1
|
Zimmern V, Minassian B. Progressive Myoclonus Epilepsy: A Scoping Review of Diagnostic, Phenotypic and Therapeutic Advances. Genes (Basel) 2024; 15:171. [PMID: 38397161 PMCID: PMC10888128 DOI: 10.3390/genes15020171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Revised: 01/23/2024] [Accepted: 01/26/2024] [Indexed: 02/25/2024] Open
Abstract
The progressive myoclonus epilepsies (PME) are a diverse group of disorders that feature both myoclonus and seizures that worsen gradually over a variable timeframe. While each of the disorders is individually rare, they collectively make up a non-trivial portion of the complex epilepsy and myoclonus cases that are seen in tertiary care centers. The last decade has seen substantial progress in our understanding of the pathophysiology, diagnosis, prognosis, and, in select disorders, therapies of these diseases. In this scoping review, we examine English language publications from the past decade that address diagnostic, phenotypic, and therapeutic advances in all PMEs. We then highlight the major lessons that have been learned and point out avenues for future investigation that seem promising.
Collapse
Affiliation(s)
- Vincent Zimmern
- Division of Child Neurology, University of Texas Southwestern, Dallas, TX 75390, USA;
| | | |
Collapse
|
2
|
Žerovnik E. Human stefin B: from its structure, folding, and aggregation to its function in health and disease. Front Mol Neurosci 2022; 15:1009976. [PMID: 36340691 PMCID: PMC9634419 DOI: 10.3389/fnmol.2022.1009976] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 09/01/2022] [Indexed: 01/11/2024] Open
Abstract
Mutations in the gene for human stefin B (cystatin B) cause progressive myoclonic epilepsy type 1 (EPM1), a neurodegenerative disorder. The most common change is dodecamer repeats in the promoter region of the gene, though missense and frameshift mutations also appear. Human stefin B primarily acts as a cysteine cathepsin inhibitor, and it also exhibits alternative functions. It plays a protective role against oxidative stress, likely via reducing mitochondrial damage and thus generating fewer mitochondrial reactive oxygen species (ROS). Accordingly, lack of stefin B results in increased inflammation and NLRP3 inflammasome activation, producing more ROS. The protein is cytosolic but also has an important role in the nucleus, where it prevents cleavage of the N terminal part of histone 3 by inhibiting cathepsins L and B and thus regulates transcription and cell cycle. Furthermore, it has been shown that stefin B is oligomeric in cells and that it has a specific role in the physiology of the synapse and in vesicular transport. On the basis of my research team's data on the structure, folding, and aggregation of stefin B, we have proposed that it might regulate proteostasis, possessing a chaperone-like function. In this review, I synthesize these observations and derive some conclusions on possible sources of EPM1 pathology. The interaction partners of stefin B and other gene mutations leading to EPM1-like pathology are discussed and common pathways are pinpointed.
Collapse
Affiliation(s)
- Eva Žerovnik
- Department of Biochemistry and Molecular and Structural Biology, Jožef Stefan Institute, Ljubljana, Slovenia
- Jožef Stefan International Postgraduate School, Ljubljana, Slovenia
| |
Collapse
|
3
|
Jahić Mujkić A, Tušek Žnidarič M, Berbić S, Žerovnik E. Synergy of the Inhibitory Action of Polyphenols Plus Vitamin C on Amyloid Fibril Formation: Case Study of Human Stefin B. Antioxidants (Basel) 2021; 10:1471. [PMID: 34573102 PMCID: PMC8464686 DOI: 10.3390/antiox10091471] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 09/10/2021] [Accepted: 09/13/2021] [Indexed: 12/06/2022] Open
Abstract
In order to study how polyphenols and vitamin C (vitC) together affect protein aggregation to amyloid fibrils, we performed similar in vitro studies as before using stefin B as a model and a potentially amyloid-forming protein (it aggregates upon overexpression, under stressful conditions and some progressive myoclonus epilepsy of tape 1-EPM1-missense mutations). In addition to the chosen polyphenol, this time, we added a proven antioxidant concentration of 0.5 mM vitC into the fibrillation mixture and varied concentrations of resveratrol, quercetin, and curcumin. Synergy with vitC was observed with curcumin and quercetin.
