogenesis of the ischemic hind limb in diabetic mice. CONCLUSION SNHG15 is a novel protector for hyperglycemia-induced endothelial dysfunction via decreasing TXNIP expression.
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Affiliation(s)
- Qian-Qian Zhu
- Department of Vascular Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, China
| | - Ming-Chun Lai
- Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, China
| | - Tian-Chi Chen
- Department of Vascular Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, China
| | - Xun Wang
- Department of Vascular Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, China
| | - Lu Tian
- Department of Vascular Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, China
| | - Dong-Lin Li
- Department of Vascular Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, China.
| | - Zi-Heng Wu
- Department of Vascular Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, China
| | - Xiao-Hui Wang
- Department of Vascular Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, China
| | - Yun-Yun He
- Department of Vascular Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, China
| | - Yang-Yan He
- Department of Vascular Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, China
| | - Tao Shang
- Department of Vascular Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, China
| | - Yi-Lang Xiang
- Department of Vascular Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, China
| | - Hong-Kun Zhang
- Department of Vascular Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, China.
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18
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Domingues A, Jolibois J, Marquet de Rougé P, Nivet-Antoine V. The Emerging Role of TXNIP in Ischemic and Cardiovascular Diseases; A Novel Marker and Therapeutic Target. Int J Mol Sci 2021; 22:ijms22041693. [PMID: 33567593 PMCID: PMC7914816 DOI: 10.3390/ijms22041693] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 02/03/2021] [Accepted: 02/04/2021] [Indexed: 12/17/2022] Open
Abstract
Thioredoxin interacting protein (TXNIP) is a metabolism- oxidative- and inflammation-related marker induced in cardiovascular diseases and is believed to represent a possible link between metabolism and cellular redox status. TXNIP is a potential biomarker in cardiovascular and ischemic diseases but also a novel identified target for preventive and curative medicine. The goal of this review is to focus on the novelties concerning TXNIP. After an overview in TXNIP involvement in oxidative stress, inflammation and metabolism, the remainder of this review presents the clues used to define TXNIP as a new marker at the genetic, blood, or ischemic site level in the context of cardiovascular and ischemic diseases.
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Affiliation(s)
- Alison Domingues
- INSERM 1140, Innovative Therapies in Haemostasis, Faculty of Pharmacy, Université de Paris, 75006 Paris, France; (A.D.); (J.J.); (P.M.d.R.)
| | - Julia Jolibois
- INSERM 1140, Innovative Therapies in Haemostasis, Faculty of Pharmacy, Université de Paris, 75006 Paris, France; (A.D.); (J.J.); (P.M.d.R.)
| | - Perrine Marquet de Rougé
- INSERM 1140, Innovative Therapies in Haemostasis, Faculty of Pharmacy, Université de Paris, 75006 Paris, France; (A.D.); (J.J.); (P.M.d.R.)
| | - Valérie Nivet-Antoine
- INSERM 1140, Innovative Therapies in Haemostasis, Faculty of Pharmacy, Université de Paris, 75006 Paris, France; (A.D.); (J.J.); (P.M.d.R.)
- Clinical Biochemistry Department, Assistance Publique des Hôpitaux de Paris, Necker Hospital, 75015 Paris, France
- Correspondence:
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19
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Kahlhofer J, Leon S, Teis D, Schmidt O. The α-arrestin family of ubiquitin ligase adaptors links metabolism with selective endocytosis. Biol Cell 2021; 113:183-219. [PMID: 33314196 DOI: 10.1111/boc.202000137] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 12/03/2020] [Indexed: 12/14/2022]
Abstract
The regulation of nutrient uptake into cells is important, as it allows to either increase biomass for cell growth or to preserve homoeostasis. A key strategy to adjust cellular nutrient uptake is the reconfiguration of the nutrient transporter repertoire at the plasma membrane by the addition of nutrient transporters through the secretory pathway and by their endocytic removal. In this review, we focus on the mechanisms that regulate selective nutrient transporter endocytosis, which is mediated by the α-arrestin protein family. In the budding yeast Saccharomyces cerevisiae, 14 different α-arrestins (also named arrestin-related trafficking adaptors, ARTs) function as adaptors for the ubiquitin ligase Rsp5. They instruct Rsp5 to ubiquitinate subsets of nutrient transporters to orchestrate their endocytosis. The ART proteins are under multilevel control of the major nutrient sensing systems, including amino acid sensing by the general amino acid control and target of rapamycin pathways, and energy sensing by 5'-adenosine-monophosphate-dependent kinase. The function of the six human α-arrestins is comparably under-characterised. Here, we summarise the current knowledge about the function, regulation and substrates of yeast ARTs and human α-arrestins, and highlight emerging communalities and general principles.
