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MicroRNA profiling reveals unique miRNA signatures in IGF-1 treated embryonic striatal stem cell fate decisions in striatal neurogenesis in vitro. BIOMED RESEARCH INTERNATIONAL 2014; 2014:503162. [PMID: 25254208 PMCID: PMC4165568 DOI: 10.1155/2014/503162] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Revised: 06/25/2014] [Accepted: 07/02/2014] [Indexed: 01/20/2023]
Abstract
The striatum is considered to be the central processing unit of the basal ganglia in locomotor activity and cognitive function of the brain. IGF-1 could act as a control switch for the long-term proliferation and survival of EGF+bFGF-responsive cultured embryonic striatal stem cell (ESSC), while LIF imposes a negative impact on cell proliferation. The IGF-1-treated ESSCs also showed elevated hTERT expression with demonstration of self-renewal and trilineage commitment (astrocytes, oligodendrocytes, and neurons). In order to decipher the underlying regulatory microRNA (miRNA)s in IGF-1/LIF-treated ESSC-derived neurogenesis, we performed in-depth miRNA profiling at 12 days in vitro and analyzed the candidates using the Partek Genome Suite software. The annotated miRNA fingerprints delineated the differential expressions of miR-143, miR-433, and miR-503 specific to IGF-1 treatment. Similarly, the LIF-treated ESSCs demonstrated specific expression of miR-326, miR-181, and miR-22, as they were nonsignificant in IGF-treated ESSCs. To elucidate the possible downstream pathways, we performed in silico mapping of the said miRNAs into ingenuity pathway analysis. Our findings revealed the important mRNA targets of the miRNAs and suggested specific interactomes. The above studies introduced a new genre of miRNAs for ESSC-based neuroregenerative therapeutic applications.
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2
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Transglutaminase 2: biology, relevance to neurodegenerative diseases and therapeutic implications. Pharmacol Ther 2011; 133:392-410. [PMID: 22212614 DOI: 10.1016/j.pharmthera.2011.12.003] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Accepted: 12/06/2011] [Indexed: 12/24/2022]
Abstract
Neurodegenerative disorders are characterized by progressive neuronal loss and the aggregation of disease-specific pathogenic proteins in hallmark neuropathologic lesions. Many of these proteins, including amyloid Αβ, tau, α-synuclein and huntingtin, are cross-linked by the enzymatic activity of transglutaminase 2 (TG2). Additionally, the expression and activity of TG2 is increased in affected brain regions in these disorders. These observations along with experimental evidence in cellular and mouse models suggest that TG2 can contribute to the abnormal aggregation of disease causing proteins and consequently to neuronal damage. This accumulating evidence has provided the impetus to develop inhibitors of TG2 as possible neuroprotective agents. However, TG2 has other enzymatic activities in addition to its cross-linking function and can modulate multiple cellular processes including apoptosis, autophagy, energy production, synaptic function, signal transduction and transcription regulation. These diverse properties must be taken into consideration in designing TG2 inhibitors. In this review, we discuss the biochemistry of TG2, its various physiologic functions and our current understanding about its role in degenerative diseases of the brain. We also describe the different approaches to designing TG2 inhibitors that could be developed as potential disease-modifying therapies.
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Hoffner G, Vanhoutteghem A, André W, Djian P. Transglutaminase in epidermis and neurological disease or what makes a good cross-linking substrate. ADVANCES IN ENZYMOLOGY AND RELATED AREAS OF MOLECULAR BIOLOGY 2011; 78:97-160. [PMID: 22220473 DOI: 10.1002/9781118105771.ch3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Guylaine Hoffner
- Unité Propre de Recherche 2228 du Centre National de la Recherche Scientifique, Régulation de la Transcription et Maladies Génétiques, Université Paris Descartes, Paris, France
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Nemes Z. Effects and Analysis of Transglutamination on Protein Aggregation and Clearance in Neurodegenerative Diseases. ADVANCES IN ENZYMOLOGY - AND RELATED AREAS OF MOLECULAR BIOLOGY 2011; 78:347-83. [DOI: 10.1002/9781118105771.ch8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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5
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Kim SY. Transglutaminase 2: a new paradigm for NF-kappaB involvement in disease. ADVANCES IN ENZYMOLOGY AND RELATED AREAS OF MOLECULAR BIOLOGY 2011; 78:161-95. [PMID: 22220474 DOI: 10.1002/9781118105771.ch4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Soo-Youl Kim
- Division of Cancer Biology, Research Institute, National Cancer Center, Kyonggi-do, Republic of Korea
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Park D, Choi SS, Ha KS. Transglutaminase 2: a multi-functional protein in multiple subcellular compartments. Amino Acids 2010; 39:619-31. [PMID: 20148342 DOI: 10.1007/s00726-010-0500-z] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2009] [Accepted: 01/23/2010] [Indexed: 12/16/2022]
Abstract
Transglutaminase 2 (TG2) is a multifunctional protein that can function as a transglutaminase, G protein, kinase, protein disulfide isomerase, and as an adaptor protein. These multiple biochemical activities of TG2 account for, at least in part, its involvement in a wide variety of cellular processes encompassing differentiation, cell death, inflammation, cell migration, and wound healing. The individual biochemical activities of TG2 are regulated by several cellular factors, including calcium, nucleotides, and redox potential, which vary depending on its subcellular location. Thus, the microenvironments of the subcellular compartments to which TG2 localizes, such as the cytosol, plasma membrane, nucleus, mitochondria, or extracellular space, are important determinants to switch on or off various TG2 biochemical activities. Furthermore, TG2 interacts with a distinct subset of proteins and/or substrates depending on its subcellular location. In this review, the biological functions and molecular interactions of TG2 will be discussed in the context of the unique environments of the subcellular compartments to which TG2 localizes.