Collapse
Affiliation(s)
- Alma Jahić Mujkić
- Department of Biochemistry and Molecular and Structural Biology, Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
- Department of Biochemistry, Faculty of Pharmacy, University of Tuzla, Univerzitetska 1, 75000 Tuzla, Bosnia and Herzegovina; (A.J.M.); (S.B.)
| | - Magda Tušek Žnidarič
- Department of Biotechnology and Systems Biology, National Institute of Biology, Večna pot 111, 1000 Ljubljana, Slovenia;
| | - Selma Berbić
- Department of Biochemistry, Faculty of Pharmacy, University of Tuzla, Univerzitetska 1, 75000 Tuzla, Bosnia and Herzegovina; (A.J.M.); (S.B.)
| | - Eva Žerovnik
- Department of Biochemistry and Molecular and Structural Biology, Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
- Jožef Stefan International Postgraduate School, Jamova 39, 1000 Ljubljana, Slovenia
| |
Collapse
|
4
|
The effect of three polyphenols and some other antioxidant substances on amyloid fibril formation by Human cystatin C. Neurochem Int 2020; 140:104806. [DOI: 10.1016/j.neuint.2020.104806] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 05/26/2020] [Accepted: 07/07/2020] [Indexed: 01/24/2023]
|
5
|
mTOR-Related Cell-Clearing Systems in Epileptic Seizures, an Update. Int J Mol Sci 2020; 21:ijms21051642. [PMID: 32121250 PMCID: PMC7084443 DOI: 10.3390/ijms21051642] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 02/25/2020] [Accepted: 02/26/2020] [Indexed: 02/06/2023] Open
Abstract
Recent evidence suggests that autophagy impairment is implicated in the epileptogenic mechanisms downstream of mTOR hyperactivation. This holds true for a variety of genetic and acquired epileptic syndromes besides malformations of cortical development which are classically known as mTORopathies. Autophagy suppression is sufficient to induce epilepsy in experimental models, while rescuing autophagy prevents epileptogenesis, improves behavioral alterations, and provides neuroprotection in seizure-induced neuronal damage. The implication of autophagy in epileptogenesis and maturation phenomena related to seizure activity is supported by evidence indicating that autophagy is involved in the molecular mechanisms which are implicated in epilepsy. In general, mTOR-dependent autophagy regulates the proliferation and migration of inter-/neuronal cortical progenitors, synapse development, vesicular release, synaptic plasticity, and importantly, synaptic clustering of GABAA receptors and subsequent excitatory/inhibitory balance in the brain. Similar to autophagy, the ubiquitin–proteasome system is regulated downstream of mTOR, and it is implicated in epileptogenesis. Thus, mTOR-dependent cell-clearing systems are now taking center stage in the field of epilepsy. In the present review, we discuss such evidence in a variety of seizure-related disorders and models. This is expected to provide a deeper insight into the molecular mechanisms underlying seizure activity.
Collapse
|
6
|
Mao XY, Zhou HH, Jin WL. Redox-Related Neuronal Death and Crosstalk as Drug Targets: Focus on Epilepsy. Front Neurosci 2019; 13:512. [PMID: 31191222 PMCID: PMC6541114 DOI: 10.3389/fnins.2019.00512] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Accepted: 05/03/2019] [Indexed: 12/16/2022] Open
Abstract
Cell death has a vital role in embryonic development and organismal homeostasis. Biochemical, pharmacological, behavioral, and electrophysiological evidences support the idea that dysregulation of cell death programs are involved in neuropathological conditions like epilepsy. The brain is particularly vulnerable to oxidative damage due to higher oxygen consumption and lower endogenous antioxidant defense than other bodily organ. Thus, in this review, we focused on the comprehensive summarization of evidence for redox-associated cell death pathways including apoptosis, autophagy, necroptosis, and pyroptosis in epilepsy and the oxidative stress-related signaling in this process. We specially proposed that the molecular crosstalk of various redox-linked neuronal cell death modalities might occur in seizure onset and/or epileptic conditions according to the published data. Additionally, abundance of polyunsaturated fatty acids in neuronal membrane makes the brain susceptible to lipid peroxidation. This presumption was then formalized in the proposal that ferroptosis, a novel type of lipid reactive oxygen species (ROS)-dependent regulatory cell death, is likely to be a critical mechanism for the emergence of epileptic phenotype. Targeting ferroptosis process or combination treatment with multiple cell death pathway inhibitors may shed new light on the therapy of epilepsy.
