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Zhao Y, Lin M, Zhai F, Chen J, Jin X. Exploring the Role of Ubiquitin-Proteasome System in the Pathogenesis of Parkinson's Disease. Pharmaceuticals (Basel) 2024; 17:782. [PMID: 38931449 PMCID: PMC11207014 DOI: 10.3390/ph17060782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2024] [Revised: 05/23/2024] [Accepted: 06/08/2024] [Indexed: 06/28/2024] Open
Abstract
Parkinson's disease (PD) is a prevalent neurodegenerative disorder among the elderly population. The pathogenesis of PD encompasses genetic alterations, environmental factors, and age-related neurodegenerative processes. Numerous studies have demonstrated that aberrant functioning of the ubiquitin-proteasome system (UPS) plays a crucial role in the initiation and progression of PD. Notably, E3 ubiquitin ligases serve as pivotal components determining substrate specificity within UPS and are intimately associated with the regulation of various proteins implicated in PD pathology. This review comprehensively summarizes the mechanisms by which E3 ubiquitin ligases and deubiquitinating enzymes modulate PD-associated proteins and signaling pathways, while exploring the intricate relationship between UPS dysfunctions and PD etiology. Furthermore, this article discusses recent research advancements regarding inhibitors targeting PD-related E3 ubiquitin ligases.
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Affiliation(s)
- Yiting Zhao
- Department of Chemoradiotherapy, The Affiliated People’s Hospital of Ningbo University, Ningbo 315040, China; (Y.Z.); (M.L.)
- Department of Ultrasound Medicine, The Affiliated People’s Hospital of Ningbo University, Ningbo 315040, China
- Zhejiang Key Laboratory of Pathophysiology, Department of Biochemistry and Molecular Biology, Health Science Center of Ningbo University, Ningbo 315211, China;
| | - Man Lin
- Department of Chemoradiotherapy, The Affiliated People’s Hospital of Ningbo University, Ningbo 315040, China; (Y.Z.); (M.L.)
- Zhejiang Key Laboratory of Pathophysiology, Department of Biochemistry and Molecular Biology, Health Science Center of Ningbo University, Ningbo 315211, China;
| | - Fengguang Zhai
- Zhejiang Key Laboratory of Pathophysiology, Department of Biochemistry and Molecular Biology, Health Science Center of Ningbo University, Ningbo 315211, China;
| | - Jun Chen
- Department of Chemoradiotherapy, The Affiliated People’s Hospital of Ningbo University, Ningbo 315040, China; (Y.Z.); (M.L.)
- Zhejiang Key Laboratory of Pathophysiology, Department of Biochemistry and Molecular Biology, Health Science Center of Ningbo University, Ningbo 315211, China;
| | - Xiaofeng Jin
- Department of Chemoradiotherapy, The Affiliated People’s Hospital of Ningbo University, Ningbo 315040, China; (Y.Z.); (M.L.)
- Zhejiang Key Laboratory of Pathophysiology, Department of Biochemistry and Molecular Biology, Health Science Center of Ningbo University, Ningbo 315211, China;
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2
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Lottes EN, Ciger F, Bhattacharjee S, Timmins EA, Tete B, Tran T, Matta J, Patel AA, Cox DN. CCT and Cullin1 Regulate the TORC1 Pathway to Promote Dendritic Arborization in Health and Disease. Cells 2024; 13:1029. [PMID: 38920658 PMCID: PMC11201622 DOI: 10.3390/cells13121029] [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: 01/27/2024] [Revised: 06/03/2024] [Accepted: 06/09/2024] [Indexed: 06/27/2024] Open
Abstract
The development of cell-type-specific dendritic arbors is integral to the proper functioning of neurons within their circuit networks. In this study, we examine the regulatory relationship between the cytosolic chaperonin CCT, key insulin pathway genes, and an E3 ubiquitin ligase (Cullin1) in dendritic development. CCT loss of function (LOF) results in dendritic hypotrophy in Drosophila Class IV (CIV) multi-dendritic larval sensory neurons, and CCT has recently been shown to fold components of the TOR (Target of Rapamycin) complex 1 (TORC1) in vitro. Through targeted genetic manipulations, we confirm that an LOF of CCT and the TORC1 pathway reduces dendritic complexity, while overexpression of key TORC1 pathway genes increases the dendritic complexity in CIV neurons. Furthermore, both CCT and TORC1 LOF significantly reduce microtubule (MT) stability. CCT has been previously implicated in regulating proteinopathic aggregation, thus, we examine CIV dendritic development in disease conditions as well. The expression of mutant Huntingtin leads to dendritic hypotrophy in a repeat-length-dependent manner, which can be rescued by Cullin1 LOF. Together, our data suggest that Cullin1 and CCT influence dendritic arborization through the regulation of TORC1 in both health and disease.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Daniel N. Cox
- Neuroscience Institute, Georgia State University, Atlanta, GA 30303, USA
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3
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Fishman-Jacob T, Youdim MBH. A sporadic Parkinson's disease model via silencing of the ubiquitin-proteasome/E3 ligase component, SKP1A. J Neural Transm (Vienna) 2024; 131:675-707. [PMID: 37644186 PMCID: PMC11192832 DOI: 10.1007/s00702-023-02687-6] [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: 04/28/2023] [Accepted: 08/15/2023] [Indexed: 08/31/2023]
Abstract
