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Onwunma J, Binsabaan S, Allen SP, Sankaran B, Wohlever ML. The structural and biophysical basis of substrate binding to the hydrophobic groove in Ubiquilin Sti1 domains. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.10.602902. [PMID: 39026758 PMCID: PMC11257586 DOI: 10.1101/2024.07.10.602902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
Ubiquilins are a family of cytosolic proteins that ferry ubiquitinated substrates to the proteasome for degradation. Recent work has demonstrated that Ubiquilins can also act as molecular chaperones, utilizing internal Sti1 domains to directly bind to hydrophobic sequences. Ubiquilins are associated with several neurodegenerative diseases with point mutations in UBQLN2 causing dominant, X-linked Amyotrophic Lateral Sclerosis (ALS). The molecular basis of Ubiquilin chaperone activity and how ALS mutations in the Sti1 domains affect Ubiquilin activity are poorly understood. This study presents the first crystal structure of the Sti1 domain from a fungal Ubiquilin homolog bound to a transmembrane domain (TMD). The structure reveals that two Sti1 domains form a head-to-head dimer, creating a hydrophobic cavity that accommodates two TMDs. Mapping the UBQLN2 sequence onto the structure shows that several ALS mutations are predicted to disrupt the hydrophobic groove. Using a newly developed competitive binding assay, we show that Ubiquilins preferentially bind to hydrophobic substrates with low helical propensity, motifs that are enriched in both substrates and in Ubiquilins. This study provides insights into the molecular and structural basis for Ubiquilin substrate binding, with broad implications for the role of the Sti1 domain in phase separation and ALS.
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Affiliation(s)
- Joan Onwunma
- Previously at University of Toledo, Department of Chemistry & Biochemistry
| | | | - Shawn P Allen
- Previously at University of Toledo, Department of Chemistry & Biochemistry
- University of Pittsburgh, Department of Cell Biology
| | - Banumathi Sankaran
- Lawrence Berkley National Lab, Berkeley Center for Structural Biology, Molecular Biophysics and Integrated Bioimaging
| | - Matthew L Wohlever
- Previously at University of Toledo, Department of Chemistry & Biochemistry
- University of Pittsburgh, Department of Cell Biology
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2
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Jacob SM, Lee S, Kim SH, Sharkey KA, Pfeffer G, Nguyen MD. Brain-body mechanisms contribute to sexual dimorphism in amyotrophic lateral sclerosis. Nat Rev Neurol 2024:10.1038/s41582-024-00991-7. [PMID: 38965379 DOI: 10.1038/s41582-024-00991-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/07/2024] [Indexed: 07/06/2024]
Abstract
Amyotrophic lateral sclerosis (ALS) is the most common form of human motor neuron disease. It is characterized by the progressive degeneration of upper and lower motor neurons, leading to generalized motor weakness and, ultimately, respiratory paralysis and death within 3-5 years. The disease is shaped by genetics, age, sex and environmental stressors, but no cure or routine biomarkers exist for the disease. Male individuals have a higher propensity to develop ALS, and a different manifestation of the disease phenotype, than female individuals. However, the mechanisms underlying these sex differences remain a mystery. In this Review, we summarize the epidemiology of ALS, examine the sexually dimorphic presentation of the disease and highlight the genetic variants and molecular pathways that might contribute to sex differences in humans and animal models of ALS. We advance the idea that sexual dimorphism in ALS arises from the interactions between the CNS and peripheral organs, involving vascular, metabolic, endocrine, musculoskeletal and immune systems, which are strikingly different between male and female individuals. Finally, we review the response to treatments in ALS and discuss the potential to implement future personalized therapeutic strategies for the disease.
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Affiliation(s)
- Sarah M Jacob
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
- Department of Clinical Neurosciences, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Sukyoung Lee
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
- Department of Clinical Neurosciences, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
- Department of Cell Biology and Anatomy, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Seung Hyun Kim
- Department of Neurology, Hanyang University Hospital, Seoul, South Korea
| | - Keith A Sharkey
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
- Snyder Institute for Chronic Diseases, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Gerald Pfeffer
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
- Department of Clinical Neurosciences, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
- Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
| | - Minh Dang Nguyen
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
- Department of Clinical Neurosciences, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
- Department of Cell Biology and Anatomy, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
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3
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Dao TP, Rajendran A, Galagedera SKK, Haws W, Castañeda CA. Short disordered termini and proline-rich domain are major regulators of UBQLN1/2/4 phase separation. Biophys J 2024; 123:1449-1457. [PMID: 38041404 PMCID: PMC11163289 DOI: 10.1016/j.bpj.2023.11.3401] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Revised: 11/28/2023] [Accepted: 11/29/2023] [Indexed: 12/03/2023] Open
Abstract
Highly homologous ubiquitin-binding shuttle proteins UBQLN1, UBQLN2, and UBQLN4 differ in both their specific protein quality control functions and their propensities to localize to stress-induced condensates, cellular aggregates, and aggresomes. We previously showed that UBQLN2 phase separates in vitro, and that the phase separation propensities of UBQLN2 deletion constructs correlate with their ability to form condensates in cells. Here, we demonstrated that full-length UBQLN1, UBQLN2, and UBQLN4 exhibit distinct phase behaviors in vitro. Strikingly, UBQLN4 phase separates at a much lower saturation concentration than UBQLN1. However, neither UBQLN1 nor UBQLN4 phase separates with a strong temperature dependence, unlike UBQLN2. We determined that the temperature-dependent phase behavior of UBQLN2 stems from its unique proline-rich region, which is absent in the other UBQLNs. We found that the short N-terminal disordered regions of UBQLN1, UBQLN2, and UBQLN4 inhibit UBQLN phase separation via electrostatics interactions. Charge variants of the N-terminal regions exhibit altered phase behaviors. Consistent with the sensitivity of UBQLN phase separation to the composition of the N-terminal regions, epitope tags placed on the N-termini of the UBQLNs tune phase separation. Overall, our in vitro results have important implications for studies of UBQLNs in cells, including the identification of phase separation as a potential mechanism to distinguish the cellular roles of UBQLNs and the need to apply caution when using epitope tags to prevent experimental artifacts.
