1
|
Lee WS, Al-Ramahi I, Jeong HH, Jang Y, Lin T, Adamski CJ, Lavery LA, Rath S, Richman R, Bondar VV, Alcala E, Revelli JP, Orr HT, Liu Z, Botas J, Zoghbi HY. Cross-species genetic screens identify transglutaminase 5 as a regulator of polyglutamine-expanded ataxin-1. J Clin Invest 2022; 132:e156616. [PMID: 35499073 PMCID: PMC9057624 DOI: 10.1172/jci156616] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 03/08/2022] [Indexed: 12/31/2022] Open
Abstract
Many neurodegenerative disorders are caused by abnormal accumulation of misfolded proteins. In spinocerebellar ataxia type 1 (SCA1), accumulation of polyglutamine-expanded (polyQ-expanded) ataxin-1 (ATXN1) causes neuronal toxicity. Lowering total ATXN1, especially the polyQ-expanded form, alleviates disease phenotypes in mice, but the molecular mechanism by which the mutant ATXN1 is specifically modulated is not understood. Here, we identified 22 mutant ATXN1 regulators by performing a cross-species screen of 7787 and 2144 genes in human cells and Drosophila eyes, respectively. Among them, transglutaminase 5 (TG5) preferentially regulated mutant ATXN1 over the WT protein. TG enzymes catalyzed cross-linking of ATXN1 in a polyQ-length-dependent manner, thereby preferentially modulating mutant ATXN1 stability and oligomerization. Perturbing Tg in Drosophila SCA1 models modulated mutant ATXN1 toxicity. Moreover, TG5 was enriched in the nuclei of SCA1-affected neurons and colocalized with nuclear ATXN1 inclusions in brain tissue from patients with SCA1. Our work provides a molecular insight into SCA1 pathogenesis and an opportunity for allele-specific targeting for neurodegenerative disorders.
Collapse
Affiliation(s)
- Won-Seok Lee
- Integrative Molecular and Biomedical Science Program, and
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Jan and Dan Duncan Neurological Research Institute, Houston, Texas, USA
| | - Ismael Al-Ramahi
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Jan and Dan Duncan Neurological Research Institute, Houston, Texas, USA
| | - Hyun-Hwan Jeong
- Jan and Dan Duncan Neurological Research Institute, Houston, Texas, USA
- Department of Pediatrics-Neurology, and
| | - Youjin Jang
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Jan and Dan Duncan Neurological Research Institute, Houston, Texas, USA
| | - Tao Lin
- Jan and Dan Duncan Neurological Research Institute, Houston, Texas, USA
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, Texas, USA
| | - Carolyn J. Adamski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Jan and Dan Duncan Neurological Research Institute, Houston, Texas, USA
- Howard Hughes Medical Institute, Houston, Texas, USA
| | - Laura A. Lavery
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Jan and Dan Duncan Neurological Research Institute, Houston, Texas, USA
| | - Smruti Rath
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Jan and Dan Duncan Neurological Research Institute, Houston, Texas, USA
| | - Ronald Richman
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Jan and Dan Duncan Neurological Research Institute, Houston, Texas, USA
- Howard Hughes Medical Institute, Houston, Texas, USA
| | - Vitaliy V. Bondar
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Jan and Dan Duncan Neurological Research Institute, Houston, Texas, USA
| | - Elizabeth Alcala
- Exceptional Research Opportunities Program, Howard Hughes Medical Institute, Houston, Texas, USA
| | - Jean-Pierre Revelli
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Jan and Dan Duncan Neurological Research Institute, Houston, Texas, USA
| | - Harry T. Orr
- Institute for Translational Neuroscience, University of Minnesota, Minneapolis, Minnesota, USA
| | - Zhandong Liu
- Jan and Dan Duncan Neurological Research Institute, Houston, Texas, USA
- Department of Pediatrics-Neurology, and
| | - Juan Botas
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Jan and Dan Duncan Neurological Research Institute, Houston, Texas, USA
| | - Huda Y. Zoghbi
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Jan and Dan Duncan Neurological Research Institute, Houston, Texas, USA
- Department of Pediatrics-Neurology, and
- Howard Hughes Medical Institute, Houston, Texas, USA
| |
Collapse
|
2
|
Lee SH, Lee WK, Kim N, Kang JH, Kim KH, Kim SG, Lee JS, Lee S, Lee J, Joo J, Kwon WS, Rha SY, Kim SY. Renal Cell Carcinoma Is Abrogated by p53 Stabilization through Transglutaminase 2 Inhibition. Cancers (Basel) 2018; 10:cancers10110455. [PMID: 30463244 PMCID: PMC6267221 DOI: 10.3390/cancers10110455] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 11/08/2018] [Accepted: 11/14/2018] [Indexed: 02/07/2023] Open
Abstract
In general, expression of transglutaminase 2 (TGase 2) is upregulated in renal cell carcinoma (RCC), resulting in p53 instability. Previous studies show that TGase 2 binds to p53 and transports it to the autophagosome. Knockdown or inhibition of TGase 2 in RCC induces p53-mediated apoptosis. Here, we screened a chemical library for TGase 2 inhibitors and identified streptonigrin as a potential therapeutic compound for RCC. Surface plasmon resonance and mass spectroscopy were used to measure streptonigrin binding to TGase 2. Mass spectrometry analysis revealed that streptonigrin binds to the N-terminus of TGase 2 (amino acids 95–116), which is associated with inhibition of TGase 2 activity in vitro and with p53 stabilization in RCC. The anti-cancer effects of streptonigrin on RCC cell lines were demonstrated in cell proliferation and cell death assays. In addition, a single dose of streptonigrin (0.2 mg/kg) showed marked anti-tumor effects in a preclinical RCC model by stabilizing p53. Inhibition of TGase 2 using streptonigrin increased p53 stability, which resulted in p53-mediated apoptosis of RCC. Thus, targeting TGase 2 may be a new therapeutic approach to RCC.
