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Treadmill exercise rescues mitochondrial function and motor behavior in the CAG140 knock-in mouse model of Huntington's disease. Chem Biol Interact 2020; 315:108907. [DOI: 10.1016/j.cbi.2019.108907] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 11/14/2019] [Accepted: 11/25/2019] [Indexed: 02/07/2023]
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Rama Rao KV, Jayakumar AR, Norenberg MD. Brain edema in acute liver failure: mechanisms and concepts. Metab Brain Dis 2014; 29:927-36. [PMID: 24567229 DOI: 10.1007/s11011-014-9502-y] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Accepted: 02/05/2014] [Indexed: 12/18/2022]
Abstract
Brain edema and associated increase in intracranial pressure continue to be lethal complications of acute liver failure (ALF). Abundant evidence suggests that the edema in ALF is largely cytotoxic brought about by swelling of astrocytes. Elevated blood and brain ammonia levels have been strongly implicated in the development of the brain edema. Additionally, inflammation and sepsis have been shown to contribute to the astrocyte swelling/brain edema in the setting of ALF. We posit that ammonia initiates a number of signaling events, including oxidative/nitrative stress (ONS), the mitochondrial permeability transition (mPT), activation of the transcription factor (NF-κB) and signaling kinases, all of which have been shown to contribute to the mechanism of astrocyte swelling. All of these factors also impact ion-transporters, including Na(+), K(+), Cl(-) cotransporter and the sulfonylurea receptor 1, as well as the water channel protein aquaporin-4 resulting in a perturbation of cellular ion and water homeostasis, ultimately resulting in astrocyte swelling/brain edema. All of these events are also potentiated by inflammation. This article reviews contemporary knowledge regarding mechanisms of astrocyte swelling/brain edema formation which hopefully will facilitate the identification of therapeutic targets capable of mitigating the brain edema associated with ALF.
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Affiliation(s)
- Kakulavarapu V Rama Rao
- Department of Pathology, University of Miami Miller School of Medicine, PO Box 016960, Miami, FL, 33101, USA,
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Quintanilla RA, Jin YN, von Bernhardi R, Johnson GVW. Mitochondrial permeability transition pore induces mitochondria injury in Huntington disease. Mol Neurodegener 2013; 8:45. [PMID: 24330821 PMCID: PMC3878840 DOI: 10.1186/1750-1326-8-45] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 12/02/2013] [Indexed: 12/13/2022] Open
Abstract
Background Mitochondrial impairment has been implicated in the pathogenesis of Huntington’s disease (HD). However, how mutant huntingtin impairs mitochondrial function and thus contributes to HD has not been fully elucidated. In this study, we used striatal cells expressing wild type (STHdhQ7/Q7) or mutant (STHdhQ111/Q111) huntingtin protein, and cortical neurons expressing the exon 1 of the huntingtin protein with physiological or pathological polyglutamine domains, to examine the interrelationship among specific mitochondrial functions. Results Depolarization induced by KCl resulted in similar changes in calcium levels without compromising mitochondrial function, both in wild type and mutant cells. However, treatment of mutant cells with thapsigargin (a SERCA antagonist that raises cytosolic calcium levels), resulted in a pronounced decrease in mitochondrial calcium uptake, increased production of reactive oxygen species (ROS), mitochondrial depolarization and fragmentation, and cell viability loss. The mitochondrial dysfunction in mutant cells was also observed in cortical neurons expressing exon 1 of the huntingtin protein with 104 Gln residues (Q104-GFP) when they were exposed to calcium stress. In addition, calcium overload induced opening of the mitochondrial permeability transition pore (mPTP) in mutant striatal cells. The mitochondrial impairment observed in mutant cells and cortical neurons expressing Q104-GFP was prevented by pre-treatment with cyclosporine A (CsA) but not by FK506 (an inhibitor of calcineurin), indicating a potential role for mPTP opening in the mitochondrial dysfunction induced by calcium stress in mutant huntingtin cells. Conclusions Expression of mutant huntingtin alters mitochondrial and cell viability through mPTP opening in striatal cells and cortical neurons.