Collapse
Affiliation(s)
- Xiao-Yuan Mao
- Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha, China.,Institute of Clinical Pharmacology, Central South University, Hunan Key Laboratory of Pharmacogenetics, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
| | - Hong-Hao Zhou
- Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha, China.,Institute of Clinical Pharmacology, Central South University, Hunan Key Laboratory of Pharmacogenetics, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
| | - Wei-Lin Jin
- Center for Translational Medicine, Ruikang Hospital, Guangxi University of Chinese Medicine, Nanning, China.,Institute of Nano Biomedicine and Engineering, Department of Instrument Science and Engineering, Key Laboratory for Thin Film and Microfabrication Technology of Ministry of Education, School of Electronic Information and Electronic Engineering, Shanghai Jiao Tong University, Shanghai, China
| |
Collapse
|
7
|
Žerovnik E. Possible Mechanisms by which Stefin B could Regulate Proteostasis and Oxidative Stress. Cells 2019; 8:E70. [PMID: 30669344 PMCID: PMC6357131 DOI: 10.3390/cells8010070] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 12/19/2018] [Accepted: 01/09/2019] [Indexed: 01/19/2023] Open
Abstract
Human stefin B is a protease inhibitor from the family of cystatins. It was reported that it forms oligomers in cells. We have shown that it has a role in cell's response to misfolded proteins. We also have shown that its oligomers bind amyloid-beta (Aβ). Here, we discuss ways, how stefin B could reduce build-up of protein aggregates by other proteins and consequently reduces ROS and, how this might be connected to autophagy. When overexpressed, stefin B forms protein aggregates itself and these protein aggregates induce autophagy. Similarly, cystatin C was shown to bind Aβ and to induce autophagy. It is also suggested how more knowledge about the role of stefin B in a cell's response to misfolded proteins could be used to modulate progressive myoclonus epilepsy of type 1 EPM1 disease.
Collapse
Affiliation(s)
- Eva Žerovnik
- Department of Biochemistry and Molecular and Structural Biology, Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia.
| |
Collapse
|
8
|
Sragovich S, Merenlender-Wagner A, Gozes I. ADNP Plays a Key Role in Autophagy: From Autism to Schizophrenia and Alzheimer's Disease. Bioessays 2017; 39. [PMID: 28940660 DOI: 10.1002/bies.201700054] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 08/13/2017] [Indexed: 12/19/2022]
Abstract
Activity-dependent neuroprotective protein (ADNP), discovered in our laboratory in 1999, has been characterized as a master gene vital for mammalian brain formation. ADNP de novo mutations in humans result in a syndromic form of autism-like spectrum disorder (ASD), including cognitive and motor deficits, the ADNP syndrome (Helsmoortel-Van Der Aa). One of the most important cellular processes associated with ADNP is the autophagy pathway, recently discovered by us as a key player in the pathophysiology of schizophrenia. In this regard, given the link between the microtubule and autophagy systems, the ADNP microtubule end binding protein motif, namely, the neuroprotective NAP (NAPVSIPQ), was found to enhance autophagy while protecting microtubules and augmenting ADNP's association with both systems. Thus, linking autophagy and ADNP is proposed as a major target for intervention in brain diseases from autism to Alzheimer's disease (AD) and our findings introduce autophagy as a possible novel target for treating schizophrenia.