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Affiliation(s)
- Donghyun Park
- Department of Molecular and Cellular Biochemistry, Vascular System Research Center, Kangwon National University School of Medicine, Chuncheon, Kangwon-do, 200-701, Republic of Korea
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7
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Hoffner G, Souès S, Djian P. Aggregation of expanded huntingtin in the brains of patients with Huntington disease. Prion 2009; 1:26-31. [PMID: 19172113 DOI: 10.4161/pri.1.1.4056] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Huntingtin containing an expanded polyglutamine causes neuronal death and Huntington disease. Although expanded huntingtin is found in virtually every cell type, its toxicity is limited to neurons of certain areas of the brain, such as cortex and caudate/putamen. In affected areas of the brain, expanded huntingtin is not found in its intact monomeric form. It is found instead in the form of N-terminal fragments, oligomers and polymers, all of which accumulate in the cortex. Whereas the oligomer is mostly soluble, the polymers and the fragments associate with each other and with other proteins to form the insoluble inclusions characteristic of the disease. It is likely that the aggregates containing expanded huntingtin are toxic to neurons, but it remains to be determined whether the oligomer or the inclusion is the toxic species.
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Affiliation(s)
- Guylaine Hoffner
- Unité Propre de Recherche 2228 du Centre National de la Recherche Scientifique, Institut Interdisciplinaire des Sciences du Vivant des Saints-Pères, Université René Descartes, Paris, France
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8
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Abstract
Tissue transglutaminase (tTG) is a multifunctional enzyme that catalyzes both transamidation and GTPase reactions. In cell culture models tTG-mediated transamidation positively regulates many processes that occur in vivo during the mammalian brain growth spurt (BGS), including neuronal differentiation, neurite outgrowth, synaptogenesis and cell death mechanisms. However, little is known about the levels of tTG expression and transglutaminase (TG) activity during mammalian brain development. In this study, C57BL/6 mouse forebrains were collected at embryonic day (E) 12, E14, E17, postnatal day (P) 0, P7 and P56 and analyzed for tTG expression and TG activity. RT-PCR analysis demonstrated that tTG mRNA content increases during mouse forebrain development, whereas immunoblot analysis demonstrated that tTG protein content decreases during this time. TG activity was low in prenatal mouse forebrain but increased fivefold to peak at P0, which corresponds with the beginning of the mouse BGS. Further analysis demonstrated that the lack of temporal correlation between tTG protein content and TG activity is the result of an endogenous inhibitor of tTG that is present in prenatal but not postnatal mouse forebrain. These results demonstrate for the first time that tTG enzymatic activity in the mammalian forebrain is developmentally regulated by post-translational mechanisms.
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Affiliation(s)
- Craig D C Bailey
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, Alabama, USA
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9
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Zemaitaitis MO, Kim SY, Halverson RA, Troncoso JC, Lee JM, Muma NA. Transglutaminase activity, protein, and mRNA expression are increased in progressive supranuclear palsy. J Neuropathol Exp Neurol 2003; 62:173-84. [PMID: 12578227 DOI: 10.1093/jnen/62.2.173] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Transglutaminases catalyze the covalent cross-linking of substrate proteins to form insoluble protein complexes that are resistant to degradation. Our previous studies demonstrated that transglutaminase-induced cross-linking of tau proteins occurs in Alzheimer disease and progressive supranuclear palsy (PSP). The current study was designed to measure transglutaminase enzyme activity and the mRNA and protein levels of 3 transglutaminase isoforms that are expressed in human brain. Overall, transglutaminase activity was significantly increased in the globus pallidus (182% of control) and pons in PSP (171% of control) but not the occipital cortex (a region spared from pathology). Using a Spearman rank correlation test, we found that tissues with more transglutaminase-activity had more neurofibrillary tangles. Protein and mRNA levels of transglutaminase 1 were increased in globus pallidus of PSP as compared to controls. There were also significantly higher mRNA levels of the short form of transglutaminase 2 in globus pallidus of PSP (974% of control). Transglutaminase 1 mRNA and the long isoform of transglutaminase 2 mRNA (2212% of control) were significantly higher in PSP in the dentate of cerebellum. Together, these findings suggest that transglutaminase 1 and 2 enzymes may be involved in the formation and/or stabilization of neurofibrillary tangles in selectively vulnerable brain regions in PSP. These transglutaminases may be potential targets for therapeutic intervention.
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Affiliation(s)
- Magdalena O Zemaitaitis
- Department of Pharmacology, Loyola University Stritch School of Medicine, Maywood, Illinois 60153, USA
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10
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Sárvári M, Fésüs L, Nemes Z. Transglutaminase-mediated crosslinking of neural proteins in Alzheimer's disease and other primary dementias. Drug Dev Res 2002. [DOI: 10.1002/ddr.10098] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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11
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Abstract
The presence of an expanded polyglutamine produces a toxic gain of function in huntingtin. Protein aggregation resulting from this gain of function is likely to be the cause of neuronal death. Two main mechanisms of aggregation have been proposed: hydrogen bonding by polar-zipper formation and covalent bonding by transglutaminase-catalyzed cross-linking. In cell culture models of Huntington's disease, aggregates are mostly stabilized by hydrogen bonds, but covalent bonds are also likely to occur. Nothing is known about the nature of the bonds that stabilize the aggregates in the brain of patients with Huntington's disease. It seems that the nature of the bond stabilizing the aggregates is one of the most important questions, as the answer would condition the therapeutic approach to Huntington's disease.
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Affiliation(s)
- Guylaine Hoffner
- UPR 2228-CNRS, Institut Interdisciplinaire des Sciences du Vivant des Saints-Pères, Université René-Descartes, 45, rue des Saints-Pères, 75270 cedex 6, Paris, France
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12
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Abstract
Transglutaminases (TGases) are enzymes that are widely used in many biological systems for generic tissue stabilization purposes. Mutations resulting in lost activity underlie several serious disorders. In addition, new evidence documents that they may also be aberrantly activated in tissues and cells and contribute to a variety of diseases, including neurodegenerative diseases such as Alzheimer's and Huntington's diseases. In these cases, the TGases appear to be a factor in the formation of inappropriate proteinaceous aggregates that may be cytotoxic. In other cases such as celiac disease, however, TGases are involved in the generation of autoantibodies. Further, in diseases such as progressive supranuclear palsy, Huntington's, Alzheimer's and Parkinson's diseases, the aberrant activation of TGases may be caused by oxidative stress and inflammation. This review will examine the role and activation of TGases in a variety of diseases.