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Affiliation(s)
- Thuy P Dao
- Departments of Biology and Chemistry, Syracuse University, Syracuse, New York
| | - Anitha Rajendran
- Departments of Biology and Chemistry, Syracuse University, Syracuse, New York
| | | | - William Haws
- Departments of Biology and Chemistry, Syracuse University, Syracuse, New York
| | - Carlos A Castañeda
- Departments of Biology and Chemistry, Syracuse University, Syracuse, New York; Interdisciplinary Neuroscience Program, Syracuse University, Syracuse, New York; BioInspired Institute, Syracuse University, Syracuse, New York.
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4
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Hu N, Zhang L, Shen D, Yang X, Liu M, Cui L. Incidence of amyotrophic lateral sclerosis-associated genetic variants: a clinic-based study. Neurol Sci 2024; 45:1515-1522. [PMID: 37952009 DOI: 10.1007/s10072-023-07178-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Accepted: 10/31/2023] [Indexed: 11/14/2023]
Abstract
OBJECTIVE This study is to determine the incidence of genetic forms of amyotrophic lateral sclerosis (ALS) in clinic-based population. METHODS Next-generation sequencing (NGS) of whole exome sequencing (WES) was conducted among a total of 374 patients with definite or probable ALS to identify ALS-associated genes based on ALSoD database ( https://alsod.ac.uk ) [2023-07-01]. RESULTS Variants of ALS-associated genes were detected in 54.01% (202/374) ALS patients, among which 8.29% (31/374) were pathogenic/likely pathogenic (P/LP). The detection rates of P/LP variants were significantly higher in familial ALS than sporadic ALS (42.31% vs 5.75%, p < 0.001), while VUS mutations were more commonly detected in sporadic ALS (23.07% vs 47.13%, p = 0.018). There is no significant difference in detection rate between patients with and without early onset (8.93% vs 7.77%), rapid progression (9.30% vs 8.91%), cognitive decline (15.00% vs 7.93%), and cerebellar ataxia (20.00% vs 8.15%) (p > 0.05). CONCLUSION Over half of our ALS patients carried variants of ALS-related genes, most of which were variants of uncertain significance (VUS). Family history of ALS could work as strong evidence for carrying P/LP variants regarding ALS. There was no additionally suggestive effect of indicators including early onset, progression rate, cognitive decline, or cerebellar ataxia on the recommendation of genetic testing in clinical practice.
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Affiliation(s)
- Nan Hu
- Department of Neurology, Peking Union Medical College and Chinese Academy of Medical Sciences, Peking Union Medical College Hospital, Beijing, 100730, China
| | - Lei Zhang
- Department of Neurology, Peking Union Medical College and Chinese Academy of Medical Sciences, Peking Union Medical College Hospital, Beijing, 100730, China
| | - Dongchao Shen
- Department of Neurology, Peking Union Medical College and Chinese Academy of Medical Sciences, Peking Union Medical College Hospital, Beijing, 100730, China
| | - Xunzhe Yang
- Department of Neurology, Peking Union Medical College and Chinese Academy of Medical Sciences, Peking Union Medical College Hospital, Beijing, 100730, China
| | - Mingsheng Liu
- Department of Neurology, Peking Union Medical College and Chinese Academy of Medical Sciences, Peking Union Medical College Hospital, Beijing, 100730, China.
| | - Liying Cui
- Department of Neurology, Peking Union Medical College and Chinese Academy of Medical Sciences, Peking Union Medical College Hospital, Beijing, 100730, China.
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5
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Safren N, Dao TP, Mohan HM, Huang C, Trotter B, Castañeda CA, Paulson H, Barmada S, Sharkey LM. Pathogenic mutations in UBQLN2 exhibit diverse aggregation propensity and neurotoxicity. Sci Rep 2024; 14:6049. [PMID: 38472280 PMCID: PMC10933299 DOI: 10.1038/s41598-024-55582-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Accepted: 02/26/2024] [Indexed: 03/14/2024] Open
Abstract
The ubiquitin-adaptor protein UBQLN2 promotes degradation of several aggregate-prone proteins implicated in neurodegenerative diseases. Missense UBQLN2 mutations also cause X-linked amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Previously we demonstrated that the liquid-like properties of UBQLN2 molecular assemblies are altered by a specific pathogenic mutation, P506T, and that the propensity of UBQLN2 to aggregate correlated with neurotoxicity. Here, we systematically assess the effects of multiple, spatially distinct ALS/FTD-linked missense mutations on UBQLN2 aggregation propensity, neurotoxicity, phase separation, and autophagic flux. In contrast to what we observed for the P506T mutation, no other tested pathogenic mutant exhibited a clear correlation between aggregation propensity and neurotoxicity. These results emphasize the unique nature of pathogenic UBQLN2 mutations and argue against a generalizable link between aggregation propensity and neurodegeneration in UBQLN2-linked ALS/FTD.
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Affiliation(s)
- Nathaniel Safren
- Department of Neurology, University of Michigan, Ann Arbor, MI, 48109-2200, USA.