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Affiliation(s)
- Jennifer Kahlhofer
- Institute for Cell Biology, Biocenter, Medical University Innsbruck, Innsbruck, Austria
| | - Sebastien Leon
- Université de Paris, CNRS, Institut Jacques Monod, Paris, France
| | - David Teis
- Institute for Cell Biology, Biocenter, Medical University Innsbruck, Innsbruck, Austria
| | - Oliver Schmidt
- Institute for Cell Biology, Biocenter, Medical University Innsbruck, Innsbruck, Austria
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20
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Anselmi M, Calligari P, Hub JS, Tartaglia M, Bocchinfuso G, Stella L. Structural Determinants of Phosphopeptide Binding to the N-Terminal Src Homology 2 Domain of the SHP2 Phosphatase. J Chem Inf Model 2020; 60:3157-3171. [PMID: 32395997 PMCID: PMC8007070 DOI: 10.1021/acs.jcim.0c00307] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Indexed: 11/28/2022]
Abstract
SH2 domain-containing tyrosine phosphatase 2 (SHP2), encoded by PTPN11, plays a fundamental role in the modulation of several signaling pathways. Germline and somatic mutations in PTPN11 are associated with different rare diseases and hematologic malignancies, and recent studies have individuated SHP2 as a central node in oncogenesis and cancer drug resistance. The SHP2 structure includes two Src homology 2 domains (N-SH2 and C-SH2) followed by a catalytic protein tyrosine phosphatase (PTP) domain. Under basal conditions, the N-SH2 domain blocks the active site, inhibiting phosphatase activity. Association of the N-SH2 domain with binding partners containing short amino acid motifs comprising a phosphotyrosine residue (pY) leads to N-SH2/PTP dissociation and SHP2 activation. Considering the relevance of SHP2 in signaling and disease and the central role of the N-SH2 domain in its allosteric regulation mechanism, we performed microsecond-long molecular dynamics (MD) simulations of the N-SH2 domain complexed to 12 different peptides to define the structural and dynamical features determining the binding affinity and specificity of the domain. Phosphopeptide residues at position -2 to +5, with respect to pY, have significant interactions with the SH2 domain. In addition to the strong interaction of the pY residue with its conserved binding pocket, the complex is stabilized hydrophobically by insertion of residues +1, +3, and +5 in an apolar groove of the domain and interaction of residue -2 with both the pY and a protein surface residue. Additional interactions are provided by hydrogen bonds formed by the backbone of residues -1, +1, +2, and +4. Finally, negatively charged residues at positions +2 and +4 are involved in electrostatic interactions with two lysines (Lys89 and Lys91) specific for the SHP2 N-SH2 domain. Interestingly, the MD simulations illustrated a previously undescribed conformational flexibility of the domain, involving the core β sheet and the loop that closes the pY binding pocket.