Collapse
Affiliation(s)
- Shlomo Sragovich
- The Lily and Avraham Gildor Chair for the Investigation of Growth Factors The Elton Laboratory for Neuroendocrinology Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Sagol School of Neuroscience and Adams Super Center for Brain Studies, Tel Aviv University, Tel Aviv 69978, Israel
| | - Avia Merenlender-Wagner
- The Lily and Avraham Gildor Chair for the Investigation of Growth Factors The Elton Laboratory for Neuroendocrinology Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Sagol School of Neuroscience and Adams Super Center for Brain Studies, Tel Aviv University, Tel Aviv 69978, Israel
| | - Illana Gozes
- The Lily and Avraham Gildor Chair for the Investigation of Growth Factors The Elton Laboratory for Neuroendocrinology Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Sagol School of Neuroscience and Adams Super Center for Brain Studies, Tel Aviv University, Tel Aviv 69978, Israel
| |
Collapse
|
9
|
Wang J, Liu Y, Li XH, Zeng XC, Li J, Zhou J, Xiao B, Hu K. Curcumin protects neuronal cells against status-epilepticus-induced hippocampal damage through induction of autophagy and inhibition of necroptosis. Can J Physiol Pharmacol 2016; 95:501-509. [PMID: 28177687 DOI: 10.1139/cjpp-2016-0154] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Status epilepticus, the most severe form of epilepsy, is characterized by progressive functional and structural damage in the hippocampus, ultimately leading to the development and clinical appearance of spontaneous, recurrent seizures. Although the pathogenesis underlying epileptogenesis processes remains unclear, a substantial body of evidence has shown that status epilepticus acts as an important initial factor in triggering epileptogenesis. Notably, besides classical cell death mechanisms such as apoptosis and necrosis, 2 novel regulators of cell fate known as necroptosis and autophagy, are demonstrated to be involved in neuronal damage in various neurodegenerative and neuropsychiatric disorders. However, whether necroptosis and autophagy play a role in post-status-epilepticus rat hippocampus and other epilepsy mechanisms deserves further research effort. In addition, research is needed to determine whether compounds from traditional Chinese herbs possess antiepileptic effects through the modulation of necroptosis and autophagy. In this study, we found that curcumin, a polyphenolic phytochemical extracted from the Curcuma longa plant, protects neuronal cells against status-epilepticus-induced hippocampal neuronal damage in the lithium-pilocarpine-induced status epilepticus rat model through induction of autophagy and inhibition of necroptosis.
Collapse
Affiliation(s)
- Jin Wang
- a Department of Pharmacology, Xiangya School of Medicine, Central South University, Changsha 410008, China
| | - Yuan Liu
- b Department of Anesthesia, Xiangya School of Medicine, Central South University, Changsha 410008, China
| | - Xiao-Hui Li
- a Department of Pharmacology, Xiangya School of Medicine, Central South University, Changsha 410008, China
| | - Xiang-Chang Zeng
- c Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha 410008, China.,d Institute of Clinical Pharmacology, Hunan Key Laboratory of Pharmacogenetics, Central South University, Changsha 410078, China
| | - Jian Li
- e Department of Laboratory Medicine, Xiangya School of Medicine, Central South University, Changsha 410008, China
| | - Jun Zhou
- f Medical Science Research Center, Xiangya Hospital, Central South University, Changsha 410008, China
| | - Bo Xiao
- g Department of Neurology, Xiangya Hospital, Central South University, Changsha 410008, China
| | - Kai Hu
- g Department of Neurology, Xiangya Hospital, Central South University, Changsha 410008, China
| |
Collapse
|
10
|