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Affiliation(s)
- Soo Youl Kim
- Laboratory of Skin Biology, NIAMS, NIH, MD, USA.
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13
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Maggio N, Sellitti S, Capano CP, Papa M. Tissue-transglutaminase in rat and human brain: light and electron immunocytochemical analysis and in situ hybridization study. Brain Res Bull 2001; 56:173-82. [PMID: 11719248 DOI: 10.1016/s0361-9230(01)00649-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Tissue-type transglutaminases constitute a family of enzymes having a dual role. They catalyze the post-translational modification of proteins and play a role in signal transduction pathways, several isoforms have been cloned in the brain. Many in vitro experiments and post-mortem studies have claimed that the enzyme plays a central role in the development of neurodegenerative disorders, especially in CAG-triplet diseases. In the present investigation, we conducted an immunocytochemical study using two different antibodies raised against tissue-type transglutaminase. To confirm the enzyme expression, non-radioactive in situ hybridization was performed on adjacent sections. The study was completed by analyzing the ultrastructural localization of the enzyme by electron microscopy. Tissue-type transglutaminase was widely expressed in both the human and rat brain. Many positive cells exhibiting neuronal features were found in the brain and cerebellum. There was a preferential expression in elements of pyramidal and extrapyramidal pathways with less expression in the somatosensory system. The mRNA detection confirmed the distribution of the enzyme. The ultrastructural approach revealed the presence of the enzyme in all neuronal compartments. Light and electron microscopy studies showed the ubiquitous nature of the enzyme and its putative role in functional as well as putative pathological processes.
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Affiliation(s)
- N Maggio
- Istituto di Anatomia Umana, Facoltà di Medicina, Seconda Università di Napoli, Napoli, Italy
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14
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Tucholski J, Lesort M, Johnson GV. Tissue transglutaminase is essential for neurite outgrowth in human neuroblastoma SH-SY5Y cells. Neuroscience 2001; 102:481-91. [PMID: 11166134 DOI: 10.1016/s0306-4522(00)00482-6] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Tissue transglutaminase is a normal constituent of the central and peripheral nervous systems and in rats transglutaminase activity in brain and spinal cord is highest during fetal stages when axonal outgrowth is occurring. Further, treatment of human neuroblastoma SH-SY5Y cells with retinoic acid results in the cells withdrawing from the cell cycle and extending neurites, in the same time frame that tissue transglutaminase expression significantly increases. Considering these and other previous findings, this study was carried out to determine whether tissue transglutaminase is involved in neuronal differentiation of SH-SY5Y cells. For these studies SH-SY5Y cells stably overexpressing wild-type tissue transglutaminase, an inactive tissue transglutaminase mutant (C277S) or an antisense tissue transglutaminase construct (which decreased endogenous tissue transglutaminase below detectable levels) were used. SH-SY5Y cells overexpressing wild-type tissue transglutaminase spontaneously differentiated into a neuronal phenotype when grown in low-serum media. In contrast, cells overexpressing inactive tissue transglutaminase or the antisense tissue transglutaminase continued to proliferate and exhibit a flat polygenic morphology even when maintained in low-serum conditions. In addition, increased tissue transglutaminase expression in response to retinoic acid was abolished in the antisense tissue transglutaminase cells, and antisense and mutant tissue transglutaminase expressing cells did not extend neurites in response to retinoic acid. Moreover, wild-type and inactive tissue transglutaminase exhibited differential intracellular localization. These data indicate that tissue transglutaminase is necessary and sufficient for neuronal differentiation of human neuroblastoma SH-SY5Y cells.
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Affiliation(s)
- J Tucholski
- Department of Psychiatry and Behavioral Neurobiology, 1720 7th Ave. South, SC 1061, University of Alabama at Birmingham, AL 35294-0017, Birmingham, USA
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15
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Affiliation(s)
- V L Turgeon
- Furman University, Department of Biology, Greenville, SC 29613, USA.
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16
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Lesort M, Tucholski J, Miller ML, Johnson GV. Tissue transglutaminase: a possible role in neurodegenerative diseases. Prog Neurobiol 2000; 61:439-63. [PMID: 10748319 DOI: 10.1016/s0301-0082(99)00052-0] [Citation(s) in RCA: 123] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Tissue transglutaminase is a multifunctional protein that is likely to play a role in numerous processes in the nervous system. Tissue transglutaminase posttranslationally modifies proteins by transamidation of specific polypeptide bound glutamines. This action results in the formation of protein crosslinks or the incorporation of polyamines into substrate proteins, modifications that likely have significant effects on neural function. Tissue transglutaminase is a unique member of the transglutaminase family as in addition to catalyzing the calcium-dependent transamidation reaction, it also binds and hydrolyzes ATP and Guanosine 5'-triphosphate and may play a role in signal transduction. Tissue transglutaminase is a highly regulated and inducible enzyme that is developmentally regulated in the nervous system. In vitro, numerous substrates of tissue transglutaminase have been identified, and several of these proteins have been shown to be in situ substrates as well. Several specific roles for tissue transglutaminase have been described and there is evidence that tissue transglutaminase may also play a role in apoptosis. Recent findings have provided evidence that dysregulation of tissue transglutaminase may contribute to the pathology of several neurodegenerative conditions including Alzheimer's disease and Huntington's disease. In both of these diseases tissue transglutaminase and transglutaminase activity are elevated compared to age-matched controls. Further, immunohistochemical studies have demonstrated that there is an increase in tissue transglutaminase reactivity in affected neurons in both Alzheimer's and Huntington's disease. Although intriguing, many issues remain to be addressed to definitively establish a role for tissue transglutaminase in these neurodegenerative diseases.
