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Emerson J, Delgado T, Hong M, Keillor JW, Johnson GVW. Stabilizing transglutaminase 2 in the open conformation results in reactive astrocytes being more neurosupportive. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.15.589192. [PMID: 38659783 PMCID: PMC11042235 DOI: 10.1101/2024.04.15.589192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Astrocytes play critical roles in supporting structural and metabolic homeostasis in the central nervous system (CNS). Inflammatory conditions bring about a range of poorly understood, heterogeneous, reactive phenotypes in astrocytes. Finding ways to manipulate the phenotype of reactive astrocytes, and leveraging a pro-recovery phenotype, holds promise in treating CNS injury. Previous studies have shown that the protein transglutaminase 2 (TG2) plays a significant role in determining the phenotype of reactive astrocytes. Recently it has been demonstrated that ablation of TG2 from astrocytes improves injury outcomes both in vitro and in vivo. Excitingly, in an in vivo mouse model, pharmacological inhibition of TG2 with the irreversible inhibitor VA4 phenocopies the neurosupportive effects of TG2 deletion in astrocytes. The focus of this study was to provide insights into the mechanisms by which TG2 deletion or inhibition of TG2 with VA4 result in a more neurosupportive astrocytic phenotype. Using a neuron-astrocyte co-culture model of neurite outgrowth, we show that VA4 treatment improves the ability of astrocytes to support neurite outgrowth on an injury-relevant matrix, further validating the ability of VA4 to phenocopy astrocytic TG2 deletion. VA4 treatment of neurons alone had no effect on neurite outgrowth. VA4 covalently binds to active site residues of TG2 that are exposed in its open conformation and are critical for its enzymatic function, and prevents TG2 from taking on a closed conformation, which interferes with its protein scaffolding function. To begin to understand how pharmacologically altering TG2's conformation affects its ability to regulate reactive astrocyte phenotypes, we assayed the impact of VA4 on TG2's interaction with Zbtb7a, a transcription factor that we have previously identified as a TG2 interactor, and whose functional outputs are significantly regulated by TG2. The results of these studies demonstrated that VA4 significantly decreases the interaction of TG2 and Zbtb7a. Further, previous findings indicate that TG2 may act as an epigenetic regulator, through its nuclear protein-protein interactions, to modulate gene expression. Since both TG2 and Zbtb7a interact with members of the Sin3a chromatin repressor complex, we assayed the effect of TG2 deletion and VA4 treatment on histone acetylation and found significantly greater acetylation with TG2 deletion or inhibition with VA4. Overall, this work points toward a possible epigenetic mechanism by which genetic deletion or acute inhibition of TG2 leads to enhanced astrocytic support of neurons.
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Affiliation(s)
- Jacen Emerson
- 601 Elmwood Ave, box 604, Department of Anesthesiology and Perioperative Medicine, University of Rochester, Rochester, NY, 14620, USA
| | - Thomas Delgado
- 601 Elmwood Ave, box 604, Department of Anesthesiology and Perioperative Medicine, University of Rochester, Rochester, NY, 14620, USA
| | - Matthew Hong
- 601 Elmwood Ave, box 604, Department of Anesthesiology and Perioperative Medicine, University of Rochester, Rochester, NY, 14620, USA
| | - Jeffrey W. Keillor
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON K1N6N5, Canada
| | - Gail VW Johnson
- 601 Elmwood Ave, box 604, Department of Anesthesiology and Perioperative Medicine, University of Rochester, Rochester, NY, 14620, USA
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Liu C, Gao X, Shi R, Wang Y, He X, Du H, Hu B, Jiao J, Liu C, Teng Z. Microglial transglutaminase 2 deficiency causes impaired synaptic remodelling and cognitive deficits in mice. Cell Prolif 2023; 56:e13439. [PMID: 36878712 PMCID: PMC10472527 DOI: 10.1111/cpr.13439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 02/14/2023] [Accepted: 02/20/2023] [Indexed: 03/08/2023] Open
Abstract
Microglia are the primary source of transglutaminase 2 (TGM2) in the brain; however, the roles of microglial TGM2 in neural development and disease are still not well known. The aim of this study is to elucidate the role and mechanisms of microglial TGM2 in the brain. A mouse line with a specific knockout of Tgm2 in microglia was generated. Immunohistochemistry, Western blot and qRT-PCR assays were performed to evaluate the expression levels of TGM2, PSD-95 and CD68. Confocal imaging, immunofluorescence staining and behavioural analyses were conducted to identify phenotypes of microglial TGM2 deficiency. Finally, RNA sequencing, qRT-PCR and co-culture of neurons and microglia were used to explore the potential mechanisms. Deletion of microglial Tgm2 causes impaired synaptic pruning, reduced anxiety and increased cognitive deficits in mice. At the molecular level, the phagocytic genes, such as Cq1a, C1qb and Tim4, are significantly down-regulated in TGM2-deficient microglia. This study elucidates a novel role of microglial TGM2 in regulating synaptic remodelling and cognitive function, indicating that microglia Tgm2 is essential for proper neural development.
