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Wainwright SM, Hopkins BR, Mendes CC, Sekar A, Kroeger B, Hellberg JEEU, Fan SJ, Pavey A, Marie PP, Leiblich A, Sepil I, Charles PD, Thézénas ML, Fischer R, Kessler BM, Gandy C, Corrigan L, Patel R, Wigby S, Morris JF, Goberdhan DCI, Wilson C. Drosophila Sex Peptide controls the assembly of lipid microcarriers in seminal fluid. Proc Natl Acad Sci U S A 2021; 118:e2019622118. [PMID: 33495334 PMCID: PMC7865141 DOI: 10.1073/pnas.2019622118] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Seminal fluid plays an essential role in promoting male reproductive success and modulating female physiology and behavior. In the fruit fly, Drosophila melanogaster, Sex Peptide (SP) is the best-characterized protein mediator of these effects. It is secreted from the paired male accessory glands (AGs), which, like the mammalian prostate and seminal vesicles, generate most of the seminal fluid contents. After mating, SP binds to spermatozoa and is retained in the female sperm storage organs. It is gradually released by proteolytic cleavage and induces several long-term postmating responses, including increased ovulation, elevated feeding, and reduced receptivity to remating, primarily signaling through the SP receptor (SPR). Here, we demonstrate a previously unsuspected SPR-independent function for SP. We show that, in the AG lumen, SP and secreted proteins with membrane-binding anchors are carried on abundant, large neutral lipid-containing microcarriers, also found in other SP-expressing Drosophila species. These microcarriers are transferred to females during mating where they rapidly disassemble. Remarkably, SP is a key microcarrier assembly and disassembly factor. Its absence leads to major changes in the seminal proteome transferred to females upon mating. Males expressing nonfunctional SP mutant proteins that affect SP's binding to and release from sperm in females also do not produce normal microcarriers, suggesting that this male-specific defect contributes to the resulting widespread abnormalities in ejaculate function. Our data therefore reveal a role for SP in formation of seminal macromolecular assemblies, which may explain the presence of SP in Drosophila species that lack the signaling functions seen in Dmelanogaster.
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Feneberg E, Charles PD, Finelli MJ, Scott C, Kessler BM, Fischer R, Ansorge O, Gray E, Talbot K, Turner MR. Detection and quantification of novel C-terminal TDP-43 fragments in ALS-TDP. Brain Pathol 2021; 31:e12923. [PMID: 33300249 PMCID: PMC8412074 DOI: 10.1111/bpa.12923] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 11/13/2020] [Accepted: 12/07/2020] [Indexed: 12/25/2022] Open
Abstract
The pathological hallmark of amyotrophic lateral sclerosis (ALS) is the presence of cytoplasmic inclusions, containing C-terminal fragments of the protein TDP-43. Here, we tested the hypothesis that highly sensitive mass spectrometry with parallel reaction monitoring (MS-PRM) can generate a high-resolution map of pathological TDP-43 peptide ratios to form the basis for quantitation of abnormal C-terminal TDP-43 fragment enrichment. Human cortex and spinal cord, microscopically staged for the presence of p-TDP-43, p-tau, alpha-synuclein, and beta-amyloid pathology, were biochemically fractionated and analyzed by immunoblot and MS for the detection of full-length and truncated (disease-specific) TDP-43 peptides. This informed the synthesis of heavy isotope-labeled peptides for absolute quantification of TDP-43 by MS-PRM across 16 ALS, 8 Parkinson's, 8 Alzheimer's disease, and 8 aged control cases. We confirmed by immunoblot the previously described enrichment of pathological C-terminal fragments in ALS-TDP urea fractions. Subsequent MS analysis resolved specific TDP-43 N- and C-terminal peptides, including a novel N-terminal truncation site-specific peptide. Absolute quantification of peptides by MS-PRM showed an increased C:N-terminal TDP-43 peptide ratio in ALS-TDP brain compared to normal and disease controls. A C:N-terminal ratio >1.5 discriminated ALS from controls with a sensitivity of 100% (CI 79.6-100) and specificity of 100% (CI 68-100), and from Parkinson's and Alzheimer's disease with a sensitivity of 93% (CI 70-100) and specificity of 100% (CI 68-100). N-terminal truncation site-specific peptides were increased in ALS in line with C-terminal fragment enrichment, but were also found in a proportion of Alzheimer cases with normal C:N-terminal ratio but coexistent limbic TDP-43 neuropathological changes. In conclusion this is a novel, sensitive, and specific method to quantify the enrichment of pathological TDP-43 fragments in human brain, which could form the basis for an antibody-free assay. Our methodology has the potential to help clarify if specific pathological TDP-43 peptide signatures are associated with primary or secondary TDP-43 proteinopathies.
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Shorrocks AMK, Jones SE, Tsukada K, Morrow CA, Belblidia Z, Shen J, Vendrell I, Fischer R, Kessler BM, Blackford AN. The Bloom syndrome complex senses RPA-coated single-stranded DNA to restart stalled replication forks. Nat Commun 2021; 12:585. [PMID: 33500419 PMCID: PMC7838300 DOI: 10.1038/s41467-020-20818-5] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Accepted: 12/22/2020] [Indexed: 01/30/2023] Open
Abstract
The Bloom syndrome helicase BLM interacts with topoisomerase IIIα (TOP3A), RMI1 and RMI2 to form the BTR complex, which dissolves double Holliday junctions to produce non-crossover homologous recombination (HR) products. BLM also promotes DNA-end resection, restart of stalled replication forks, and processing of ultra-fine DNA bridges in mitosis. How these activities of the BTR complex are regulated in cells is still unclear. Here, we identify multiple conserved motifs within the BTR complex that interact cooperatively with the single-stranded DNA (ssDNA)-binding protein RPA. Furthermore, we demonstrate that RPA-binding is required for stable BLM recruitment to sites of DNA replication stress and for fork restart, but not for its roles in HR or mitosis. Our findings suggest a model in which the BTR complex contains the intrinsic ability to sense levels of RPA-ssDNA at replication forks, which controls BLM recruitment and activation in response to replication stress.