Gruber HE, Hoelscher GL, Ingram JA, Bethea S, Hanley EN. Autophagy in the Degenerating Human Intervertebral Disc: In Vivo Molecular and Morphological Evidence, and Induction of Autophagy in Cultured Annulus Cells Exposed to Proinflammatory Cytokines-Implications for Disc Degeneration. Spine (Phila Pa 1976) 2015; 40:773-82. [PMID: 26091153 DOI: 10.1097/brs.0000000000000865] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Autophagy-related gene expression and ultrastructural features of autophagy were studied in human discs. OBJECTIVE To obtain molecular/morphological data on autophagy in human disc degeneration and cultured human annulus cells exposed to proinflammatory cytokines. SUMMARY OF BACKGROUND DATA Autophagy is an important process by which cytoplasm and organelles are degraded; this adaptive response to sublethal stresses (such as nutrient deprivation present in disc degeneration) supplies needed metabolites. Little is known about autophagic processes during disc degeneration. METHODS Human disc specimens were obtained after institutional review board approval. Annulus mRNA was analyzed to determine autophagy-related gene expression levels. Immunolocalization and ultrastructural studies for p62, ATG3, ATG4B, ATG4C, ATG7, L3A, ULK-2, and beclin were conducted. In vitro experiments used IL-1β- or TNF-α-treated human annulus cells to test for autophagy-related gene expression. RESULTS More degenerated versus healthier discs showed significantly greater upregulation of well-recognized autophagy-related genes (P ≤ 0.028): beclin 1 (upregulated 1.6-fold); ATG8 (LC3) (upregulated 2.0-fold); ATG12 (upregulated 4.0-fold); presenilin 1 (upregulated 1.6-fold); cathepsin B (upregulated 4.5-fold). p62 was localized, and ultrastructure showed autophagic vacuolization and autophagosomes with complex, redundant whorls of membrane-derived material. In vitro, proinflammatory cytokines significantly upregulated autophagy-related genes (P ≤ 0.04): DRAM1 (6.24-fold); p62 (4.98-fold); PIM-2 oncogene, a positive regulator of autophagy (3-fold); WIPI49 (linked to starvation-induced autophagy) (upregulated 2.3-fold). CONCLUSION Data provide initial molecular and morphological evidence for the presence of autophagy in the degenerating human annulus. In vivo gene analyses showed greater autophagy-related gene expression in more degenerated than healthier discs. In vitro data suggested a mechanism implicating a role of TNF-α and IL-1β in disc autophagy. Findings suggest the importance of future work to investigate the relationship of autophagy to apoptosis, cell death, cell senescence, and mitochondrial dysfunction in the aging and degenerating disc. LEVEL OF EVIDENCE N/A.
Collapse
Affiliation(s)
- Helen E Gruber
- From the Department of Orthopaedic Surgery, Carolinas HealthCare System, Charlotte, NC
| | | | | | | | | |
Collapse
|
11
|
Giorgi FS, Biagioni F, Lenzi P, Frati A, Fornai F. The role of autophagy in epileptogenesis and in epilepsy-induced neuronal alterations. J Neural Transm (Vienna) 2014; 122:849-62. [DOI: 10.1007/s00702-014-1312-1] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 09/09/2014] [Indexed: 12/12/2022]
|
12
|
Gain in toxic function of stefin B EPM1 mutants aggregates: Correlation between cell death, aggregate number/size and oxidative stress. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:2089-99. [DOI: 10.1016/j.bbamcr.2014.05.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Revised: 05/28/2014] [Accepted: 05/29/2014] [Indexed: 11/19/2022]
|
13
|
Polajnar M, Zerovnik E. Impaired autophagy: a link between neurodegenerative and neuropsychiatric diseases. J Cell Mol Med 2014; 18:1705-11. [PMID: 25139375 PMCID: PMC4196646 DOI: 10.1111/jcmm.12349] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2014] [Accepted: 05/16/2014] [Indexed: 12/12/2022] Open
Abstract
Protein misfolding, and subsequent aggregation have been proven as the leading cause of most known dementias. Many of these, in addition to neurodegeneration, show profound changes in behaviour and thinking, thus, psychiatric symptoms. On the basis of the observation that progressive myoclonic epilepsies and neurodegenerative diseases share some common features of neurodegeneration, we proposed autophagy as a possible common impairment in these diseases. Here, we argue along similar lines for some neuropsychiatric conditions, among them depression and schizophrenia. We propose that existing and new therapies for these seemingly different diseases could be augmented with drugs used for neurodegenerative or neuropsychiatric diseases, respectively, among them some which modulate or augment autophagy.