Our and other's laboratory microarray-derived transcriptomic studies in human PD substantia nigra pars compacta (SNpc) samples have opened an avenue to concentrate on potential gene intersections or cross-talks along the dopaminergic (DAergic) neurodegenerative cascade in sporadic PD (SPD). One emerging gene candidate identified was SKP1A (p19, S-phase kinase-associated protein 1A), found significantly decreased in the SNpc as confirmed later at the protein level. SKP1 is part of the Skp1, Cullin 1, F-box protein (SCF) complex, the largest known class of sophisticated ubiquitin-proteasome/E3-ligases and was found to directly interact with FBXO7, a gene defective in PARK15-linked PD. This finding has led us to the hypothesis that a targeted site-specific reduction of Skp1 levels in DAergic neuronal cell culture and animal systems may result in a progressive loss of DAergic neurons and hopefully recreate motor disabilities in animals. The second premise considers the possibility that both intrinsic and extrinsic factors (e.g., manipulation of selected genes and mitochondria impairing toxins), alleged to play central roles in DAergic neurodegeneration in PD, may act in concert as modifiers of Skp1 deficiency-induced phenotype alterations ('dual-hit' hypothesis of neurodegeneration). To examine a possible role of Skp1 in DAergic phenotype, we have initially knocked down the expression of SKP1A gene in an embryonic mouse SN-derived cell line (SN4741) with short hairpin RNA (shRNA) lentiviruses (LVs). The deficiency of SKP1A closely recapitulated cardinal features of the DAergic pathology of human PD, such as decreased expression of DAergic phenotypic markers and cell cycle aberrations. Furthermore, the knocked down cells displayed a lethal phenotype when induced to differentiate exhibiting proteinaceous round inclusion structures, which were almost identical in composition to human Lewy bodies, a hallmark of PD. These findings support a role for Skp1 in neuronal phenotype, survival, and differentiation. The identification of Skp1 as a key player in DAergic neuron function suggested that a targeted site-specific reduction of Skp1 levels in mice SNpc may result in a progressive loss of DAergic neurons and terminal projections in the striatum. The injected LV SKP1shRNA to mouse SN resulted in decreased expression of Skp1 protein levels within DAergic neurons and loss of tyrosine hydroxylase immunoreactivity (TH-IR) in both SNpc and striatum that was accompanied by time-dependent motor disabilities. The reduction of the vertical movements, that is rearing, may be reminiscent of the early occurrence of hypokinesia and axial, postural instability in PD. According to the 'dual-hit' hypothesis of neurodegenerative diseases, it is predicted that gene-gene and/or gene-environmental factors would act in concert or sequentially to propagate the pathological process of PD. Our findings are compatible with this conjecture showing that the genetic vulnerability caused by knock down of SKP1A renders DAergic SN4741 cells especially sensitive to genetic reduction of Aldh1 and exposure to the external stressors MPP+ and DA, which have been implicated in PD pathology. Future consideration should be given in manipulation SKP1A expression as therapeutic window, via its induction genetically or pharmacological, to prevent degeneration of the nigra striatal dopamine neurons, since UPS is defective.
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Affiliation(s)
- Tali Fishman-Jacob
- Youdim Pharmaceutical Ltd, New Northern Industrial Park, 1 Ha- Tsmikha St, Stern Building, Fl-3, P. O. Box 72, 2069207, Yokneam, Israel
| | - Moussa B H Youdim
- Youdim Pharmaceutical Ltd, New Northern Industrial Park, 1 Ha- Tsmikha St, Stern Building, Fl-3, P. O. Box 72, 2069207, Yokneam, Israel.
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4
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Li L, Li Y, Zeng K, Wang Q. Mercuric sulfide nanoparticles suppress the neurobehavioral functions of Caenorhabditis elegans through a Skp1-dependent mechanism. Food Chem Toxicol 2024; 186:114576. [PMID: 38458533 DOI: 10.1016/j.fct.2024.114576] [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: 11/27/2023] [Revised: 02/11/2024] [Accepted: 03/05/2024] [Indexed: 03/10/2024]
Abstract
Cinnabar is the naturally occurring mercuric sulfide (HgS) and concerns about its safety have been grown. However, the molecular mechanism of HgS-related neurotoxicity remains unclear. S-phase kinase-associated protein 1 (Skp1), identified as the target protein of HgS, plays a crucial role in the development of neurological diseases. This study aims to investigate the neurotoxic effects and molecular mechanism of HgS based on Skp1 using the Caenorhabditis elegans (C. elegans) model. We prepared the HgS nanoparticles and conducted a comparative analysis of neurobehavioral differences in both wild-type C. elegans (N2) and a transgenic strain of C. elegans (VC1241) with a knockout of the SKP1 homologous gene after exposure to HgS nanoparticles. Our results showed that HgS nanoparticles could suppress locomotion, defecation, egg-laying, and associative learning behaviors in N2 C. elegans, while no significant alterations were observed in the VC1241 C. elegans. Furthermore, we conducted a 4D label-free proteomics analysis and screened 504 key proteins significantly affected by HgS nanoparticles through Skp1. These proteins play pivotal roles in various pathways, including SNARE interactions in vesicular transport, TGF-beta signaling pathway, calcium signaling pathway, FoxO signaling pathway, etc. In summary, HgS nanoparticles at high doses suppress the neurobehavioral functions of C. elegans through a Skp1-dependent mechanism.
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Affiliation(s)
- Ludi Li
- Department of Toxicology, School of Public Health, Peking University, Beijing, 100191, China.
| | - Yingzi Li
- Department of Toxicology, School of Public Health, Peking University, Beijing, 100191, China.
| | - Kewu Zeng
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing, 100191, China.
| | - Qi Wang
- Department of Toxicology, School of Public Health, Peking University, Beijing, 100191, China; Key Laboratory of State Administration of Traditional Chinese Medicine for Compatibility Toxicology, Beijing, 100191, China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing, 100191, China.