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Harris LD, Le Pen J, Scholz N, Mieszczanek J, Vaughan N, Davis S, Berridge G, Kessler BM, Bienz M, Licchesi JDF. The deubiquitinase TRABID stabilizes the K29/K48-specific E3 ubiquitin ligase HECTD1. J Biol Chem 2021; 296:100246. [PMID: 33853758 PMCID: PMC7948964 DOI: 10.1074/jbc.ra120.015162] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 12/23/2020] [Accepted: 12/30/2020] [Indexed: 12/18/2022] Open
Abstract
Ubiquitin is a versatile posttranslational modification, which is covalently attached to protein targets either as a single moiety or as a ubiquitin chain. In contrast to K48 and K63-linked chains, which have been extensively studied, the regulation and function of most atypical ubiquitin chains are only starting to emerge. The deubiquitinase TRABID/ZRANB1 is tuned for the recognition and cleavage of K29 and K33-linked chains. Yet, substrates of TRABID and the cellular functions of these atypical ubiquitin signals remain unclear. We determined the interactome of two TRABID constructs rendered catalytic dead either through a point mutation in the catalytic cysteine residue or through removal of the OTU catalytic domain. We identified 50 proteins trapped by both constructs and which therefore represent candidate substrates of TRABID. The E3 ubiquitin ligase HECTD1 was then validated as a substrate of TRABID and used UbiCREST and Ub-AQUA proteomics to show that HECTD1 preferentially assembles K29- and K48-linked ubiquitin chains. Further in vitro autoubiquitination assays using ubiquitin mutants established that while HECTD1 can assemble short homotypic K29 and K48-linked chains, it requires branching at K29/K48 in order to achieve its full ubiquitin ligase activity. We next used transient knockdown and genetic knockout of TRABID in mammalian cells in order to determine the functional relationship between TRABID and HECTD1. This revealed that upon TRABID depletion, HECTD1 is readily degraded. Thus, this study identifies HECTD1 as a mammalian E3 ligase that assembles branched K29/K48 chains and also establishes TRABID-HECTD1 as a DUB/E3 pair regulating K29 linkages.
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Chen O, Manig F, Lehmann L, Sorour N, Löck S, Yu Z, Dubrovska A, Baumann M, Kessler BM, Stasyk O, Kunz-Schughart LA. Dual role of ER stress in response to metabolic co-targeting and radiosensitivity in head and neck cancer cells. Cell Mol Life Sci 2020; 78:3021-3044. [PMID: 33230565 PMCID: PMC8004506 DOI: 10.1007/s00018-020-03704-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 10/19/2020] [Accepted: 11/04/2020] [Indexed: 12/12/2022]
Abstract
Arginine deprivation therapy (ADT) is a new metabolic targeting approach with high therapeutic potential for various solid cancers. Combination of ADT with low doses of the natural arginine analog canavanine effectively sensitizes malignant cells to irradiation. However, the molecular mechanisms determining the sensitivity of intrinsically non-auxotrophic cancers to arginine deficiency are still poorly understood. We here show for the first time that arginine deficiency is accompanied by global metabolic changes and protein/membrane breakdown, and results in the induction of specific, more or less pronounced (severe vs. mild) ER stress responses in head and neck squamous cell carcinoma (HNSCC) cells that differ in their intrinsic ADT sensitivity. Combination of ADT with canavanine triggered catastrophic ER stress via the eIF2α-ATF4(GADD34)-CHOP pathway, thereby inducing apoptosis; the same signaling arm was irrelevant in ADT-related radiosensitization. The particular strong supra-additive effect of ADT, canavanine and irradiation in both intrinsically more and less sensitive cancer cells supports the rational of ER stress pathways as novel target for improving multi-modal metabolic anti-cancer therapy.
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Thorne AM, Huang H, O'Brien DP, Eijken M, Krogstrup NV, Norregaard R, Møller B, Ploeg RJ, Jespersen B, Kessler BM. Subclinical effects of remote ischaemic conditioning in human kidney transplants revealed by quantitative proteomics. Clin Proteomics 2020; 17:39. [PMID: 33292164 PMCID: PMC7607690 DOI: 10.1186/s12014-020-09301-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2020] [Accepted: 10/10/2020] [Indexed: 01/13/2023] Open
Abstract
Background Remote ischaemic conditioning (RIC) is currently being explored as a non-invasive method to attenuate ischaemia/reperfusion injuries in organs. A randomised clinical study (CONTEXT) evaluated the effects of RIC compared to non-RIC controls in human kidney transplants. Methods RIC was induced prior to kidney reperfusion by episodes of obstruction to arterial flow in the leg opposite the transplant using a tourniquet (4 × 5 min). Although RIC did not lead to clinical improvement of transplant outcomes, we explored whether RIC induced molecular changes through precision analysis of CONTEXT recipient plasma and kidney tissue samples by high-resolution tandem mass spectrometry (MS/MS). Results We observed an accumulation of muscle derived proteins and altered amino acid metabolism in kidney tissue proteomes, likely provoked by RIC, which was not reflected in plasma. In addition, MS/MS analysis demonstrated transient upregulation of several acute phase response proteins (SAA1, SAA2, CRP) in plasma, 1 and 5 days post-transplant in RIC and non-RIC conditions with a variable effect on the magnitude of acute inflammation. Conclusions Together, our results indicate sub-clinical systemic and organ-localised effects of RIC.