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Affiliation(s)
- M Lesort
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, 1720 Seventh Avenue S., SC1061, Birmingham 35294-0017, USA
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17
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Hartenstine MJ, Goodman MF, Petruska J. Base stacking and even/odd behavior of hairpin loops in DNA triplet repeat slippage and expansion with DNA polymerase. J Biol Chem 2000; 275:18382-90. [PMID: 10849445 DOI: 10.1074/jbc.275.24.18382] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Repetitions of CAG or CTG triplets in DNA can form intrastrand hairpin loops with combinations of normal and mismatched base pairs that easily rearrange. Such loops may promote primer-template slippage in DNA replication or repair to give triplet-repeat expansions like those associated with neurodegenerative diseases. Using self-priming sequences (e.g. (CAG)(16)(CTG)(4)), we resolve all hairpin loops formed and measure their slippage and expansion rates with DNA polymerase at 37 degrees C. Comparing CAG/CTG loop structures with GAC/GTC structures, having similar hydrogen bonding but different base stacking, we find that CAG, CTG, and GTC triplets predominantly form even-membered loops that slip in steps of two triplets, whereas GAC triplets favor odd-numbered loops. Slippage rates decline as hairpin stability increases, supporting the idea that slippage initiates more easily in less stable regions. Loop stabilities (in low salt) increase in the order GTC < CAG < GAC < CTG, while slippage rates decrease in the order GTC > CAG approximately GAC > CTG. Loops of GTC compared with CTG melt 9 degrees C lower and slip 6-fold faster. We interpret results in terms of base stacking, by relating melting temperature to standard enthalpy changes for doublets of base pairs and mispairs, considering enthalpy-entropy compensation.
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Affiliation(s)
- M J Hartenstine
- Department of Biological Sciences, Hedco Molecular Biology Laboratories, University of Southern California, Los Angeles, California 90089-1340, USA
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18
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Kim SY, Grant P, Lee JH, Pant HC, Steinert PM. Differential expression of multiple transglutaminases in human brain. Increased expression and cross-linking by transglutaminases 1 and 2 in Alzheimer's disease. J Biol Chem 1999; 274:30715-21. [PMID: 10521460 DOI: 10.1074/jbc.274.43.30715] [Citation(s) in RCA: 174] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The transglutaminase (TGase) family of enzymes, of which seven different members are known in the human genome, participate in many biological processes involving cross-linking proteins into large macromolecular assemblies. The TGase 2 enzyme is known to be present in neuronal tissues and may play a role in neuronal degenerative diseases such as Alzheimer's disease (AD) by aberrantly cross-linking proteins. In this paper, we demonstrate by reverse transcriptase-polymerase chain reaction and immunological methods with specific antibodies that in fact three members, the TGase 1, TGase 2, and TGase 3 enzymes, and are differentially expressed in various regions of normal human brain tissues. Interestingly, the TGase 1 and 3 enzymes and their proteolytically processed forms are involved in terminal differentiation programs of epithelial cell development and barrier function. In addition, we found that the levels of expression and activity of the TGase 1 and 2 enzymes were both increased in the cortex and cerebellum of AD patients. Furthermore, whereas normal brain tissues contain approximately 1 residue of cross-link/10,000 residues, AD patient cortex and cerebellum tissues contain 30-50 residues of cross-link/10,000 residues. Together, these findings suggest that multiple TGase enzymes are involved in normal neuronal structure and function, but their elevated expression and cross-linking activity may also contribute to neuronal degenerative disease.
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Affiliation(s)
- S Y Kim
- Laboratory of Skin Biology, NIAMS, National Institutes of Health, Bethesda, Maryland 20892, USA
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19
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Fesus L. Transglutaminase-catalyzed protein cross-linking in the molecular program of apoptosis and its relationship to neuronal processes. Cell Mol Neurobiol 1998; 18:683-94. [PMID: 9876874 DOI: 10.1023/a:1020638020024] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
1. One type of transglutaminase is usually accumulated in various forms of naturally occurring cell death and apoptosis. The accumulated enzyme is activated during the death process, leading to the formation of cross-linked protein structures. Degradation of the cross-linked apoptotic bodies results in the elevation of the epsilon (gamma-glutamyl)lysine isodipeptide concentration in body fluids, which may provide a diagnostic tool to monitor the apoptosis rate in various tissues under normal and pathologic conditions. 2. Extensive protein cross-linking may be directly related to the act of killing in some cells. In others, the effect of protein cross-linking is palliative, preventing leakage of macromolecules and enhancing phagocytosis of the dead cells. 3. Tissue transglutaminase has been implicated in some physiologic functions of the nervous system. 4. The molecular machinery of apoptosis is present and easily evoked in neuronal cells. 5. Effector elements of the apoptosis process have been associated with the pathogenesis of neurologic disorders. Tissue transglutaminase, representing one of the effector elements of apoptosis, may be induced and activated in cells following ischemia. It may also participate in the formation of abnormal cell inclusions and A beta deposits in amyloid plaques.
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Affiliation(s)
- L Fesus
- Department of Biochemistry, University School of Medicine, Debrecen, Hungary
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20
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Johnson GV, Cox TM, Lockhart JP, Zinnerman MD, Miller ML, Powers RE. Transglutaminase activity is increased in Alzheimer's disease brain. Brain Res 1997; 751:323-9. [PMID: 9099822 DOI: 10.1016/s0006-8993(96)01431-x] [Citation(s) in RCA: 142] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Transglutaminase is a calcium-activated enzyme that crosslinks substrate proteins into insoluble, often filamentous aggregates resistant to proteases. Because the neurofibrillary tangles in Alzheimer's disease have similar characteristics, and because tau protein, the major component of these tangles is an excellent substrate of transglutaminase in vitro, transglutaminase activity and levels were measured in control and Alzheimer's disease brain. Frozen prefrontal cortex and cerebellum samples from Alzheimer's disease and control cases matched for age and postmortem interval were used in the analyses. Total transglutaminase activity was significantly higher in the Alzheimer's disease prefrontal cortex compared to control. In addition the levels of tissue transglutaminase, as determined by quantitative immunoblotting, were elevated approximately 3-fold in Alzheimer's disease prefrontal cortex compared to control. To our knowledge, this is the first demonstration that transglutaminase is increased in Alzheimer's disease brain. There were no significant differences in transglutaminase activity or levels in the cerebellum between control and Alzheimer's disease cases. Because the elevation of transglutaminase in the Alzheimer's disease samples occurred in the prefrontal cortex, where neurofibrillary pathology is usually abundant, and not in the cerebellum, which is usually spared in Alzheimer's disease, it can be suggested that transglutaminase could be a contributing factor in neurofibrillary tangle formation.