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Affiliation(s)
- Cong Liu
- State Key Laboratory of Stem Cell and Reproductive BiologyInstitute of Zoology, Chinese Academy of SciencesBeijingChina
- Beijing Institute for Stem Cell and Regenerative MedicineBeijingChina
- Institute for Stem Cell and RegenerationChinese Academy of SciencesBeijingChina
| | - Xing Gao
- State Key Laboratory of Stem Cell and Reproductive BiologyInstitute of Zoology, Chinese Academy of SciencesBeijingChina
- Savaid Medical SchoolUniversity of Chinese Academy of SciencesBeijingChina
| | - Ruo‐Xi Shi
- State Key Laboratory of Stem Cell and Reproductive BiologyInstitute of Zoology, Chinese Academy of SciencesBeijingChina
- Savaid Medical SchoolUniversity of Chinese Academy of SciencesBeijingChina
| | - Ying‐Ying Wang
- State Key Laboratory of Stem Cell and Reproductive BiologyInstitute of Zoology, Chinese Academy of SciencesBeijingChina
- Beijing Institute for Stem Cell and Regenerative MedicineBeijingChina
- Institute for Stem Cell and RegenerationChinese Academy of SciencesBeijingChina
- Savaid Medical SchoolUniversity of Chinese Academy of SciencesBeijingChina
| | - Xuan‐Cheng He
- State Key Laboratory of Stem Cell and Reproductive BiologyInstitute of Zoology, Chinese Academy of SciencesBeijingChina
- Beijing Institute for Stem Cell and Regenerative MedicineBeijingChina
- Institute for Stem Cell and RegenerationChinese Academy of SciencesBeijingChina
| | - Hong‐Zhen Du
- State Key Laboratory of Stem Cell and Reproductive BiologyInstitute of Zoology, Chinese Academy of SciencesBeijingChina
- Beijing Institute for Stem Cell and Regenerative MedicineBeijingChina
- Institute for Stem Cell and RegenerationChinese Academy of SciencesBeijingChina
| | - Baoyang Hu
- State Key Laboratory of Stem Cell and Reproductive BiologyInstitute of Zoology, Chinese Academy of SciencesBeijingChina
- Beijing Institute for Stem Cell and Regenerative MedicineBeijingChina
- Institute for Stem Cell and RegenerationChinese Academy of SciencesBeijingChina
- Savaid Medical SchoolUniversity of Chinese Academy of SciencesBeijingChina
| | - Jianwei Jiao
- State Key Laboratory of Stem Cell and Reproductive BiologyInstitute of Zoology, Chinese Academy of SciencesBeijingChina
- Beijing Institute for Stem Cell and Regenerative MedicineBeijingChina
- Institute for Stem Cell and RegenerationChinese Academy of SciencesBeijingChina
- Savaid Medical SchoolUniversity of Chinese Academy of SciencesBeijingChina
| | - Chang‐Mei Liu
- State Key Laboratory of Stem Cell and Reproductive BiologyInstitute of Zoology, Chinese Academy of SciencesBeijingChina
- Beijing Institute for Stem Cell and Regenerative MedicineBeijingChina
- Institute for Stem Cell and RegenerationChinese Academy of SciencesBeijingChina
- Savaid Medical SchoolUniversity of Chinese Academy of SciencesBeijingChina
| | - Zhao‐Qian Teng
- State Key Laboratory of Stem Cell and Reproductive BiologyInstitute of Zoology, Chinese Academy of SciencesBeijingChina
- Beijing Institute for Stem Cell and Regenerative MedicineBeijingChina
- Institute for Stem Cell and RegenerationChinese Academy of SciencesBeijingChina
- Savaid Medical SchoolUniversity of Chinese Academy of SciencesBeijingChina
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Emerson J, Delgado T, Girardi P, Johnson GVW. Deletion of Transglutaminase 2 from Mouse Astrocytes Significantly Improves Their Ability to Promote Neurite Outgrowth on an Inhibitory Matrix. Int J Mol Sci 2023; 24:6058. [PMID: 37047031 PMCID: PMC10094709 DOI: 10.3390/ijms24076058] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 03/01/2023] [Accepted: 03/16/2023] [Indexed: 04/14/2023] Open
Abstract
Astrocytes are the primary support cells of the central nervous system (CNS) that help maintain the energetic requirements and homeostatic environment of neurons. CNS injury causes astrocytes to take on reactive phenotypes with an altered overall function that can range from supportive to harmful for recovering neurons. The characterization of reactive astrocyte populations is a rapidly developing field, and the underlying factors and signaling pathways governing which type of reactive phenotype that astrocytes take on are poorly understood. Our previous studies suggest that transglutaminase 2 (TG2) has an important role in determining the astrocytic response to injury. Selectively deleting TG2 from astrocytes improves functional outcomes after CNS injury and causes widespread changes in gene regulation, which is associated with its nuclear localization. To begin to understand how TG2 impacts astrocytic function, we used a neuron-astrocyte co-culture paradigm to compare the effects of TG2-/- and wild-type (WT) mouse astrocytes on neurite outgrowth and synapse formation. Neurons were grown on a control substrate or an injury-simulating matrix comprised of inhibitory chondroitin sulfate proteoglycans (CSPGs). Compared to WT astrocytes, TG2-/- astrocytes supported neurite outgrowth to a significantly greater extent only on the CSPG matrix, while synapse formation assays showed mixed results depending on the pre- and post-synaptic markers analyzed. We hypothesize that TG2 regulates the supportive functions of astrocytes in injury conditions by modulating gene expression through interactions with transcription factors and transcription complexes. Based on the results of a previous yeast two-hybrid screen for TG2 interactors, we further investigated the interaction of TG2 with Zbtb7a, a ubiquitously expressed transcription factor. Co-immunoprecipitation and colocalization analyses confirmed the interaction of TG2 and Zbtb7a in the nucleus of astrocytes. Overexpression or knockdown of Zbtb7a levels in WT and TG2-/- astrocytes revealed that Zbtb7a robustly influenced astrocytic morphology and the ability of astrocytes to support neuronal outgrowth, which was significantly modulated by the presence of TG2. These findings support our hypothesis that astrocytic TG2 acts as a transcriptional regulator to influence astrocytic function, with greater influence under injury conditions that increase its expression, and Zbtb7a likely contributes to the overall effects observed with astrocytic TG2 deletion.