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Peng Y, Mentzer AJ, Liu G, Yao X, Yin Z, Dong D, Dejnirattisai W, Rostron T, Supasa P, Liu C, López-Camacho C, Slon-Campos J, Zhao Y, Stuart DI, Paesen GC, Grimes JM, Antson AA, Bayfield OW, Hawkins DEDP, Ker DS, Wang B, Turtle L, Subramaniam K, Thomson P, Zhang P, Dold C, Ratcliff J, Simmonds P, de Silva T, Sopp P, Wellington D, Rajapaksa U, Chen YL, Salio M, Napolitani G, Paes W, Borrow P, Kessler BM, Fry JW, Schwabe NF, Semple MG, Baillie JK, Moore SC, Openshaw PJM, Ansari MA, Dunachie S, Barnes E, Frater J, Kerr G, Goulder P, Lockett T, Levin R, Zhang Y, Jing R, Ho LP, Cornall RJ, Conlon CP, Klenerman P, Screaton GR, Mongkolsapaya J, McMichael A, Knight JC, Ogg G, Dong T. Broad and strong memory CD4 + and CD8 + T cells induced by SARS-CoV-2 in UK convalescent individuals following COVID-19. Nat Immunol 2020; 21:1336-1345. [PMID: 32887977 PMCID: PMC7611020 DOI: 10.1038/s41590-020-0782-6] [Citation(s) in RCA: 845] [Impact Index Per Article: 211.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 08/11/2020] [Indexed: 01/08/2023]
Abstract
The development of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines and therapeutics will depend on understanding viral immunity. We studied T cell memory in 42 patients following recovery from COVID-19 (28 with mild disease and 14 with severe disease) and 16 unexposed donors, using interferon-γ-based assays with peptides spanning SARS-CoV-2 except ORF1. The breadth and magnitude of T cell responses were significantly higher in severe as compared with mild cases. Total and spike-specific T cell responses correlated with spike-specific antibody responses. We identified 41 peptides containing CD4+ and/or CD8+ epitopes, including six immunodominant regions. Six optimized CD8+ epitopes were defined, with peptide-MHC pentamer-positive cells displaying the central and effector memory phenotype. In mild cases, higher proportions of SARS-CoV-2-specific CD8+ T cells were observed. The identification of T cell responses associated with milder disease will support an understanding of protective immunity and highlights the potential of including non-spike proteins within future COVID-19 vaccine design.
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Olie CS, van der Wal E, Cikes D, Maton L, de Greef JC, Lin IH, Chen YF, Kareem E, Penninger JM, Kessler BM, Raz V. Cytoskeletal disorganization underlies PABPN1-mediated myogenic disability. Sci Rep 2020; 10:17621. [PMID: 33077830 PMCID: PMC7572364 DOI: 10.1038/s41598-020-74676-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 09/28/2020] [Indexed: 12/30/2022] Open
Abstract
Muscle wasting and atrophy are regulated by multiple molecular processes, including mRNA processing. Reduced levels of the polyadenylation binding protein nucleus 1 (PABPN1), a multifactorial regulator of mRNA processing, cause muscle atrophy. A proteomic study in muscles with reduced PABPN1 levels suggested dysregulation of sarcomeric and cytoskeletal proteins. Here we investigated the hypothesis that reduced PABPN1 levels lead to an aberrant organization of the cytoskeleton. MURC, a plasma membrane-associated protein, was found to be more abundant in muscles with reduced PABPN1 levels, and it was found to be expressed at regions showing regeneration. A polarized cytoskeletal organization is typical for muscle cells, but muscle cells with reduced PABPN1 levels (named as shPAB) were characterized by a disorganized cytoskeleton that lacked polarization. Moreover, cell mechanical features and myogenic differentiation were significantly reduced in shPAB cells. Importantly, restoring cytoskeletal stability, by actin overexpression, was beneficial for myogenesis, expression of sarcomeric proteins and proper localization of MURC in shPAB cell cultures and in shPAB muscle bundle. We suggest that poor cytoskeletal mechanical features are caused by altered expression levels of cytoskeletal proteins and contribute to muscle wasting and atrophy.
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Vere G, Kealy R, Kessler BM, Pinto-Fernandez A. Ubiquitomics: An Overview and Future. Biomolecules 2020; 10:E1453. [PMID: 33080838 PMCID: PMC7603029 DOI: 10.3390/biom10101453] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 10/13/2020] [Accepted: 10/14/2020] [Indexed: 12/12/2022] Open
Abstract
Covalent attachment of ubiquitin, a small globular polypeptide, to protein substrates is a key post-translational modification that determines the fate, function, and turnover of most cellular proteins. Ubiquitin modification exists as mono- or polyubiquitin chains involving multiple ways how ubiquitin C-termini are connected to lysine, perhaps other amino acid side chains, and N-termini of proteins, often including branching of the ubiquitin chains. Understanding this enormous complexity in protein ubiquitination, the so-called 'ubiquitin code', in combination with the ∼1000 enzymes involved in controlling ubiquitin recognition, conjugation, and deconjugation, calls for novel developments in analytical techniques. Here, we review different headways in the field mainly driven by mass spectrometry and chemical biology, referred to as "ubiquitomics", aiming to understand this system's biological diversity.