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Affiliation(s)
- G V Johnson
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, 35294-0017, USA.
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21
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Monsonego A, Shani Y, Friedmann I, Paas Y, Eizenberg O, Schwartz M. Expression of GTP-dependent and GTP-independent tissue-type transglutaminase in cytokine-treated rat brain astrocytes. J Biol Chem 1997; 272:3724-32. [PMID: 9013629 DOI: 10.1074/jbc.272.6.3724] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Tissue-type transglutaminases (TGases) were recently shown to exert dual enzymatic activities; they catalyze the posttranslational modification of proteins by transamidation, and they also act as guanosine triphosphatase (GTPase). Here we show that a tissue-type TGase is expressed in rat brain astrocytes in vitro, and is induced by the inflammation-associated cytokines interleukin-1beta and to a lesser extent by tumor necrosis factor-alpha. Induction is accompanied by overexpression and appearance of an additional shorter clone, which does not contain the long 3'-untranslated region and encodes for a novel TGase enzyme whose C terminus lacks a site that affects the enzyme's interaction with guanosine triphosphate (GTP). Expression of two clones revealed that the long form is inhibited noncompetitively by GTP, but the short form significantly less so. The different affinities for GTP may account for the difference in physiological function between these two enzymes.
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Affiliation(s)
- A Monsonego
- Department of Neurobiology, The Weizmann Institute of Science, 76100 Rehovot, Israel
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22
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Appelt DM, Balin BJ. The association of tissue transglutaminase with human recombinant tau results in the formation of insoluble filamentous structures. Brain Res 1997; 745:21-31. [PMID: 9037390 DOI: 10.1016/s0006-8993(96)01121-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
To determine possible mechanisms by which NFTs are formed in Alzheimer's disease (AD), we investigated the ability of tissue transglutaminase (TGase) to convert human recombinant tau proteins into insoluble filamentous structures. TGase derived from guinea pig liver was activated by calcium to catalyze the in vitro cross-linking of the largest soluble recombinant tau isoform (htau40) into insoluble complexes as determined by electrophoresis following incubation in 4 M urea and SDS. The TGase-catalyzed formation of these insoluble complexes occurred within 15 min to 24 h and the decreased migration of the insoluble material correlated with increased calcium concentrations ranging from 2 mM to 50 mM when analyzed electrophoretically. TGase-treated human recombinant tau formed filamentous structures in vitro that were immunoreactive with antibodies to tau and TGase. These structures retained the insoluble characteristics typical of AD PHF/NFTs. Immunolabeling with the TGase antibody revealed that TGase is associated with the filaments formed from human recombinant tau in vitro as well as with PHFs isolated from NFTs from AD brains. These novel findings support an in vitro model for investigating the biophysical changes that occur in converting soluble tau proteins into an insoluble matrix consistent with the insoluble PHFs/NFTs which may contribute to neuronal degeneration and cell death in the AD brain.
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Affiliation(s)
- D M Appelt
- Department of Anatomy and Neurobiology, Allegheny University of the Health Sciences, Philadelphia, PA 19102-1192, USA
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23
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Zhang W, Johnson BR, Bjornsson TD. Pharmacologic inhibition of transglutaminase-induced cross-linking of Alzheimer's amyloid beta-peptide. Life Sci 1997; 60:2323-32. [PMID: 9194688 DOI: 10.1016/s0024-3205(97)00288-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The brain of Alzheimer's disease (AD) patients contains deposits of amyloid beta-peptide (A beta). Recent studies have shown that A beta is a substrate for tissue transglutaminase (TGase), which induces the formation of cross-linked dimers and polymers, and that tacrine, indomethacin and deferoxamine, which have widely different chemical structures, attenuate the progression of symptoms of AD. This report evaluated the potential of a total of ten different pharmacological agents to inhibit TGase-induced cross-linking of A beta, including known TGase inhibitors (dansylcadaverine, spermine), non-steroidal anti-inflammatory drugs (indomethacin, meclofenamic acid, diflunisal, salicylic acid), monoamine oxidase inhibitors (tranylcypromine, phenelzine), an acetylcholinesterase inhibitor (tacrine), and an iron chelating agent (deferoxamine). All but one (salicylic acid) of these ten agents had an inhibitory effect on TGase-induced A beta cross-linking. These results suggest that inhibition of TGase-induced cross-linking of A beta is a potential pharmacologic target for the treatment of AD. A method is also presented for the determination of percent inhibition of TGase-induced A beta cross-linking based on the separated monomer, dimer and polymer bands on SDS-PAGE gels.