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5
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Salas-Leal AC, Salas-Pacheco SM, Hernández-Cosaín EI, Vélez-Vélez LM, Antuna-Salcido EI, Castellanos-Juárez FX, Méndez-Hernández EM, Llave-León OL, Quiñones-Canales G, Arias-Carrión O, Sandoval-Carrillo AA, Salas-Pacheco JM. Differential expression of PSMC4, SKP1, and HSPA8 in Parkinson's disease: insights from a Mexican mestizo population. Front Mol Neurosci 2023; 16:1298560. [PMID: 38115821 PMCID: PMC10728481 DOI: 10.3389/fnmol.2023.1298560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 11/13/2023] [Indexed: 12/21/2023] Open
Abstract
Parkinson's disease (PD) is a complex neurodegenerative condition characterized by alpha-synuclein aggregation and dysfunctional protein degradation pathways. This study investigates the differential gene expression of pivotal components (UBE2K, PSMC4, SKP1, and HSPA8) within these pathways in a Mexican-Mestizo PD population compared to healthy controls. We enrolled 87 PD patients and 87 controls, assessing their gene expression levels via RT-qPCR. Our results reveal a significant downregulation of PSMC4, SKP1, and HSPA8 in the PD group (p = 0.033, p = 0.003, and p = 0.002, respectively). Logistic regression analyses establish a strong association between PD and reduced expression of PSMC4, SKP1, and HSPA8 (OR = 0.640, 95% CI = 0.415-0.987; OR = 0.000, 95% CI = 0.000-0.075; OR = 0.550, 95% CI = 0.368-0.823, respectively). Conversely, UBE2K exhibited no significant association or expression difference between the groups. Furthermore, we develop a gene expression model based on HSPA8, PSMC4, and SKP1, demonstrating robust discrimination between healthy controls and PD patients. Notably, the model's diagnostic efficacy is particularly pronounced in early-stage PD. In conclusion, our study provides compelling evidence linking decreased gene expression of PSMC4, SKP1, and HSPA8 to PD in the Mexican-Mestizo population. Additionally, our gene expression model exhibits promise as a diagnostic tool, particularly for early-stage PD diagnosis.
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Affiliation(s)
- Alma C. Salas-Leal
- Instituto de Investigación Científica, Universidad Juárez del Estado de Durango, Durango, México
| | - Sergio M. Salas-Pacheco
- Instituto de Investigación Científica, Universidad Juárez del Estado de Durango, Durango, México
| | - Erik I. Hernández-Cosaín
- Instituto de Investigación Científica, Universidad Juárez del Estado de Durango, Durango, México
| | - Lilia M. Vélez-Vélez
- Instituto de Investigación Científica, Universidad Juárez del Estado de Durango, Durango, México
| | | | | | - Edna M. Méndez-Hernández
- Instituto de Investigación Científica, Universidad Juárez del Estado de Durango, Durango, México
| | - Osmel La Llave-León
- Instituto de Investigación Científica, Universidad Juárez del Estado de Durango, Durango, México
| | | | - Oscar Arias-Carrión
- Unidad de Trastornos del Movimiento y Sueño, Hospital General Dr. Manuel Gea González, Ciudad de México, México
| | - Ada A. Sandoval-Carrillo
- Instituto de Investigación Científica, Universidad Juárez del Estado de Durango, Durango, México
| | - José M. Salas-Pacheco
- Instituto de Investigación Científica, Universidad Juárez del Estado de Durango, Durango, México
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Lottes EN, Ciger FH, Bhattacharjee S, Timmins-Wilde EA, Tete B, Tran T, Matta J, Patel AA, Cox DN. CCT and Cullin1 regulate the TORC1 pathway to promote dendritic arborization in health and disease. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.31.551324. [PMID: 37577581 PMCID: PMC10418059 DOI: 10.1101/2023.07.31.551324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
The development of cell-type-specific dendritic arbors is integral to the proper functioning of neurons within their circuit networks. In this study, we examine the regulatory relationship between the cytosolic chaperonin CCT, key insulin pathway genes, and an E3 ubiquitin ligase (Cullin1) in homeostatic dendritic development. CCT loss of function (LOF) results in dendritic hypotrophy in Drosophila Class IV (CIV) multidendritic larval sensory neurons, and CCT has recently been shown to fold components of the TOR (Target of Rapamycin) complex 1 (TORC1), in vitro. Through targeted genetic manipulations, we have confirmed that LOF of CCT and the TORC1 pathway reduces dendritic complexity, while overexpression of key TORC1 pathway genes increases dendritic complexity in CIV neurons. Both CCT and TORC1 LOF significantly reduce microtubule (MT) stability. CCT has been previously implicated in regulating proteinopathic aggregation, thus we examined CIV dendritic development in disease conditions as well. Expression of mutant Huntingtin leads to dendritic hypotrophy in a repeat-length-dependent manner, which can be rescued by TORC1 disinhibition via Cullin1 LOF. Together, our data suggest that Cullin1 and CCT influence dendritic arborization through regulation of TORC1 in both health and disease.