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, 60611, USA.
| | - Thuy P Dao
- Departments of Biology and Chemistry, Syracuse University, Syracuse, NY, 13244, USA
| | - Harihar Milaganur Mohan
- Department of Neurology, University of Michigan, Ann Arbor, MI, 48109-2200, USA
- Cellular and Molecular Biology Program, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Camellia Huang
- Department of Neurology, University of Michigan, Ann Arbor, MI, 48109-2200, USA
| | - Bryce Trotter
- Department of Neurology, University of Michigan, Ann Arbor, MI, 48109-2200, USA
| | - Carlos A Castañeda
- Departments of Biology and Chemistry, Syracuse University, Syracuse, NY, 13244, USA
| | - Henry Paulson
- Department of Neurology, University of Michigan, Ann Arbor, MI, 48109-2200, USA
- Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI, 48109-2200, USA
| | - Sami Barmada
- Department of Neurology, University of Michigan, Ann Arbor, MI, 48109-2200, USA
- Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI, 48109-2200, USA
| | - Lisa M Sharkey
- Department of Neurology, University of Michigan, Ann Arbor, MI, 48109-2200, USA.
- Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI, 48109-2200, USA.
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6
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Longobardi A, Catania M, Geviti A, Salvi E, Vecchi ER, Bellini S, Saraceno C, Nicsanu R, Squitti R, Binetti G, Di Fede G, Ghidoni R. Autophagy Markers Are Altered in Alzheimer's Disease, Dementia with Lewy Bodies and Frontotemporal Dementia. Int J Mol Sci 2024; 25:1125. [PMID: 38256197 PMCID: PMC10816165 DOI: 10.3390/ijms25021125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 01/12/2024] [Accepted: 01/15/2024] [Indexed: 01/24/2024] Open
Abstract
The accumulation of protein aggregates defines distinct, yet overlapping pathologies such as Alzheimer's disease (AD), dementia with Lewy bodies (DLB), and frontotemporal dementia (FTD). In this study, we investigated ATG5, UBQLN2, ULK1, and LC3 concentrations in 66 brain specimens and 120 plasma samples from AD, DLB, FTD, and control subjects (CTRL). Protein concentration was measured with ELISA kits in temporal, frontal, and occipital cortex specimens of 32 AD, 10 DLB, 10 FTD, and 14 CTRL, and in plasma samples of 30 AD, 30 DLB, 30 FTD, and 30 CTRL. We found alterations in ATG5, UBQLN2, ULK1, and LC3 levels in patients; ATG5 and UBQLN2 levels were decreased in both brain specimens and plasma samples of patients compared to those of the CTRL, while LC3 levels were increased in the frontal cortex of DLB and FTD patients. In this study, we demonstrate alterations in different steps related to ATG5, UBQLN2, and LC3 autophagy pathways in DLB and FTD patients. Molecular alterations in the autophagic processes could play a role in a shared pathway involved in the pathogenesis of neurodegeneration, supporting the hypothesis of a common molecular mechanism underlying major neurodegenerative dementias and suggesting different potential therapeutic targets in the autophagy pathway for these disorders.
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Affiliation(s)
- Antonio Longobardi
- Molecular Markers Laboratory, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, 25125 Brescia, Italy; (S.B.); (C.S.); (R.N.); (R.S.); (R.G.)
| | - Marcella Catania
- Neurology 5/Neuropathology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133 Milan, Italy; (M.C.); (E.R.V.); (G.D.F.)
| | - Andrea Geviti
- Service of Statistics, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, 25125 Brescia, Italy;
| | - Erika Salvi
- Neuroalgology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133 Milan, Italy;
- Data Science Center, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133 Milan, Italy
| | - Elena Rita Vecchi
- Neurology 5/Neuropathology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133 Milan, Italy; (M.C.); (E.R.V.); (G.D.F.)
| | - Sonia Bellini
- Molecular Markers Laboratory, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, 25125 Brescia, Italy; (S.B.); (C.S.); (R.N.); (R.S.); (R.G.)
| | - Claudia Saraceno
- Molecular Markers Laboratory, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, 25125 Brescia, Italy; (S.B.); (C.S.); (R.N.); (R.S.); (R.G.)
| | - Roland Nicsanu
- Molecular Markers Laboratory, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, 25125 Brescia, Italy; (S.B.); (C.S.); (R.N.); (R.S.); (R.G.)
| | - Rosanna Squitti
- Molecular Markers Laboratory, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, 25125 Brescia, Italy; (S.B.); (C.S.); (R.N.); (R.S.); (R.G.)
- Dipartimento di Scienze di Laboratorio, Ospedale Isola Tiberina-Gemelli Isola, 00186 Rome, Italy
| | - Giuliano Binetti
- MAC-Memory Clinic and Molecular Markers Laboratory, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, 25125 Brescia, Italy;
| | - Giuseppe Di Fede
- Neurology 5/Neuropathology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133 Milan, Italy; (M.C.); (E.R.V.); (G.D.F.)
| | - Roberta Ghidoni
- Molecular Markers Laboratory, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, 25125 Brescia, Italy; (S.B.); (C.S.); (R.N.); (R.S.); (R.G.)