Collapse
Affiliation(s)
- Seon-Hyeong Lee
- Tumor Microenvironment Research Branch, Division of Cancer Biology, National Cancer Center, Goyang, Gyeonggi-do 10408, Korea.
| | - Won-Kyu Lee
- Tumor Microenvironment Research Branch, Division of Cancer Biology, National Cancer Center, Goyang, Gyeonggi-do 10408, Korea.
- New Drug Development Center, Osong Medical Innovation Foundation, Cheongju, Chungbuk 28160, Korea.
| | - Nayeon Kim
- Tumor Microenvironment Research Branch, Division of Cancer Biology, National Cancer Center, Goyang, Gyeonggi-do 10408, Korea.
- Department of Chemistry, College of Science, Dongguk University, 30 Pildong-ro 2-gil, Jung-gu, Seoul 04620, Korea.
| | - Joon Hee Kang
- Tumor Microenvironment Research Branch, Division of Cancer Biology, National Cancer Center, Goyang, Gyeonggi-do 10408, Korea.
| | - Kyung-Hee Kim
- Omics Core Lab, National Cancer Center, Goyang, Gyeonggi-do 10408, Korea.
| | - Seul-Gi Kim
- Tumor Microenvironment Research Branch, Division of Cancer Biology, National Cancer Center, Goyang, Gyeonggi-do 10408, Korea.
| | - Jae-Seon Lee
- Tumor Microenvironment Research Branch, Division of Cancer Biology, National Cancer Center, Goyang, Gyeonggi-do 10408, Korea.
| | - Soohyun Lee
- Tumor Microenvironment Research Branch, Division of Cancer Biology, National Cancer Center, Goyang, Gyeonggi-do 10408, Korea.
| | - Jongkook Lee
- College of Pharmacy, Kangwon National University, Chuncheon, Gangwon-do 24341, Korea.
| | - Jungnam Joo
- Biometric Research Branch, Division of Cancer Epidemiology and Prevention, National Cancer Center, Goyang, Gyeonggi-do 10408, Korea.
| | - Woo Sun Kwon
- Songdang Institute for Cancer Research, Yonsei University College of Medicine, Seoul 03722, Korea.
| | - Sun Young Rha
- Songdang Institute for Cancer Research, Division of Medical Oncology, Department of Internal Medicine, Yonsei Cancer Center, Yonsei University College of Medicine, Seoul 03722, Korea.
| | - Soo-Youl Kim
- Tumor Microenvironment Research Branch, Division of Cancer Biology, National Cancer Center, Goyang, Gyeonggi-do 10408, Korea.
| |
Collapse
|
3
|
Wan L, Xu K, Chen Z, Tang B, Jiang H. Roles of Post-translational Modifications in Spinocerebellar Ataxias. Front Cell Neurosci 2018; 12:290. [PMID: 30283301 PMCID: PMC6156280 DOI: 10.3389/fncel.2018.00290] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2018] [Accepted: 08/13/2018] [Indexed: 12/17/2022] Open
Abstract
Post-translational modifications (PTMs), including phosphorylation, acetylation, ubiquitination, SUMOylation, etc., of proteins can modulate protein properties such as intracellular distribution, activity, stability, aggregation, and interactions. Therefore, PTMs are vital regulatory mechanisms for multiple cellular processes. Spinocerebellar ataxias (SCAs) are hereditary, heterogeneous, neurodegenerative diseases for which the primary manifestation involves ataxia. Because the pathogenesis of most SCAs is correlated with mutant proteins directly or indirectly, the PTMs of disease-related proteins might functionally affect SCA development and represent potential therapeutic interventions. Here, we review multiple PTMs related to disease-causing proteins in SCAs pathogenesis and their effects. Furthermore, we discuss these PTMs as potential targets for treating SCAs and describe translational therapies targeting PTMs that have been published.
Collapse
Affiliation(s)
- Linlin Wan
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Keqin Xu
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Zhao Chen
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Beisha Tang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
- National Clinical Research Center for Geriatric Diseases, Central South University, Changsha, China
- Key Laboratory of Hunan Province in Neurodegenerative Disorders, Central South University, Changsha, China
- Laboratory of Medical Genetics, Central South University, Changsha, China
- Parkinson’s Disease Center of Beijing Institute for Brain Disorders, Beijing, China
- Collaborative Innovation Center for Brain Science, Shanghai, China
- Collaborative Innovation Center for Genetics and Development, Shanghai, China
| | - Hong Jiang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
- National Clinical Research Center for Geriatric Diseases, Central South University, Changsha, China
- Key Laboratory of Hunan Province in Neurodegenerative Disorders, Central South University, Changsha, China
- Laboratory of Medical Genetics, Central South University, Changsha, China
- Department of Neurology, Xinjiang Medical University, Ürümqi, China
| |
Collapse
|
4
|
Haddock CJ, Blomenkamp K, Gautam M, James J, Mielcarska J, Gogol E, Teckman J, Skowyra D. PiZ mouse liver accumulates polyubiquitin conjugates that associate with catalytically active 26S proteasomes. PLoS One 2014; 9:e106371. [PMID: 25210780 PMCID: PMC4161314 DOI: 10.1371/journal.pone.0106371] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2014] [Accepted: 07/29/2014] [Indexed: 11/19/2022] Open
Abstract
Accumulation of aggregation-prone human alpha 1 antitrypsin mutant Z (AT-Z) protein in PiZ mouse liver stimulates features of liver injury typical of human alpha 1 antitrypsin type ZZ deficiency, an autosomal recessive genetic disorder. Ubiquitin-mediated proteolysis by the 26S proteasome counteracts AT-Z accumulation and plays other roles that, when inhibited, could exacerbate the injury. However, it is unknown how the conditions of AT-Z mediated liver injury affect the 26S proteasome. To address this question, we developed a rapid extraction strategy that preserves polyubiquitin conjugates in the presence of catalytically active 26S proteasomes and allows their separation from deposits of insoluble AT-Z. Compared to WT, PiZ extracts had about 4-fold more polyubiquitin conjugates with no apparent change in the levels of the 26S and 20S proteasomes, and unassembled subunits. The polyubiquitin conjugates had similar affinities to ubiquitin-binding domain of Psmd4 and co-purified with similar amounts of catalytically active 26S complexes. These data show that polyubiquitin conjugates were accumulating despite normal recruitment to catalytically active 26S proteasomes that were available in excess, and suggest that a defect at the 26S proteasome other than compromised binding to polyubiquitin chain or peptidase activity played a role in the accumulation. In support of this idea, PiZ extracts were characterized by high molecular weight, reduction-sensitive forms of selected subunits, including ATPase subunits that unfold substrates and regulate access to proteolytic core. Older WT mice acquired similar alterations, implying that they result from common aspects of oxidative stress. The changes were most pronounced on unassembled subunits, but some subunits were altered even in the 26S proteasomes co-purified with polyubiquitin conjugates. Thus, AT-Z protein aggregates indirectly impair degradation of polyubiquitinated proteins at the level of the 26S proteasome, possibly by inducing oxidative stress-mediated modifications that compromise substrate delivery to proteolytic core.