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Affiliation(s)
- Erin N. Lottes
- Neuroscience Institute, Georgia State University, Atlanta, GA 30303, United States
| | - Feyza H. Ciger
- Neuroscience Institute, Georgia State University, Atlanta, GA 30303, United States
| | | | | | - Benoit Tete
- Neuroscience Institute, Georgia State University, Atlanta, GA 30303, United States
| | - Tommy Tran
- Neuroscience Institute, Georgia State University, Atlanta, GA 30303, United States
| | - Jais Matta
- Neuroscience Institute, Georgia State University, Atlanta, GA 30303, United States
| | - Atit A. Patel
- Neuroscience Institute, Georgia State University, Atlanta, GA 30303, United States
| | - Daniel N. Cox
- Neuroscience Institute, Georgia State University, Atlanta, GA 30303, United States
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Li R, Sano T, Mizokami A, Fukuda T, Shinjo T, Iwashita M, Yamashita A, Sanui T, Nakatsu Y, Sotomaru Y, Asano T, Kanematsu T, Nishimura F. miR-582-5p targets Skp1 and regulates NF-κB signaling-mediated inflammation. Arch Biochem Biophys 2023; 734:109501. [PMID: 36592647 DOI: 10.1016/j.abb.2022.109501] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Revised: 12/15/2022] [Accepted: 12/30/2022] [Indexed: 01/01/2023]
Abstract
A well-tuned inflammatory response is crucial for an effective immune process. Nuclear factor-kappa B (NF-κB) is a key mediator of inflammatory and innate immunity responses, and its dysregulation is closely associated with immune-related diseases. MicroRNAs (miRNAs) are important inflammation modulators. However, miRNA-regulated mechanisms that implicate NF-κB activity are not fully understood. This study aimed to identify a potential miRNA that could modulate the dysregulated NF-κB signaling during inflammation. We identified miR-582-5p that was significantly downregulated in inflamed murine adipose tissues and RAW264.7 cells. S-phase kinase-associated protein 1 (SKP1), a core component of an E3 ubiquitin ligase that regulates the NF-κB pathway, was proposed as a biological target of miR-582-5p by using TargetScan. The binding of miR-582-5p to a 3'-untranslated region site on Skp1 was confirmed using a dual-luciferase reporter assay; in addition, transfection with a miR-582-5p mimic suppressed SKP1 expression in RAW264.7 cells. Importantly, exogenous miR-582-5p attenuated the production of pro-inflammatory cytokines such as tumor necrosis factor-alpha, interleukin-1 beta, and interleukin-6 through suppressing the degradation of the NF-κB inhibitor alpha, followed by the nuclear translocation of NF-κB. Therefore, exogenously applied miR-582-5p can attenuate the NF-κB signaling pathway via targeting Skp1; this provides a prospective therapeutic strategy for treating inflammatory and immune diseases.
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Affiliation(s)
- Rongzhi Li
- Department of Periodontology, Division of Oral Rehabilitation, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Tomomi Sano
- Department of Cell Biology, Aging Science, and Pharmacology, Division of Oral Biological Sciences, Faculty of Dental Science, Kyushu University, Fukuoka, Japan.
| | - Akiko Mizokami
- Oral, Brain and Total Health Science, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Takao Fukuda
- Department of Periodontology, Division of Oral Rehabilitation, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Takanori Shinjo
- Department of Periodontology, Division of Oral Rehabilitation, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Misaki Iwashita
- Department of Periodontology, Division of Oral Rehabilitation, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Akiko Yamashita
- Department of Periodontology, Division of Oral Rehabilitation, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Terukazu Sanui
- Department of Periodontology, Division of Oral Rehabilitation, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Yusuke Nakatsu
- Department of Biological Chemistry, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Yusuke Sotomaru
- Natural Science Center for Basic Research and Development, Hiroshima University, Hiroshima, Japan
| | - Tomoichiro Asano
- Department of Biological Chemistry, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Takashi Kanematsu
- Department of Cell Biology, Aging Science, and Pharmacology, Division of Oral Biological Sciences, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Fusanori Nishimura
- Department of Periodontology, Division of Oral Rehabilitation, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
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Thompson LL, Rutherford KA, Lepage CC, McManus KJ. Aberrant SKP1 Expression: Diverse Mechanisms Impacting Genome and Chromosome Stability. Front Cell Dev Biol 2022; 10:859582. [PMID: 35345853 PMCID: PMC8957228 DOI: 10.3389/fcell.2022.859582] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 02/22/2022] [Indexed: 11/26/2022] Open
Abstract
The S-phase Kinase-Associated Protein 1 (SKP1) is a core component of the SKP1, Cullin 1, F-box protein (SCF) complex, an E3 ubiquitin ligase that serves to poly-ubiquitinate a vast array of protein targets as a signal for their proteasomal degradation, thereby playing a critical role in the regulation of downstream biological processes. Many of the proteins regulated by SKP1 and the SCF complex normally function within pathways that are essential for maintaining genome stability, including DNA damage repair, apoptotic signaling, and centrosome dynamics. Accordingly, aberrant SKP1 and SCF complex expression and function is expected to disrupt these essential pathways, which may have pathological implications in diseases like cancer. In this review, we summarize the central role SKP1 plays in regulating essential cellular processes; we describe functional models in which SKP1 expression is altered and the corresponding impacts on genome stability; and we discuss the prevalence of SKP1 somatic copy number alterations, mutations, and altered protein expression across different cancer types, to identify a potential link between SKP1 and SCF complex dysfunction to chromosome/genome instability and cancer pathogenesis. Ultimately, understanding the role of SKP1 in driving chromosome instability will expand upon our rudimentary understanding of the key events required for genome/chromosome stability that may aid in our understanding of cancer pathogenesis, which will be critical for future studies to establish whether SKP1 may be useful as prognostic indicator or as a therapeutic target.