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Dwane L, O'Connor AE, Das S, Moran B, Mulrane L, Pinto-Fernandez A, Ward E, Blümel AM, Cavanagh BL, Mooney B, Dirac AM, Jirström K, Kessler BM, Ní Chonghaile T, Bernards R, Gallagher WM, O'Connor DP. A Functional Genomic Screen Identifies the Deubiquitinase USP11 as a Novel Transcriptional Regulator of ERα in Breast Cancer. Cancer Res 2020; 80:5076-5088. [PMID: 33004351 DOI: 10.1158/0008-5472.can-20-0214] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 06/26/2020] [Accepted: 09/15/2020] [Indexed: 01/23/2023]
Abstract
Approximately 70% of breast cancers express estrogen receptor α (ERα) and depend on this key transcriptional regulator for proliferation and differentiation. While patients with this disease can be treated with targeted antiendocrine agents, drug resistance remains a significant issue, with almost half of patients ultimately relapsing. Elucidating the mechanisms that control ERα function may further our understanding of breast carcinogenesis and reveal new therapeutic opportunities. Here, we investigated the role of deubiquitinases (DUB) in regulating ERα in breast cancer. An RNAi loss-of-function screen in breast cancer cells targeting all DUBs identified USP11 as a regulator of ERα transcriptional activity, which was further validated by assessment of direct transcriptional targets of ERα. USP11 expression was induced by estradiol, an effect that was blocked by tamoxifen and not observed in ERα-negative cells. Mass spectrometry revealed a significant change to the proteome and ubiquitinome in USP11-knockdown (KD) cells in the presence of estradiol. RNA sequencing in LCC1 USP11-KD cells revealed significant suppression of cell-cycle-associated and ERα target genes, phenotypes that were not observed in LCC9 USP11-KD, antiendocrine-resistant cells. In a breast cancer patient cohort coupled with in silico analysis of publicly available cohorts, high expression of USP11 was significantly associated with poor survival in ERα-positive (ERα+) patients. Overall, this study highlights a novel role for USP11 in the regulation of ERα activity, where USP11 may represent a prognostic marker in ERα+ breast cancer. SIGNIFICANCE: A newly identified role for USP11 in ERα transcriptional activity represents a novel mechanism of ERα regulation and a pathway to be exploited for the management of ER-positive breast cancer.
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Cusack M, King HW, Spingardi P, Kessler BM, Klose RJ, Kriaucionis S. Distinct contributions of DNA methylation and histone acetylation to the genomic occupancy of transcription factors. Genome Res 2020; 30:1393-1406. [PMID: 32963030 PMCID: PMC7605266 DOI: 10.1101/gr.257576.119] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 08/21/2020] [Indexed: 12/12/2022]
Abstract
Epigenetic modifications on chromatin play important roles in regulating gene expression. Although chromatin states are often governed by multilayered structure, how individual pathways contribute to gene expression remains poorly understood. For example, DNA methylation is known to regulate transcription factor binding but also to recruit methyl-CpG binding proteins that affect chromatin structure through the activity of histone deacetylase complexes (HDACs). Both of these mechanisms can potentially affect gene expression, but the importance of each, and whether these activities are integrated to achieve appropriate gene regulation, remains largely unknown. To address this important question, we measured gene expression, chromatin accessibility, and transcription factor occupancy in wild-type or DNA methylation-deficient mouse embryonic stem cells following HDAC inhibition. We observe widespread increases in chromatin accessibility at retrotransposons when HDACs are inhibited, and this is magnified when cells also lack DNA methylation. A subset of these elements has elevated binding of the YY1 and GABPA transcription factors and increased expression. The pronounced additive effect of HDAC inhibition in DNA methylation-deficient cells demonstrates that DNA methylation and histone deacetylation act largely independently to suppress transcription factor binding and gene expression.
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Feneberg E, Gordon D, Thompson AG, Finelli MJ, Dafinca R, Candalija A, Charles PD, Mäger I, Wood MJ, Fischer R, Kessler BM, Gray E, Turner MR, Talbot K. An ALS-linked mutation in TDP-43 disrupts normal protein interactions in the motor neuron response to oxidative stress. Neurobiol Dis 2020; 144:105050. [PMID: 32800996 DOI: 10.1016/j.nbd.2020.105050] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 07/19/2020] [Accepted: 08/08/2020] [Indexed: 02/06/2023] Open
Abstract
TDP-43 pathology is a key feature of amyotrophic lateral sclerosis (ALS), but the mechanisms linking TDP-43 to altered cellular function and neurodegeneration remain unclear. We have recently described a mouse model in which human wild-type or mutant TDP-43 are expressed at low levels and where altered stress granule formation is a robust phenotype of TDP-43M337V/- expressing cells. In the present study we use this model to investigate the functional connectivity of human TDP-43 in primary motor neurons under resting conditions and in response to oxidative stress. The interactome of human TDP-43WT or TDP-43M337V was compared by mass spectrometry, and gene ontology enrichment analysis identified pathways dysregulated by the M337V mutation. We found that under normal conditions the interactome of human TDP-43WT was enriched for proteins involved in transcription, translation and poly(A)-RNA binding. In response to oxidative stress, TDP-43WT recruits proteins of the endoplasmic reticulum and endosomal-extracellular transport pathways, interactions which are reduced in the presence of the M337V mutation. Specifically, TDP-43M337V impaired protein-protein interactions involved in stress granule formation including reduced binding to the translation initiation factors Poly(A)-binding protein and Eif4a1 and the endoplasmic reticulum chaperone Grp78. The M337V mutation also affected interactions involved in endosomal-extracellular transport and this this was associated with reduced extracellular vesicle secretion in primary motor neurons from TDP-43M337V/- mice and in human iPSCs-derived motor neurons. Taken together, our analysis highlights a TDP-43 interaction network in motor neurons and demonstrates that an ALS associated mutation may alter the interactome to drive aberrant pathways involved in the pathogenesis of ALS.