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Affiliation(s)
- Rodrigo A Quintanilla
- Department of Anesthesiology, University of Rochester Medical Center, 601 Elmwood Ave, Box 604 (for courier: Rm 4-6314), Rochester, NY 14642, USA.
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Wityak J, Prime ME, Brookfield FA, Courtney SM, Erfan S, Johnsen S, Johnson PD, Li M, Marston RW, Reed L, Vaidya D, Schaertl S, Pedret-Dunn A, Beconi M, Macdonald D, Muñoz-Sanjuan I, Dominguez C. SAR Development of Lysine-Based Irreversible Inhibitors of Transglutaminase 2 for Huntington's Disease. ACS Med Chem Lett 2012; 3:1024-8. [PMID: 24900424 DOI: 10.1021/ml300241m] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2012] [Accepted: 10/04/2012] [Indexed: 11/29/2022] Open
Abstract
We report a series of irreversible transglutaminase 2 inhibitors starting from a known lysine dipeptide bearing an acrylamide warhead. We established new SARs resulting in compounds demonstrating improved potency and better physical and calculated properties. Transglutaminase selectivity profiling and in vitro ADME properties of selected compounds are also reported.
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Affiliation(s)
- John Wityak
- CHDI Management/CHDI Foundation, 6080 Center Drive, Suite 100, Los Angeles, California 90045, United States
| | - Michael E. Prime
- Evotec (U.K.) Ltd., 114 Milton Park, Abingdon, OX14 4SA, United Kingdom
| | | | | | - Sayeh Erfan
- Evotec (U.K.) Ltd., 114 Milton Park, Abingdon, OX14 4SA, United Kingdom
| | - Siw Johnsen
- Evotec (U.K.) Ltd., 114 Milton Park, Abingdon, OX14 4SA, United Kingdom
| | - Peter D. Johnson
- Evotec (U.K.) Ltd., 114 Milton Park, Abingdon, OX14 4SA, United Kingdom
| | - Marie Li
- Evotec (U.K.) Ltd., 114 Milton Park, Abingdon, OX14 4SA, United Kingdom
| | | | - Laura Reed
- Evotec (U.K.) Ltd., 114 Milton Park, Abingdon, OX14 4SA, United Kingdom
| | - Darshan Vaidya
- Evotec (U.K.) Ltd., 114 Milton Park, Abingdon, OX14 4SA, United Kingdom
| | - Sabine Schaertl
- Evotec AG, Manfred Eigen Campus, Essener Bogen 7, 22419 Hamburg, Germany
| | - Anna Pedret-Dunn
- Evotec (U.K.) Ltd., 114 Milton Park, Abingdon, OX14 4SA, United Kingdom
| | - Maria Beconi
- CHDI Management/CHDI Foundation, 6080 Center Drive, Suite 100, Los Angeles, California 90045, United States
| | - Douglas Macdonald
- CHDI Management/CHDI Foundation, 6080 Center Drive, Suite 100, Los Angeles, California 90045, United States
| | - Ignacio Muñoz-Sanjuan
- CHDI Management/CHDI Foundation, 6080 Center Drive, Suite 100, Los Angeles, California 90045, United States
| | - Celia Dominguez
- CHDI Management/CHDI Foundation, 6080 Center Drive, Suite 100, Los Angeles, California 90045, United States
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Prime ME, Brookfield FA, Courtney SM, Gaines S, Marston RW, Ichihara O, Li M, Vaidya D, Williams H, Pedret-Dunn A, Reed L, Schaertl S, Toledo-Sherman L, Beconi M, Macdonald D, Muñoz-Sanjuan I, Dominguez C, Wityak J. Irreversible 4-Aminopiperidine Transglutaminase 2 Inhibitors for Huntington's Disease. ACS Med Chem Lett 2012; 3:731-5. [PMID: 24900540 DOI: 10.1021/ml3001352] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Accepted: 08/09/2012] [Indexed: 11/28/2022] Open
Abstract
A new series of potent TG2 inhibitors are reported that employ a 4-aminopiperidine core bearing an acrylamide warhead. We establish the structure-activity relationship of this new series and report on the transglutaminase selectivity and in vitro ADME properties of selected compounds. We demonstrate that the compounds do not conjugate glutathione in an in vitro setting and have superior plasma stability over our previous series.