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Affiliation(s)
| | | | - Peter Girardi
- Department of Anesthesiology and Perioperative Medicine, University of Rochester, 601 Elmwood Ave., Box 604, Rochester, NY 14620, USA
| | - Gail V. W. Johnson
- Department of Anesthesiology and Perioperative Medicine, University of Rochester, 601 Elmwood Ave., Box 604, Rochester, NY 14620, USA
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Emerson J, Delgado T, Girardi P, Johnson GVW. Deletion of transglutaminase 2 from astrocytes significantly improves their ability to promote neurite outgrowth on an inhibitory matrix. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.06.527263. [PMID: 36798305 PMCID: PMC9934526 DOI: 10.1101/2023.02.06.527263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Astrocytes are the primary support cells of the central nervous system (CNS) that help maintain the energetic requirements and homeostatic environment of neurons. CNS injury causes astrocytes to take on reactive phenotypes with altered overall function that can range from supportive to harmful for recovering neurons. The characterization of reactive astrocyte populations is a rapidly developing field, and the underlying factors and signaling pathways governing which type of reactive phenotype that astrocytes take on is poorly understood. Our previous studies suggest that transglutaminase 2 (TG2) has an important role in determining the astrocytic response to injury. TG2 is upregulated in astrocytes across multiple injury models, and selectively deleting TG2 from astrocytes improves functional outcomes after CNS injury and causes widespread changes in gene regulation, which is associated with its nuclear localization. The underlying molecular mechanisms by which TG2 causes these functional changes are unknown, and its interactions in the nucleus of astrocytes has not yet been described. To begin to understand how TG2 impacts astrocytic function, we used a neuron-astrocyte co-culture paradigm to compare the effects of TG2-/- and wild type (WT) astrocytes on neurite outgrowth and synapse formation. We assayed neurons on both a growth-supportive substrate and an injury-simulating matrix comprised of inhibitory chondroitin sulfate proteoglycans (CSPGs). Compared to WT astrocytes, TG2-/- astrocytes supported neurite outgrowth to a significantly greater extent only on the CSPG matrix, while synapse formation assays showed mixed results depending on the pre- and post-synaptic markers analyzed. We hypothesize that TG2 regulates the supportive functions of astrocytes in injury conditions by modulating the expression of a wide range of genes through interactions with transcription factors and transcription complexes. Based on results of a previous yeast two-hybrid screen for TG2 interactors, we further investigated the interaction of TG2 with Zbtb7a, a ubiquitously expressed transcription factor. Coimmunoprecipitation and colocalization analyses confirmed the interaction of TG2 and Zbtb7a in the nucleus of astrocytes. Genetic overexpression or knockdown of Zbtb7a levels in TG2-/- and WT astrocytes revealed that Zbtb7a robustly influenced astrocytic morphology and the ability of astrocytes to support neuronal outgrowth, which was significantly modulated by the presence of TG2. These findings support our hypothesis that astrocytic TG2 acts as a transcriptional regulator to influence astrocytic function, with greater influence under injury conditions that increase its expression, and Zbtb7a likely contributes to the overall effects observed with astrocytic TG2 deletion.
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Affiliation(s)
- Jacen Emerson
- 601 Elmwood Ave, Box 604, Department of Anesthesiology and Perioperative Medicine, University of Rochester, Rochester, NY 14620, USA
| | - Thomas Delgado
- 601 Elmwood Ave, Box 604, Department of Anesthesiology and Perioperative Medicine, University of Rochester, Rochester, NY 14620, USA
| | - Peter Girardi
- 601 Elmwood Ave, Box 604, Department of Anesthesiology and Perioperative Medicine, University of Rochester, Rochester, NY 14620, USA
| | - Gail VW Johnson
- 601 Elmwood Ave, Box 604, Department of Anesthesiology and Perioperative Medicine, University of Rochester, Rochester, NY 14620, USA,Correspondence: ; Tel.: +1-585-276-3740
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5
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Tonoli E, Verduci I, Gabrielli M, Prada I, Forcaia G, Coveney C, Savoca MP, Boocock DJ, Sancini G, Mazzanti M, Verderio C, Verderio EAM. Extracellular transglutaminase-2, nude or associated with astrocytic extracellular vesicles, modulates neuronal calcium homeostasis. Prog Neurobiol 2022; 216:102313. [PMID: 35760142 DOI: 10.1016/j.pneurobio.2022.102313] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 06/15/2022] [Accepted: 06/22/2022] [Indexed: 01/12/2023]
Abstract
We have uncovered a novel role for astrocytes-derived extracellular vesicles (EVs) in controlling intraneuronal Ca2+ concentration ([Ca2+]i) and identified transglutaminase-2 (TG2) as a surface-cargo of astrocytes-derived EVs. Incubation of hippocampal neurons with primed astrocyte-derived EVs have led to an increase in [Ca2+]i, unlike EVs from TG2-knockout astrocytes. Exposure of neurons or brain slices to extracellular TG2 promoted a [Ca2+]i rise, which was reversible upon TG2 removal and was dependent on Ca2+ influx through the plasma membrane. Patch-clamp and calcium imaging recordings revealed TG2-dependent neuronal membrane depolarization and activation of inward currents, due to the Na+/Ca2+-exchanger (NCX) operating in the reverse mode and indirect activation of L-type VOCCs, as indicated by VOCCs/NCX pharmacological inhibitors. A subunit of Na+/K+-ATPase was selected by comparative proteomics and identified as being functionally inhibited by extracellular TG2, implicating Na+/K+-ATPase inhibition in NCX reverse mode-switching leading to Ca2+ influx and higher basal [Ca2+]i. These data suggest that reactive astrocytes control intraneuronal [Ca2+]i through release of EVs with TG2 as responsible cargo, which could have a significant impact on synaptic activity in brain inflammation.
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Affiliation(s)
- Elisa Tonoli
- School of Science and Technology, Centre for Health, Ageing and Understanding of Disease, Nottingham Trent University, Nottingham NG11 8NS, United Kingdom
| | - Ivan Verduci
- Department of Bioscience, University of Milan, Milano 20133, Italy
| | | | - Ilaria Prada
- CNR Institute of Neuroscience, Vedano al Lambro 20854, Italy
| | - Greta Forcaia
- Human Physiology Lab., School of Medicine and Surgery, University of Milano-Bicocca, Monza 20900, Italy
| | - Clare Coveney
- School of Science and Technology, The John van Geest Cancer Research Centre, Nottingham Trent University, Nottingham NG11 8NS, United Kingdom
| | - Maria Pia Savoca
- School of Science and Technology, Centre for Health, Ageing and Understanding of Disease, Nottingham Trent University, Nottingham NG11 8NS, United Kingdom
| | - David J Boocock
- School of Science and Technology, The John van Geest Cancer Research Centre, Nottingham Trent University, Nottingham NG11 8NS, United Kingdom
| | - Giulio Sancini
- Human Physiology Lab., School of Medicine and Surgery, University of Milano-Bicocca, Monza 20900, Italy; NeuroMI (Milan Center for Neuroscience), School of Medicine and Surgery, University of Milano-Bicocca, Monza 20900, Italy
| | - Michele Mazzanti
- Department of Bioscience, University of Milan, Milano 20133, Italy
| | - Claudia Verderio
- CNR Institute of Neuroscience, Vedano al Lambro 20854, Italy; NeuroMI (Milan Center for Neuroscience), School of Medicine and Surgery, University of Milano-Bicocca, Monza 20900, Italy.
| | - Elisabetta A M Verderio
- School of Science and Technology, Centre for Health, Ageing and Understanding of Disease, Nottingham Trent University, Nottingham NG11 8NS, United Kingdom; Biological Sciences Department (BiGeA), University of Bologna, Bologna 40126, Italy.