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Mulder MPC, Kessler BM. In Memoriam: Professor Huib Ovaa (1973-2020): A Uniquely Brilliant and Enthusiastic Scientist, a Pioneer in Chemical Biology and the Ubiquitin Field. Front Chem 2020. [PMCID: PMC7468445 DOI: 10.3389/fchem.2020.00627] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
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Thompson AG, Gray E, Mäger I, Thézénas ML, Charles PD, Talbot K, Fischer R, Kessler BM, Wood M, Turner MR. CSF extracellular vesicle proteomics demonstrates altered protein homeostasis in amyotrophic lateral sclerosis. Clin Proteomics 2020; 17:31. [PMID: 32821252 PMCID: PMC7433176 DOI: 10.1186/s12014-020-09294-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 08/07/2020] [Indexed: 02/06/2023] Open
Abstract
Background Extracellular vesicles (EVs) released by neurons and glia reach the cerebrospinal fluid (CSF). Studying the proteome of CSF-derived EVs offers a novel perspective on the key intracellular processes associated with the pathogenesis of the neurodegenerative disease amyotrophic lateral sclerosis (ALS) and a potential source from which to develop biomarkers. Methods CSF EVs were extracted using ultrafiltration liquid chromatography from ALS patients and controls. EV size distribution and concentration was measured using nanoparticle tracking analysis and liquid chromatography-tandem mass spectrometry proteomic analysis performed. Results CSF EV concentration and size distribution did not differ between ALS and control groups, nor between a sub-group of ALS patients with or without an associated hexanucleotide repeat expansion (HRE) in C9orf72. Univariate proteomic analysis identified downregulation of the pentameric proteasome-like protein Bleomycin hydrolase in ALS patients, whilst Gene Ontology enrichment analysis demonstrated downregulation of proteasome core complex proteins (8/8 proteins, normalized enrichment ratio -1.77, FDR-adjusted p = 0.057) in the ALS group. The sub-group of ALS patients associated with the C9orf72 HRE showed upregulation in Ubiquitin-like modifying-activating protein 1 (UBA1) compared to non-C9orf72 cases. Conclusions Proteomic analysis of CSF EVs in ALS detects intracellular alterations in protein homeostatic mechanisms, previously only identified in pathological tissues. This supports the wider use of CSF EVs as a source of novel biomarkers reflecting key and potentially druggable pathological intracellular pathway alterations in ALS.
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Pinto-Fernandez A, Greenwood H, Salio M, Chen J, Partridge T, Vere G, Scott HC, Damianou A, Borrow P, Muschel R, Cerundolo V, Kessler BM. Abstract LB-080: USP18 modulates the ISGylome, immune signaling and sensitizes tumor cells to irradiation and CTL recognition. Cancer Res 2020. [DOI: 10.1158/1538-7445.am2020-lb-080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
The innate immune response plays a critical role in modulating the efficacy of and mechanisms conferring resistance to immune checkpoint blockade (ICB) therapies in humans. A major negative regulator of the Interferon (IFN) stimulated gene (ISG) pathway, is the ubiquitin-specific protease 18 (USP18). USP18 is the predominant human deubiquitylating enzyme that processes Interferon Stimulated Gene 15 ISG15, a ubiquitin-like protein that covalently modifies protein substrates, a tightly regulated process in the context of innate immunity. In this study, using advanced mass spectrometry and chemical biology tools, we defined the USP18 Interactome and ISG15ylome in chronic myeloid leukemia (CML)-derived cells (HAP1) treated with Interferon alpha (IFNα). Novel ISG15ylation targets were characterized that reduce the sensing of innate ligands and secretion of cytokines. In addition, we show that USP18 deletion leads to enhanced ISG15ylation profiles. Furthermore, we demonstrate that CML USP18-/- cells are more antigenic, leading to increased activation of cytotoxic T lymphocytes (CTLs), and are more susceptible to irradiation. Our results reinforce the role of USP18 as a key “brake” for inflammatory signals in tumor cells. As USP18 expression is upregulated in lung, breast and colon cancers, USP18 pharmacological inhibition may reflect a target opportunity in cancer immunotherapy.
Citation Format: Adan Pinto-Fernandez, Helene Greenwood, Mariolina Salio, Jianzhou Chen, Thomas Partridge, George Vere, Hannah C. Scott, Andreas Damianou, Persephone Borrow, Ruth Muschel, Vincenzo Cerundolo, Benedikt M. Kessler. USP18 modulates the ISGylome, immune signaling and sensitizes tumor cells to irradiation and CTL recognition [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr LB-080.
