1
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Ha KS. Transglutaminase 2 in diabetes mellitus: Unraveling its multifaceted role and therapeutic implications for vascular complications. Theranostics 2024; 14:2329-2344. [PMID: 38646650 PMCID: PMC11024853 DOI: 10.7150/thno.95742] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Accepted: 03/17/2024] [Indexed: 04/23/2024] Open
Abstract
Diabetes, a severe metabolic disease characterized by chronic hypoglycemia, poses debilitating and life-threatening risks of microvascular and macrovascular complications, including blindness, kidney failure, heart attacks, and limb amputation. Addressing these complications is paramount, urging the development of interventions targeting diabetes-associated vascular dysfunctions. To effectively combat diabetes, a comprehensive understanding of the pathological mechanisms underlying complications and identification of precise therapeutic targets are imperative. Transglutaminase 2 (TGase2) is a multifunctional enzyme implicated in the pathogenesis of diverse diseases such as neurodegenerative disorders, fibrosis, and inflammatory conditions. TGase2 has recently emerged as a key player in both the pathogenesis and therapeutic intervention of diabetic complications. This review highlights TGase2 as a therapeutic target for diabetic complications and explores TGase2 inhibition as a promising therapeutic approach in their treatment.
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Affiliation(s)
- Kwon-Soo Ha
- Department of Molecular and Cellular Biochemistry, Kangwon National University School of Medicine, Chuncheon, Kangwon-do 24341, Korea
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2
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Gallo M, Ferrari E, Terrazzan A, Brugnoli F, Spisni A, Taccioli C, Aguiari G, Trentini A, Volinia S, Keillor JW, Bergamini CM, Bianchi N, Pertinhez TA. Metabolic characterisation of transglutaminase 2 inhibitor effects in breast cancer cell lines. FEBS J 2023; 290:5411-5433. [PMID: 37597264 DOI: 10.1111/febs.16931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 07/04/2023] [Accepted: 08/09/2023] [Indexed: 08/21/2023]
Abstract
Transglutaminase 2 (TG2), which mediates post-translational modifications of multiple intracellular enzymes, is involved in the pathogenesis and progression of cancer. We used 1 H-NMR metabolomics to study the effects of AA9, a novel TG2 inhibitor, on two breast cancer cell lines with distinct phenotypes, MCF-7 and MDA-MB-231. AA9 can promote apoptosis in both cell lines, but it is particularly effective in MD-MB-231, inhibiting transamidation reactions and decreasing cell migration and invasiveness. This metabolomics study provides evidence of a major effect of AA9 on MDA-MB-231 cells, impacting glutamate and aspartate metabolism, rather than on MCF-7 cells, characterised by choline and O-phosphocholine decrease. Interestingly, AA9 treatment induces myo-inositol alteration in both cell lines, indicating action on phosphatidylinositol metabolism, likely modulated by the G protein activity of TG2 on phospholipase C. Considering the metabolic deregulations that characterise various breast cancer subtypes, the existence of a metabolic pathway affected by AA9 further points to TG2 as a promising hot spot. The metabolomics approach provides a powerful tool to monitor the effectiveness of inhibitors and better understand the role of TG2 in cancer.