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Affiliation(s)
- W Zhang
- Department of Medicine, Jefferson Medical College of Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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24
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Affiliation(s)
- L Lorand
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, IL 60611, USA
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25
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Perry MJ, Mahoney SA, Haynes LW. Transglutaminase C in cerebellar granule neurons: regulation and localization of substrate cross-linking. Neuroscience 1995; 65:1063-76. [PMID: 7617162 DOI: 10.1016/0306-4522(94)00556-k] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Covalent cross-linking of cell surface proteins by the calcium-dependent enzyme transglutaminase C may be implicated in cell-cell interactions and growth regulation. We demonstrate the presence of the enzyme in rat cerebellar cortex during postnatal development. Transglutaminase C was induced in cerebellar granule neurons in culture by retinoic acid, dibutyryl- and 8-bromo-cyclic AMP analogues and by cultivation on a biomatrix substratum. Cyclic AMP analogues stimulated transglutaminase activity in protein synthesis-dependent and -independent phases. The enzyme was distributed at focal adhesion sites on the axon. By calcium-dependent covalent incorporation of the primary amine acceptor substrate, 5-(biotinamido)pentylamine, an increase in the Ca(2+)-dependent cross-linking of at least 11 substrate proteins in the presence of retinoic acid and dibutyryl-cyclic AMP was detected. Of these substrates, a subset was labelled on the surface of living granule neurons. A low-molecular-weight substrate, p18, was tentatively identified as the retinoic acid-inducible neurite-promoting factor, midkine. Transglutaminase-mediated amine incorporation, midkine and isopeptide cross-links were co-localized to axonal adhesion sites. The results provide evidence of transglutaminase C-catalysed protein cross-linking activity in cerebellar granule neurons and its possible implication in cell-substratum interactions.
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Affiliation(s)
- M J Perry
- School of Biological Sciences, University of Bristol, UK
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26
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Ho GJ, Gregory EJ, Smirnova IV, Zoubine MN, Festoff BW. Cross-linking of beta-amyloid protein precursor catalyzed by tissue transglutaminase. FEBS Lett 1994; 349:151-4. [PMID: 7913896 DOI: 10.1016/0014-5793(94)00663-6] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Alzheimer's disease is characterized by progressive dementia, cortical atrophy with synaptic loss, and the accumulation of neurofibrillary tangles and senile plaques containing beta-amyloid. The beta-amyloid protein precursor (beta-APP), may normally be involved in cell adhesion related to synaptic maintenance. Loss of synapses correlates with dementia, suggesting that synaptic deficits may underlie the disease. Synapse stability may depend on the action of tissue transglutaminase (tTG), an enzyme capable of crosslinking large, multi-domain extracellular glycoproteins, that is active and present at synapses. We now show that beta-APP is a substrate for tTG in vitro that results in dimers and multimers by silver staining and immunoblotting. This novel post-translational modification suggests further roles for beta-APP in synaptic function as well as in Alzheimer's disease.
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Affiliation(s)
- G J Ho
- Neurobiology Research Laboratory (151R), VA Medical Center, Kansas City, MO 64128
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27
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Murphy S, Huang CC, Lajevardi N, Tammela O, Wilson DF, Pastuszko A. Effect of hypoxia and reoxygenation on the activity of transglutaminase in brain of newborn piglets. Neurosci Lett 1994; 172:42-6. [PMID: 7916143 DOI: 10.1016/0304-3940(94)90658-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The transglutaminase activity in five regions of the brain of newborn piglets was measured and the effects of hypoxia and posthypoxic period on this activity evaluated. Enzyme activity was measured in homogenates from cortex, hippocampus, striatum, thalamus and midbrain. The control activities were 7.2, 6.2, 6.0, 5.7 and 4.6 pmol/mg protein/min, respectively. The activities at the end of an 18 min period of hypoxia induced by an FiO2 of 9% were not significantly different from control activities. By 3 h after the hypoxic episode, however, the transglutaminase activities were significantly above control levels in all five regions of the brain. Measurements of the kinetic constants of tranglutaminase indicated that increases in enzyme activity were associated with an increase in Vmax with no significant change in the apparent affinity of the enzyme for the substrate, putrescine. The increased activity of transglutaminase during the posthypoxic period, with no changes immediately after hypoxia, suggest that the increases could be due to increased enzyme synthesis rather than activation of existing enzyme. The rise in transglutaminase activity subsequent to a hypoxic episode may contribute significantly to the long-term disturbances in cellular metabolism in the immature brain induced by hypoxic episodes.
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Affiliation(s)
- S Murphy
- Department of Biochemistry and Biophysics, Medical School, University of Pennsylvania, Philadelphia 19104
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28
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Ho GJ, Smirnova IV, Akaaboune M, Hantaï D, Festoff BW. Serine proteases and their serpin inhibitors in Alzheimer's disease. Biomed Pharmacother 1994; 48:296-304. [PMID: 7858160 DOI: 10.1016/0753-3322(94)90175-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Our article documents recent studies in the proteolytic processing of the Alzheimer's beta-amyloid protein precursor (beta-APP), as well as the role of thrombin and its potent inhibitor, protease nexin I in Alzheimer's disease (AD). Since synapse loss correlates best with cognitive decline in AD, we also present in detail, our model of synapse formation and elimination, reviewing recent findings related to the subject as well as our own original data. Recent exciting findings concerning the involvement of thrombin-like activity in synapse elimination, which we feel to be important in neural plasticity are also discussed.