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Affiliation(s)
- Massimiliano Anselmi
- Department
of Chemical Science and Technologies, University
of Rome Tor Vergata, 00133, Rome, Italy
| | - Paolo Calligari
- Department
of Chemical Science and Technologies, University
of Rome Tor Vergata, 00133, Rome, Italy
| | - Jochen S. Hub
- Theoretical
Physics and Center for Biophysics, Saarland
University, Campus E2 6, 66123 Saarbrücken, Germany
| | - Marco Tartaglia
- Genetics
and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, IRCCS, 00146 Rome, Italy
| | - Gianfranco Bocchinfuso
- Department
of Chemical Science and Technologies, University
of Rome Tor Vergata, 00133, Rome, Italy
| | - Lorenzo Stella
- Department
of Chemical Science and Technologies, University
of Rome Tor Vergata, 00133, Rome, Italy
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21
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A Tyrosine Switch on NEDD4-2 E3 Ligase Transmits GPCR Inflammatory Signaling. Cell Rep 2019; 24:3312-3323.e5. [PMID: 30232011 PMCID: PMC6226018 DOI: 10.1016/j.celrep.2018.08.061] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 07/05/2018] [Accepted: 08/21/2018] [Indexed: 02/03/2023] Open
Abstract
Ubiquitination is essential for protein degradation and signaling and pivotal to many physiological processes. Ubiquitination of a subset of G-protein-coupled receptors (GPCRs) by the E3 ligase NEDD4–2 is required for p38 activation, but how GPCRs activate NEDD4–2 to promote ubiquitinmediated signaling is not known. Here, we report that the GPCR protease-activated receptor-1 (PAR1) stimulates c-Src-mediated tyrosine phosphorylation and activation of NEDD4–2 to promote p38 signaling and endothelial barrier disruption. Using mass spectrometry, we identified a unique phosphorylated tyrosine (Y)-485 within the 2,3-linker peptide between WW domain 2 and 3 of NEDD4–2 in agonist-stimulated cells. Mutation of NEDD4–2 Y485 impaired E3 ligase activity and failed to rescue PAR1-stimulated p38 activation and endothelial barrier permeability. The purinergic P2Y1 receptor also required c-Src and NEDD4–2 tyrosine phosphorylation for p38 activation. These studies reveal a novel role for c-Src in GPCR-induced NEDD4–2 activation, which is critical for driving ubiquitin-mediated p38 inflammatory signaling. Grimsey et al. report that GPCRs stimulate activation of NEDD4–2 E3 ubiquitin ligase via c-Src to induce endothelial p38 inflammatory signaling. c-Src phosphorylates NEDD4–2 at tyrosine-485, releasing the autoinhibitory linker peptide that is critical for enhancing E3 ligase activity, and provides mechanistic insight of how GPCRs activate E3 ubiquitin ligases.
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22
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Dafre AL, Schmitz AE, Maher P. Rapid and persistent loss of TXNIP in HT22 neuronal cells under carbonyl and hyperosmotic stress. Neurochem Int 2019; 132:104585. [PMID: 31678323 DOI: 10.1016/j.neuint.2019.104585] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 10/27/2019] [Accepted: 10/28/2019] [Indexed: 12/11/2022]
Abstract
Thioredoxin interacting protein (TXNIP) binds to thioredoxin thereby limiting its activity, but it also promotes internalization of glucose transporters, participates in inflammasome activation, and controls autophagy. Published data and this work demonstrate that TXNIP responds to a number of apparently unrelated stresses, such as serum deprivation, pH change, and oxidative, osmotic and carbonyl stress. Interestingly, we noticed that hyperosmotic (NaCl) and carbonyl (methylglyoxal, MGO) stresses in HT22 neuronal cells produced a rapid loss of TXNIP (half-life ∼12 min), prompting us to search for possible mechanisms controlling this TXNIP loss, including pH change, serum deprivation, calcium metabolism and inhibition of the proteasome and other proteases, autophagy and MAPKs. None of these routes stopped the TXNIP loss induced by hyperosmotic and carbonyl stress. Besides transcriptional, translational and microRNA regulation, there is evidence indicating that mTOR and AMPK also control TXNIP expression. Indeed, AMPK-deficient mouse embryonic fibroblasts failed to respond to phenformin (AMPK activator) and compound C (AMPK inhibitor), while rapamycin induced a marked increase in TXNIP levels, confirming the known AMPK/mTOR control over TXNIP. However, the TXNIP loss induced by NaCl or MGO were observed even in AMPK deficient MEFs or after mTOR inhibition, indicating AMPK/mTOR does not participate in this rapid TXNIP loss. These results suggest that rapid TXNIP loss is a general and immediate response to stress that can improve energy availability and antioxidant protection, eventually culminating in better cell survival.
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Affiliation(s)
- Alcir Luiz Dafre
- Biochemistry Department, Federal University of Santa Catarina, 88040-900, Florianópolis, SC, Brazil.
| | - Ariana Ern Schmitz
- Biochemistry Department, Federal University of Santa Catarina, 88040-900, Florianópolis, SC, Brazil
| | - Pamela Maher
- Cellular Neurobiology Laboratory, Salk Institute for Biological Studies, CA, 92037, La Jolla, United States.