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Affiliation(s)
- Mariana Gallo
- Department of Medicine and Surgery, University of Parma, Italy
| | - Elena Ferrari
- Department of Medicine and Surgery, University of Parma, Italy
| | - Anna Terrazzan
- Department of Translational Medicine, University of Ferrara, Italy
| | | | - Alberto Spisni
- Department of Medicine and Surgery, University of Parma, Italy
| | - Cristian Taccioli
- Department of Animal Medicine, Production and Health (MAPS), University of Padua, Italy
| | - Gianluca Aguiari
- Department of Neuroscience and Rehabilitation, University of Ferrara, Italy
| | - Alessandro Trentini
- Department of Environmental Sciences and Prevention, University of Ferrara, Italy
| | - Stefano Volinia
- Department of Translational Medicine, University of Ferrara, Italy
| | - Jeffrey W Keillor
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Canada
| | - Carlo M Bergamini
- Department of Neuroscience and Rehabilitation, University of Ferrara, Italy
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3
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Canella R, Brugnoli F, Gallo M, Keillor JW, Terrazzan A, Ferrari E, Grassilli S, Gates EWJ, Volinia S, Bertagnolo V, Bianchi N, Bergamini CM. A Multidisciplinary Approach Establishes a Link between Transglutaminase 2 and the Kv10.1 Voltage-Dependent K + Channel in Breast Cancer. Cancers (Basel) 2022; 15:cancers15010178. [PMID: 36612174 PMCID: PMC9818547 DOI: 10.3390/cancers15010178] [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: 10/21/2022] [Revised: 12/15/2022] [Accepted: 12/24/2022] [Indexed: 12/29/2022] Open
Abstract
Since the multifunctionality of transglutaminase 2 (TG2) includes extra- and intracellular functions, we investigated the effects of intracellular administration of TG2 inhibitors in three breast cancer cell lines, MDA-MB-231, MDA-MB-436 and MDA-MB-468, which are representative of different triple-negative phenotypes, using a patch-clamp technique. The first cell line has a highly voltage-dependent a membrane current, which is low in the second and almost absent in the third one. While applying a voltage protocol to responsive single cells, injection of TG2 inhibitors triggered a significant decrease of the current in MDA-MB-231 that we attributed to voltage-dependent K+ channels using the specific inhibitors 4-aminopyridine and astemizole. Since the Kv10.1 channel plays a dominant role as a marker of cell migration and survival in breast cancer, we investigated its relationship with TG2 by immunoprecipitation. Our data reveal their physical interaction affects membrane currents in MDA-MB-231 but not in the less sensitive MDA-MB-436 cells. We further correlated the efficacy of TG2 inhibition with metabolic changes in the supernatants of treated cells, resulting in increased concentration of methyl- and dimethylamines, representing possible response markers. In conclusion, our findings highlight the interference of TG2 inhibitors with the Kv10.1 channel as a potential therapeutic tool depending on the specific features of cancer cells.
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Affiliation(s)
- Rita Canella
- Department of Neuroscience and Rehabilitation, University of Ferrara, 44121 Ferrara, Italy
| | - Federica Brugnoli
- Department of Translational Medicine, University of Ferrara, 44121 Ferrara, Italy
| | - Mariana Gallo
- Department of Medicine and Surgery, University of Parma, 43125 Parma, Italy
| | - Jeffrey W. Keillor
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Anna Terrazzan
- Department of Translational Medicine, University of Ferrara, 44121 Ferrara, Italy
| | - Elena Ferrari
- Department of Medicine and Surgery, University of Parma, 43125 Parma, Italy
| | - Silvia Grassilli
- Department of Translational Medicine, University of Ferrara, 44121 Ferrara, Italy
| | - Eric W. J. Gates
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Stefano Volinia
- Department of Translational Medicine, University of Ferrara, 44121 Ferrara, Italy
| | - Valeria Bertagnolo
- Department of Translational Medicine, University of Ferrara, 44121 Ferrara, Italy
| | - Nicoletta Bianchi
- Department of Translational Medicine, University of Ferrara, 44121 Ferrara, Italy
- Correspondence: ; Tel.: +39-0532-455854
| | - Carlo M. Bergamini
- Department of Neuroscience and Rehabilitation, University of Ferrara, 44121 Ferrara, Italy
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4
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Galbiati A, Zana A, Conti P. Covalent inhibitors of GAPDH: From unspecific warheads to selective compounds. Eur J Med Chem 2020; 207:112740. [PMID: 32898762 DOI: 10.1016/j.ejmech.2020.112740] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 07/23/2020] [Accepted: 08/05/2020] [Indexed: 11/18/2022]
Abstract
Targeting glycolysis is an attractive approach for the treatment of a wide range of pathologies, such as various tumors and parasitic infections. Due to its pivotal role in the glycolysis, Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) represents a rate-limiting enzyme in those cells that mostly, or exclusively rely on this pathway for energy production. In this context, GAPDH inhibition can be a valuable approach for the development of anticancer and antiparasitic drugs. In addition to its glycolytic role, GAPDH possesses several moonlight functions, whose deregulation is involved in some pathological conditions. Covalent modification on different amino acids of GAPDH, in particular on cysteine residues, can lead to a modulation of the enzyme activity. The selectivity towards specific cysteine residues is essential to achieve a specific phenotypic effect. In this work we report an extensive overview of the latest advances on the numerous compounds able to inhibit GAPDH through the covalent binding to cysteine residues, ranging from endogenous metabolites and xenobiotics, which may serve as pharmacological tools to actual drug-like compounds with promising therapeutic perspectives. Furthermore, we focused on the potentialities of the different warheads, shedding light on the possibility to exploit a combination of a finely tuned electrophilic group with a well-designed recognition moiety. These findings can provide useful information for the rational design of novel covalent inhibitors of GAPDH, with the final goal to expand the current treatment options.