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Affiliation(s)
- G J Ho
- Neurobiology Research laboratory (151), Veterans Affairs Medical Center, Kansas City, MO
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29
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Abstract
Enzymes of the transglutaminase family catalyze the Ca(2+)-dependent covalent cross-linking of peptide-bound glutamine residues of proteins and glycoproteins to the epsilon-amino group of lysine residues to create inter- or intramolecular isopeptide bonds. Transglutaminases can also covalently link a variety of primary amines to peptide-bound glutamine residues giving rise to two possibilities; firstly, where the primary amine has two or more amino groups, further catalysis can result in the formation of cross-linked bridges between glutamine residues, and secondly, where the primary amine is a monoamine, glutamine residues are rendered inert to further modification. The products are therefore in the main, homo- or heterodimers, or extensive, metabolically-stable multimeric complexes or matrices. Ca(2+)-dependent transglutaminase activity is present in the mammalian peripheral and central nervous systems and transglutaminase-catalyzed cross-linking of endogenous substrates has been demonstrated in neurons of Aplysia and the mammalian brain. Transglutaminase activity increases in the brain during development, principally owing to the increasing preponderance of glial cell activity. In a few regions including the cerebellar cortex, activity is also high in early development. Cellular transglutaminases occur widely in differentiating cells and tissues in mammals, with more than one transglutaminase frequently associated with a single cell type. The primary protein sequences of three cellular transglutaminases have been fully determined in different species, together with that of a mammalian protein homologue (band 4.2) which shares extensive sequence homologies with transglutaminases, but lacks the active site cysteine residue. The upstream sequences of two mammalian cellular transglutaminase genes (C and K) contain numerous regulatory sites, and an invertebrate transglutaminase, annulin, is spatially regulated within homeodomains. Multiple molecular forms of transglutaminase C and possibly other cellular transglutaminases exist in mammalian brain. The emerging picture is one of a family of cytosolic and membrane-bound proteins central to several regulatory pathways whose functions is to stabilize the cellular and intercellular superstructure in growing organisms. The targeted formation of glu-lys isopeptide bonds between proteins is central to this function. Cytoskeletal proteins, membrane-associated receptors, enzymes in signal transduction pathways and extracellular glycoproteins are candidate substrates as are polyamines, but few cellular proteins have been identified as components of naturally-occurring covalently-bonded matrices. Transglutaminases participate in the programme of neuronal differentiation in some but not all classes of neurone. Both neuronal and non-neuronal expression of transglutaminases may be important for guidance of migrating neurons or growth cones and sustainment of cell shape and coordinates during development.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- D Hand
- Department of Zoology, University of Bristol, U.K
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30
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Hand D, Campoy FJ, Clark S, Fisher A, Haynes LW. Activity and distribution of tissue transglutaminase in association with nerve-muscle synapses. J Neurochem 1993; 61:1064-72. [PMID: 8103079 DOI: 10.1111/j.1471-4159.1993.tb03621.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
We have measured, characterized, and localized calcium-dependent protein cross-linking activity in rat skeletal muscle, and in myotubes cultured independently or in coculture with spinal neurones, catalyzed by the enzyme tissue transglutaminase (tTG). The enzyme activity was present in both motor endplate and endplate-free zones of rat diaphragm muscle. tTG in the endplate zone was more tightly associated with the tissue. This form of association was absent in extracts of peripheral nerve. Cross-linking of endogenous proteins, as measured by the content of epsilon-(gamma-glutamyl)lysine isopeptide, was higher in the endplate than in the nonendplate zone. Cytosolic (C) and particulate (B) forms of tTG were separated by ion-exchange chromatography from both regions of the muscle. In the motor endplate zone, a higher proportion of tightly bound tTG was recovered as a separate (B1) particulate form. Km values for calcium activation of the three forms of tTG were in the range of 5-15 microM. Immunocytochemistry with polyclonal and monoclonal antibodies revealed the enzyme at motor endplates and at contacts between neurites of rat embryo spinal neurones and myotubes in primary cocultures. Appearance of the B1 transglutaminase could be induced by coculturing myotubes of the mouse C2C12 cell line with neurones. The results suggest that tTG is most concentrated and active at the motor endplate.
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Affiliation(s)
- D Hand
- Department of Zoology, University of Bristol, England
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31
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Ikura K, Takahata K, Sasaki R. Cross-linking of a synthetic partial-length (1-28) peptide of the Alzheimer beta/A4 amyloid protein by transglutaminase. FEBS Lett 1993; 326:109-11. [PMID: 8100780 DOI: 10.1016/0014-5793(93)81772-r] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Cerebral deposits of beta/A4 amyloid protein is a pathologic sign of Alzheimer's disease. A synthetic partial-length (1-28) peptide of this protein contains one glutamine and two lysine residues. Here we show that this peptide can be a substrate of transglutaminase, which catalyzes cross-linking between glutamine and lysine residues in peptides, by demonstrating the formation of multimeric peptides due to the action of this enzyme. A modified (Lys28 to L-norleucine) version of the synthetic peptide was also cross-linked, but another modified version (Lys16 to L-norleucine) was very poorly cross-linked, indicating that Lys16 is involved exclusively in the cross-linking of the partial-length peptide catalyzed by transglutaminase.
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Affiliation(s)
- K Ikura
- Department of Chemistry and Materials Technology, Kyoto Institute of Technology, Japan
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32
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33
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Gilad GM, Gilad VH. Polyamines can protect against ischemia-induced nerve cell death in gerbil forebrain. Exp Neurol 1991; 111:349-55. [PMID: 1999235 DOI: 10.1016/0014-4886(91)90102-i] [Citation(s) in RCA: 97] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We have previously demonstrated that administration of the polyamines putrescine, spermidine, or spermine can prevent neuronal degeneration in rats during naturally occurring cell death or after injurious treatments such as nerve injury or monosodium glutamate neurotoxicity. The present study demonstrates that also in adult gerbils polyamine treatment can protect forebrain neurons from degeneration after ischemia. Neurons in the hippocampus and striatum were rescued from delayed cell death after brief (5 min) global ischemia in gerbils which were treated with daily injections (10 mg/kg) of polyamines. The evidence accrued, so far, indicates that systemic polyamines can protect a wide variety of central and peripheral neurons from natural or induced degeneration.
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Affiliation(s)
- G M Gilad
- Neuropsychiatry Branch, NIMH Neuroscience Center, Saint Elizabeths, Washington, D.C. 20032
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34
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Abstract
The uptake, binding and release of the polyamines, spermidine and spermine, and of their diamine precursor, putrescine, were examined in synaptosomal preparations from rat hippocampus. The specific and relatively high-affinity uptake by synaptosomes was found only with putrescine (Vmax = 21.6 pmol/mg protein per h; Km = 28.6 nM) and not with the other polyamines. In contrast, specific binding to membranes was found for spermidine (Bmax = 28.6 pmol/mg protein; Kd = 42.9 nM) and for spermine (Bmax = 156.3 pmol/mg protein; Kd = 83.3 nM), but not for putrescine. High potassium concentrations (35 mM) both induced the release of accumulated polyamines from synaptosomes and inhibited their binding. Specific polyamine binding evidently occurs selectively on the inner but not on the outer synaptosomal membranes.