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Sepil I, Hopkins BR, Dean R, Bath E, Friedman S, Swanson B, Ostridge HJ, Harper L, Buehner NA, Wolfner MF, Konietzny R, Thézénas ML, Sandham E, Charles PD, Fischer R, Steinhauer J, Kessler BM, Wigby S. Male reproductive aging arises via multifaceted mating-dependent sperm and seminal proteome declines, but is postponable in Drosophila. Proc Natl Acad Sci U S A 2020; 117:17094-17103. [PMID: 32611817 PMCID: PMC7382285 DOI: 10.1073/pnas.2009053117] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Declining ejaculate performance with male age is taxonomically widespread and has broad fitness consequences. Ejaculate success requires fully functional germline (sperm) and soma (seminal fluid) components. However, some aging theories predict that resources should be preferentially diverted to the germline at the expense of the soma, suggesting differential impacts of aging on sperm and seminal fluid and trade-offs between them or, more broadly, between reproduction and lifespan. While harmful effects of male age on sperm are well known, we do not know how much seminal fluid deteriorates in comparison. Moreover, given the predicted trade-offs, it remains unclear whether systemic lifespan-extending interventions could ameliorate the declining performance of the ejaculate as a whole. Here, we address these problems using Drosophila melanogaster. We demonstrate that seminal fluid deterioration contributes to male reproductive decline via mating-dependent mechanisms that include posttranslational modifications to seminal proteins and altered seminal proteome composition and transfer. Additionally, we find that sperm production declines chronologically with age, invariant to mating activity such that older multiply mated males become infertile principally via reduced sperm transfer and viability. Our data, therefore, support the idea that both germline and soma components of the ejaculate contribute to male reproductive aging but reveal a mismatch in their aging patterns. Our data do not generally support the idea that the germline is prioritized over soma, at least, within the ejaculate. Moreover, we find that lifespan-extending systemic down-regulation of insulin signaling results in improved late-life ejaculate performance, indicating simultaneous amelioration of both somatic and reproductive aging.
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Thanh TT, Casals-Pascual C, Ny NTH, Ngoc NM, Geskus R, Nhu LNT, Hong NTT, Duc DT, Thu DDA, Uyen PN, Ngoc VB, Chau LTM, Quynh VX, Hanh NHH, Thuong NTT, Diem LT, Hanh BTB, Hang VTT, Oanh PKN, Fischer R, Phu NH, Nghia HDT, Chau NVV, Hoa NT, Kessler BM, Thwaites G, Tan LV. Value of lipocalin 2 as a potential biomarker for bacterial meningitis. Clin Microbiol Infect 2020; 27:S1198-743X(20)30408-0. [PMID: 32659386 PMCID: PMC8128987 DOI: 10.1016/j.cmi.2020.07.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 06/30/2020] [Accepted: 07/04/2020] [Indexed: 12/16/2022]
Abstract
OBJECTIVES Central nervous system (CNS) infections are common causes of morbidity and mortality worldwide. We aimed to discover protein biomarkers that could rapidly and accurately identify the likely cause of the infections, essential for clinical management and improving outcome. METHODS We applied liquid chromatography tandem mass spectrometry on 45 cerebrospinal fluid (CSF) samples from a cohort of adults with and without CNS infections to discover potential diagnostic biomarkers. We then validated the diagnostic performance of a selected biomarker candidate in an independent cohort of 364 consecutively treated adults with CNS infections admitted to a referral hospital in Vietnam. RESULTS In the discovery cohort, we identified lipocalin 2 (LCN2) as a potential biomarker of bacterial meningitis (BM) other than tuberculous meningitis. The analysis of the validation cohort showed that LCN2 could discriminate BM from other CNS infections (including tuberculous meningitis, cryptococcal meningitis and virus/antibody-mediated encephalitis), with sensitivity of 0.88 (95% confident interval (CI), 0.77-0.94), specificity of 0.91 (95% CI, 0.88-0.94) and diagnostic odds ratio of 73.8 (95% CI, 31.8-171.4). LCN2 outperformed other CSF markers (leukocytes, glucose, protein and lactate) commonly used in routine care worldwide. The combination of LCN2, CSF leukocytes, glucose, protein and lactate resulted in the highest diagnostic performance for BM (area under the receiver operating characteristics curve, 0.96; 95% CI, 0.93-0.99). Data are available via ProteomeXchange with identifier PXD020510. CONCLUSIONS LCN2 is a sensitive and specific biomarker for discriminating BM from a broad spectrum of other CNS infections. A prospective study is needed to assess the diagnostic utility of LCN2 in the diagnosis and management of CNS infections.