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7
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Eck RJ, Stair JG, Kraemer BC, Liachko NF. Simple models to understand complex disease: 10 years of progress from Caenorhabditis elegans models of amyotrophic lateral sclerosis and frontotemporal lobar degeneration. Front Neurosci 2024; 17:1300705. [PMID: 38239833 PMCID: PMC10794587 DOI: 10.3389/fnins.2023.1300705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Accepted: 11/28/2023] [Indexed: 01/22/2024] Open
Abstract
The nematode Caenorhabditis elegans are a powerful model system to study human disease, with numerous experimental advantages including significant genetic and cellular homology to vertebrate animals, a short lifespan, and tractable behavioral, molecular biology and imaging assays. Beginning with the identification of SOD1 as a genetic cause of amyotrophic lateral sclerosis (ALS), C. elegans have contributed to a deeper understanding of the mechanistic underpinnings of this devastating neurodegenerative disease. More recently this work has expanded to encompass models of other types of ALS and the related disease frontotemporal lobar degeneration (FTLD-TDP), including those characterized by mutation or accumulation of the proteins TDP-43, C9orf72, FUS, HnRNPA2B1, ALS2, DCTN1, CHCHD10, ELP3, TUBA4A, CAV1, UBQLN2, ATXN3, TIA1, KIF5A, VAPB, GRN, and RAB38. In this review we summarize these models and the progress and insights from the last ten years of using C. elegans to study the neurodegenerative diseases ALS and FTLD-TDP.
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Affiliation(s)
- Randall J. Eck
- Graduate Program in Neuroscience, University of Washington, Seattle, WA, United States
- Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Washington, Seattle, WA, United States
| | - Jade G. Stair
- Geriatrics Research Education and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle, WA, United States
| | - Brian C. Kraemer
- Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Washington, Seattle, WA, United States
- Geriatrics Research Education and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle, WA, United States
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA, United States
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, United States
| | - Nicole F. Liachko
- Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Washington, Seattle, WA, United States
- Geriatrics Research Education and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle, WA, United States
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8
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Dao TP, Rajendran A, Galagedera SKK, Haws W, Castañeda CA. Short N-terminal disordered regions and the proline-rich domain are major regulators of phase transitions for full-length UBQLN1, UBQLN2 and UBQLN4. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.27.559790. [PMID: 37808720 PMCID: PMC10557701 DOI: 10.1101/2023.09.27.559790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
Highly homologous ubiquitin-binding shuttle proteins UBQLN1, UBQLN2 and UBQLN4 differ in both their specific protein quality control functions and their propensities to localize to stress-induced condensates, cellular aggregates and aggresomes. We previously showed that UBQLN2 phase separates in vitro, and that the phase separation propensities of UBQLN2 deletion constructs correlate with their ability to form condensates in cells. Here, we demonstrated that full-length UBQLN1, UBQLN2 and UBQLN4 exhibit distinct phase behaviors in vitro. Strikingly, UBQLN4 phase separates at a much lower saturation concentration than UBQLN1. However, neither UBQLN1 nor UBQLN4 phase separates with a strong temperature dependence, unlike UBQLN2. We determined that the temperature-dependent phase behavior of UBQLN2 stems from its unique proline-rich (Pxx) region, which is absent in the other UBQLNs. We found that the short N-terminal disordered regions of UBQLN1, UBQLN2 and UBQLN4 inhibit UBQLN phase separation via electrostatics interactions. Charge variants of the N-terminal regions exhibit altered phase behaviors. Consistent with the sensitivity of UBQLN phase separation to the composition of the N-terminal regions, epitope tags placed on the N-termini of the UBQLNs tune phase separation. Overall, our in vitro results have important implications for studies of UBQLNs in cells, including the identification of phase separation as a potential mechanism to distinguish the cellular roles of UBQLNs, and the need to apply caution when using epitope tags to prevent experimental artifacts.
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Affiliation(s)
- Thuy P. Dao
- Departments of Biology and Chemistry, Syracuse University, Syracuse, NY 13244, USA
| | - Anitha Rajendran
- Departments of Biology and Chemistry, Syracuse University, Syracuse, NY 13244, USA
| | | | - William Haws
- Departments of Biology and Chemistry, Syracuse University, Syracuse, NY 13244, USA
| | - Carlos A. Castañeda
- Departments of Biology and Chemistry, Syracuse University, Syracuse, NY 13244, USA
- Interdisciplinary Neuroscience Program, Syracuse University, Syracuse, NY 13244, USA
- BioInspired Institute, Syracuse University, Syracuse, NY 13244, USA
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9
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Schilling CM, Weber-Ban E. Catching proteins for degradation. Science 2023; 381:834-835. [PMID: 37616357 DOI: 10.1126/science.adj8230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/26/2023]
Abstract
Aubiquitin-independent pathway targets nuclear proteins to the proteasome.
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Affiliation(s)
| | - Eilika Weber-Ban
- Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
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10
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Iazzi M, Sadeghi S, Gupta GD. A Proteomic Survey of the Cystic Fibrosis Transmembrane Conductance Regulator Surfaceome. Int J Mol Sci 2023; 24:11457. [PMID: 37511222 PMCID: PMC10380767 DOI: 10.3390/ijms241411457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 07/08/2023] [Accepted: 07/12/2023] [Indexed: 07/30/2023] Open
Abstract
The aim of this review article is to collate recent contributions of proteomic studies to cystic fibrosis transmembrane conductance regulator (CFTR) biology. We summarize advances from these studies and create an accessible resource for future CFTR proteomic efforts. We focus our attention on the CFTR interaction network at the cell surface, thus generating a CFTR 'surfaceome'. We review the main findings about CFTR interactions and highlight several functional categories amongst these that could lead to the discovery of potential biomarkers and drug targets for CF.