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Affiliation(s)
- G M Gilad
- Neuropsychiatry Branch, NIMH Neuroscience Center, Saint Elizabeths Hospital, Washington, DC 20032
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35
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Paschen W, Röhn G, Schmidt-Kastner R. Transglutaminase activity in reversible cerebral ischemia in the rat. Neurosci Lett 1990; 110:232-6. [PMID: 1970143 DOI: 10.1016/0304-3940(90)90817-s] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Transglutaminase (TG, EC 2.3.2.13) activity and levels of putrescine (a natural acyl-acceptor in the transglutaminase reaction) were measured in rat brains after 30 min ischemia and 8 or 24 h recirculation. TG activity was significantly increased in the striatum and hippocampus already during cerebral ischemia and, more pronounced, after 8 and 24 h recirculation. In the cortex, in contrast, TG activity did not change during ischemia and 8 h recirculation but was significantly increased after 24 h recirculation. Putrescine levels were sharply increased after 8 h recirculation and even further after 24 h recirculation. It is suggested that in vivo during ischemia and early recirculation, when cells are overloaded with calcium ions, a pathological increase in the TG-catalyzed cross-linking of proteins may be apparent especially in the nerve endings of the hippocampus where the intrinsic concentration of the acyl-donor (protein-bound glutamyl-moiety) has been shown to be high.
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Affiliation(s)
- W Paschen
- Max-Planck-Institute for Neurological Research, Department of Experimental Neurology, Cologne, F.R.G
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36
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Hand D, Elliott BM, Griffin M. Expression of the cytosolic and particulate forms of transglutaminase during chemically induced rat liver carcinogenesis. BIOCHIMICA ET BIOPHYSICA ACTA 1988; 970:137-45. [PMID: 2898262 DOI: 10.1016/0167-4889(88)90172-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Transglutaminase (EC 2.3.2.13) activity in chemically induced rat hepatocellular carcinomas was reduced by some 65% when compared to normal rat livers. The majority of the remaining activity (approx. 85%) was found in the particulate fraction. The use of non-ionic detergent to extract the transglutaminase activity present in both normal and tumour tissue followed by its separation on a Mono-Q column revealed two distinct peaks of activity. These peaks of activity were equivalent to those previously identified as a membrane-bound transglutaminase and the more characteristic cytosolic or tissue transglutaminase. The ratio of the activity of the cytosolic enzyme to that of the membrane-bound enzyme in normal liver was calculated as 5:1. In hepatocellular carcinomas, this ratio was reduced to 0.4:1. No significant change in the activity of the membrane-bound enzyme was detectable in tumour tissue. Comparison of the cytosolic enzyme found in hepatocellular carcinomas with that found in normal liver indicated no change in its molecular weight, Km,app for putrescine incorporation into N,N'-dimethylcasein and sensitivity to activation by Ca2+. These observations suggest that the reduction in transglutaminase activity observed in the hepatocellular carcinoma is due to a selective reduction in the expression of the cytosolic transglutaminase.
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Affiliation(s)
- D Hand
- Department of Life Sciences, Trent Polytechnic, Nottingham, U.K
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37
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Gentile V, Esposito C, Fusco A, Popoli M, Porta R. Spermine binding to subsynaptosomal fractions of rat brain cortex. Neurochem Res 1988; 13:369-76. [PMID: 3393265 DOI: 10.1007/bf00972487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Binding sites for [14C]spermine have been identified in rat brain cortex subcellular fractions. The binding, characterized by using synaptosomal membranes, is specific for spermine. It was not detected below 20 degrees C and increased about three/four-fold with a temperature rise of 10 degrees C. Binding occurred only in the presence of -SH reducing agents. It was completely suppressed by metal chelating agents, and was stimulated about four-fold by 1-5 x 10(-5) M Fe2+. Smaller increases were observed in the presence of Mn2+, Ni2+, Ca2+, Mg2+, and Zn2+; in contrast, millimolar concentrations of most divalent cations inhibited the binding differently (Mn2+ = Ni2+ = Zn2+ = Co2+ much greater than Mg2+ greater than Ca2+). Bound radioactive spermine was not displaced by the addition of high concentrations of unlabelled polyamine or chelating agents, nor by precipitation and washing of the membranes with 10 percent trichloroacetic acid, or by boiling of the precipitate in the presence of 1.0 percent SDS and 10 percent beta-mercaptoethanol. The trichloroacetic acid precipitate showed two radioactive bands, corresponding to low Mr (less than 8,000) components, after SDS-polyacrylamide gel electrophoresis and fluorography. The Fe2+-stimulated [14C]spermine binding was neither influenced by a previous heating of the membranes at 100 degrees C for 30 min nor by trypsin or pronase digestion, whereas the heat-treatment increased the binding occurring in the absence of Fe2+ by about two fold. A non-enzymatic formation of a spermine-metal complex tightly bound to some membrane peptide(s) is suggested.
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Affiliation(s)
- V Gentile
- Istituto di Chimica e Chimica Biologica, 1a Facoltà di Medicina e Chirurgia, Napoli, Italy
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38
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Gilad GM, Gilad VH. Cytotoxic effects of monodansylcadaverine and methylamine in primary cultures of rat cerebellar neurons. Int J Dev Neurosci 1986; 4:401-5. [PMID: 3455600 DOI: 10.1016/0736-5748(86)90022-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The effects of dansylcadaverine and methylamine, competitive inhibitors of transglutaminase, were examined in primary cultures of dissociated rat cerebellar neurons. Addition of the drugs at plating time resulted 24 hr later in irreversible cytotoxic effects evidenced by failure of aggregation and neurite formation. Cytotoxicity was dose-dependent with methylamine being more potent (IC50 = 20 microM) than dansylcadaverine (IC50 = 30 microM). The cytotoxic effects were less potent when drugs were added 24 hr after plating, the time when neurons had already begun to extend neurites. Drugs were effective in the various sera and heat-inactivated sera tested. We concluded that low doses of methylamine and dansylcadaverine have potent toxic effects on primary neuronal cultures.
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Affiliation(s)
- G M Gilad
- Center for Neurosciences and Behavioral Research, Weizmann Institute of Science, Rehovot, Israel
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