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Zhang Q, Qiao S, Yang C, Jiang G. Nuclear factor-kappa B and effector molecules in photoaging. Cutan Ocul Toxicol 2022; 41:187-193. [PMID: 35658705 DOI: 10.1080/15569527.2022.2081702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Nuclear factor-kappa B (NF-κB) has important but complex functions in the photoaging of the human skin. This protein complex is activated upon UV irradiation and plays a key role in the signalling pathway of the inflammatory cascade. NF-κB induces the expression of various proinflammatory cytokines, such as tumour necrosis factor (TNF) and interleukin-1 (IL-1). These proinflammatory cytokines can in turn stimulate the activation of NF-κB, forming a vicious cycle. These processes cause chronic inflammation and contribute to skin ageing. In addition, the activation of NF-κB upregulates the expression of matrix metalloproteinases (MMPs) and leads to the degradation of structural proteins in the dermis. NF-κB disrupts the barrier function of the skin under prolonged and repeated UV stimulations in these ways. Such activity causes chronic skin damage, followed by the formation of wrinkles, dryness, roughness, laxity, and other photoaging manifestations. This study on the NF-κB signalling pathway and effector molecules provides a new perspective to understand and prevent photoaging.
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Affiliation(s)
- Qiang Zhang
- Department of Dermatology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, China.,Department of Dermatology, Xuzhou Medical University, Xuzhou, China
| | - Shiyun Qiao
- Department of Dermatology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, China.,Department of Dermatology, Xuzhou Medical University, Xuzhou, China
| | - Chunsheng Yang
- Department of Dermatology, The Affiliated Huai'an Hospital of Xuzhou Medical University, The Second People's Hospital of Huai'an, Huai'an, China
| | - Guan Jiang
- Department of Dermatology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, China.,Department of Dermatology, Xuzhou Medical University, Xuzhou, China
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Elahi A, Emerson J, Rudlong J, Keillor JW, Salois G, Visca A, Girardi P, Johnson GV, Pröschel C. Deletion or Inhibition of Astrocytic Transglutaminase 2 Promotes Functional Recovery after Spinal Cord Injury. Cells 2021; 10:2942. [PMID: 34831164 PMCID: PMC8616117 DOI: 10.3390/cells10112942] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 10/20/2021] [Accepted: 10/21/2021] [Indexed: 01/23/2023] Open
Abstract
Following CNS injury, astrocytes become "reactive" and exhibit pro-regenerative or harmful properties. However, the molecular mechanisms that cause astrocytes to adopt either phenotype are not well understood. Transglutaminase 2 (TG2) plays a key role in regulating the response of astrocytes to insults. Here, we used mice in which TG2 was specifically deleted in astrocytes (Gfap-Cre+/- TG2fl/fl, referred to here as TG2-A-cKO) in a spinal cord contusion injury (SCI) model. Deletion of TG2 from astrocytes resulted in a significant improvement in motor function following SCI. GFAP and NG2 immunoreactivity, as well as number of SOX9 positive cells, were significantly reduced in TG2-A-cKO mice. RNA-seq analysis of spinal cords from TG2-A-cKO and control mice 3 days post-injury identified thirty-seven differentially expressed genes, all of which were increased in TG2-A-cKO mice. Pathway analysis revealed a prevalence for fatty acid metabolism, lipid storage and energy pathways, which play essential roles in neuron-astrocyte metabolic coupling. Excitingly, treatment of wild type mice with the selective TG2 inhibitor VA4 significantly improved functional recovery after SCI, similar to what was observed using the genetic model. These findings indicate the use of TG2 inhibitors as a novel strategy for the treatment of SCI and other CNS injuries.
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Affiliation(s)
- Anissa Elahi
- Department of Biomedical Genetics, University of Rochester, Rochester, NY 14620, USA; (A.E.); (G.S.); (A.V.); (C.P.)
| | - Jacen Emerson
- Department of Anesthesiology and Perioperative Medicine, University of Rochester, Rochester, NY 14620, USA; (J.E.); (J.R.); (P.G.)
| | - Jacob Rudlong
- Department of Anesthesiology and Perioperative Medicine, University of Rochester, Rochester, NY 14620, USA; (J.E.); (J.R.); (P.G.)
| | - Jeffrey W. Keillor
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada;
| | - Garrick Salois
- Department of Biomedical Genetics, University of Rochester, Rochester, NY 14620, USA; (A.E.); (G.S.); (A.V.); (C.P.)
| | - Adam Visca
- Department of Biomedical Genetics, University of Rochester, Rochester, NY 14620, USA; (A.E.); (G.S.); (A.V.); (C.P.)
| | - Peter Girardi
- Department of Anesthesiology and Perioperative Medicine, University of Rochester, Rochester, NY 14620, USA; (J.E.); (J.R.); (P.G.)
| | - Gail V.W. Johnson
- Department of Anesthesiology and Perioperative Medicine, University of Rochester, Rochester, NY 14620, USA; (J.E.); (J.R.); (P.G.)
| | - Christoph Pröschel
- Department of Biomedical Genetics, University of Rochester, Rochester, NY 14620, USA; (A.E.); (G.S.); (A.V.); (C.P.)