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23
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Smad7 Binds Differently to Individual and Tandem WW3 and WW4 Domains of WWP2 Ubiquitin Ligase Isoforms. Int J Mol Sci 2019; 20:ijms20194682. [PMID: 31546607 PMCID: PMC6801763 DOI: 10.3390/ijms20194682] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 09/17/2019] [Accepted: 09/18/2019] [Indexed: 12/13/2022] Open
Abstract
WWP2 is an E3 ubiquitin ligase that differentially regulates the contextual tumour suppressor/progressor TGFβ signalling pathway by alternate isoform expression. WWP2 isoforms select signal transducer Smad2/3 or inhibitor Smad7 substrates for degradation through different compositions of protein–protein interaction WW domains. The WW4 domain-containing WWP2-C induces Smad7 turnover in vivo and positively regulates the metastatic epithelial–mesenchymal transition programme. This activity and the overexpression of these isoforms in human cancers make them candidates for therapeutic intervention. Here, we use NMR spectroscopy to solve the solution structure of the WWP2 WW4 domain and observe the binding characteristics of Smad7 substrate peptide. We also reveal that WW4 has an enhanced affinity for a Smad7 peptide phosphorylated at serine 206 adjacent to the PPxY motif. Using the same approach, we show that the WW3 domain also binds Smad7 and has significantly enhanced Smad7 binding affinity when expressed in tandem with the WW4 domain. Furthermore, and relevant to these biophysical findings, we present evidence for a novel WWP2 isoform (WWP2C-ΔHECT) comprising WW3–WW4 tandem domains and a truncated HECT domain that can inhibit TGFβ signalling pathway activity, providing a further layer of complexity and feedback to the WWP2 regulatory apparatus. Collectively, our data reveal a structural platform for Smad substrate selection by WWP2 isoform WW domains that may be significant in the context of WWP2 isoform switching linked to tumorigenesis.
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24
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Lin Z, Yang Z, Xie R, Ji Z, Guan K, Zhang M. Decoding WW domain tandem-mediated target recognitions in tissue growth and cell polarity. eLife 2019; 8:49439. [PMID: 31486770 PMCID: PMC6744271 DOI: 10.7554/elife.49439] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 09/04/2019] [Indexed: 02/06/2023] Open
Abstract
WW domain tandem-containing proteins such as KIBRA, YAP, and MAGI play critical roles in cell growth and polarity via binding to and positioning target proteins in specific subcellular regions. An immense disparity exists between promiscuity of WW domain-mediated target bindings and specific roles of WW domain proteins in cell growth regulation. Here, we discovered that WW domain tandems of KIBRA and MAGI, but not YAP, bind to specific target proteins with extremely high affinity and exquisite sequence specificity. Via systematic structural biology and biochemistry approaches, we decoded the target binding rules of WW domain tandems from cell growth regulatory proteins and uncovered a list of previously unknown WW tandem binding proteins including β-Dystroglycan, JCAD, and PTPN21. The WW tandem-mediated target recognition mechanisms elucidated here can guide functional studies of WW domain proteins in cell growth and polarity as well as in other cellular processes including neuronal synaptic signaling.
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Affiliation(s)
- Zhijie Lin
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Hong Kong, China
| | - Zhou Yang
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Hong Kong, China
| | - Ruiling Xie
- Department of Pharmacology and Moores Cancer Center, University of California, San Diego, La Jolla, United States.,Department of Otolaryngology, Head and Neck Surgery, Peking University First Hospital, Beijing, China
| | - Zeyang Ji
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Hong Kong, China
| | - Kunliang Guan
- Department of Pharmacology and Moores Cancer Center, University of California, San Diego, La Jolla, United States
| | - Mingjie Zhang
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Hong Kong, China.,Center of Systems Biology and Human Health, Hong Kong University of Science and Technology, Kowloon, China
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25
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Kelleher ZT, Wang C, Forrester MT, Foster MW, Marshall HE. ERK-dependent proteasome degradation of Txnip regulates thioredoxin oxidoreductase activity. J Biol Chem 2019; 294:13336-13343. [PMID: 31320475 DOI: 10.1074/jbc.ra119.007733] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 06/26/2019] [Indexed: 12/14/2022] Open
Abstract
Dynamic control of thioredoxin (Trx) oxidoreductase activity is essential for balancing the need of cells to rapidly respond to oxidative/nitrosative stress and to temporally regulate thiol-based redox signaling. We have previously shown that cytokine stimulation of the respiratory epithelium induces a precipitous decline in cell S-nitrosothiol, which depends upon enhanced Trx activity and proteasome-mediated degradation of Txnip (thioredoxin-interacting protein). We now show that tumor necrosis factor-α-induced Txnip degradation in A549 respiratory epithelial cells is regulated by the extracellular signal-regulated protein kinase (ERK) mitogen-activated protein kinase pathway and that ERK inhibition augments both intracellular reactive oxygen species and S-nitrosothiol. ERK-dependent Txnip ubiquitination and proteasome degradation depended upon phosphorylation of a PXTP motif threonine (Thr349) located within the C-terminal α-arrestin domain and proximal to a previously characterized E3 ubiquitin ligase-binding site. Collectively, these findings demonstrate the ERK mitogen-activated protein kinase pathway to be integrally involved in regulating Trx oxidoreductase activity and that the regulation of Txnip lifetime via ERK-dependent phosphorylation is an important mediator of this effect.