Collapse
Affiliation(s)
- Christopher J. Haddock
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
| | - Keith Blomenkamp
- Department of Pediatrics, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
| | - Madhav Gautam
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
| | - Jared James
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
| | - Joanna Mielcarska
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
| | - Edward Gogol
- School of Biological Sciences, University of Missouri – Kansas City, Kansas City, Missouri, United States of America
| | - Jeffrey Teckman
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
- Department of Pediatrics, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
| | - Dorota Skowyra
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
| |
Collapse
|
5
|
Dantuma NP, Bott LC. The ubiquitin-proteasome system in neurodegenerative diseases: precipitating factor, yet part of the solution. Front Mol Neurosci 2014; 7:70. [PMID: 25132814 PMCID: PMC4117186 DOI: 10.3389/fnmol.2014.00070] [Citation(s) in RCA: 213] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2014] [Accepted: 07/09/2014] [Indexed: 01/17/2023] Open
Abstract
The ubiquitin-proteasome system (UPS) has been implicated in neurodegenerative diseases based on the presence of deposits consisting of ubiquitylated proteins in affected neurons. It has been postulated that aggregation-prone proteins associated with these disorders, such as α-synuclein, β-amyloid peptide, and polyglutamine proteins, compromise UPS function, and delay the degradation of other proteasome substrates. Many of these substrates play important regulatory roles in signaling, cell cycle progression, or apoptosis, and their inadvertent stabilization due to an overloaded and improperly functioning UPS may thus be responsible for cellular demise in neurodegeneration. Over the past decade, numerous studies have addressed the UPS dysfunction hypothesis using various model systems and techniques that differ in their readout and sensitivity. While an inhibitory effect of some disease proteins on the UPS has been demonstrated, increasing evidence attests that the UPS remains operative in many disease models, which opens new possibilities for treatment. In this review, we will discuss the paradigm shift that repositioned the UPS from being a prime suspect in the pathophysiology of neurodegeneration to an attractive therapeutic target that can be harnessed to accelerate the clearance of disease-linked proteins.
Collapse
Affiliation(s)
- Nico P Dantuma
- Department of Cell and Molecular Biology, Karolinska Institutet Stockholm, Sweden
| | - Laura C Bott
- Department of Cell and Molecular Biology, Karolinska Institutet Stockholm, Sweden ; Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health Bethesda, MD, USA
| |
Collapse
|
6
|
Beyond the glutamine expansion: influence of posttranslational modifications of ataxin-1 in the pathogenesis of spinocerebellar ataxia type 1. Mol Neurobiol 2014; 50:866-874. [PMID: 24752589 DOI: 10.1007/s12035-014-8703-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Accepted: 03/31/2014] [Indexed: 01/05/2023]
Abstract
Posttranslational modifications are crucial mechanisms that modulate various cellular signaling pathways, and their dysregulation is associated with many human diseases. Spinocerebellar ataxia type 1 (SCA1) is a dominantly inherited neurodegenerative disease characterized by progressive ataxia, mild cognitive impairments, difficulty with speaking and swallowing, and respiratory failure. It is caused by the expansion of an unstable CAG trinucleotide repeat encoding a glutamine tract in Ataxin-1 (ATXN1). Although the expansion of the polyglutamine tract is the key determinant of the disease, protein domains outside of the polyglutamine tract and posttranslational modifications of ATXN1 significantly alter the neurotoxicity of SCA1. ATXN1 undergoes several posttranslational modifications, including phosphorylation, ubiquitination, sumoylation, and transglutamination. Such modifications can alter the stability of ATXN1 or its activity in the regulation of target gene expression and therefore contribute to SCA1 toxicity. This review outlines different types of posttranslational modifications in ATXN1 and discusses their potential regulatory mechanisms and effects on SCA1 pathogenesis. Finally, the manipulation of posttranslational modifications as a potential therapeutic approach will be discussed.
Collapse
|
7
|
Odii BO, Coussons P. Biological functionalities of transglutaminase 2 and the possibility of its compensation by other members of the transglutaminase family. ScientificWorldJournal 2014; 2014:714561. [PMID: 24778599 PMCID: PMC3981525 DOI: 10.1155/2014/714561] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Accepted: 10/30/2013] [Indexed: 02/01/2023] Open
Abstract
Transglutaminase 2 (TG2) is the most widely distributed and most abundantly expressed member of the transglutaminase family of enzymes, a group of intracellular and extracellular proteins that catalyze the Ca²⁺-dependent posttranslational modification of proteins. It is a unique member of the transglutaminase family owing to its specialized biochemical, structural and functional elements, ubiquitous tissue distribution and subcellular localization, and substrate specificity. The broad substrate specificity of TG2 and its flexible interaction with numerous other gene products may account for its multiple biological functions. In addition to the classic Ca²⁺-dependent transamidation of proteins, which is a hallmark of transglutaminase enzymes, additional Ca²⁺-independent enzymatic and nonenzymatic activities of TG2 have been identified. Many such activities have been directly or indirectly implicated in diverse cellular physiological events, including cell growth and differentiation, cell adhesion and morphology, extracellular matrix stabilization, wound healing, cellular development, receptor-mediated endocytosis, apoptosis, and disease pathology. Given the wide range of activities of the transglutaminase gene family it has been suggested that, in the absence of active versions of TG2, its function could be compensated for by other members of the transglutaminase family. It is in the light of this assertion that we review, herein, TG2 activities and the possibilities and premises for compensation for its absence.