Collapse
Affiliation(s)
- Mira Polajnar
- Department of Biochemistry and Molecular and Structural Biology, Jožef Stefan Institute, Ljubljana, Slovenia
| | | |
Collapse
|
14
|
Polajnar M, Zavašnik-Bergant T, Škerget K, Vizovišek M, Vidmar R, Fonović M, Kopitar-Jerala N, Petrovič U, Navarro S, Ventura S, Žerovnik E. Human stefin B role in cell's response to misfolded proteins and autophagy. PLoS One 2014; 9:e102500. [PMID: 25047918 PMCID: PMC4105463 DOI: 10.1371/journal.pone.0102500] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Accepted: 06/18/2014] [Indexed: 11/30/2022] Open
Abstract
Alternative functions, apart from cathepsins inhibition, are being discovered for stefin B. Here, we investigate its role in vesicular trafficking and autophagy. Astrocytes isolated from stefin B knock-out (KO) mice exhibited an increased level of protein aggregates scattered throughout the cytoplasm. Addition of stefin B monomers or small oligomers to the cell medium reverted this phenotype, as imaged by confocal microscopy. To monitor the identity of proteins embedded within aggregates in wild type (wt) and KO cells, the insoluble cell lysate fractions were isolated and analyzed by mass spectrometry. Chaperones, tubulins, dyneins, and proteosomal components were detected in the insoluble fraction of wt cells but not in KO aggregates. In contrast, the insoluble fraction of KO cells exhibited increased levels of apolipoprotein E, fibronectin, clusterin, major prion protein, and serpins H1 and I2 and some proteins of lysosomal origin, such as cathepsin D and CD63, relative to wt astrocytes. Analysis of autophagy activity demonstrated that this pathway was less functional in KO astrocytes. In addition, synthetic dosage lethality (SDL) gene interactions analysis in Saccharomyces cerevisiae expressing human stefin B suggests a role in transport of vesicles and vacuoles These activities would contribute, directly or indirectly to completion of autophagy in wt astrocytes and would account for the accumulation of protein aggregates in KO cells, since autophagy is a key pathway for the clearance of intracellular protein aggregates.
Collapse
Affiliation(s)
- Mira Polajnar
- Department of Biochemistry and Molecular and Structural Biology, Jožef Stefan Institute, Ljubljana, Slovenia
- Jožef Stefan International Postgraduate School, Ljubljana, Slovenia
| | - Tina Zavašnik-Bergant
- Department of Biochemistry and Molecular and Structural Biology, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Katja Škerget
- Department of Biochemistry and Molecular and Structural Biology, Jožef Stefan Institute, Ljubljana, Slovenia
- Department of Molecular and Biomedical Science, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Matej Vizovišek
- Department of Biochemistry and Molecular and Structural Biology, Jožef Stefan Institute, Ljubljana, Slovenia
- Jožef Stefan International Postgraduate School, Ljubljana, Slovenia
| | - Robert Vidmar
- Department of Biochemistry and Molecular and Structural Biology, Jožef Stefan Institute, Ljubljana, Slovenia
- Jožef Stefan International Postgraduate School, Ljubljana, Slovenia
| | - Marko Fonović
- Department of Biochemistry and Molecular and Structural Biology, Jožef Stefan Institute, Ljubljana, Slovenia
- Jožef Stefan International Postgraduate School, Ljubljana, Slovenia
| | - Nataša Kopitar-Jerala
- Department of Biochemistry and Molecular and Structural Biology, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Uroš Petrovič
- Department of Molecular and Biomedical Science, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Susanna Navarro
- Institute of Biotechnology and Biomedicine, Autonomous University of Barcelona, Bellaterra, Spain
| | - Salvador Ventura
- Institute of Biotechnology and Biomedicine, Autonomous University of Barcelona, Bellaterra, Spain
| | - Eva Žerovnik
- Department of Biochemistry and Molecular and Structural Biology, Jožef Stefan Institute, Ljubljana, Slovenia
- Jožef Stefan International Postgraduate School, Ljubljana, Slovenia
- CipKeBip - Center of Excellence for integrated approaches in chemistry and biology of proteins, Ljubljana, Slovenia
- * E-mail:
| |
Collapse
|
15
|
Rationale for using intermittent calorie restriction as a dietary treatment for drug resistant epilepsy. Epilepsy Behav 2014; 33:110-4. [PMID: 24657501 DOI: 10.1016/j.yebeh.2014.02.026] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Revised: 02/18/2014] [Accepted: 02/23/2014] [Indexed: 01/23/2023]
Abstract
There has been resurgence in the use of dietary treatment, principally the classical ketogenic diet and its variants, for people with epilepsy. These diets generally require significant medical and dietician support. An effective but less restrictive dietary regimen is likely to be more acceptable and more widely used. Calorie-restricted diets appear to produce a range of biochemical and metabolic changes including reduced glucose levels, reduced inflammatory markers, increased sirtuins, increased AMPK signaling, inhibition of mTOR signaling, and increase in autophagy. There are studies in animal seizure models that suggest that these biochemical and metabolic changes may decrease ictogenesis and epileptogenesis. A calorie-restricted diet might be effective in reducing seizures in people with epilepsy. Hence, there is a sufficient rationale to undertake clinical trials to assess the efficacy and safety of calorie-restricted diets in people with epilepsy.