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Affiliation(s)
| | | | - Gagan D. Gupta
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, ON M5B 2K3, Canada
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11
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Idera A, Sharkey LM, Kurauchi Y, Kadoyama K, Paulson HL, Katsuki H, Seki T. Wild-type and pathogenic forms of ubiquilin 2 differentially modulate components of the autophagy-lysosome pathways. J Pharmacol Sci 2023; 152:182-192. [PMID: 37257946 DOI: 10.1016/j.jphs.2023.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 04/14/2023] [Accepted: 05/08/2023] [Indexed: 06/02/2023] Open
Abstract
Missense mutations of ubiquilin 2 (UBQLN2) have been identified to cause X-linked amyotrophic lateral sclerosis (ALS). Proteasome-mediated protein degradation is reported to be impaired by ALS-associated mutations of UBQLN2. However, it remains unknown how these mutations affect autophagy-lysosome protein degradation, which consists of macroautophagy (MA), microautophagy (mA), and chaperone-mediated autophagy (CMA). Using a CMA/mA fluorescence reporter we found that overexpression of wild-type UBQLN2 impairs CMA. Conversely, knockdown of endogenous UBQLN2 increases CMA activity, suggesting that normally UBQLN2 negatively regulates CMA. ALS-associated mutant forms of UBQLN2 exacerbate this impairment of CMA. Using cells stably transfected with wild-type or ALS-associated mutant UBQLN2, we further determined that wild-type UBQLN2 increased the ratio of LAMP2A (a CMA-related protein) to LAMP1 (a lysosomal protein). This could represent a compensatory reaction to the impairment of CMA by wild-type UBQLN2. However, ALS-associated mutant UBQLN2 failed to show this compensation, exacerbating the impairment of CMA by mutant UBQLN2. We further demonstrated that ALS-associated mutant forms of UBQLN2 also impair MA, but wild-type UBQLN2 does not. These results support the view that ALS-associated mutant forms of UBQLN2 impair both CMA and MA which may contribute to the neurodegeneration observed in patients with UBQLN2-mediated ALS.
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Affiliation(s)
- Akiko Idera
- Department of Chemico-Pharmacological Sciences, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
| | - Lisa M Sharkey
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Yuki Kurauchi
- Department of Chemico-Pharmacological Sciences, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
| | - Keiichi Kadoyama
- Department of Pharmacology, Faculty of Pharmaceutical Sciences, Himeji Dokkyo University, Japan
| | - Henry L Paulson
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Hiroshi Katsuki
- Department of Chemico-Pharmacological Sciences, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
| | - Takahiro Seki
- Department of Chemico-Pharmacological Sciences, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan; Department of Pharmacology, Faculty of Pharmaceutical Sciences, Himeji Dokkyo University, Japan.
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Xiong Q, Feng R, Fischer S, Karow M, Stumpf M, Meßling S, Nitz L, Müller S, Clemen CS, Song N, Li P, Wu C, Eichinger L. Proteasomes of Autophagy-Deficient Cells Exhibit Alterations in Regulatory Proteins and a Marked Reduction in Activity. Cells 2023; 12:1514. [PMID: 37296637 PMCID: PMC10252828 DOI: 10.3390/cells12111514] [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: 04/03/2023] [Accepted: 05/26/2023] [Indexed: 06/12/2023] Open
Abstract
Autophagy and the ubiquitin proteasome system are the two major processes for the clearance and recycling of proteins and organelles in eukaryotic cells. Evidence is accumulating that there is extensive crosstalk between the two pathways, but the underlying mechanisms are still unclear. We previously found that autophagy 9 (ATG9) and 16 (ATG16) proteins are crucial for full proteasomal activity in the unicellular amoeba Dictyostelium discoideum. In comparison to AX2 wild-type cells, ATG9-and ATG16- cells displayed a 60%, and ATG9-/16- cells a 90%, decrease in proteasomal activity. Mutant cells also showed a significant increase in poly-ubiquitinated proteins and contained large ubiquitin-positive protein aggregates. Here, we focus on possible reasons for these results. Reanalysis of published tandem mass tag-based quantitative proteomic results of AX2, ATG9-, ATG16-, and ATG9-/16- cells revealed no change in the abundance of proteasomal subunits. To identify possible differences in proteasome-associated proteins, we generated AX2 wild-type and ATG16- cells expressing the 20S proteasomal subunit PSMA4 as GFP-tagged fusion protein, and performed co-immunoprecipitation experiments followed by mass spectrometric analysis. The results revealed no significant differences in the abundance of proteasomes between the two strains. However, we found enrichment as well as depletion of proteasomal regulators and differences in the ubiquitination of associated proteins for ATG16-, as compared to AX2 cells. Recently, proteaphagy has been described as a means to replace non-functional proteasomes. We propose that autophagy-deficient D. discoideum mutants suffer from inefficient proteaphagy, which results in the accumulation of modified, less-active, and also of inactive, proteasomes. As a consequence, these cells exhibit a dramatic decrease in proteasomal activity and deranged protein homeostasis.