Collapse
Affiliation(s)
- Benedict Onyekachi Odii
- Biomedical Research Group, Department of Life Sciences, Faculty of Science & Technology, Anglia Ruskin University, East Road, Cambridge, CB1 1PT, UK
| | - Peter Coussons
- Biomedical Research Group, Department of Life Sciences, Faculty of Science & Technology, Anglia Ruskin University, East Road, Cambridge, CB1 1PT, UK
| |
Collapse
|
8
|
Chua JP, Reddy SL, Merry DE, Adachi H, Katsuno M, Sobue G, Robins DM, Lieberman AP. Transcriptional activation of TFEB/ZKSCAN3 target genes underlies enhanced autophagy in spinobulbar muscular atrophy. Hum Mol Genet 2013; 23:1376-86. [PMID: 24150846 DOI: 10.1093/hmg/ddt527] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Spinobulbar muscular atrophy (SBMA) is an inherited neuromuscular disorder caused by the expansion of a CAG repeat encoding a polyglutamine tract in exon 1 of the androgen receptor (AR) gene. SBMA demonstrates androgen-dependent toxicity due to unfolding and aggregation of the mutant protein. There are currently no disease-modifying therapies, but of increasing interest for therapeutic targeting is autophagy, a highly conserved cellular process mediating protein quality control. We have previously shown that genetic manipulations inhibiting autophagy diminish skeletal muscle atrophy and extend the lifespan of AR113Q knock-in mice. In contrast, manipulations inducing autophagy worsen muscle atrophy, suggesting that chronic, aberrant upregulation of autophagy contributes to pathogenesis. Since the degree to which autophagy is altered in SBMA and the mechanisms responsible for such alterations are incompletely defined, we sought to delineate autophagic status in SBMA using both cellular and mouse models. Here, we confirm that autophagy is induced in cellular and knock-in mouse models of SBMA and show that the transcription factors transcription factor EB (TFEB) and ZKSCAN3 operate in opposing roles to underlie these changes. We demonstrate upregulation of TFEB target genes in skeletal muscle from AR113Q male mice and SBMA patients. Furthermore, we observe a greater response in AR113Q mice to physiological stimulation of autophagy by both nutrient starvation and exercise. Taken together, our results indicate that transcriptional signaling contributes to autophagic dysregulation and provides a mechanistic framework for the pathologic increase of autophagic responsiveness in SBMA.
Collapse
|
9
|
Beitel LK, Alvarado C, Mokhtar S, Paliouras M, Trifiro M. Mechanisms mediating spinal and bulbar muscular atrophy: investigations into polyglutamine-expanded androgen receptor function and dysfunction. Front Neurol 2013; 4:53. [PMID: 23720649 PMCID: PMC3654311 DOI: 10.3389/fneur.2013.00053] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2013] [Accepted: 04/26/2013] [Indexed: 11/13/2022] Open
Abstract
Spinal and bulbar muscular atrophy (SBMA, Kennedy’s disease), a late-onset neuromuscular disorder, is caused by expansion of the polymorphic polyglutamine tract in the androgen receptor (AR). The AR is a ligand-activated transcription factor, but plays roles in other cellular pathways. In SBMA, selective motor neuron degeneration occurs in the brainstem and spinal cord, thus the causes of neuronal dysfunction have been studied. However, pathogenic pathways in muscles may also be involved. Cultured cells, fly and mouse models are used to study the molecular mechanisms leading to SBMA. Both the structure of the polyglutamine-expanded AR (polyQ AR) and its interactions with other proteins are altered relative to the normal AR. The ligand-dependent translocation of the polyQ AR to the nucleus appears to be critical, as are interdomain interactions. The polyQ AR, or fragments thereof, can form nuclear inclusions, but their pathogenic or protective nature is unclear. Other data suggests soluble polyQ AR oligomers can be harmful. Post-translational modifications such as phosphorylation, acetylation, and ubiquitination influence AR function and modulate the deleterious effects of the polyQ AR. Transcriptional dysregulation is highly likely to be a factor in SBMA; deregulation of non-genomic AR signaling may also be involved. Studies on polyQ AR-protein degradation suggest inhibition of the ubiquitin proteasome system and changes to autophagic pathways may be relevant. Mitochondrial function and axonal transport may also be affected by the polyQ AR. Androgens, acting through the AR, can be neurotrophic and are important in muscle development; hence both loss of normal AR functions and gain of novel harmful functions by the polyQ AR can contribute to neurodegeneration and muscular atrophy. Thus investigations into polyQ AR function have shown that multiple complex mechanisms lead to the initiation and progression of SBMA.