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Rusilowicz-Jones EV, Jardine J, Kallinos A, Pinto-Fernandez A, Guenther F, Giurrandino M, Barone FG, McCarron K, Burke CJ, Murad A, Martinez A, Marcassa E, Gersch M, Buckmelter AJ, Kayser-Bricker KJ, Lamoliatte F, Gajbhiye A, Davis S, Scott HC, Murphy E, England K, Mortiboys H, Komander D, Trost M, Kessler BM, Ioannidis S, Ahlijanian MK, Urbé S, Clague MJ. USP30 sets a trigger threshold for PINK1-PARKIN amplification of mitochondrial ubiquitylation. Life Sci Alliance 2020; 3:3/8/e202000768. [PMID: 32636217 PMCID: PMC7362391 DOI: 10.26508/lsa.202000768] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 06/25/2020] [Accepted: 06/26/2020] [Indexed: 12/12/2022] Open
Abstract
A new inhibitor of the deubiquitylase USP30, an actionable target relevant to Parkinson’s Disease, is introduced and characterised for parameters related to mitophagy. The mitochondrial deubiquitylase USP30 negatively regulates the selective autophagy of damaged mitochondria. We present the characterisation of an N-cyano pyrrolidine compound, FT3967385, with high selectivity for USP30. We demonstrate that ubiquitylation of TOM20, a component of the outer mitochondrial membrane import machinery, represents a robust biomarker for both USP30 loss and inhibition. A proteomics analysis, on a SHSY5Y neuroblastoma cell line model, directly compares the effects of genetic loss of USP30 with chemical inhibition. We have thereby identified a subset of ubiquitylation events consequent to mitochondrial depolarisation that are USP30 sensitive. Within responsive elements of the ubiquitylome, several components of the outer mitochondrial membrane transport (TOM) complex are prominent. Thus, our data support a model whereby USP30 can regulate the availability of ubiquitin at the specific site of mitochondrial PINK1 accumulation following membrane depolarisation. USP30 deubiquitylation of TOM complex components dampens the trigger for the Parkin-dependent amplification of mitochondrial ubiquitylation leading to mitophagy. Accordingly, PINK1 generation of phospho-Ser65 ubiquitin proceeds more rapidly in cells either lacking USP30 or subject to USP30 inhibition.
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Fenech EJ, Lari F, Charles PD, Fischer R, Laétitia-Thézénas M, Bagola K, Paton AW, Paton JC, Gyrd-Hansen M, Kessler BM, Christianson JC. Interaction mapping of endoplasmic reticulum ubiquitin ligases identifies modulators of innate immune signalling. eLife 2020; 9:e57306. [PMID: 32614325 PMCID: PMC7332293 DOI: 10.7554/elife.57306] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 06/11/2020] [Indexed: 12/25/2022] Open
Abstract
Ubiquitin ligases (E3s) embedded in the endoplasmic reticulum (ER) membrane regulate essential cellular activities including protein quality control, calcium flux, and sterol homeostasis. At least 25 different, transmembrane domain (TMD)-containing E3s are predicted to be ER-localised, but for most their organisation and cellular roles remain poorly defined. Using a comparative proteomic workflow, we mapped over 450 protein-protein interactions for 21 stably expressed, full-length E3s. Bioinformatic analysis linked ER-E3s and their interactors to multiple homeostatic, regulatory, and metabolic pathways. Among these were four membrane-embedded interactors of RNF26, a polytopic E3 whose abundance is auto-regulated by ubiquitin-proteasome dependent degradation. RNF26 co-assembles with TMEM43, ENDOD1, TMEM33 and TMED1 to form a complex capable of modulating innate immune signalling through the cGAS-STING pathway. This RNF26 complex represents a new modulatory axis of STING and innate immune signalling at the ER membrane. Collectively, these data reveal the broad scope of regulation and differential functionalities mediated by ER-E3s for both membrane-tethered and cytoplasmic processes.
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Mulder MPC, Zhuang Z, Liu L, Kessler BM, Ovaa H. Editorial: Probing the Ubiquitin Landscape. Front Chem 2020; 8:449. [PMID: 32509738 PMCID: PMC7251165 DOI: 10.3389/fchem.2020.00449] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 04/29/2020] [Indexed: 11/13/2022] Open
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Bálint Š, Müller S, Fischer R, Kessler BM, Harkiolaki M, Valitutti S, Dustin ML. Supramolecular attack particles are autonomous killing entities released from cytotoxic T cells. Science 2020; 368:897-901. [PMID: 32381591 DOI: 10.1126/science.aay9207] [Citation(s) in RCA: 89] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 01/28/2020] [Accepted: 04/09/2020] [Indexed: 12/15/2022]
Abstract
Cytotoxic T lymphocytes (CTLs) kill infected and cancerous cells. We detected transfer of cytotoxic multiprotein complexes, called supramolecular attack particles (SMAPs), from CTLs to target cells. SMAPs were rapidly released from CTLs and were autonomously cytotoxic. Mass spectrometry, immunochemical analysis, and CRISPR editing identified a carboxyl-terminal fragment of thrombospondin-1 as an unexpected SMAP component that contributed to target killing. Direct stochastic optical reconstruction microscopy resolved a cytotoxic core surrounded by a thrombospondin-1 shell of ~120 nanometer diameter. Cryo-soft x-ray tomography analysis revealed that SMAPs had a carbon-dense shell and were stored in multicore granules. We propose that SMAPs are autonomous extracellular killing entities that deliver cytotoxic cargo targeted by the specificity of shell components.
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Ward JA, Pinto-Fernandez A, Cornelissen L, Bonham S, Díaz-Sáez L, Riant O, Huber KVM, Kessler BM, Feron O, Tate EW. Re-Evaluating the Mechanism of Action of α,β-Unsaturated Carbonyl DUB Inhibitors b-AP15 and VLX1570: A Paradigmatic Example of Unspecific Protein Cross-linking with Michael Acceptor Motif-Containing Drugs. J Med Chem 2020; 63:3756-3762. [PMID: 32109059 PMCID: PMC7152998 DOI: 10.1021/acs.jmedchem.0c00144] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
![]()
Deubiquitinating
enzymes (DUBs) are a growing target class across
multiple disease states, with several inhibitors now reported. b-AP15
and VLX1570 are two structurally related USP14/UCH-37 inhibitors.