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Affiliation(s)
- Qiuhong Xiong
- Shanxi Provincial Key Laboratory of Medical Molecular Cell Biology, Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institutes of Biomedical Sciences, Shanxi University, No. 92 Wucheng Road, Taiyuan 030006, China
| | - Rong Feng
- Shanxi Provincial Key Laboratory of Medical Molecular Cell Biology, Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institutes of Biomedical Sciences, Shanxi University, No. 92 Wucheng Road, Taiyuan 030006, China
| | - Sarah Fischer
- Center for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
| | - Malte Karow
- Center for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
| | - Maria Stumpf
- Center for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
| | - Susanne Meßling
- Center for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
| | - Leonie Nitz
- Center for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
| | - Stefan Müller
- CECAD Proteomics Facility, Center for Molecular Medicine Cologne, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 26, 50931 Cologne, Germany
| | - Christoph S. Clemen
- Institute of Aerospace Medicine, German Aerospace Center (DLR), 51147 Cologne, Germany
- Institute of Vegetative Physiology, Medical Faculty, University of Cologne, 50931 Cologne, Germany
| | - Ning Song
- Shanxi Provincial Key Laboratory of Medical Molecular Cell Biology, Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institutes of Biomedical Sciences, Shanxi University, No. 92 Wucheng Road, Taiyuan 030006, China
| | - Ping Li
- Shanxi Provincial Key Laboratory of Medical Molecular Cell Biology, Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institutes of Biomedical Sciences, Shanxi University, No. 92 Wucheng Road, Taiyuan 030006, China
| | - Changxin Wu
- Shanxi Provincial Key Laboratory of Medical Molecular Cell Biology, Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institutes of Biomedical Sciences, Shanxi University, No. 92 Wucheng Road, Taiyuan 030006, China
| | - Ludwig Eichinger
- Center for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
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Phung TH, Tatman M, Monteiro MJ. UBQLN2 undergoes a reversible temperature-induced conformational switch that regulates binding with HSPA1B: ALS/FTD mutations cripple the switch but do not destroy HSPA1B binding. Biochim Biophys Acta Gen Subj 2023; 1867:130284. [PMID: 36423739 PMCID: PMC9792439 DOI: 10.1016/j.bbagen.2022.130284] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 10/23/2022] [Accepted: 11/18/2022] [Indexed: 11/23/2022]
Abstract
Here we present evidence, based on alterations of its intrinsic tryptophan fluorescence, that UBQLN2 protein undergoes a conformational switch when the temperature is raised from 37 °C to 42 °C. The switch is reset on restoration of the temperature. We speculate that the switch regulates UBQLN2 function in the heat shock response because elevation of the temperature from 37 °C to 42 °C dramatically increased in vitro binding between UBQLN2 and HSPA1B. Furthermore, restoration of the temperature to 37 °C decreased HSPA1B binding. By comparison to wild type (WT) UBQLN2, we found that all five ALS/FTD mutant UBQLN2 proteins we examined had attenuated alterations in tryptophan fluorescence when shifted to 42 °C, suggesting that the conformational switch is crippled in the mutants. Paradoxically, all five mutants bound similar amounts of HSPA1B compared to WT UBQLN2 protein at 42 °C, suggesting that either the conformational switch is not instrumental for HSPA1B binding, or that, although damaged, it is still functional. Comparison of the poly-ubiquitin chain binding revealed that WT UBQLN2 binds more avidly with K63 than with K48 chains. The avidity may explain the involvement of UBQLN2 in autophagy and cell signaling. Consistent with its function in autophagy, we found UBQLN2 binds directly with LC3, the autophagosomal-specific membrane-tethered protein. Finally, we provide evidence that WT UBQLN2 can homodimerize, and heterodimerize with WT UBQLN1. We show that ALS mutant P497S-UBQLN2 protein can oligomerize with either WT UBQLN1 or 2, providing a possible mechanism for how mutant UBQLN2 proteins could bind and inactivate UBQLN proteins, causing loss of function.
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Affiliation(s)
- Trong H Phung
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD, USA; Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Micaela Tatman
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD, USA; Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Mervyn J Monteiro
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD, USA; Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA.
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14
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Silencing UBQLN2 Enhances the Radiosensitivity of Esophageal Squamous Cell Carcinoma (ESCC) via Activating p38 MAPK. JOURNAL OF ONCOLOGY 2023; 2023:2339732. [PMID: 36644234 PMCID: PMC9836790 DOI: 10.1155/2023/2339732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Revised: 12/23/2022] [Accepted: 12/26/2022] [Indexed: 01/07/2023]
Abstract
Background Ubiquilin 2 (UBQLN2) is an adaptor of ubiquitinated proteins and the proteasome. The potential role of UBQLN2 in carcinogenesis has been demonstrated. However, its role in modulating the radiosensitivity of cancer is not clear. Here, we explored the radiosensitizing effect of silencing UBQLN2 on esophageal squamous cell carcinoma (ESCC) and its mechanisms. Methods We analyzed the prognostic role of UBQLN2 in the ESCC patient cohort from the Cancer Genomic Atlas (TCGA) database and our hospital. We also conducted a series of experiments in vivo and in vitro to investigate the effect of silencing UBQLN2 on ESCC radiosensitivity and its mechanisms. Results UBQLN2 is highly expressed in ESCC tissues and positively correlated with poor overall survival (OS). The knockdown of UBQLN2 dramatically increased the radiosensitivity of ESCC cells. Mechanically, UBQLN2 suppression substantially upregulated p38 mitogen-activated protein kinases (MAPK). The p38 MAPK inhibitor SB203580 could reverse the radiation-enhancing effect induced by UBQLN2 knockdown. The direct interaction between UBQLN2 and p38 MAPK was confirmed by co-immunoprecipitation (CO-IP) assay. Furthermore, silencing UBQLN2 also inhibited the expression of phosphorylated DNA-dependent protein kinase catalytic subunit (p-DNA-PKcs) after irradiation. Finally, the xenografted tumor experiment confirmed the radiosensitizing effect of silencing UBQLN2 on ESCC in vivo. Conclusion Our results suggest that silencing UBQLN2 enhances the radiosensitivity of ESCC by activating p38 MAPK, and UBQLN2 may be a potential target to enhance the radiosensitivity of ESCC.