Collapse
Affiliation(s)
- Lenore K Beitel
- Lady Davis Institute for Medical Research, Jewish General Hospital Montreal, QC, Canada ; Department of Medicine, McGill University Montreal, QC, Canada ; Department of Human Genetics, McGill University Montreal, QC, Canada
| | | | | | | | | |
Collapse
|
10
|
Hipp MS, Patel CN, Bersuker K, Riley BE, Kaiser SE, Shaler TA, Brandeis M, Kopito RR. Indirect inhibition of 26S proteasome activity in a cellular model of Huntington's disease. J Cell Biol 2012; 196:573-87. [PMID: 22371559 PMCID: PMC3307690 DOI: 10.1083/jcb.201110093] [Citation(s) in RCA: 124] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Pathognomonic accumulation of ubiquitin (Ub) conjugates in human neurodegenerative diseases, such as Huntington's disease, suggests that highly aggregated proteins interfere with 26S proteasome activity. In this paper, we examine possible mechanisms by which an N-terminal fragment of mutant huntingtin (htt; N-htt) inhibits 26S function. We show that ubiquitinated N-htt-whether aggregated or not-did not choke or clog the proteasome. Both Ub-dependent and Ub-independent proteasome reporters accumulated when the concentration of mutant N-htt exceeded a solubility threshold, indicating that stabilization of 26S substrates is not linked to impaired Ub conjugation. Above this solubility threshold, mutant N-htt was rapidly recruited to cytoplasmic inclusions that were initially devoid of Ub. Although synthetically polyubiquitinated N-htt competed with other Ub conjugates for access to the proteasome, the vast majority of mutant N-htt in cells was not Ub conjugated. Our data confirm that proteasomes are not directly impaired by aggregated N-terminal fragments of htt; instead, our data suggest that Ub accumulation is linked to impaired function of the cellular proteostasis network.
Collapse
Affiliation(s)
- Mark S Hipp
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | | | | | | | | | | | | | | |
Collapse
|
11
|
Kuo TF, Tatsukawa H, Kojima S. New insights into the functions and localization of nuclear transglutaminase 2. FEBS J 2011; 278:4756-67. [PMID: 22051117 DOI: 10.1111/j.1742-4658.2011.08409.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Transglutaminase 2 (TG2; EC 2.3.2.13) is the most abundantly expressed member of the transglutaminase family and exerts opposing effects on cell growth, differentiation and apoptosis via multiple activities, including transamidase, GTPase, cell adhesion, protein disulfide isomerase, kinase and scaffold activities. It is distributed in and around various parts of a cell, including the extracellular matrix, plasma membrane, cytosol, mitochondria and nucleus. Generally, nuclear TG2 represents only 5-7% of the total TG2 in a cell, and various stimuli will increase nuclear TG2 via cellular stress and/or an increased intracellular Ca(2+) concentration. There is increasing evidence indicating the importance of nuclear TG2 in regulating gene expression via post-translational modification of (or interaction with) transcriptional factors and related proteins. These include E2F1, hypoxia inducible factor 1, Sp1 and histones. Through this mechanism, TG2 controls cell growth or survival, differentiation and apoptosis, and is involved in the pathogenesis and/or treatment of neurodegenerative diseases, liver diseases and cancers. The balance between import from the cytoplasm to the nucleus, and export from the nucleus to the cytoplasm, determines the level of TG2 in the nucleus. Selective regulation of the expression, activity or localization of nuclear TG2 will be important for basic research, as well as clinical applications, suggesting a new era for this long-studied enzyme.
Collapse
Affiliation(s)
- Ting-Fang Kuo
- Chemical Biology Department, RIKEN Advanced Science Institute, Wako, Saitama, Japan
| | | | | |
Collapse
|
12
|
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
| | | | | | | |
Collapse
|
13
|
Microarray analysis of gene expression by skeletal muscle of three mouse models of Kennedy disease/spinal bulbar muscular atrophy. PLoS One 2010; 5:e12922. [PMID: 20886071 PMCID: PMC2944863 DOI: 10.1371/journal.pone.0012922] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2010] [Accepted: 09/01/2010] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Emerging evidence implicates altered gene expression within skeletal muscle in the pathogenesis of Kennedy disease/spinal bulbar muscular atrophy (KD/SBMA). We therefore broadly characterized gene expression in skeletal muscle of three independently generated mouse models of this disease. The mouse models included a polyglutamine expanded (polyQ) AR knock-in model (AR113Q), a polyQ AR transgenic model (AR97Q), and a transgenic mouse that overexpresses wild type AR solely in skeletal muscle (HSA-AR). HSA-AR mice were included because they substantially reproduce the KD/SBMA phenotype despite the absence of polyQ AR. METHODOLOGY/PRINCIPAL FINDINGS We performed microarray analysis of lower hindlimb muscles taken from these three models relative to wild type controls using high density oligonucleotide arrays. All microarray comparisons were made with at least 3 animals in each condition, and only those genes having at least 2-fold difference and whose coefficient of variance was less than 100% were considered to be differentially expressed. When considered globally, there was a similar overlap in gene changes between the 3 models: 19% between HSA-AR and AR97Q, 21% between AR97Q and AR113Q, and 17% between HSA-AR and AR113Q, with 8% shared by all models. Several patterns of gene expression relevant to the disease process were observed. Notably, patterns of gene expression typical of loss of AR function were observed in all three models, as were alterations in genes involved in cell adhesion, energy balance, muscle atrophy and myogenesis. We additionally measured changes similar to those observed in skeletal muscle of a mouse model of Huntington's Disease, and to those common to muscle atrophy from diverse causes. CONCLUSIONS/SIGNIFICANCE By comparing patterns of gene expression in three independent models of KD/SBMA, we have been able to identify candidate genes that might mediate the core myogenic features of KD/SBMA.
Collapse
|
14
|
TG2 protects neuroblastoma cells against DNA-damage-induced stress, suppresses p53 activation. Amino Acids 2010; 39:523-32. [PMID: 20112034 DOI: 10.1007/s00726-009-0468-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2009] [Accepted: 12/26/2009] [Indexed: 12/11/2022]
Abstract
Tissue transglutaminase (TG2) is a multifunctional member of the transglutaminase (TGase) family (E.C.2.3.2.13), which catalyzes in a calcium-dependent reaction the formation of covalent bonds between the gamma-carboxamide groups of peptide-bound glutamine residues and various primary amines. Here, we investigated the role of TG2 in a response of the neuroblastoma SH-SY5Y cells to topoisomerase II inhibitor etoposide, known to trigger DNA-damage cell response. We found an early and transient (approximately 2 h) increase of the TG2 protein in SH-SY5Y cells treated with etoposide, along with the increase of phosphorylated and total levels of the p53 protein. Next, we showed that SH-SY5Y cells, which overexpress wild-type TG2 were significantly protected against etoposide-induced cell death. The TG2 protective effect was associated only with the transamidation active form of TG2, because overexpression the wild-type TG2, but not its transamidation inactive C277S form, resulted in a pronounced suppression of caspase-3 activity as well as p53 phosphorylation during the etoposide-induced stress. In addition, exacerbation of cell death with a significant increase in caspase-3 and p53 activation was observed in SH/anti-TG2 cells, in which expression of the endogenous TG2 protein has been greatly reduced by the antisense cDNA construct. Though the cell signaling and molecular mechanisms of the TG2-driven suppression of the cell death machinery remain to be investigated, our findings strongly suggest that TG2 plays an active role in the response of neuroblastoma cells to DNA-damage-induced stress by exerting a strong protective effect, likely by the suppression of p53 activation and p53-driven cell signaling events.