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Affiliation(s)
- Laura L Thompson
- CancerCare Manitoba Research Institute, CancerCare Manitoba, Winnipeg, MB, Canada.,Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, MB, Canada
| | - Kailee A Rutherford
- CancerCare Manitoba Research Institute, CancerCare Manitoba, Winnipeg, MB, Canada.,Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, MB, Canada
| | - Chloe C Lepage
- CancerCare Manitoba Research Institute, CancerCare Manitoba, Winnipeg, MB, Canada.,Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, MB, Canada
| | - Kirk J McManus
- CancerCare Manitoba Research Institute, CancerCare Manitoba, Winnipeg, MB, Canada.,Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, MB, Canada
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Kinterová V, Kaňka J, Bartková A, Toralová T. SCF Ligases and Their Functions in Oogenesis and Embryogenesis-Summary of the Most Important Findings throughout the Animal Kingdom. Cells 2022; 11:cells11020234. [PMID: 35053348 PMCID: PMC8774150 DOI: 10.3390/cells11020234] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 01/07/2022] [Accepted: 01/09/2022] [Indexed: 12/10/2022] Open
Abstract
SCF-dependent proteolysis was first discovered via genetic screening of budding yeast almost 25 years ago. In recent years, more and more functions of SCF (Skp1-Cullin 1-F-box) ligases have been described, and we can expect the number of studies on this topic to increase. SCF ligases, which are E3 ubiquitin multi-protein enzymes, catalyse protein ubiquitination and thus allow protein degradation mediated by the 26S proteasome. They play a crucial role in the degradation of cell cycle regulators, regulation of the DNA repair and centrosome cycle and play an important role in several diseases. SCF ligases seem to be needed during all phases of development, from oocyte formation through fertilization, activation of the embryonic genome to embryo implantation. In this review, we summarize known data on SCF ligase-mediated degradation during oogenesis and embryogenesis. In particular, SCFβTrCP and SCFSEL-10/FBXW7 are among the most important and best researched ligases during early development. SCFβTrCP is crucial for the oogenesis of Xenopus and mouse and also in Xenopus and Drosophila embryogenesis. SCFSEL-10/FBXW7 participates in the degradation of several RNA-binding proteins and thereby affects the regulation of gene expression during the meiosis of C. elegans. Nevertheless, a large number of SCF ligases that are primarily involved in embryogenesis remain to be elucidated.
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Affiliation(s)
- Veronika Kinterová
- Laboratory of Developmental Biology, Institute of Animal Physiology and Genetics of the Czech Academy of Sciences, 27721 Libechov, Czech Republic; (J.K.); (A.B.); (T.T.)
- Correspondence:
| | - Jiří Kaňka
- Laboratory of Developmental Biology, Institute of Animal Physiology and Genetics of the Czech Academy of Sciences, 27721 Libechov, Czech Republic; (J.K.); (A.B.); (T.T.)
| | - Alexandra Bartková
- Laboratory of Developmental Biology, Institute of Animal Physiology and Genetics of the Czech Academy of Sciences, 27721 Libechov, Czech Republic; (J.K.); (A.B.); (T.T.)
- Faculty of Natural Sciences, Constantine the Philosopher University in Nitra, 949 01 Nitra, Slovakia
| | - Tereza Toralová
- Laboratory of Developmental Biology, Institute of Animal Physiology and Genetics of the Czech Academy of Sciences, 27721 Libechov, Czech Republic; (J.K.); (A.B.); (T.T.)
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10
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Dabool L, Hakim-Mishnaevski K, Juravlev L, Flint-Brodsly N, Mandel S, Kurant E. Drosophila Skp1 Homologue SkpA Plays a Neuroprotective Role in Adult Brain. iScience 2020; 23:101375. [PMID: 32739834 PMCID: PMC7399183 DOI: 10.1016/j.isci.2020.101375] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 06/14/2020] [Accepted: 07/14/2020] [Indexed: 11/17/2022] Open
Abstract
Skp1, a component of the ubiquitin E3 ligases, was found to be decreased in the brains of sporadic Parkinson's disease (PD) patients, and its overexpression prevented death of murine neurons in culture. Here we expose the neuroprotective role of the Drosophila skp1 homolog, skpA, in the adult brain. Neuronal knockdown of skpA leads to accumulation of ubiquitinated protein aggregates and loss of dopaminergic neurons accompanied by motor dysfunction and reduced lifespan. Conversely, neuronal overexpression of skpA reduces aggregate load, improves age-related motor decline, and prolongs lifespan. Moreover, SkpA rescues neurodegeneration in a Drosophila model of PD. We also show that a Drosophila homolog of FBXO7, the F Box protein, Nutcracker (Ntc), works in the same pathway with SkpA. However, skpA overexpression rescues ntc knockdown phenotype, suggesting that SkpA interacts with additional F box proteins in the adult brain neurons. Collectively, our study discloses Skp1/SkpA as a potential therapeutic target in neurodegenerative diseases. SkpA-mediated protein degradation is required for normal function of the adult brain SkpA overexpression rescues neurodegeneration in α-synuclein-induced fly PD model SkpA and Ntc work in the same pathway of protein degradation in adult brain neurons
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Affiliation(s)
- Lital Dabool
- Department of Human Biology, Faculty of Natural Sciences, University of Haifa, 199 Aba Khoushy Avenue, Mount Carmel, Haifa 34988-38, Israel; The Rappaport Family Institute for Research in the Medical Sciences, Faculty of Medicine, Technion - Israel Institute of Technology, Haifa 31096, Israel
| | - Ketty Hakim-Mishnaevski
- Department of Human Biology, Faculty of Natural Sciences, University of Haifa, 199 Aba Khoushy Avenue, Mount Carmel, Haifa 34988-38, Israel
| | - Liza Juravlev
- Department of Human Biology, Faculty of Natural Sciences, University of Haifa, 199 Aba Khoushy Avenue, Mount Carmel, Haifa 34988-38, Israel
| | - Naama Flint-Brodsly
- Department of Human Biology, Faculty of Natural Sciences, University of Haifa, 199 Aba Khoushy Avenue, Mount Carmel, Haifa 34988-38, Israel
| | - Silvia Mandel
- The Rappaport Family Institute for Research in the Medical Sciences, Faculty of Medicine, Technion - Israel Institute of Technology, Haifa 31096, Israel
| | - Estee Kurant
- Department of Human Biology, Faculty of Natural Sciences, University of Haifa, 199 Aba Khoushy Avenue, Mount Carmel, Haifa 34988-38, Israel; The Rappaport Family Institute for Research in the Medical Sciences, Faculty of Medicine, Technion - Israel Institute of Technology, Haifa 31096, Israel.