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Affiliation(s)
- Michael E. Prime
- Evotec (U.K.) Ltd., 114 Milton Park, Abingdon OX14
4SA, United Kingdom
| | | | | | - Simon Gaines
- Evotec (U.K.) Ltd., 114 Milton Park, Abingdon OX14
4SA, United Kingdom
| | | | - Osamu Ichihara
- Evotec (U.K.) Ltd., 114 Milton Park, Abingdon OX14
4SA, United Kingdom
| | - Marie Li
- Evotec (U.K.) Ltd., 114 Milton Park, Abingdon OX14
4SA, United Kingdom
| | - Darshan Vaidya
- Evotec (U.K.) Ltd., 114 Milton Park, Abingdon OX14
4SA, United Kingdom
| | - Helen Williams
- Evotec (U.K.) Ltd., 114 Milton Park, Abingdon OX14
4SA, United Kingdom
| | - Anna Pedret-Dunn
- Evotec (U.K.) Ltd., 114 Milton Park, Abingdon OX14
4SA, United Kingdom
| | - Laura Reed
- Evotec (U.K.) Ltd., 114 Milton Park, Abingdon OX14
4SA, United Kingdom
| | - Sabine Schaertl
- Evotec AG, Manfred Eigen Campus, Essener Bogen 7, 22419
Hamburg, Germany
| | - Leticia Toledo-Sherman
- CHDI Management/CHDI Foundation, 6080 Center Drive,
Suite 100, Los Angeles, California 90045, United States
| | - Maria Beconi
- CHDI Management/CHDI Foundation, 6080 Center Drive,
Suite 100, Los Angeles, California 90045, United States
| | - Douglas Macdonald
- CHDI Management/CHDI Foundation, 6080 Center Drive,
Suite 100, Los Angeles, California 90045, United States
| | - Ignacio Muñoz-Sanjuan
- CHDI Management/CHDI Foundation, 6080 Center Drive,
Suite 100, Los Angeles, California 90045, United States
| | - Celia Dominguez
- CHDI Management/CHDI Foundation, 6080 Center Drive,
Suite 100, Los Angeles, California 90045, United States
| | - John Wityak
- CHDI Management/CHDI Foundation, 6080 Center Drive,
Suite 100, Los Angeles, California 90045, United States
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Yoo JO, Lim YC, Kim YM, Ha KS. Transglutaminase 2 promotes both caspase-dependent and caspase-independent apoptotic cell death via the calpain/Bax protein signaling pathway. J Biol Chem 2012; 287:14377-88. [PMID: 22418443 DOI: 10.1074/jbc.m111.326074] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Transglutaminase 2 (TG2) is a versatile protein that is implicated in significant biological processes, including cell death and degenerative diseases. A possible role of TG2 in the apoptotic death of cancer cells induced by photodynamic therapy (PDT) was suggested recently; however, the mechanism by which TG2 regulates apoptotic responses to PDT remains to be elucidated. In this study, we investigated the key signaling pathways stimulated during apoptotic cell death following PDT and whether inhibition of TG2 activation using pharmacological approaches and siRNAs affects the signaling pathways. PDT caused the release of both cytochrome c and apoptosis-inducing factor (AIF) by damaging mitochondria, which resulted in caspase-dependent and caspase-independent apoptotic cell death, respectively. Released AIF translocated to the nucleus and, synergistically with the caspase-dependent pathway, led to apoptotic cell death. Both the caspase cascade and the activation of AIF following PDT were mediated by TG2 activation. In addition, PDT-activated calpain was responsible for the sequential events of Bax translocation, the collapse of ΔΨ(m), caspase-3 activation, and AIF translocation, all of which were provoked by TG2 activation. Together, these results demonstrate that PDT with a chlorin-based photosensitizer targets TG2 by activating calpain-induced Bax translocation, which induces apoptotic cell death through both caspase-dependent and AIF-mediated pathways. Moreover, these results indicate that TG2 may be a possible therapeutic target for PDT treatment of cancer.