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Keillor JW, Johnson GVW. Transglutaminase 2 as a therapeutic target for neurological conditions. Expert Opin Ther Targets 2021; 25:721-731. [PMID: 34607527 DOI: 10.1080/14728222.2021.1989410] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 10/01/2021] [Indexed: 12/14/2022]
Abstract
INTRODUCTION Transglutaminase 2 (TG2) has been implicated in numerous neurological conditions, including neurodegenerative diseases, multiple sclerosis, and CNS injury. Early studies on the role of TG2 in neurodegenerative conditions focused on its ability to 'crosslink' proteins into insoluble aggregates. However, more recent studies have suggested that this is unlikely to be the primary mechanism by which TG2 contributes to the pathogenic processes. Although the specific mechanisms by which TG2 is involved in neurological conditions have not been clearly defined, TG2 regulates numerous cellular processes through which it could contribute to a specific disease. Given the fact that TG2 is a stress-induced gene and elevated in disease or injury conditions, TG2 inhibitors may be useful neurotherapeutics. AREAS COVERED Overview of TG2 and different TG2 inhibitors. A brief review of TG2 in neurodegenerative diseases, multiple sclerosis and CNS injury and inhibitors that have been tested in different models. Database search: https://pubmed.ncbi.nlm.nih.gov prior to 1 July 2021. EXPERT OPINION Currently, it appears unlikely that inhibiting TG2 in the context of neurodegenerative diseases would be therapeutically advantageous. However, for multiple sclerosis and CNS injuries, TG2 inhibitors may have the potential to be therapeutically useful and thus there is rationale for their further development.
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Affiliation(s)
- Jeffrey W Keillor
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON, Canada
| | - Gail V W Johnson
- Department of Anesthesiology and Perioperative Medicine, University of Rochester, Rochester, NY, USA
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Rudlong J, Cheng A, Johnson GVW. The role of transglutaminase 2 in mediating glial cell function and pathophysiology in the central nervous system. Anal Biochem 2019; 591:113556. [PMID: 31866289 DOI: 10.1016/j.ab.2019.113556] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 12/04/2019] [Accepted: 12/18/2019] [Indexed: 12/13/2022]
Abstract
The ubiquitously expressed transglutaminase 2 (TG2) has diverse functions in virtually all cell types, with its role depending not only on cell type, but also on specific subcellular localization. In the central nervous system (CNS) different types of glial cells, such as astrocytes, microglia, and oligodendrocytes and their precursor cells (OPCs), play pivotal supportive functions. This review is focused on what is currently known about the role of TG2 in each type of glial cell, in the context of normal function and pathophysiology. For example, astrocytic TG2 facilitates their migration and proliferation, but hinders their ability to protect neurons after CNS injury. The review also examines the interactions between glial cell types, and how TG2 in one cell type may affect another, as well as implications for specific TG2 populations as therapeutic targets in CNS pathology.
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Affiliation(s)
- Jacob Rudlong
- Department of Anesthesiology and Perioperative Medicine and the Neuroscience Graduate Program, University of Rochester, Rochester, NY, 14620, USA
| | - Anson Cheng
- Department of Anesthesiology and Perioperative Medicine and the Neuroscience Graduate Program, University of Rochester, Rochester, NY, 14620, USA
| | - Gail V W Johnson
- Department of Anesthesiology and Perioperative Medicine and the Neuroscience Graduate Program, University of Rochester, Rochester, NY, 14620, USA.
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10
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Li W, Dong M, Chu L, Feng L, Sun X. MicroRNA‑451 relieves inflammation in cerebral ischemia‑reperfusion via the Toll‑like receptor 4/MyD88/NF‑κB signaling pathway. Mol Med Rep 2019; 20:3043-3054. [PMID: 31432179 PMCID: PMC6755191 DOI: 10.3892/mmr.2019.10587] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 04/25/2019] [Indexed: 12/25/2022] Open
Abstract
The present study was designed to investigate the role of microRNA-451 (miRNA-451) on cerebral ischemia-reperfusion and to explore its possible mechanism. The expression of miRNA-451 was downregulated in rats with cerebral ischemia-reperfusion. In an in vitro model of cerebral ischemia-reperfusion, the downregulation of miRNA-451 increased inflammation, demonstrated by increased levels of tumor necrosis factor α, interleukin (IL)-1b, IL-6 and IL-18. However, the upregulation of miRNA-451 expression decreased inflammation in the same in vitro model of cerebral ischemia-reperfusion. In addition, it was found that the downregulation of miRNA-451 induced the expression of Toll-like receptor 4 (TLR4), myeloid differentiation primary response protein MyD88 (MyD88) and nuclear factor-κB (NF-κB)/p65. Moreover, the administration of a MyD88 inhibitor, ST 2825, reduced the expression of MyD88 and NF-κB/p65 in the in vitro model of cerebral ischemia-reperfusion, inhibiting the effects of miRNA-451 upregulation on inflammation. A TLR4 inhibitor, TAK-242, was used to reduce the expression of TLR4 in the in vitro model of cerebral ischemia-reperfusion. TAK-242 suppressed the effects of miRNA-451 downregulation on inflammation. The present study suggested that miRNA-451 regulated cerebral ischemia-reperfusion-induced inflammation, which is mediated through the TLR4/MyD88/NF-κB signaling pathway.
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Affiliation(s)
- Wenyan Li
- Department of Neurosurgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
| | - Minghao Dong
- Department of Neurosurgery, The Affiliated Hospital of Guizhou Medical University, Guiyang, Guizhou 550004, P.R. China
| | - Liangzhao Chu
- Department of Neurosurgery, The Affiliated Hospital of Guizhou Medical University, Guiyang, Guizhou 550004, P.R. China
| | - Luqian Feng
- Department of Neurosurgery, The Affiliated Hospital of Guizhou Medical University, Guiyang, Guizhou 550004, P.R. China
| | - Xiaochuan Sun
- Department of Neurosurgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
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11
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Shi W, Que Y, Lv D, Bi S, Xu Z, Wang D, Zhang Z. Overexpression of TG2 enhances the differentiation of ectomesenchymal stem cells into neuron‑like cells and promotes functional recovery in adult rats following spinal cord injury. Mol Med Rep 2019; 20:2763-2773. [PMID: 31322240 PMCID: PMC6691247 DOI: 10.3892/mmr.2019.10502] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2018] [Accepted: 05/31/2019] [Indexed: 12/15/2022] Open
Abstract
Ectomesenchymal stem cells (EMSCs) represent a type of adult stem cells derived from the cranial neural crest. These cells are capable of self-renewal and have the potential for multidirectional differentiation. Tissue transglutaminase type 2 (TG2) is a ubiquitously expressed member of the transglutaminase family of Ca2+-dependent crosslinking enzymes. However, the effect of TG2 on neural differentiation and proliferation of EMSCs remains unknown. To determine whether TG2 improves EMSC proliferation and neurogenesis, a stable TG2-overexpressing EMSC cell line (TG2-EMSCs) was established by using an adenovirus system. Immunofluorescence staining and western blot analyses demonstrated that TG2 overexpression had beneficial effects on the rate of EMSC neurogenesis, and that the proliferative capacity of TG2-EMSCs was higher than that of controls. Furthermore, the results of western blotting revealed that extracellular matrix (ECM) and neurotrophic factors were upregulated during the differentiation of TG2-EMSCs. Notably, TG2-EMSC transplantation in an animal model of spinal cord injury (SCI), TG2-EMSCs differentiated into neuron-like cells and enhanced the repair of SCI. Taken together, these results demonstrated that TG2 gene transfection may offer a novel strategy to enhance EMSC proliferation and neurogenesis in vivo and in vitro, which may ultimately facilitate EMSC-based transplantation therapy in patients with SCI.