Collapse
|
16
|
Singh PK, Singh S, Ganesh S. Activation of serum/glucocorticoid-induced kinase 1 (SGK1) underlies increased glycogen levels, mTOR activation, and autophagy defects in Lafora disease. Mol Biol Cell 2013; 24:3776-86. [PMID: 24131995 PMCID: PMC3861076 DOI: 10.1091/mbc.e13-05-0261] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Lafora disease (LD), a fatal genetic form of myoclonic epilepsy, is characterized by abnormally high levels of cellular glycogen and its accumulation as Lafora bodies in affected tissues. Therefore the two defective proteins in LD-laforin phosphatase and malin ubiquitin ligase-are believed to be involved in glycogen metabolism. We earlier demonstrated that laforin and malin negatively regulate cellular glucose uptake by preventing plasma membrane targeting of glucose transporters. We show here that loss of laforin results in activation of serum/glucocorticoid-induced kinase 1 (SGK1) in cellular and animals models and that inhibition of SGK1 in laforin-deficient cells reduces the level of plasma membrane-bound glucose transporter, glucose uptake, and the consequent glycogen accumulation. We also provide evidence to suggest that mammalian target of rapamycin (mTOR) activates SGK1 kinase in laforin-deficient cells. The mTOR activation appears to be a glucose-dependent event, and overexpression of dominant-negative SGK1 suppresses mTOR activation, suggesting the existence of a feedforward loop between SGK1 and mTOR. Our findings indicate that inhibition of SGK1 activity could be an effective therapeutic approach to suppress glycogen accumulation, inhibit mTOR activity, and rescue autophagy defects in LD.
Collapse
Affiliation(s)
- Pankaj Kumar Singh
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India
| | | | | |
Collapse
|
17
|
Polajnar M, Ceru S, Kopitar-Jerala N, Zerovnik E. Human stefin B normal and patho-physiological role: molecular and cellular aspects of amyloid-type aggregation of certain EPM1 mutants. Front Mol Neurosci 2012; 5:88. [PMID: 22936898 PMCID: PMC3426797 DOI: 10.3389/fnmol.2012.00088] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2012] [Accepted: 08/03/2012] [Indexed: 11/24/2022] Open
Abstract
Epilepsies are characterized by abnormal electrophysiological activity of the brain. Among various types of inherited epilepsies different epilepsy syndromes, among them progressive myoclonus epilepsies with features of ataxia and neurodegeneration, are counted. The progressive myoclonus epilepsy of type 1 (EPM1), also known as Unverricht-Lundborg disease presents with features of cerebellar atrophy and increased oxidative stress. It has been found that EPM1 is caused by mutations in human cystatin B gene (human stefin B). We first describe the role of protein aggregation in other neurodegenerative conditions. Protein aggregates appear intraneurally but are also excreted, such as is the case with senile plaques of amyloid-β (Aβ) that accumulate in the brain parenchyma and vessel walls. A common characteristic of such diseases is the change of the protein conformation toward β secondary structure that accounts for the strong tendency of such proteins to aggregate and form amyloid fibrils. Second, we describe the patho-physiology of EPM1 and the normal and aberrant roles of stefin B in a mouse model of the disease. Furthermore, we discuss how the increased protein aggregation observed with some of the mutants of human stefin B may relate to the neurodegeneration that occurs in rare EPM1 patients. Our hypothesis (Ceru et al., 2005) states that some of the EPM1 mutants of human stefin B may undergo aggregation in neural cells, thus gaining additional toxic function (apart from loss of normal function). Our in vitro experiments thus far have confirmed that four mutants undergo increased aggregation relative to the wild-type protein. It has been shown that the R68X mutant forms amyloid-fibrils very rapidly, even at neutral pH and forms perinuclear inclusions, whereas the G4R mutant exhibits a prolonged lag phase, during which the toxic prefibrillar aggregates accumulate and are scattered more diffusely over the cytoplasm. Initial experiments on the G50E and Q71P missense EPM1 mutants are described.