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Affiliation(s)
- Je-Ok Yoo
- Department of Molecular and Cellular Biochemistry and Institute of Medical Science, Kangwon National University School of Medicine, Kangwon-do 200-701, Korea
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Prime ME, Andersen OA, Barker JJ, Brooks MA, Cheng RKY, Toogood-Johnson I, Courtney SM, Brookfield FA, Yarnold CJ, Marston RW, Johnson PD, Johnsen SF, Palfrey JJ, Vaidya D, Erfan S, Ichihara O, Felicetti B, Palan S, Pedret-Dunn A, Schaertl S, Sternberger I, Ebneth A, Scheel A, Winkler D, Toledo-Sherman L, Beconi M, Macdonald D, Muñoz-Sanjuan I, Dominguez C, Wityak J. Discovery and structure-activity relationship of potent and selective covalent inhibitors of transglutaminase 2 for Huntington's disease. J Med Chem 2012; 55:1021-46. [PMID: 22224594 DOI: 10.1021/jm201310y] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Tissue transglutaminase 2 (TG2) is a multifunctional protein primarily known for its calcium-dependent enzymatic protein cross-linking activity via isopeptide bond formation between glutamine and lysine residues. TG2 overexpression and activity have been found to be associated with Huntington's disease (HD); specifically, TG2 is up-regulated in the brains of HD patients and in animal models of the disease. Interestingly, genetic deletion of TG2 in two different HD mouse models, R6/1 and R6/2, results in improved phenotypes including a reduction in neuronal death and prolonged survival. Starting with phenylacrylamide screening hit 7d, we describe the SAR of this series leading to potent and selective TG2 inhibitors. The suitability of the compounds as in vitro tools to elucidate the biology of TG2 was demonstrated through mode of inhibition studies, characterization of druglike properties, and inhibition profiles in a cell lysate assay.
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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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Piacentini M, D'Eletto M, Falasca L, Farrace MG, Rodolfo C. Transglutaminase 2 at the crossroads between cell death and survival. ADVANCES IN ENZYMOLOGY AND RELATED AREAS OF MOLECULAR BIOLOGY 2011; 78:197-246. [PMID: 22220475 DOI: 10.1002/9781118105771.ch5] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Mauro Piacentini
- Department of Biology, University of Rome "Tor Vergata", Rome, Italy
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Transglutaminase 2: a molecular Swiss army knife. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1823:406-19. [PMID: 22015769 DOI: 10.1016/j.bbamcr.2011.09.012] [Citation(s) in RCA: 174] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Revised: 09/02/2011] [Accepted: 09/06/2011] [Indexed: 12/26/2022]
Abstract
Transglutaminase 2 (TG2) is the most widely distributed member of the transglutaminase family with almost all cell types in the body expressing TG2 to varying extents. In addition to being widely expressed, TG2 is an extremely versatile protein exhibiting transamidating, protein disulphide isomerase and guanine and adenine nucleotide binding and hydrolyzing activities. TG2 can also act as a protein scaffold or linker. This unique protein also undergoes extreme conformational changes and exhibits localization diversity. Being mainly a cytosolic protein; it is also found in the nucleus, associated with the cell membrane (inner and outer side) and with the mitochondria, and also in the extracellular matrix. These different activities, conformations and localization need to be carefully considered while assessing the role of TG2 in physiological and pathological processes. For example, it is becoming evident that the role of TG2 in cell death processes is dependent upon the cell type, stimuli, subcellular localization and conformational state of the protein. In this review we discuss in depth the conformational and functional diversity of TG2 in the context of its role in numerous cellular processes. In particular, we have highlighted how differential localization, conformation and activities of TG2 may distinctly mediate cell death processes.