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Affiliation(s)
- Andrea Galbiati
- Department of Pharmaceutical Sciences, Università degli Studi di Milano, Via Mangiagalli 25, 20133, Milano, Italy.
| | - Aureliano Zana
- Department of Pharmaceutical Sciences, Università degli Studi di Milano, Via Mangiagalli 25, 20133, Milano, Italy
| | - Paola Conti
- Department of Pharmaceutical Sciences, Università degli Studi di Milano, Via Mangiagalli 25, 20133, Milano, Italy
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5
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Marcus K, Lelong C, Rabilloud T. What Room for Two-Dimensional Gel-Based Proteomics in a Shotgun Proteomics World? Proteomes 2020; 8:proteomes8030017. [PMID: 32781532 PMCID: PMC7563651 DOI: 10.3390/proteomes8030017] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Revised: 08/02/2020] [Accepted: 08/04/2020] [Indexed: 02/07/2023] Open
Abstract
Two-dimensional gel electrophoresis was instrumental in the birth of proteomics in the late 1980s. However, it is now often considered as an outdated technique for proteomics—a thing of the past. Although this opinion may be true for some biological questions, e.g., when analysis depth is of critical importance, for many others, two-dimensional gel electrophoresis-based proteomics still has a lot to offer. This is because of its robustness, its ability to separate proteoforms, and its easy interface with many powerful biochemistry techniques (including western blotting). This paper reviews where and why two-dimensional gel electrophoresis-based proteomics can still be profitably used. It emerges that, rather than being a thing of the past, two-dimensional gel electrophoresis-based proteomics is still highly valuable for many studies. Thus, its use cannot be dismissed on simple fashion arguments and, as usual, in science, the tree is to be judged by the fruit.
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Affiliation(s)
- Katrin Marcus
- Medizinisches Proteom-Center, Medical Faculty & Medical Proteome Analysis, Center for Proteindiagnostics (PRODI) Ruhr-University Bochum Gesundheitscampus, 4 44801 Bochum, Germany;
| | - Cécile Lelong
- CBM UMR CNRS5249, Université Grenoble Alpes, CEA, CNRS, 17 rue des Martyrs, CEDEX 9, 38054 Grenoble, France;
| | - Thierry Rabilloud
- Laboratory of Chemistry and Biology of Metals, UMR 5249, Université Grenoble Alpes, CNRS, 38054 Grenoble, France
- Correspondence: ; Tel.: +33-438-783-212
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6
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Young D, Pedre B, Ezeriņa D, De Smet B, Lewandowska A, Tossounian MA, Bodra N, Huang J, Astolfi Rosado L, Van Breusegem F, Messens J. Protein Promiscuity in H 2O 2 Signaling. Antioxid Redox Signal 2019; 30:1285-1324. [PMID: 29635930 DOI: 10.1089/ars.2017.7013] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
SIGNIFICANCE Decrypting the cellular response to oxidative stress relies on a comprehensive understanding of the redox signaling pathways stimulated under oxidizing conditions. Redox signaling events can be divided into upstream sensing of oxidants, midstream redox signaling of protein function, and downstream transcriptional redox regulation. Recent Advances: A more and more accepted theory of hydrogen peroxide (H2O2) signaling is that of a thiol peroxidase redox relay, whereby protein thiols with low reactivity toward H2O2 are instead oxidized through an oxidative relay with thiol peroxidases. CRITICAL ISSUES These ultrareactive thiol peroxidases are the upstream redox sensors, which form the first cellular port of call for H2O2. Not all redox-regulated interactions between thiol peroxidases and cellular proteins involve a transfer of oxidative equivalents, and the nature of redox signaling is further complicated through promiscuous functions of redox-regulated "moonlighting" proteins, of which the precise cellular role under oxidative stress can frequently be obscured by "polygamous" interactions. An ultimate goal of redox signaling is to initiate a rapid response, and in contrast to prokaryotic oxidant-responsive transcription factors, mammalian systems have developed redox signaling pathways, which intersect both with kinase-dependent activation of transcription factors, as well as direct oxidative regulation of transcription factors through peroxiredoxin (Prx) redox relays. FUTURE DIRECTIONS We highlight that both transcriptional regulation and cell fate can be modulated either through oxidative regulation of kinase pathways, or through distinct redox-dependent associations involving either Prxs or redox-responsive moonlighting proteins with functional promiscuity. These protein associations form systems of crossregulatory networks with multiple nodes of potential oxidative regulation for H2O2-mediated signaling.