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11
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Tarazona S, Bernabeu E, Carmona H, Gómez-Giménez B, García-Planells J, Leonards PEG, Jung S, Conesa A, Felipo V, Llansola M. A Multiomics Study To Unravel the Effects of Developmental Exposure to Endosulfan in Rats: Molecular Explanation for Sex-Dependent Effects. ACS Chem Neurosci 2019; 10:4264-4279. [PMID: 31464424 DOI: 10.1021/acschemneuro.9b00304] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Exposure to low levels of environmental contaminants, including pesticides, induces neurodevelopmental toxicity. Environmental and food contaminants can reach the brain of the fetus, affecting brain development and leading to neurological dysfunction. The pesticide endosulfan is a persistent pollutant, and significant levels still remain detectable in the environment although its use is banned in some countries. In rats, endosulfan exposure during brain development alters motor activity, coordination, learning, and memory, even several months after uptake, and does so in a sex-dependent way. However, the molecular mechanisms driving these effects have not been studied in detail. In this work, we performed a multiomics study in cerebellum from rats exposed to endosulfan during embryonic development. Pregnant rats were orally exposed to a low dose (0.5 mg/kg) of endosulfan, daily, from gestational day 7 to postnatal day 21. The progeny was evaluated for cognitive and motor functions at adulthood. Expression of messenger RNA and microRNA genes, as well as protein and metabolite levels, were measured on cerebellar samples from males and females. An integrative analysis was conducted to identify altered processes under endosulfan effect. Effects between males and females were compared. Pathways significantly altered by endosulfan exposure included the phosphatidylinositol signaling system, calcium signaling, the cGMP-PKG pathway, the inflammatory and immune system, protein processing in the endoplasmic reticulum, and GABA and taurine metabolism. Sex-dependent effects of endosulfan in the omics results that matched sex differences in cognitive and motor tests were found. These results shed light on the molecular basis of impaired neurodevelopment and contribute to the identification of new biomarkers of neurotoxicity.
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Affiliation(s)
- Sonia Tarazona
- Department of Genomics of Gene Expression, Centro de Investigación Príncipe Felipe, 46012 Valencia, Spain
- Department of Applied Statistics, Operations Research and Quality, Universitat Politècnica de València, 46022 Valencia, Spain
| | - Elena Bernabeu
- Department of Genomics of Gene Expression, Centro de Investigación Príncipe Felipe, 46012 Valencia, Spain
| | - Héctor Carmona
- Department of Genomics of Gene Expression, Centro de Investigación Príncipe Felipe, 46012 Valencia, Spain
| | - Belén Gómez-Giménez
- Laboratory of Neurobiology, Centro de Investigación Príncipe Felipe, 46012 Valencia, Spain
| | - Javier García-Planells
- IMEGEN, Instituto de Medicina Genómica, S.L. Parc Científic de la Universitat de València, 46980 Paterna, Spain
| | - Pim E. G. Leonards
- Department of Environment & Health, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands
| | - Stephan Jung
- Proteome Sciences R&D GmbH & Co. KG, 60438 Frankfurt, Germany
| | - Ana Conesa
- Microbiology and Cell Science Department, Institute for Food and Agricultural Sciences, University of Florida, Gainesville, Florida 32603, United States
- Genetics Institute, University of Florida, Gainesville, Florida 32603, United States
| | - Vicente Felipo
- Laboratory of Neurobiology, Centro de Investigación Príncipe Felipe, 46012 Valencia, Spain
| | - Marta Llansola
- Laboratory of Neurobiology, Centro de Investigación Príncipe Felipe, 46012 Valencia, Spain
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12
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Pajarillo E, Rizor A, Lee J, Aschner M, Lee E. The role of posttranslational modifications of α-synuclein and LRRK2 in Parkinson's disease: Potential contributions of environmental factors. Biochim Biophys Acta Mol Basis Dis 2018; 1865:1992-2000. [PMID: 30481588 PMCID: PMC6534484 DOI: 10.1016/j.bbadis.2018.11.017] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 10/29/2018] [Accepted: 11/19/2018] [Indexed: 12/20/2022]
Abstract
Parkinson's disease (PD) is the second most common neurodegenerative disease after Alzheimer's disease (AD), and the most prevalent movement disorder. PD is characterized by dopaminergic neurodegeneration in the substantia nigra, but its etiology has yet to be established. Among several genetic variants contributing to PD pathogenesis, α-synuclein and leucine-rich repeat kinase (LRRK2) are widely associated with neuropathological phenotypes in familial and sporadic PD. α-Synuclein and LRRK2 found in Lewy bodies, a pathogenic hallmark of PD, are often posttranslationally modified. As posttranslational modifications (PTMs) are key processes in regulating the stability, localization, and function of proteins, PTMs have emerged as important modulators of α-synuclein and LRRK2 pathology. Aberrant PTMs altering phosphorylation, ubiquitination, nitration and truncation of these proteins promote PD pathogenesis, while other PTMs such as sumoylation may be protective. Although the causes of many aberrant PTMs are unknown, environmental risk factors may contribute to their aberrancy. Environmental toxicants such as rotenone and paraquat have been shown to interact with these proteins and promote their abnormal PTMs. Notably, manganese (Mn) exposure leads to a PD-like neurological disorder referred to as manganism-and induces pathogenic PTMs of α-synuclein and LRRK2. In this review, we highlight the role of PTMs of α-synuclein and LRRK2 in PD pathogenesis and discuss the impact of environmental risk factors on their aberrancy.