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11
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Depletion of cathepsin D by transglutaminase 2 through protein cross-linking promotes cell survival. Amino Acids 2011; 44:73-80. [DOI: 10.1007/s00726-011-1089-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2011] [Accepted: 09/15/2011] [Indexed: 11/26/2022]
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12
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Yoo JO, Lim YC, Kim YM, Ha KS. Differential cytotoxic responses to low- and high-dose photodynamic therapy in human gastric and bladder cancer cells. J Cell Biochem 2011; 112:3061-71. [DOI: 10.1002/jcb.23231] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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13
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Cytosolic guanine nucledotide binding deficient form of transglutaminase 2 (R580a) potentiates cell death in oxygen glucose deprivation. PLoS One 2011; 6:e16665. [PMID: 21304968 PMCID: PMC3031627 DOI: 10.1371/journal.pone.0016665] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Accepted: 01/10/2011] [Indexed: 01/15/2023] Open
Abstract
Transglutaminase 2 (TG2) is a hypoxia-responsive protein that is a calcium-activated transamidating enzyme, a GTPase and a scaffolding/linker protein. Upon activation TG2 undergoes a large conformational change, which likely affects not only its enzymatic activities but its non-catalytic functions as well. The focus of this study was on the role of transamidating activity, conformation and localization of TG2 in ischemic cell death. Cells expressing a GTP binding deficient form of TG2 (TG2-R580A) with high basal transamidation activity and a more extended conformation showed significantly increased cell death in response to oxygen-glucose deprivation; however, targeting TG2-R580A to the nucleus abrogated its detrimental role in oxygen-glucose deprivation. Treatment of cells expressing wild type TG2, TG2-C277S (a transamidating inactive mutant) and TG2-R580A with Cp4d, a reversible TG2 inhibitor, did not affect cell death in response to oxygen-glucose deprivation. These findings indicate that the pro-cell death effects of TG2 are dependent on its localization to the cytosol and independent of its transamidation activity. Further, the conformational state of TG2 is likely an important determinant in cell survival and the prominent function of TG2 in ischemic cell death is as a scaffold to modulate cellular processes.
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Schaertl S, Prime M, Wityak J, Dominguez C, Munoz-Sanjuan I, Pacifici RE, Courtney S, Scheel A, Macdonald D. A profiling platform for the characterization of transglutaminase 2 (TG2) inhibitors. ACTA ACUST UNITED AC 2010; 15:478-87. [PMID: 20395409 DOI: 10.1177/1087057110366035] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Huntington's disease (HD) is associated with increased expression levels and activity of tissue transglutaminase (TG2), an enzyme primarily known for its cross-linking of proteins. To validate TG2 as a therapeutic target for HD in transgenic models and for eventual clinical development, a selective and brain-permeable inhibitor is required. Here, a comprehensive profiling platform of biochemical and cellular assays is presented which has been established to evaluate the potency, cellular efficacy, subtype selectivity and the mechanism-of-action of known and novel TG2 inhibitors. Several classes of inhibitors have been characterized including: the commonly used pseudo-substrate inhibitors, cystamine and putrescine (which are generally nonspecific for TG2 and therefore not practical for drug development), the various peptidic inhibitors that target the active site cysteine residue (which display excellent selectivity but in general have poor cellular activity), and the allosteric reversible small-molecule hydrazides (which show poor selectivity and a lack of cellular activity and could not be improved despite considerable medicinal chemistry efforts). In addition, a set of inhibitors identified from a collection of pharmacologically active compounds was found to be unselective for TG2. Moreover, inhibition at the guanosine triphosphate binding site has been examined, but apart from guanine nucleotides, no such inhibitors have been identified. In addition, the promising pharmacological profile of a TG2 inhibitor is presented which is currently in lead optimization to be developed as a tool compound.