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Affiliation(s)
- David Young
- 1 Center for Structural Biology, VIB, Brussels, Belgium.,2 Brussels Center for Redox Biology, Brussels, Belgium.,3 Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Brandan Pedre
- 1 Center for Structural Biology, VIB, Brussels, Belgium.,2 Brussels Center for Redox Biology, Brussels, Belgium.,3 Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Daria Ezeriņa
- 1 Center for Structural Biology, VIB, Brussels, Belgium.,2 Brussels Center for Redox Biology, Brussels, Belgium.,3 Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Barbara De Smet
- 1 Center for Structural Biology, VIB, Brussels, Belgium.,2 Brussels Center for Redox Biology, Brussels, Belgium.,3 Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium.,4 Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium.,5 Center for Plant Systems Biology, VIB, Ghent, Belgium
| | - Aleksandra Lewandowska
- 1 Center for Structural Biology, VIB, Brussels, Belgium.,2 Brussels Center for Redox Biology, Brussels, Belgium.,3 Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium.,4 Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium.,5 Center for Plant Systems Biology, VIB, Ghent, Belgium
| | - Maria-Armineh Tossounian
- 1 Center for Structural Biology, VIB, Brussels, Belgium.,2 Brussels Center for Redox Biology, Brussels, Belgium.,3 Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Nandita Bodra
- 1 Center for Structural Biology, VIB, Brussels, Belgium.,2 Brussels Center for Redox Biology, Brussels, Belgium.,3 Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium.,4 Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium.,5 Center for Plant Systems Biology, VIB, Ghent, Belgium
| | - Jingjing Huang
- 1 Center for Structural Biology, VIB, Brussels, Belgium.,2 Brussels Center for Redox Biology, Brussels, Belgium.,3 Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium.,4 Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium.,5 Center for Plant Systems Biology, VIB, Ghent, Belgium
| | - Leonardo Astolfi Rosado
- 1 Center for Structural Biology, VIB, Brussels, Belgium.,2 Brussels Center for Redox Biology, Brussels, Belgium.,3 Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Frank Van Breusegem
- 2 Brussels Center for Redox Biology, Brussels, Belgium.,4 Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium.,5 Center for Plant Systems Biology, VIB, Ghent, Belgium
| | - Joris Messens
- 1 Center for Structural Biology, VIB, Brussels, Belgium.,2 Brussels Center for Redox Biology, Brussels, Belgium.,3 Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
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7
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Sivadó É, El Alaoui M, Kiraly R, Fesüs L, Delolme F, Page A, El Alaoui S. Optimised methods (SDS/PAGE and LC-MS) reveal deamidation in all examined transglutaminase-mediated reactions. FEBS Open Bio 2019; 9:396-404. [PMID: 30761263 PMCID: PMC6356169 DOI: 10.1002/2211-5463.12575] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 11/19/2018] [Accepted: 11/20/2018] [Indexed: 01/06/2023] Open
Abstract