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Affiliation(s)
- Wentao Shi
- Department of Orthopedics, Gaochun People's Hospital of Nanjing, Nanjing, Jiangsu 211300, P.R. China
| | - Yunduan Que
- Department of Orthopedics, Gaochun People's Hospital of Nanjing, Nanjing, Jiangsu 211300, P.R. China
| | - Demin Lv
- Department of Embryology, School of Medicine, Jiangsu University, Zhenjiang, Jiangsu 212001, P.R. China
| | - Shiqi Bi
- Department of Embryology, School of Medicine, Jiangsu University, Zhenjiang, Jiangsu 212001, P.R. China
| | - Zhonghua Xu
- Department of Orthopedics, Gaochun People's Hospital of Nanjing, Nanjing, Jiangsu 211300, P.R. China
| | - Dongmin Wang
- Department of Orthopedics, Gaochun People's Hospital of Nanjing, Nanjing, Jiangsu 211300, P.R. China
| | - Zhijian Zhang
- Department of Embryology, School of Medicine, Jiangsu University, Zhenjiang, Jiangsu 212001, P.R. China
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12
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Ji C, Tang M, Harrison J, Paciorkowski A, Johnson GVW. Nuclear transglutaminase 2 directly regulates expression of cathepsin S in rat cortical neurons. Eur J Neurosci 2018; 48:3043-3051. [PMID: 30239049 DOI: 10.1111/ejn.14159] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 08/14/2018] [Accepted: 08/28/2018] [Indexed: 01/06/2023]
Abstract
Transglutaminase 2 (TG2) is a protein that modulates neuronal survival processes. Although TG2 is primarily cytosolic, data have suggested the nuclear localization of TG2 is strongly associated with neuronal viability. Depletion of TG2 in neurons results in neurite retraction and loss of viability, which is likely due to a dysregulation in gene expression. To begin to understand how TG2 regulates neuronal gene expression, chromatin immunoprecipitation was performed in neurons with TG2 overexpression. The resulting genomic DNA was recovered and sequenced. Bioinformatics analyses revealed that a signature DNA motif was enriched in the TG2 immunoprecipitated genomic DNA. In particular, this motif strongly mapped to a region proximate to the gene Ctss (cathepsin S). Knockdown of TG2 resulted in a significant increase in cathepsin S expression, which preceded the loss of neuronal viability. This is the first demonstration that TG2 directly associates with genomic DNA and regulates gene expression in neurons. Given that expression of cathepsin S is increased in neurological disease states, our data suggest that TG2 may play a role in promoting neuron health in part by repressing the expression of cathepsin S. Overall these data provide new insights into the function of nuclear TG2 in neurons.
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Affiliation(s)
- Changyi Ji
- Department of Anesthesiology and Perioperative Medicine, University of Rochester, Rochester, New York
| | - Maoping Tang
- Department of Anesthesiology and Perioperative Medicine, University of Rochester, Rochester, New York
| | - Jarreau Harrison
- Department of Pharmacology and Physiology, University of Rochester, Rochester, New York
| | - Alex Paciorkowski
- Departments of Neurology, Pediatrics, Biomedical Genetics, and Neuroscience, University of Rochester Medical Center, Rochester, New York.,Del Monte Institute for Neuroscience, University of Rochester, Rochester, New York
| | - Gail V W Johnson
- Department of Anesthesiology and Perioperative Medicine, University of Rochester, Rochester, New York.,Department of Pharmacology and Physiology, University of Rochester, Rochester, New York.,Del Monte Institute for Neuroscience, University of Rochester, Rochester, New York
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13
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Mižíková I, Pfeffer T, Nardiello C, Surate Solaligue DE, Steenbock H, Tatsukawa H, Silva DM, Vadász I, Herold S, Pease RJ, Iismaa SE, Hitomi K, Seeger W, Brinckmann J, Morty RE. Targeting transglutaminase 2 partially restores extracellular matrix structure but not alveolar architecture in experimental bronchopulmonary dysplasia. FEBS J 2018; 285:3056-3076. [PMID: 29935061 DOI: 10.1111/febs.14596] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 06/12/2018] [Accepted: 06/21/2018] [Indexed: 12/21/2022]
Abstract
The generation, maturation and remodelling of the extracellular matrix (ECM) are essential for the formation of alveoli during lung development. Alveoli formation is disturbed in preterm infants that develop bronchopulmonary dysplasia (BPD), where collagen fibres are malformed, and perturbations to lung ECM structures may underlie BPD pathogenesis. Malformed ECM structures might result from abnormal protein cross-linking, in part attributable to the increased expression and activity of transglutaminase 2 (TGM2) that have been noted in affected patient lungs, as well as in hyperoxia-based BPD animal models. The objective of the present study was to assess whether TGM2 plays a causal role in normal and aberrant lung alveolarization. Targeted deletion of Tgm2 in C57BL/6J mice increased septal thickness and reduced gas-exchange surface area in otherwise normally developing lungs. During aberrant lung alveolarization that occurred under hyperoxic conditions, collagen structures in Tgm2-/- mice were partially protected from the impact of hyperoxia, where normal dihydroxylysinonorleucine and hydroxylysylpiridinoline collagen cross-link abundance was restored; however, the lung alveolar architecture remained abnormal. Inhibition of transglutaminases (including TGM2) with cysteamine appreciably reduced transglutaminase activity in vivo, as assessed by Nε -(γ-l-glutamyl)-l-lysine abundance and TGM catalytic activity, and restored normal dihydroxylysinonorleucine and hydroxylysylpiridinoline collagen cross-link abundance under pathological conditions. Furthermore, a moderate improvement in alveoli size and gas-exchange surface density was noted in cysteamine-treated mouse lungs in which BPD was modelled. These data indicate that TGM2 plays a role in normal lung alveolarization, and contributes to the formation of aberrant ECM structures during disordered lung alveolarization.