Collapse
Affiliation(s)
- Mira Polajnar
- Department of Biochemistry and Molecular and Structural Biology, Jožef Stefan Institute Ljubljana, Slovenia
| | | | | | | |
Collapse
|
18
|
Romá-Mateo C, Sanz P, Gentry MS. Deciphering the role of malin in the lafora progressive myoclonus epilepsy. IUBMB Life 2012; 64:801-8. [PMID: 22815132 DOI: 10.1002/iub.1072] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Accepted: 06/15/2012] [Indexed: 12/21/2022]
Abstract
Lafora disease (LD) is a fatal, autosomal recessive neurodegenerative disorder that results in progressive myoclonus epilepsy. A hallmark of LD is the accumulation of insoluble, aberrant glycogen-like structures called Lafora bodies. LD is caused by mutations in the gene encoding the E3 ubiquitin ligase malin or the glucan phosphatase laforin. Although LD was first described in 1911, its symptoms are still lacking a consistent molecular explanation and, consequently, a cure is far from being achieved. Some data suggest that malin forms a functional complex with laforin. This complex promotes the ubiquitination of proteins involved in glycogen metabolism and misregulation of pathways involved in this process results in Lafora body formation. In addition, recent results obtained from both cell culture and LD mouse models have highlighted a role of the laforin-malin complex in the regulation of endoplasmic reticulum-stress and protein clearance pathways. These results suggest that LD should be considered as a novel member of the group of protein clearance diseases such as Parkinson's, Huntington's, or Alzheimer's, in addition to being a glycogen metabolism disease. Herein, we review the latest results concerning the role of malin in LD and attempt to decipher its function. © 2012 IUBMB IUBMB Life, 64(10): 801-808, 2012.
Collapse
Affiliation(s)
- Carlos Romá-Mateo
- Instituto de Biomedicina de Valencia, CSIC and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Valencia, Spain
| | | | | |
Collapse
|
19
|
Orzi F, Casolla B, Rocchi R, Fornai F. Prion-like mechanisms in epileptogenesis. Neurol Sci 2012; 34:1035-8. [PMID: 22777569 DOI: 10.1007/s10072-012-1148-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Accepted: 06/22/2012] [Indexed: 01/06/2023]
Abstract
Epilepsy often follows a focal insult, and develops with a time delay so to reveal a complex cascade of events. Both clinical and experimental findings suggest that the initial insult triggers a self-promoted pathological process, currently named epileptogenesis. An early phase reflects the complex response of the nervous system to the insult, which includes pro-injury and pro-repair mechanisms. Successively, the sprouting and probably neurogenesis and gliosis set up the stage for the onset of spontaneous seizures. Thus, local changes in excitability would cause a functional change within a network, and the altered circuitry would favor the seizures. A latent or clinically silent period, as long as years, may precede epilepsy. In spite of the substantial knowledge on the biochemical and morphological changes associated with epileptogenesis, the mechanisms supposedly underlying the process are still uncertain. The uncertainty refers mostly to the silent period, a stage in which most, if not all, the receptor and ion changes are supposedly settled. It is tempting to explore the nature of the factors promoting the epileptogenesis within the notional field of neurodegeneration. Specifically, several observations converge to support the hypothesis that a prion-like mechanism promotes the "maturation" process underlying epileptogenesis. The mechanism, consistently with data from different neurodegenerative diseases, is predictably associated with deposition of self-aggregating misfolded proteins and changes of the ubiquitin proteasome and autophagy-lysosome pathways.
Collapse
|