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Affiliation(s)
- Zachary T Kelleher
- Division of Pulmonary, Allergy, and Critical Care Medicine, Duke University Medical Center, Durham, North Carolina 27710
| | - Chunbo Wang
- Division of Pulmonary, Allergy, and Critical Care Medicine, Duke University Medical Center, Durham, North Carolina 27710
| | - Michael T Forrester
- Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114
| | - Matthew W Foster
- Division of Pulmonary, Allergy, and Critical Care Medicine, Duke University Medical Center, Durham, North Carolina 27710; Division of Proteomics and Metabolomics Shared Resource, Duke University Medical Center, Durham, North Carolina 27710
| | - Harvey E Marshall
- Division of Pulmonary, Allergy, and Critical Care Medicine, Duke University Medical Center, Durham, North Carolina 27710.
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26
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Lorenz S. Structural mechanisms of HECT-type ubiquitin ligases. Biol Chem 2018; 399:127-145. [PMID: 29016349 DOI: 10.1515/hsz-2017-0184] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 09/25/2017] [Indexed: 12/31/2022]
Abstract
Ubiquitin ligases (E3 enzymes) transfer ubiquitin from ubiquitin-conjugating (E2) enzymes to target proteins. By determining the selection of target proteins, modification sites on those target proteins, and the types of ubiquitin modifications that are formed, E3 enzymes are key specificity factors in ubiquitin signaling. Here, I summarize our knowledge of the structural mechanisms in the HECT E3 subfamily, many members of which play important roles in human disease. I discuss interactions of the conserved HECT domain with E2 enzymes, ubiquitin and target proteins, as well as macromolecular interactions with regulatory functions. While we understand individual steps in the catalytic cycle of HECT E3 enzymes on a structural level, this review also highlights key aspects that have yet to be elucidated. For instance, it remains unclear how diverse target proteins are presented to the catalytic center and how certain HECT E3 enzymes achieve specificity in ubiquitin linkage formation. The structural and functional properties of the N-terminal regions of HECT E3 enzymes that likely act as signaling hubs are also largely unknown. Structural insights into these aspects may open up routes for a therapeutic intervention with specific HECT E3 functions in distinct pathophysiological settings.
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Affiliation(s)
- Sonja Lorenz
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Josef-Schneider-Strasse 2, D-97080 Würzburg, Germany
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27
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K63 ubiquitylation triggers proteasomal degradation by seeding branched ubiquitin chains. Proc Natl Acad Sci U S A 2018; 115:E1401-E1408. [PMID: 29378950 DOI: 10.1073/pnas.1716673115] [Citation(s) in RCA: 176] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Different polyubiquitin chain linkages direct substrates toward distinct cellular pathways. K63-linked ubiquitylation is known to regulate proteasome-independent events such as signal transduction, but its function in the context of heterogeneous ubiquitin chains remains unclear. Here, we report that K63 ubiquitylation plays a critical role in proteasome-mediated substrate degradation by serving as a "seed" for K48/K63 branched ubiquitin chains. Quantitative analysis revealed that K48/K63 branched linkages preferentially associate with proteasomes in cells. We found that ITCH-dependent K63 ubiquitylation of the proapoptotic regulator TXNIP triggered subsequent assembly of K48/K63 branched chains by recruiting ubiquitin-interacting ligases such as UBR5, leading to TXNIP degradation. These results reveal a role for K63 chains as a substrate-specific mark for proteasomal degradation involved in regulating cell fate. Our findings provide insight into how cellular interpretation of the ubiquitin code is altered by combinations of ubiquitin linkages.