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Affiliation(s)
- Ivana Mižíková
- Department of Lung Development and Remodelling, Max Planck Institute for Heart and Lung Research, Member of the German Center for Lung Research (DZL), Giessen, Germany, Bad Nauheim, Germany.,Department of Internal Medicine (Pulmonology), University of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Germany
| | - Tilman Pfeffer
- Department of Lung Development and Remodelling, Max Planck Institute for Heart and Lung Research, Member of the German Center for Lung Research (DZL), Giessen, Germany, Bad Nauheim, Germany.,Department of Internal Medicine (Pulmonology), University of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Germany
| | - Claudio Nardiello
- Department of Lung Development and Remodelling, Max Planck Institute for Heart and Lung Research, Member of the German Center for Lung Research (DZL), Giessen, Germany, Bad Nauheim, Germany.,Department of Internal Medicine (Pulmonology), University of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Germany
| | - David E Surate Solaligue
- Department of Lung Development and Remodelling, Max Planck Institute for Heart and Lung Research, Member of the German Center for Lung Research (DZL), Giessen, Germany, Bad Nauheim, Germany.,Department of Internal Medicine (Pulmonology), University of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Germany
| | - Heiko Steenbock
- Institute of Virology and Cell Biology, University of Lübeck, Germany
| | - Hideki Tatsukawa
- Graduate School of Pharmaceutical Sciences, Nagoya University, Japan
| | - Diogo M Silva
- Department of Lung Development and Remodelling, Max Planck Institute for Heart and Lung Research, Member of the German Center for Lung Research (DZL), Giessen, Germany, Bad Nauheim, Germany.,Department of Internal Medicine (Pulmonology), University of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Germany
| | - István Vadász
- Department of Internal Medicine (Pulmonology), University of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Germany
| | - Susanne Herold
- Department of Internal Medicine (Pulmonology), University of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Germany
| | - Richard J Pease
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds, UK
| | - Siiri E Iismaa
- Victor Chang Cardiac Research Institute, Darlinghurst, Australia
| | - Kiyotaka Hitomi
- Graduate School of Pharmaceutical Sciences, Nagoya University, Japan
| | - Werner Seeger
- Department of Lung Development and Remodelling, Max Planck Institute for Heart and Lung Research, Member of the German Center for Lung Research (DZL), Giessen, Germany, Bad Nauheim, Germany.,Department of Internal Medicine (Pulmonology), University of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Germany
| | - Jürgen Brinckmann
- Institute of Virology and Cell Biology, University of Lübeck, Germany.,Department of Dermatology, University of Lübeck, Germany
| | - Rory E Morty
- Department of Lung Development and Remodelling, Max Planck Institute for Heart and Lung Research, Member of the German Center for Lung Research (DZL), Giessen, Germany, Bad Nauheim, Germany.,Department of Internal Medicine (Pulmonology), University of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Germany
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14
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Monteagudo A, Feola J, Natola H, Ji C, Pröschel C, Johnson GVW. Depletion of astrocytic transglutaminase 2 improves injury outcomes. Mol Cell Neurosci 2018; 92:128-136. [PMID: 29969654 DOI: 10.1016/j.mcn.2018.06.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 06/26/2018] [Accepted: 06/27/2018] [Indexed: 01/12/2023] Open
Abstract
Astrocytes play an indispensable role in maintaining a healthy, functional neural network in the central nervous system (CNS). A primary function of CNS astrocytes is to support the survival and function of neurons. In response to injury, astrocytes take on a reactive phenotype, which alters their molecular functions. Reactive astrocytes have been reported to be both beneficial and harmful to the CNS recovery process subsequent to injury. Understanding the molecular processes and regulatory proteins that determine the extent to which an astrocyte hinders or supports neuronal survival is important within the context of CNS repair. One protein that plays a role in modulating cellular survival is transglutaminase 2 (TG2). Global deletion of TG2 results in beneficial outcomes subsequent to in vivo ischemic brain injury. Ex vivo studies have also implicated TG2 as a negative regulator of astrocyte viability subsequent to injury. In this study we show that knocking down TG2 in astrocytes significantly increases their ability to protect neurons from oxygen glucose deprivation (OGD)/reperfusion injury. To begin to understand how deletion of TG2 in astrocytes improves their ability to protect neurons from injury, we performed transcriptome analysis of wild type and TG2-/- astrocytes. TG2 deletion resulted in alterations in genes involved in extracellular matrix remodeling, cell adhesion and axon growth/guidance. In addition, the majority of genes that showed increases in the TG2-/- astrocytes had predicted cJun/AP-1 binding motifs in their promoters. Furthermore, phospho-cJun levels were robustly elevated in TG2-/- astrocytes, a finding which was consistent with the increase in expression of AP-1 responsive genes. These in vitro data were subsequently extended into an in vivo model to determine whether the absence of astrocytic TG2 improves outcomes after CNS injury. Our results show that, following a spinal cord injury, scar formation is significantly attenuated in mice with astrocyte-specific TG2 deletion compared to mice expressing normal TG2 levels. Taken together, these data indicate that TG2 plays a pivotal role in mediating reactive astrocyte properties following CNS injury. Further, the data suggest that limiting the AP-1 mediated pro-survival injury response may be a contributing factor to that the detrimental effects of astrocytic TG2.
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Affiliation(s)
- Alina Monteagudo
- Department of Pharmacology and Physiology, University of Rochester, Rochester, NY 14642, USA
| | - Julianne Feola
- Department of Biomedical Genetics, University of Rochester, Rochester, NY 14642, USA
| | - Heather Natola
- Department of Biomedical Genetics, University of Rochester, Rochester, NY 14642, USA
| | - Changyi Ji
- Department of Anesthesiology and Perioperative Medicine, University of Rochester, Rochester, NY 14642, USA
| | - Christoph Pröschel
- Department of Biomedical Genetics, University of Rochester, Rochester, NY 14642, USA; Stem Cell and Regenerative Medicine Institute, University of Rochester, Rochester, NY 14642, USA
| | - Gail V W Johnson
- Department of Pharmacology and Physiology, University of Rochester, Rochester, NY 14642, USA; Department of Biomedical Genetics, University of Rochester, Rochester, NY 14642, USA; Department of Anesthesiology and Perioperative Medicine, University of Rochester, Rochester, NY 14642, USA.