Transglutaminases (TGs) are a family of structurally and functionally related enzymes that catalyse calcium‐dependent post‐translational modifications of proteins through protein–protein crosslinking, amine incorporation, or deamidation. For many years deamidation mediated by TGs was considered to be a side reaction, but recently substrate‐specific deamidations have been reported. Here we describe an optimised SDS/PAGE assay for the easy and rapid monitoring of the TG reaction with small peptides. The relative proportion of deamidation to transamidation was evaluated by densitometric analysis and confirmed by nano‐liquid chromatography–nano‐electrospray ionisation MS. We further investigated the effect of reaction conditions on transamidation and deamidation of TG1, TG2 and blood coagulation factor XIII A‐subunit (FXIII‐A) enzymes using a panel of glutamine‐containing peptide substrates. The ratio of transamidation to deamidation was enhanced at high excess of the acyl‐acceptor substrate and increasing pH. In addition, it was influenced by peptide substrates as well. Whereas deamidation was favoured at low cadaverine concentrations and acidic pH, no significant effect of calcium was observed on the ratio of transamidation/deamidation. Under our experimental conditions, deamidation always occurred in vitro even at high excess of the acyl‐acceptor substrate, and the reaction outcome was shifted to deamidation at neutral pH. Our results provide clear evidence of the deamidation in the TG reaction, and may serve as an important approach for in vivo analysis of deamidation to better understand the role of TGs in biological events.
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Affiliation(s)
- Éva Sivadó
- Research Department Covalab S.A.S Lyon France
| | | | - Robert Kiraly
- Department of Biochemistry and Molecular Biology Faculty of Medicine University of Debrecen Hungary
| | - László Fesüs
- Department of Biochemistry and Molecular Biology Faculty of Medicine University of Debrecen Hungary
| | - Frédéric Delolme
- Protein Science Facility SFR BioSciences CNRS UMS 3444 Inserm US 8 ENS UCBL Lyon France
| | - Adeline Page
- Protein Science Facility SFR BioSciences CNRS UMS 3444 Inserm US 8 ENS UCBL Lyon France
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8
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RNA-Seq identifies genes whose proteins are transformative in the differentiation of cytotrophoblast to syncytiotrophoblast, in human primary villous and BeWo trophoblasts. Sci Rep 2018; 8:5142. [PMID: 29572450 PMCID: PMC5865118 DOI: 10.1038/s41598-018-23379-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 03/09/2018] [Indexed: 12/20/2022] Open
Abstract
The fusion of villous cytotrophoblasts into the multinucleated syncytiotrophoblast is critical for the essential functions of the mammalian placenta. Using RNA-Seq gene expression and quantitative protein expression, we identified genes and their cognate proteins which are coordinately up- or down-regulated in two cellular models of cytotrophoblast to syncytiotrophoblast development, human primary villous and human BeWo cytotrophoblasts. These include hCGβ, TREML2, PAM, CRIP2, INHA, FLRG, SERPINF1, C17orf96, KRT17 and SAA1. These findings provide avenues for further understanding the mechanisms underlying mammalian placental synctiotrophoblast development.
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9
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Costa MA. Scrutinising the regulators of syncytialization and their expression in pregnancy-related conditions. Mol Cell Endocrinol 2016; 420:180-93. [PMID: 26586208 DOI: 10.1016/j.mce.2015.11.010] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 11/05/2015] [Accepted: 11/09/2015] [Indexed: 12/16/2022]
Abstract
The placenta is important for the success of gestation and foetal development. In fact, this specialized pregnancy organ is essential for foetal nourishment, support, and protection. In the placenta, there are different cell populations, including four subtypes of trophoblasts. Cytotrophoblasts fuse and differentiate into the multinucleated syncytiotrophoblast (syncytialization). Syncytialization is a hallmark of placentation and is highly regulated by numerous molecules with distinct roles. Placentas from pregnancies complicated by preeclampsia, intrauterine growth restriction or trisomy 21 have been associated with a defective syncytialization and an altered expression of its modulators. This work proposes to review the molecules that promote or inhibit both fusion and biochemical differentiation of cytotrophoblasts. Moreover, it will also analyse the syncytialization modulators abnormally expressed in pathological placentas, highlighting the molecules that may contribute to the aetiology of these diseases.