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28
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Verma A, Jing-Song F, Finch-Edmondson ML, Velazquez-Campoy A, Balasegaran S, Sudol M, Sivaraman J. Biophysical studies and NMR structure of YAP2 WW domain - LATS1 PPxY motif complexes reveal the basis of their interaction. Oncotarget 2018; 9:8068-8080. [PMID: 29487715 PMCID: PMC5814282 DOI: 10.18632/oncotarget.23909] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Accepted: 11/05/2017] [Indexed: 11/30/2022] Open
Abstract
YES-associated protein (YAP) is a major effector protein of the Hippo tumor suppressor pathway, and is phosphorylated by the serine/threonine kinase LATS. Their binding is mediated by the interaction between WW domains of YAP and PPxY motifs of LATS. Their isoforms, YAP2 and LATS1 contain two WW domains and two PPxY motifs respectively. Here, we report the study of the interaction of these domains both in vitro and in human cell lines, to better understand the mechanism of their binding. We show that there is a reciprocal binding preference of YAP2-WW1 with LATS1-PPxY2, and YAP2-WW2 with LATS1-PPxY1. We solved the NMR structures of these complexes and identified several conserved residues that play a critical role in binding. We further created a YAP2 mutant by swapping the WW domains, and found that YAP2 phosphorylation at S127 by LATS1 is not affected by the spatial configuration of its WW domains. This is likely because the region between the PPxY motifs of LATS1 is unstructured, even upon binding with its partner. Based on our observations, we propose possible models for the interaction between YAP2 and LATS1.
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Affiliation(s)
- Apoorva Verma
- Department of Biological Sciences, National University of Singapore, Singapore
| | - Fan Jing-Song
- Department of Biological Sciences, National University of Singapore, Singapore
| | | | - Adrian Velazquez-Campoy
- Institute of Biocomputation and Physics of Complex Systems (BIFI)-Joint Units: BIFI-IQFR (CSIC) and GBsC-CSIC, Universidad de Zaragoza, Spain, Department of Biochemistry and Molecular and Cellular Biology, Universidad de Zaragoza, Fundacion ARAID, Gobierno de Aragon, Spain, Aragon Health Research Institute (IIS Aragon), Universidad de Zaragoza, Zaragoza, Spain
| | - Shanker Balasegaran
- Department of Biological Sciences, National University of Singapore, Singapore
| | - Marius Sudol
- Mechanobiology Institute, National University of Singapore, Singapore.,Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, MD9, Singapore.,Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research, Singapore
| | - Jayaraman Sivaraman
- Department of Biological Sciences, National University of Singapore, Singapore
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30
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Identification of Redox and Glucose-Dependent Txnip Protein Interactions. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2016; 2016:5829063. [PMID: 27437069 PMCID: PMC4942636 DOI: 10.1155/2016/5829063] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Accepted: 05/26/2016] [Indexed: 01/23/2023]
Abstract
Thioredoxin-interacting protein (Txnip) acts as a negative regulator of thioredoxin function and is a critical modulator of several diseases including, but not limited to, diabetes, ischemia-reperfusion cardiac injury, and carcinogenesis. Therefore, Txnip has become an attractive therapeutic target to alleviate disease pathologies. Although Txnip has been implicated with numerous cellular processes such as proliferation, fatty acid and glucose metabolism, inflammation, and apoptosis, the molecular mechanisms underlying these processes are largely unknown. The objective of these studies was to identify Txnip interacting proteins using the proximity-based labeling method, BioID, to understand differential regulation of pleiotropic Txnip cellular functions. The BioID transgene fused to Txnip expressed in HEK293 identified 31 interacting proteins. Many protein interactions were redox-dependent and were disrupted through mutation of a previously described reactive cysteine (C247S). Furthermore, we demonstrate that this model can be used to identify dynamic Txnip interactions due to known physiological regulators such as hyperglycemia. These data identify novel Txnip protein interactions and demonstrate dynamic interactions dependent on redox and glucose perturbations, providing clarification to the pleiotropic cellular functions of Txnip.
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