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15
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Subcellular localization patterns of transglutaminase 2 in astrocytes and neurons are differentially altered by hypoxia. Neuroreport 2018; 28:1208-1214. [PMID: 28957946 DOI: 10.1097/wnr.0000000000000895] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The multifunctional protein transglutaminase 2 (TG2) has been widely implicated as a modulator of cellular viability. Specifically, TG2 expression is beneficial to neuronal survival following an ischemic injury, whereas the opposite is true in astrocytes. Furthermore, its role in mediating cell death and survival processes has been suggested to be dependent on its subcellular localization. Therefore, the aim of this study was to examine the subcellular localization patterns of neuronal and astrocytic TG2 in ischemia-relevant conditions. We found that nuclear levels of TG2 were significantly increased in neurons, but reduced in astrocytes, in response to hypoxia. In addition, there were no changes in extracellular TG2 in astrocytes exposed to hypoxia. Thus, these findings demonstrate a difference in the subcellular localization pattern of TG2 in neurons and astrocytes in ischemia-relevant conditions and provide further avenues for investigation into the role of TG2 in mediating cellular viability.
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16
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Quinn BR, Yunes-Medina L, Johnson GVW. Transglutaminase 2: Friend or foe? The discordant role in neurons and astrocytes. J Neurosci Res 2018; 96:1150-1158. [PMID: 29570839 DOI: 10.1002/jnr.24239] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 03/01/2018] [Accepted: 03/12/2018] [Indexed: 12/19/2022]
Abstract
Members of the transglutaminase family catalyze the formation of isopeptide bonds between a polypeptide-bound glutamine and a low molecular weight amine (e.g., spermidine) or the ɛ-amino group of a polypeptide-bound lysine. Transglutaminase 2 (TG2), a prominent member of this family, is unique because in addition to being a transamidating enzyme, it exhibits numerous other activities. As a result, TG2 plays a role in many physiological processes, and its function is highly cell type specific and relies upon a number of factors, including conformation, cellular compartment location, and local concentrations of Ca2+ and guanine nucleotides. TG2 is the most abundant transglutaminase in the central nervous system (CNS) and plays a pivotal role in the CNS injury response. How TG2 affects the cell in response to an insult is strikingly different in astrocytes and neurons. In neurons, TG2 supports survival. Overexpression of TG2 in primary neurons protects against oxygen and glucose deprivation (OGD)-induced cell death and in vivo results in a reduction in infarct volume subsequent to a stroke. Knockdown of TG2 in primary neurons results in a loss of viability. In contrast, deletion of TG2 from astrocytes results in increased survival following OGD and improved ability to protect neurons from injury. Here, a brief overview of TG2 is provided, followed by a discussion of the role of TG2 in transcriptional regulation, cellular dynamics, and cell death. The differing roles TG2 plays in neurons and astrocytes are highlighted and compared to how TG2 functions in other cell types.
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Affiliation(s)
- Breandan R Quinn
- Department of Pharmacology and Physiology, University of Rochester, Rochester, New York
| | - Laura Yunes-Medina
- Department of Neuroscience, University of Rochester, Rochester, New York
| | - Gail V W Johnson
- Department of Pharmacology and Physiology, University of Rochester, Rochester, New York.,Department of Neuroscience, University of Rochester, Rochester, New York.,Department of Anesthesiology and Perioperative Medicine, University of Rochester, Rochester, New York
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17
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Yunes-Medina L, Paciorkowski A, Nuzbrokh Y, Johnson GVW. Depletion of transglutaminase 2 in neurons alters expression of extracellular matrix and signal transduction genes and compromises cell viability. Mol Cell Neurosci 2017; 86:72-80. [PMID: 29197584 DOI: 10.1016/j.mcn.2017.11.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 10/20/2017] [Accepted: 11/21/2017] [Indexed: 12/22/2022] Open
Abstract
The protein transglutaminase 2 (TG2) has been implicated as a modulator of neuronal viability. TG2's role in mediating cell survival processes has been suggested to involve its ability to alter transcriptional events. The goal of this study was to examine the role of TG2 in neuronal survival and to begin to delineate the pathways it regulates. We show that depletion of TG2 significantly compromises the viability of neurons in the absence of any stressors. RNA sequencing revealed that depletion of TG2 dysregulated the expression of 86 genes with 59 of these being upregulated. The genes that were upregulated by TG2 knockdown were primarily involved in extracellular matrix function, cell signaling and cytoskeleton integrity pathways. Finally, depletion of TG2 significantly reduced neurite length. These findings suggest for the first time that TG2 plays a crucial role in mediating neuronal survival through its regulation of genes involved in neurite length and maintenance.
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Affiliation(s)
- Laura Yunes-Medina
- Department of Neuroscience, University of Rochester, 601 Elmwood Ave, Box 603, Rochester, NY 14642, United States.
| | - Alex Paciorkowski
- Department of Neuroscience, University of Rochester, 601 Elmwood Ave, Box 603, Rochester, NY 14642, United States; Department of Neurology, University of Rochester, 601 Elmwood Ave, Box 603, Rochester, NY 14642, United States; Department of Pediatrics, University of Rochester Medical Center, 601 Elmwood Ave, Box 603, Rochester, NY 14642, United States; Department Biomedical Genetics, University of Rochester Medical Center, 601 Elmwood Ave, Box 604, Rochester, NY 14642, United States.
| | - Yan Nuzbrokh
- Department of Anesthesiology and Perioperative Medicine, University of Rochester Medical Center, 601 Elmwood Ave, Box 604, Rochester, NY 14642, United States.
| | - Gail V W Johnson
- Department of Anesthesiology and Perioperative Medicine, University of Rochester Medical Center, 601 Elmwood Ave, Box 604, Rochester, NY 14642, United States; Department of Pharmacology and Physiology, University of Rochester Medical Center, 601 Elmwood Ave, Box 604, Rochester, NY 14642, United States.
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