Collapse
|
15
|
Jeitner TM, Muma NA, Battaile KP, Cooper AJ. Transglutaminase activation in neurodegenerative diseases. FUTURE NEUROLOGY 2009; 4:449-467. [PMID: 20161049 DOI: 10.2217/fnl.09.17] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The following review examines the role of calcium in promoting the in vitro and in vivo activation of transglutaminases in neurodegenerative disorders. Diseases such as Alzheimer's disease, Parkinson's disease and Huntington's disease exhibit increased transglutaminase activity and rises in intracellular calcium concentrations, which may be related. The aberrant activation of transglutaminase by calcium is thought to give rise to a variety of pathological moieties in these diseases, and the inhibition has been shown to have therapeutic benefit in animal and cellular models of neurodegeneration. Given the potential clinical relevance of transglutaminase inhibitors, we have also reviewed the recent development of such compounds.
Collapse
Affiliation(s)
- Thomas M Jeitner
- Applied Bench Core, Winthrop University Hospital, 222 Station Plaza North, Suite 502, Mineola, NY 11501, USA Tel.: +1 516 663 3455
| | | | | | | |
Collapse
|
16
|
Schwartz AL, Ciechanover A. Targeting proteins for destruction by the ubiquitin system: implications for human pathobiology. Annu Rev Pharmacol Toxicol 2009; 49:73-96. [PMID: 18834306 DOI: 10.1146/annurev.pharmtox.051208.165340] [Citation(s) in RCA: 342] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cellular proteins are in a dynamic state maintained by synthesis and degradation. The ubiquitin proteolytic pathway is responsible for the degradation of the bulk of cellular proteins including short-lived, regulatory, and misfolded/denatured proteins. Ubiquitin-mediated proteolysis involves covalent attachment of multiple ubiquitin molecules to the protein substrate and degradation of the targeted protein by the 26S proteasome. Recent understanding of the molecular mechanisms involved provides a framework to understand a wide variety of human pathophysiological states as well as therapeutic interventions. This review focuses on the response to hypoxia, inflammatory diseases, neurodegenerative diseases, and muscle-wasting disorders, as well as human papillomaviruses, cervical cancer and other malignancies.
Collapse
Affiliation(s)
- Alan L Schwartz
- Department of Pediatrics, Washington University School of Medicine and St. Louis Children's Hospital, St. Louis, Missouri 63110, USA.
| | | |
Collapse
|
17
|
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.
Collapse
Affiliation(s)
- Maria Pennuto
- Department of Neurology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
| | | | | |
Collapse
|
18
|
Transglutaminases and their substrates in biology and human diseases: 50 years of growing. Amino Acids 2008; 36:599-614. [DOI: 10.1007/s00726-008-0124-8] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2008] [Accepted: 05/15/2008] [Indexed: 12/19/2022]
|
19
|
Monks DA, Rao P, Mo K, Johansen JA, Lewis G, Kemp MQ. Androgen receptor and Kennedy disease/spinal bulbar muscular atrophy. Horm Behav 2008; 53:729-40. [PMID: 18321505 PMCID: PMC2883265 DOI: 10.1016/j.yhbeh.2007.12.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2007] [Revised: 12/13/2007] [Accepted: 12/13/2007] [Indexed: 02/06/2023]
Abstract
Kennedy Disease/Spinal Bulbar Muscular Atrophy (KD/SBMA) is a progressive neurodegenerative disease caused by genetic polyglutamine expansion of the androgen receptor. We have recently found that overexpression of wildtype androgen receptor in skeletal muscle of transgenic mice results in a KD/SBMA phenotype. This surprising result challenges the orthodox view that KD/SBMA requires expression of polyglutamine expanded androgen receptor within motoneurons. Theories relating to the etiology of this disease drawn from studies of human patients, cellular and mouse models are considered with a special emphasis on potential myogenic contributions to as well as the molecular etiology of KD/SBMA.
Collapse
Affiliation(s)
- Douglas Ashley Monks
- Department of Psychology, University of Toronto at Mississauga, 3359 Mississauga Road, Mississauga, Ontario, Canada L5L 1C6.
| | | | | | | | | | | |
Collapse
|
20
|
Zatloukal K, French SW, Stumptner C, Strnad P, Harada M, Toivola DM, Cadrin M, Omary MB. From Mallory to Mallory–Denk bodies: What, how and why? Exp Cell Res 2007; 313:2033-49. [PMID: 17531973 DOI: 10.1016/j.yexcr.2007.04.024] [Citation(s) in RCA: 235] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2007] [Revised: 04/02/2007] [Accepted: 04/03/2007] [Indexed: 12/16/2022]
Abstract
Frank B. Mallory described cytoplasmic hyaline inclusions in hepatocytes of patients with alcoholic hepatitis in 1911. These inclusions became known as Mallory bodies (MBs) and have since been associated with a variety of other liver diseases including non-alcoholic fatty liver disease. Helmut Denk and colleagues described the first animal model of MBs in 1975 that involves feeding mice griseofulvin. Since then, mouse models have been instrumental in helping understand the pathogenesis of MBs. Given the tremendous contributions made by Denk to the field, we propose renaming MBs as Mallory-Denk bodies (MDBs). The major constituents of MDBs include keratins 8 and 18 (K8/18), ubiquitin, and p62. The relevant proteins and cellular processes that contribute to MDB formation and accumulation include the type of chronic stress, the extent of stress-induced protein misfolding and consequent proteasome overload, a K8-greater-than-K18 ratio, transamidation of K8 and other proteins, presence of p62 and autophagy. Although it remains unclear whether MDBs serve a bystander, protective or injury promoting function, they do serve an important role as histological and potential progression markers in several liver diseases.