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15
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Chojdak-Łukasiewicz J, Bizoń A, Waliszewska-Prosół M, Piwowar A, Budrewicz S, Pokryszko-Dragan A. Role of Sirtuins in Physiology and Diseases of the Central Nervous System. Biomedicines 2022; 10:2434. [PMID: 36289696 PMCID: PMC9598817 DOI: 10.3390/biomedicines10102434] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 09/18/2022] [Accepted: 09/23/2022] [Indexed: 07/30/2023] Open
Abstract
Silent information regulators, sirtuins (SIRTs), are a family of enzymes which take part in major posttranslational modifications of proteins and contribute to multiple cellular processes, including metabolic and energetic transformations, as well as regulation of the cell cycle. Recently, SIRTs have gained increased attention as the object of research because of their multidirectional activity and possible role in the complex pathomechanisms underlying human diseases. The aim of this study was to review a current literature evidence of SIRTs' role in the physiology and pathology of the central nervous system (CNS). SIRTs have been demonstrated to be crucial players in the crosstalk between neuroinflammation, neurodegeneration, and metabolic alterations. The elucidation of SIRTs' role in the background of various CNS diseases offers a chance to define relevant markers of their progression and promising candidates for novel therapeutic targets. Possible diagnostic and therapeutic implications from SIRTs-related investigations are discussed, as well as their future directions and associated challenges.
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Affiliation(s)
| | - Anna Bizoń
- Department of Toxicology, Faculty of Pharmacy, Wroclaw Medical University, Borowska 211A, 50-556 Wroclaw, Poland
| | | | - Agnieszka Piwowar
- Department of Toxicology, Faculty of Pharmacy, Wroclaw Medical University, Borowska 211A, 50-556 Wroclaw, Poland
| | - Sławomir Budrewicz
- Department of Neurology, Wroclaw Medical University, Borowska 213, 50-556 Wroclaw, Poland
| | - Anna Pokryszko-Dragan
- Department of Neurology, Wroclaw Medical University, Borowska 213, 50-556 Wroclaw, Poland
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Damaged DNA Is an Early Event of Neurodegeneration in Induced Pluripotent Stem Cell-Derived Motoneurons with UBQLN2P497H Mutation. Int J Mol Sci 2022; 23:ijms231911333. [PMID: 36232630 PMCID: PMC9570184 DOI: 10.3390/ijms231911333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 09/19/2022] [Accepted: 09/22/2022] [Indexed: 12/03/2022] Open
Abstract
Ubiquilin-2 (UBQLN2) mutations lead to familial amyotrophic lateral sclerosis (FALS)/and frontotemporal dementia (FTLD) through unknown mechanisms. The combination of iPSC technology and CRISPR-mediated genome editing technology can generate an iPSC-derived motor neuron (iPSC-MN) model with disease-relevant mutations, which results in increased opportunities for disease mechanism research and drug screening. In this study, we introduced a UBQLN2-P497H mutation into a healthy control iPSC line using CRISPR/Cas9, and differentiated into MNs to study the pathology of UBQLN2-related ALS. Our in vitro MN model faithfully recapitulated specific aspects of the disease, including MN apoptosis. Under sodium arsenite (SA) treatment, we found differences in the number and the size of UBQLN2+ inclusions in UBQLN2P497H MNs and wild-type (WT) MNs. We also observed cytoplasmic TAR DNA-binding protein (TARDBP, also known as TDP-43) aggregates in UBQLN2P497H MNs, but not in WT MNs, as well as the recruitment of TDP-43 into stress granules (SGs) upon SA treatment. We noted that UBQLN2-P497H mutation induced MNs DNA damage, which is an early event in UBQLN2-ALS. Additionally, DNA damage led to an increase in compensation for FUS, whereas UBQLN2-P497H mutation impaired this function. Therefore, FUS may be involved in DNA damage repair signaling.
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17
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Dao TP, Yang Y, Presti MF, Cosgrove MS, Hopkins JB, Ma W, Loh SN, Castañeda CA. Mechanistic insights into enhancement or inhibition of phase separation by different polyubiquitin chains. EMBO Rep 2022; 23:e55056. [PMID: 35762418 PMCID: PMC9346500 DOI: 10.15252/embr.202255056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 06/06/2022] [Accepted: 06/08/2022] [Indexed: 12/03/2022] Open
Abstract
Ubiquitin‐binding shuttle UBQLN2 mediates crosstalk between proteasomal degradation and autophagy, likely via interactions with K48‐ and K63‐linked polyubiquitin chains, respectively. UBQLN2 comprises self‐associating regions that drive its homotypic liquid–liquid phase separation (LLPS). Specific interactions between one of these regions and ubiquitin inhibit UBQLN2 LLPS. Here, we show that, unlike ubiquitin, the effects of multivalent polyubiquitin chains on UBQLN2 LLPS are highly dependent on chain types. Specifically, K11‐Ub4 and K48‐Ub4 chains generally inhibit UBQLN2 LLPS, whereas K63‐Ub4, M1‐Ub4 chains, and a designed tetrameric ubiquitin construct significantly enhance LLPS. We demonstrate that these opposing effects stem from differences in chain conformations but not in affinities between chains and UBQLN2. Chains with extended conformations and increased accessibility to the ubiquitin‐binding surface promote UBQLN2 LLPS by enabling a switch between homotypic to partially heterotypic LLPS that is driven by both UBQLN2 self‐interactions and interactions between multiple UBQLN2 units with each polyubiquitin chain. Our study provides mechanistic insights into how the structural and conformational properties of polyubiquitin chains contribute to heterotypic LLPS with ubiquitin‐binding shuttles and adaptors.