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Affiliation(s)
- M A Costa
- Faculdade de Farmácia, Universidade do Porto, Porto, Portugal.
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10
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Katt WP, Antonyak MA, Cerione RA. Simultaneously targeting tissue transglutaminase and kidney type glutaminase sensitizes cancer cells to acid toxicity and offers new opportunities for therapeutic intervention. Mol Pharm 2014; 12:46-55. [PMID: 25426679 PMCID: PMC4291776 DOI: 10.1021/mp500405h] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Most cancer cells undergo characteristic metabolic changes that are commonly referred to as the Warburg effect, with one of the hallmarks being a dramatic increase in the rate of lactic acid fermentation. This leads to the production of protons, which in turn acidifies the microenvironment surrounding tumors. Cancer cells have acquired resistance to acid toxicity, allowing them to survive and grow under these detrimental conditions. Kidney type glutaminase (GLS1), which is responsible for the conversion of glutamine to glutamate, produces ammonia as part of its catalytic activities and has been shown to modulate cellular acidity. In this study, we show that tissue, or type 2, transglutaminase (TG2), a γ-glutamyl transferase that is highly expressed in metastatic cancers and produces ammonia as a byproduct of its catalytic activity, is up-regulated by decreases in cellular pH and helps protect cells from acid-induced cell death. Since both TG2 and GLS1 can similarly function to protect cancer cells, we then proceeded to demonstrate that treatment of a variety of cancer cell types with inhibitors of each of these proteins results in synthetic lethality. The combination doses of the inhibitors induce cell death, while individual treatment with each compound shows little or no ability to kill cells. These results suggest that combination drug treatments that simultaneously target TG2 and GLS1 might provide an effective strategy for killing cancer cells.
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Affiliation(s)
- William P Katt
- Department of Molecular Medicine and Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853-6401, United States
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11
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Abstract
The phenomenon of protein moonlighting was discovered in the 1980s and 1990s, and the current definition of what constitutes a moonlighting protein was provided at the end of the 1990s. Since this time, several hundred moonlighting proteins have been identified in all three domains of life, and the rate of discovery is accelerating as the importance of protein moonlighting in biology and medicine becomes apparent. The recent re-evaluation of the number of protein-coding genes in the human genome (approximately 19000) is one reason for believing that protein moonlighting may be a more general phenomenon than the current number of moonlighting proteins would suggest, and preliminary studies of the proportion of proteins that moonlight would concur with this hypothesis. Protein moonlighting could be one way of explaining the seemingly small number of proteins that are encoded in the human genome. It is emerging that moonlighting proteins can exhibit novel biological functions, thus extending the range of the human functional proteome. The several hundred moonlighting proteins so far discovered play important roles in many aspects of biology. For example, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), heat-shock protein 60 (Hsp60) and tRNA synthetases play a wide range of biological roles in eukaryotic cells, and a growing number of eukaryotic moonlighting proteins are recognized to play important roles in physiological processes such as sperm capacitation, implantation, immune regulation in pregnancy, blood coagulation, vascular regeneration and control of inflammation. The dark side of protein moonlighting finds a range of moonlighting proteins playing roles in various human diseases including cancer, cardiovascular disease, HIV and cystic fibrosis. However, some moonlighting proteins are being tested for their therapeutic potential, including immunoglobulin heavy-chain-binding protein (BiP), for rheumatoid arthritis, and Hsp90 for wound healing. In addition, it has emerged over the last 20 years that a large number of bacterial moonlighting proteins play important roles in bacteria–host interactions as virulence factors and are therefore potential therapeutic targets in bacterial infections. So as we progress in the 21st Century, it is likely that moonlighting proteins will be seen to play an increasingly important role in biology and medicine. It is hoped that some of the major unanswered questions, such as the mechanism of evolution of protein moonlighting, the structural biology of moonlighting proteins and their role in the systems biology of cellular systems can be addressed during this period.
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