Collapse
Affiliation(s)
- Kurt Zatloukal
- Institute of Pathology, Medical University of Graz, Auenbruggerplatz 25, A-8036 Graz, Austria
| | | | | | | | | | | | | | | |
Collapse
|
21
|
Yang Z, Chang YJ, Yu IC, Yeh S, Wu CC, Miyamoto H, Merry DE, Sobue G, Chen LM, Chang SS, Chang C. ASC-J9 ameliorates spinal and bulbar muscular atrophy phenotype via degradation of androgen receptor. Nat Med 2007; 13:348-53. [PMID: 17334372 DOI: 10.1038/nm1547] [Citation(s) in RCA: 130] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2006] [Accepted: 01/16/2007] [Indexed: 12/21/2022]
Abstract
Motor neuron degeneration resulting from the aggregation of the androgen receptor with an expanded polyglutamine tract (AR-polyQ) has been linked to the development of spinal and bulbar muscular atrophy (SBMA or Kennedy disease). Here we report that adding 5-hydroxy-1,7-bis(3,4-dimethoxyphenyl)-1,4,6-heptatrien-3-one (ASC-J9) disrupts the interaction between AR and its coregulators, and also increases cell survival by decreasing AR-polyQ nuclear aggregation and increasing AR-polyQ degradation in cultured cells. Intraperitoneal injection of ASC-J9 into AR-polyQ transgenic SBMA mice markedly improved disease symptoms, as seen by a reduction in muscular atrophy. Notably, unlike previous approaches in which surgical or chemical castration was used to reduce SBMA symptoms, ASC-J9 treatment ameliorated SBMA symptoms by decreasing AR-97Q aggregation and increasing VEGF164 expression with little change of serum testosterone. Moreover, mice treated with ASC-J9 retained normal sexual function and fertility. Collectively, our results point to a better therapeutic and preventative approach to treating SBMA, by disrupting the interaction between AR and AR coregulators.
Collapse
Affiliation(s)
- Zhiming Yang
- George Whipple Lab for Cancer Research, Departments of Pathology, Urology, and Radiation Oncology, and The Cancer Center, University of Rochester Medical Center, Rochester, New York 14642, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
22
|
Abstract
Regulated turnover of proteins in the cytosol and nucleus of eukaryotic cells is primarily performed by the ubiquitin–proteasome system (UPS). The UPS is involved in many essential cellular processes. Alterations in this proteolytic system are associated with a variety of human pathologies, such as neurodegenerative diseases, cancer, immunological disorders and inflammation. The precise role of the UPS in the pathophysiology of these diseases, however, remains poorly understood. Detection of UPS aberrations has been a major challenge because of the complexity of the system. Most studies focus on various aspects of the UPS, such as substrate recognition, ubiquitination, deubiquitination or proteasome activity, and do not provide a complete picture of the UPS as an integral system. To monitor the efficacy of the UPS, a number of reporter substrates have been developed based on fluorescent proteins, such as the green fluorescent protein and its spectral variants. These fluorescent UPS reporters contain specific degradation signals that target them with high efficiency and accuracy for proteasomal degradation. Several studies have shown that these reporters can probe the functionality of the UPS in cellular and animal models and provide us with important information on the status of the UPS under various conditions. Moreover, these reporters can aid the identification and development of novel anti-cancer and anti-inflammatory drugs based on UPS inhibition.
Collapse
|
23
|
Kim SY, Marekov L, Bubber P, Browne SE, Stavrovskaya I, Lee J, Steinert PM, Blass JP, Beal MF, Gibson GE, Cooper AJL. Mitochondrial Aconitase is a Transglutaminase 2 Substrate: Transglutamination is a Probable Mechanism Contributing to High-Molecular-Weight Aggregates of Aconitase and Loss of Aconitase Activity in Huntington Disease Brain. Neurochem Res 2005; 30:1245-55. [PMID: 16341586 DOI: 10.1007/s11064-005-8796-x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/10/2005] [Indexed: 10/25/2022]
Abstract
Transglutaminase activity was found to be present in highly purified non-synaptosomal rat brain mitochondria. A 78-kDa protein in these organelles was shown to be a transglutaminase 2 substrate, and incubation of a non-synaptosomal mitochondrial lysate with transglutaminase 2 yielded high-Mr proteins. The 78-kDa protein was identified as mitochondrial aconitase by MALDI-TOF analysis. Aconitase activity was decreased in a dose-dependent manner when non-synaptosomal rat brain mitochondria were incubated with transglutaminase 2. Transglutaminase activity is increased about 2-fold in the mitochondrial fraction of HD caudate. Moreover, Western blotting of the mitochondrial fraction revealed that most of the mitochondrial aconitase in HD caudate is present as high-Mr aggregates. Aconitase activity was previously shown to be decreased in Huntington disease (HD) caudate (a region severely damaged by the disease). The present findings suggest that an increase of transglutaminase activity in HD caudate may contribute to mitochondrial dysfunction by incorporating aconitase into inactive polymers.