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Affiliation(s)
- Thuy P Dao
- Departments of Biology and Chemistry Syracuse University Syracuse NY USA
| | - Yiran Yang
- Department of Chemistry Syracuse University Syracuse NY USA
| | - Maria F Presti
- Department of Biochemistry and Molecular Biology SUNY Upstate Medical University Syracuse NY USA
| | - Michael S Cosgrove
- Department of Biochemistry and Molecular Biology SUNY Upstate Medical University Syracuse NY USA
| | - Jesse B Hopkins
- The Biophysics Collaborative Access Team (BioCAT), Department of Biological Sciences Illinois Institute of Technology Chicago IL USA
| | - Weikang Ma
- The Biophysics Collaborative Access Team (BioCAT), Department of Biological Sciences Illinois Institute of Technology Chicago IL USA
| | - Stewart N Loh
- Department of Biochemistry and Molecular Biology SUNY Upstate Medical University Syracuse NY USA
| | - Carlos A Castañeda
- Departments of Biology and Chemistry Syracuse University Syracuse NY USA
- Interdisciplinary Neuroscience Program Syracuse University Syracuse NY USA
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18
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Cozzi M, Ferrari V. Autophagy Dysfunction in ALS: from Transport to Protein Degradation. J Mol Neurosci 2022; 72:1456-1481. [PMID: 35708843 PMCID: PMC9293831 DOI: 10.1007/s12031-022-02029-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 05/17/2022] [Indexed: 01/18/2023]
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease affecting upper and lower motor neurons (MNs). Since the identification of the first ALS mutation in 1993, more than 40 genes have been associated with the disorder. The most frequent genetic causes of ALS are represented by mutated genes whose products challenge proteostasis, becoming unable to properly fold and consequently aggregating into inclusions that impose proteotoxic stress on affected cells. In this context, increasing evidence supports the central role played by autophagy dysfunctions in the pathogenesis of ALS. Indeed, in early stages of disease, high levels of proteins involved in autophagy are present in ALS MNs; but at the same time, with neurodegeneration progression, autophagy-mediated degradation decreases, often as a result of the accumulation of toxic protein aggregates in affected cells. Autophagy is a complex multistep pathway that has a central role in maintaining cellular homeostasis. Several proteins are involved in its tight regulation, and importantly a relevant fraction of ALS-related genes encodes products that directly take part in autophagy, further underlining the relevance of this key protein degradation system in disease onset and progression. In this review, we report the most relevant findings concerning ALS genes whose products are involved in the several steps of the autophagic pathway, from phagophore formation to autophagosome maturation and transport and finally to substrate degradation.
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Affiliation(s)
- Marta Cozzi
- Dipartimento Di Scienze Farmacologiche E Biomolecolari, Università Degli Studi Di Milano, 20133, Milan, Italy.
| | - Veronica Ferrari
- Dipartimento Di Scienze Farmacologiche E Biomolecolari, Università Degli Studi Di Milano, 20133, Milan, Italy.
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Gundelfinger ED, Karpova A, Pielot R, Garner CC, Kreutz MR. Organization of Presynaptic Autophagy-Related Processes. Front Synaptic Neurosci 2022; 14:829354. [PMID: 35368245 PMCID: PMC8968026 DOI: 10.3389/fnsyn.2022.829354] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Accepted: 01/04/2022] [Indexed: 11/13/2022] Open
Abstract
Brain synapses pose special challenges on the quality control of their protein machineries as they are far away from the neuronal soma, display a high potential for plastic adaptation and have a high energy demand to fulfill their physiological tasks. This applies in particular to the presynaptic part where neurotransmitter is released from synaptic vesicles, which in turn have to be recycled and refilled in a complex membrane trafficking cycle. Pathways to remove outdated and damaged proteins include the ubiquitin-proteasome system acting in the cytoplasm as well as membrane-associated endolysosomal and the autophagy systems. Here we focus on the latter systems and review what is known about the spatial organization of autophagy and endolysomal processes within the presynapse. We provide an inventory of which components of these degradative systems were found to be present in presynaptic boutons and where they might be anchored to the presynaptic apparatus. We identify three presynaptic structures reported to interact with known constituents of membrane-based protein-degradation pathways and therefore may serve as docking stations. These are (i) scaffolding proteins of the cytomatrix at the active zone, such as Bassoon or Clarinet, (ii) the endocytic machinery localized mainly at the peri-active zone, and (iii) synaptic vesicles. Finally, we sketch scenarios, how presynaptic autophagic cargos are tagged and recruited and which cellular mechanisms may govern membrane-associated protein turnover in the presynapse.
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Affiliation(s)
- Eckart D. Gundelfinger
- Research Group Neuroplasticity, Leibniz Institute for Neurobiology, Magdeburg, Germany
- Institute of Pharmacology and Toxicology, Medical Faculty, Otto von Guericke University, Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany
- *Correspondence: Eckart D. Gundelfinger,
| | - Anna Karpova
- Research Group Neuroplasticity, Leibniz Institute for Neurobiology, Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany
| | - Rainer Pielot
- Institute of Pharmacology and Toxicology, Medical Faculty, Otto von Guericke University, Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany
| | - Craig C. Garner
- German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
- Charité – Universitätsmedizin Berlin, Berlin, Germany
| | - Michael R. Kreutz
- Research Group Neuroplasticity, Leibniz Institute for Neurobiology, Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany
- Center for Molecular Neurobiology (ZMNH), University Hospital Hamburg-Eppendorf, Hamburg, Germany
- German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
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