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Affiliation(s)
- Edward Pajarillo
- Department of Pharmaceutical Sciences, College of Pharmacy, Florida A&M University, Tallahassee, FL 32301, United States of America
| | - Asha Rizor
- Department of Pharmaceutical Sciences, College of Pharmacy, Florida A&M University, Tallahassee, FL 32301, United States of America
| | - Jayden Lee
- Department of Speech, Language & Hearing Sciences, Boston University, Boston, MA 02215, United States of America
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, United States of America
| | - Eunsook Lee
- Department of Pharmaceutical Sciences, College of Pharmacy, Florida A&M University, Tallahassee, FL 32301, United States of America.
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13
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Differential Alterations in Metabolism and Proteolysis-Related Proteins in Human Parkinson's Disease Substantia Nigra. Neurotox Res 2017; 33:560-568. [PMID: 29218503 DOI: 10.1007/s12640-017-9843-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 11/13/2017] [Accepted: 11/21/2017] [Indexed: 12/31/2022]
Abstract
Parkinson's disease is the most common neurodegenerative disorder after Alzheimer's disease, with the majority of cases being sporadic or "idiopathic". The aetiology of the sporadic form is still unknown, but there is a broad consensus that Parkinson's disease involves multiple pathways. In previous human post-mortem studies investigating substantia nigra of parkinsonian subjects, gene expression alterations in various metabolic pathways including protein folding, trafficking, aggregation, ubiquitination and oxidative stress were found. These studies revealed transcriptomic dysregulation of various genes, amongst others Skp1A and PSMC4 (part of ubiquitin-proteasome system), HSC70 (belonging to the chaperone family) and ALDH1A1 (an enzyme involved in the catabolism of dopamine). To investigate whether these alterations are manifested at the protein level, we performed immunohistochemical analysis in the substantia nigra of Parkinson's disease and compared them to Alzheimer's disease and non-neurological post-mortem controls. We were able to confirm cell-specific reductions in the protein content of ALHD1A1 and Skp1A in the dopaminergic neurons of the substantia nigra of Parkinsonian patients compared to Alzheimer's and control subjects. Furthermore, we observed particular distribution for HSC70 and PSMC4 in the cytoplasm and accumulation within Lewy body in the dopaminergic neurons of the substantia nigra in Parkinson patients. These findings, together with previous evidence, suggest a malfunction of the ubiquitin-proteasome and possible autophagy systems as major players in protein misfolding and aggregation in Parkinson's disease. Nevertheless, this needs further proof, possibly with trajectory time line.
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14
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Jöhnk B, Bayram Ö, Abelmann A, Heinekamp T, Mattern DJ, Brakhage AA, Jacobsen ID, Valerius O, Braus GH. SCF Ubiquitin Ligase F-box Protein Fbx15 Controls Nuclear Co-repressor Localization, Stress Response and Virulence of the Human Pathogen Aspergillus fumigatus. PLoS Pathog 2016; 12:e1005899. [PMID: 27649508 PMCID: PMC5029927 DOI: 10.1371/journal.ppat.1005899] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 08/26/2016] [Indexed: 01/27/2023] Open
Abstract
F-box proteins share the F-box domain to connect substrates of E3 SCF ubiquitin RING ligases through the adaptor Skp1/A to Cul1/A scaffolds. F-box protein Fbx15 is part of the general stress response of the human pathogenic mold Aspergillus fumigatus. Oxidative stress induces a transient peak of fbx15 expression, resulting in 3x elevated Fbx15 protein levels. During non-stress conditions Fbx15 is phosphorylated and F-box mediated interaction with SkpA preferentially happens in smaller subpopulations in the cytoplasm. The F-box of Fbx15 is required for an appropriate oxidative stress response, which results in rapid dephosphorylation of Fbx15 and a shift of the cellular interaction with SkpA to the nucleus. Fbx15 binds SsnF/Ssn6 as part of the RcoA/Tup1-SsnF/Ssn6 co-repressor and is required for its correct nuclear localization. Dephosphorylated Fbx15 prevents SsnF/Ssn6 nuclear localization and results in the derepression of gliotoxin gene expression. fbx15 deletion mutants are unable to infect immunocompromised mice in a model for invasive aspergillosis. Fbx15 has a novel dual molecular function by controlling transcriptional repression and being part of SCF E3 ubiquitin ligases, which is essential for stress response, gliotoxin production and virulence in the opportunistic human pathogen A. fumigatus. The opportunistic human fungal pathogen Aspergillus fumigatus is the most prevalent cause for severe fungal infections in immunocompromised hosts. A major virulence factor of A. fumigatus is its ability to rapidly adapt to host conditions during infection. The rapid response to environmental changes underlies a well-balanced system of production and degradation of proteins. The degradation of specific target proteins is mediated by ubiquitin-protein ligases (E3), which mark their target proteins with ubiquitin for proteasomal degradation. Multisubunit SCF Cullin1 Ring ligases (CRL) are E3 ligases where the F-box subunit functions as a substrate-specificity determining adaptor. A comprehensive control of protein production includes global co-repressors as the conserved Ssn6(SsnF)-Tup1(RcoA) complex, which reduces transcription on multiple levels. We have identified a novel connection between protein degradation and synthesis through an F-box protein. Fbx15 can be incorporated into SCF E3 ubiquitin ligases and controls upon stress the nuclear localization of the SsnF. Fbx15 plays a critical role for A. fumigatus adaptation and is essential for virulence in a murine infection model. Fbx15 is a fungal-specific protein and therefore a potential target for future drug development.