Collapse
Affiliation(s)
- Soo-Youl Kim
- Department of Neurology and Neuroscience, Weill Medical College of Cornell University, New York, NY 10021, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
24
|
Pinto JT, Van Raamsdonk JM, Leavitt BR, Hayden MR, Jeitner TM, Thaler HT, Krasnikov BF, Cooper AJL. Treatment of YAC128 mice and their wild-type littermates with cystamine does not lead to its accumulation in plasma or brain: implications for the treatment of Huntington disease. J Neurochem 2005; 94:1087-101. [PMID: 15992377 DOI: 10.1111/j.1471-4159.2005.03255.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cystamine is beneficial to Huntington disease (HD) transgenic mice. To elucidate the mechanism, cystamine metabolites were determined in brain and plasma of cystamine-treated mice. A major route for cystamine metabolism is thought to be: cystamine --> cysteamine --> hypotaurine --> taurine. Here we describe an HPLC system with coulometric detection that can rapidly measure underivatized cystamine, cysteamine and hypotaurine, as well as cysteine and glutathione in the same deproteinized tissue sample. A method is also described for the coulometric estimation of taurine as its isoindole-sulfonate derivative. Using this new methodology we showed that cystamine and cysteamine are undetectable (< or = 0.2 nmol/100 mg protein) in the brains of 3-month-old HD transgenic (YAC128) mice (or their wild-type littermates) treated daily for 2 weeks with cystamine (225 mg/kg) in their drinking water. No significant changes were observed in brain glutathione and taurine but significant increases were observed in brain cysteine. Cystamine and cysteamine were not detected in the plasma of YAC128 mice treated daily with cystamine between the ages of 4 and 12 or 7 and 12 months. These findings suggest that cystamine is not directly involved in mitigating HD but that increased brain cysteine or uncharacterized sulfur metabolites may be responsible.
Collapse
Affiliation(s)
- John T Pinto
- Burke Medical Research Institute, White Plains, New York, New York 10605, USA
| | | | | | | | | | | | | | | |
Collapse
|
25
|
Beitel LK, Scanlon T, Gottlieb B, Trifiro MA. Progress in Spinobulbar muscular atrophy research: insights into neuronal dysfunction caused by the polyglutamine-expanded androgen receptor. Neurotox Res 2005; 7:219-30. [PMID: 15897156 DOI: 10.1007/bf03036451] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Spinobulbar muscular atrophy (SBMA, Kennedy's disease) results from the dysfunction and degeneration of specific motor and sensory neurons. The underlying cause of this ligand-dependent neurodegenerative disease is expansion of the CAG trinucleotide repeat in the androgen receptor (AR) gene which leads to lengthening of the polyglutamine tract in the AR protein. Recently, the effects of the polyglutamine-expanded AR have been explored in a number of cellular and animal models. Common themes include research on polyglutamine-containing nuclear inclusions and the effect of molecular chaperone overexpression on their formation. In addition, investigations have highlighted the role that abnormal transcriptional regulation, proteasome dysfunction and altered axonal transport may play in disease pathogenesis. These studies suggest a number of potential treatments for restoring neuronal function. One of the most interesting advances in SBMA research has been the creation of mouse models that recapitulate the key features of SBMA progression in men. Lowering testosterone levels in affected transgenic male mice rescued, and even reversed the polyglutamine-induced neuromuscular phenotype, indicating that manipulating androgen levels in men could be of therapeutic benefit. Although the question of why only a distinct subset of neurons is affected by polyglutamine expansion of the AR remains unsolved, future research will provide further insights into the mechanisms contributing to disease progression in SBMA.
Collapse
Affiliation(s)
- L K Beitel
- Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, QC, H3T 1E2, Canada.
| | | | | | | |
Collapse
|
26
|
Abstract
Kennedy's disease, also known as spinal and bulbar muscular atrophy, is a progressive degenerative condition affecting lower motor neurons. It is one of nine neurodegenerative disorders caused by a polyglutamine repeat expansion. Affecting only men, Kennedy's disease is the only one of these conditions that follows an X-linked mode of inheritance. The causative protein in Kennedy's disease, with a polyglutamine expansion residing in the first N-terminal domain, is the androgen receptor. Research in this field has made significant advances in recent years, and with the increased understanding of pathogenic mechanisms, feasible approaches to treatments are being investigated. In Kennedy's disease research, the most significant issue to emerge recently is the role of androgens in exacerbating the disease process. On the basis of animal experiments, a viable hypothesis is that higher circulating levels of androgens in men could trigger the degeneration of motor neurons causing this disease, and that lower levels in heterozygous and homozygous women are protective. This is a major issue, as treatment of individuals affected by Kennedy's disease with testosterone has been considered a reasonable therapy by some neurologists. The rationale behind this approach relates to the fact that Kennedy's disease is accompanied by mild androgen insensitivity. It was therefore believed that treatment with high doses of testosterone might compensate for this loss of androgen action, with the added benefit of preventing muscle wasting. The current review provides an overview of recent advances in the field of Kennedy's disease research, including approaches to treatment.
Collapse
Affiliation(s)
- K J Greenland
- Centre for Hormone Research, Murdoch Childrens Research Institute, University of Melbourne, Royal Children's Hospital, Melbourne, Victoria, Australia
| | | |
Collapse
|
27
|
Abstract
The ubiquitin-proteasome system targets numerous cellular proteins for degradation. In addition, modifications by ubiquitin-like proteins as well as proteins containing ubiquitin-interacting and -associated motifs modulate many others. This tightly controlled process involves multiple specific and general enzymes of the system as well as many modifying and ancillary proteins. Thus, it is not surprising that ubiquitin-mediated degradation/processing/modification regulates a broad array of basic cellular processes. Moreover, aberrations in the system have been implicated, either as a primary cause or secondary consequence, in the pathogenesis of both inherited and acquired neurodegenerative diseases. Recent findings indicate that the system is involved in the pathogenesis of Parkinson's, Alzheimer's, Huntington's, and Prion diseases as well as amyotrophic lateral sclerosis. This raises hopes for a better understanding of the pathogenetic mechanisms involved in these diseases and for the development of novel, mechanism-based therapeutic modalities.
Collapse
Affiliation(s)
- Aaron Ciechanover
- Department of Biochemistry and The Rappaport Family Institute for Research in the Medical Sciences, The Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 31096, Israel.
| | | |
Collapse
|