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15
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Pennuto M, Palazzolo I, Poletti A. Post-translational modifications of expanded polyglutamine proteins: impact on neurotoxicity. Hum Mol Genet 2009; 18:R40-7. [PMID: 19297400 DOI: 10.1093/hmg/ddn412] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Polyglutamine diseases are a family of nine neurodegenerative disorders caused by expansion in different genes of a CAG triplet repeat stretch, which encodes an elongated polyglutamine tract. This polyglutamine tract is thought to confer a toxic gain of function to the bearing proteins, which leads to late onset and progressive loss of neurons in specific regions of the central nervous system. The mechanisms underlying specificity for neuronal vulnerability remain enigmatic. One explanation is that the polyglutamine tract is not the only determinant of neurodegeneration and that protein context and post-translational events may also be crucial for pathogenesis. Here, we review how post-translational modifications of the polyglutamine proteins contribute to modulate neurotoxicity.
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Affiliation(s)
- Maria Pennuto
- Department of Neurology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
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16
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Quintanilla RA, Jin YN, Fuenzalida K, Bronfman M, Johnson GVW. Rosiglitazone treatment prevents mitochondrial dysfunction in mutant huntingtin-expressing cells: possible role of peroxisome proliferator-activated receptor-gamma (PPARgamma) in the pathogenesis of Huntington disease. J Biol Chem 2008; 283:25628-25637. [PMID: 18640979 PMCID: PMC2533094 DOI: 10.1074/jbc.m804291200] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2008] [Revised: 07/15/2008] [Indexed: 01/15/2023] Open
Abstract
Peroxisome proliferator-activated receptor-gamma (PPARgamma) is a member of the PPAR family of transcription factors. Synthetic PPARgamma agonists are used as oral anti-hyperglycemic drugs for the treatment of non-insulin-dependent diabetes. However, emerging evidence indicates that PPARgamma activators can also prevent or attenuate neurodegeneration. Given these previous findings, the focus of this report is on the potential neuroprotective role of PPARgamma activation in preventing the loss of mitochondrial function in Huntington disease (HD). For these studies we used striatal cells that express wild-type (STHdh(Q7/Q7)) or mutant (STHdh(Q111/Q111)) huntingtin protein at physiological levels. Treatment of mutant cells with thapsigargin resulted in a significant decrease in mitochondrial calcium uptake, an increase in reactive oxygen species production, and a significant decrease in mitochondrial membrane potential. PPARgamma activation by rosiglitazone prevented the mitochondrial dysfunction and oxidative stress that occurred when mutant striatal cells were challenged with pathological increases in calcium. The beneficial effects of rosiglitazone were likely mediated by activation of PPARgamma, as all protective effects were prevented by the PPARgamma antagonist GW9662. Additionally, the PPARgamma signaling pathway was significantly impaired in the mutant striatal cells with decreases in PPARgamma expression and reduced PPARgamma transcriptional activity. Treatment with rosiglitazone increased mitochondrial mass levels, suggesting a role for the PPARgamma pathway in mitochondrial function in striatal cells. Altogether, this evidence indicates that PPARgamma activation by rosiglitazone attenuates mitochondrial dysfunction in mutant huntingtin-expressing striatal cells, and this could be an important therapeutic avenue to ameliorate the mitochondrial dysfunction that occurs in HD.
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Affiliation(s)
| | - Youngnam N Jin
- Department of Pharmacology and Physiology, University of Rochester, Rochester, New York 14642-0002
| | - Karen Fuenzalida
- Centro de Regulación Celular y Patologia Joaquín V. Luco and Millennium Institute for Fundamental and Applied Biology, Department of Cellular and Molecular Biology, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, Santiago 114-D, Chile
| | - Miguel Bronfman
- Centro de Regulación Celular y Patologia Joaquín V. Luco and Millennium Institute for Fundamental and Applied Biology, Department of Cellular and Molecular Biology, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, Santiago 114-D, Chile
| | - Gail V W Johnson
- Department of Anesthesiology, University of Rochester, Rochester, New York 14642; Department of Pharmacology and Physiology, University of Rochester, Rochester, New York 14642-0002.
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