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Affiliation(s)
- Bastian Jöhnk
- Department of Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Georg-August-University, Göttingen, Germany
| | - Özgür Bayram
- Department of Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Georg-August-University, Göttingen, Germany
- Department of Biology, Maynooth University, National University of Ireland, Maynooth, County Kildare, Ireland
| | - Anja Abelmann
- Department of Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Georg-August-University, Göttingen, Germany
| | - Thorsten Heinekamp
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Friedrich Schiller University, Jena, Germany
| | - Derek J. Mattern
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Friedrich Schiller University, Jena, Germany
| | - Axel A. Brakhage
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Friedrich Schiller University, Jena, Germany
| | - Ilse D. Jacobsen
- Research Group Microbial Immunology, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Friedrich Schiller University, Jena, Germany
| | - Oliver Valerius
- Department of Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Georg-August-University, Göttingen, Germany
| | - Gerhard H. Braus
- Department of Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Georg-August-University, Göttingen, Germany
- * E-mail:
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15
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Benesova V, Kinterova V, Kanka J, Toralova T. Characterization of SCF-Complex during Bovine Preimplantation Development. PLoS One 2016; 11:e0147096. [PMID: 26824694 PMCID: PMC4732672 DOI: 10.1371/journal.pone.0147096] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 12/30/2015] [Indexed: 12/28/2022] Open
Abstract
The degradation of maternal proteins is one of the most important events during early development, and it is presumed to be essential for embryonic genome activation (EGA), but the precise mechanism is still not known. It is thought that a large proportion of the degradation of maternal proteins is mediated by the ubiquitin-proteolytic system. In this study we focused on the expression of the Skp1-Cullin1-F-box (SCF) complex, a modular RING-type E3 ubiquitin-ligase, during bovine preimplantation development. The complex consists of three invariable components—Cul1, Skp1, Rbx1 and F-box protein, which determines the substrate specificity. The protein level and mRNA expression of all three invariable members were determined. Cul1 and Skp1 mRNA synthesis was activated at early embryonic stages, at the 4c and early 8c stage, respectively, which suggests that these transcripts are necessary for preparing the embryo for EGA. CUL1 protein level increased from MII to the morula stage, with a significant difference between MII and L8c, and between MII and the morula. The CUL1 protein was localized primarily to nuclei and to a lesser extent to the cytoplasm, with a lower signal in the inner cell mass (ICM) compared to the trophectoderm (TE) at the blastocyst stage. The level of SKP1 protein significantly increased from MII oocytes to 4c embryos, but then significantly decreased again. The localization of the SKP1 protein was analysed throughout the cell and similarly to CUL1 at the blastocyst stage, the staining was less intensive in the ICM. There were no statistical differences in RBX1 protein level and localization. The active SCF-complex, which is determined by the interaction of Cul1 and Skp1, was found throughout the whole embryo during preimplantation development, but there was a difference at the blastocyst stage, which exhibits a much stronger signal in the TE than in the ICM. These results suggest that all these genes could play an important role during preimplantation development. This paper reveals comprehensive expression profile, the basic but important knowledge necessary for further studying.
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Affiliation(s)
- Veronika Benesova
- Laboratory of Developmental Biology, Institute of Animal Physiology and Genetics Academy of Science of Czech Republic, v.v.i., Libechov, Czech Republic
- Faculty of Science, Charles University in Prague, Prague, Czech Republic
- * E-mail:
| | - Veronika Kinterova
- Laboratory of Developmental Biology, Institute of Animal Physiology and Genetics Academy of Science of Czech Republic, v.v.i., Libechov, Czech Republic
- Department of Veterinary Sciences, Czech University of Life Sciences in Prague, Prague, Czech Republic
| | - Jiri Kanka
- Laboratory of Developmental Biology, Institute of Animal Physiology and Genetics Academy of Science of Czech Republic, v.v.i., Libechov, Czech Republic
| | - Tereza Toralova
- Laboratory of Developmental Biology, Institute of Animal Physiology and Genetics Academy of Science of Czech Republic, v.v.i., Libechov, Czech Republic
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16
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Abstract
Poly-glutamine (polyQ) diseases are neurodegenerative disorders characterised by expanded CAG repeats in the causative genes whose proteins form inclusion bodies. Various E3 ubiquitin ligases are implicated in neurodegenerative disorders. We report that dysfunction of the SCF (Skp1-Cul1-F-box protein) complex, one of the most well-characterised ubiquitin ligases, is associated with pathology in polyQ diseases like Huntington's disease (HD) and Machado–Joseph disease (MJD). We found that Cullin1 (Cul1) and Skp1, core components of the SCF complex, are reduced in HD mice brain. A reduction in Cul1 levels was also observed in cellular HD model and fly models of both HD and MJD. We show that Cul1 is able to genetically modify mutant huntingtin aggregates because its silencing results in increased aggregate load in cultured cells. Moreover, we demonstrate that silencing dCul1 and dSkp1 in Drosophila results in increased aggregate load and enhanced polyQ-induced toxicity. Our results imply that reduced levels of SCF complex might contribute to polyQ disease pathology.
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