Through a proteomic approach, we demonstrate that these compounds
target a diverse range of proteins, resulting in the formation of
higher molecular weight (MW) complexes. Activity-based proteome profiling
identified CIAPIN1 as a submicromolar covalent target of VLX1570,
and further analysis demonstrated that high MW complex formation leads
to aggregation of CIAPIN1 in intact cells. Our results suggest that
in addition to DUB inhibition, these compounds induce nonspecific
protein aggregation, providing molecular explanation for general cellular
toxicity.
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Fielden J, Wiseman K, Torrecilla I, Li S, Hume S, Chiang SC, Ruggiano A, Narayan Singh A, Freire R, Hassanieh S, Domingo E, Vendrell I, Fischer R, Kessler BM, Maughan TS, El-Khamisy SF, Ramadan K. TEX264 coordinates p97- and SPRTN-mediated resolution of topoisomerase 1-DNA adducts. Nat Commun 2020; 11:1274. [PMID: 32152270 PMCID: PMC7062751 DOI: 10.1038/s41467-020-15000-w] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Accepted: 02/16/2020] [Indexed: 12/03/2022] Open
Abstract
Eukaryotic topoisomerase 1 (TOP1) regulates DNA topology to ensure efficient DNA replication and transcription. TOP1 is also a major driver of endogenous genome instability, particularly when its catalytic intermediate-a covalent TOP1-DNA adduct known as a TOP1 cleavage complex (TOP1cc)-is stabilised. TOP1ccs are highly cytotoxic and a failure to resolve them underlies the pathology of neurological disorders but is also exploited in cancer therapy where TOP1ccs are the target of widely used frontline anti-cancer drugs. A critical enzyme for TOP1cc resolution is the tyrosyl-DNA phosphodiesterase (TDP1), which hydrolyses the bond that links a tyrosine in the active site of TOP1 to a 3' phosphate group on a single-stranded (ss)DNA break. However, TDP1 can only process small peptide fragments from ssDNA ends, raising the question of how the ~90 kDa TOP1 protein is processed upstream of TDP1. Here we find that TEX264 fulfils this role by forming a complex with the p97 ATPase and the SPRTN metalloprotease. We show that TEX264 recognises both unmodified and SUMO1-modifed TOP1 and initiates TOP1cc repair by recruiting p97 and SPRTN. TEX264 localises to the nuclear periphery, associates with DNA replication forks, and counteracts TOP1ccs during DNA replication. Altogether, our study elucidates the existence of a specialised repair complex required for upstream proteolysis of TOP1ccs and their subsequent resolution.
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Nazri HM, Imran M, Fischer R, Heilig R, Manek S, Dragovic RA, Kessler BM, Zondervan KT, Tapmeier TT, Becker CM. Characterization of exosomes in peritoneal fluid of endometriosis patients. Fertil Steril 2020; 113:364-373.e2. [PMID: 32106990 PMCID: PMC7057257 DOI: 10.1016/j.fertnstert.2019.09.032] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 09/11/2019] [Accepted: 09/23/2019] [Indexed: 12/12/2022]
Abstract
OBJECTIVE To demonstrate the feasibility of studying exosomes directly from peritoneal fluid, we isolated exosomes from endometriosis patient samples and from controls, and characterized their cargo. DESIGN Case-control experimental study. SETTING Academic clinical center. PATIENT (S) Women with and without endometriosis who underwent laparoscopic surgery (n = 28 in total). INTERVENTION (S) None. MAIN OUTCOME MEASURE (S) Concentration of exosomes within peritoneal fluid and protein content of the isolated exosomes. RESULT (S) Peritoneal fluid samples were pooled according to the cycle phase and disease stage to form six experimental groups, from which the exosomes were isolated. Exosomes were successfully isolated from peritoneal fluid in all the study groups. The concentration varied with cycle phase and disease stage. Proteomic analysis showed specific proteins in the exosomes derived from endometriosis patients that were absent in the controls. Five proteins were found exclusively in the endometriosis groups: PRDX1, H2A type 2-C, ANXA2, ITIH4, and the tubulin α-chain. CONCLUSION (S) Exosomes are present in peritoneal fluid. The characterization of endometriosis-specific exosomes opens up new avenues for the diagnosis and investigation of endometriosis.
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Mavrommati I, Faedda R, Galasso G, Li J, Burdova K, Fischer R, Kessler BM, Carrero ZI, Guardavaccaro D, Pagano M, D'Angiolella V. β-TrCP- and Casein Kinase II-Mediated Degradation of Cyclin F Controls Timely Mitotic Progression. Cell Rep 2019; 24:3404-3412. [PMID: 30257202 PMCID: PMC6172692 DOI: 10.1016/j.celrep.2018.08.076] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 05/29/2018] [Accepted: 08/24/2018] [Indexed: 11/18/2022] Open
Abstract
Orderly progressions of events in the cell division cycle are necessary to ensure the replication of DNA and cell division. Checkpoint systems allow the accurate execution of each cell-cycle phase. The precise regulation of the levels of cyclin proteins is fundamental to coordinate cell division with checkpoints, avoiding genome instability. Cyclin F has important functions in regulating the cell cycle during the G2 checkpoint; however, the mechanisms underlying the regulation of cyclin F are poorly understood. Here, we observe that cyclin F is regulated by proteolysis through β-TrCP. β-TrCP recognizes cyclin F through a non-canonical degron site (TSGXXS) after its phosphorylation by casein kinase II. The degradation of cyclin F mediated by β-TrCP occurs at the G2/M transition. This event is required to promote mitotic progression and favors the activation of a transcriptional program required for mitosis. β-TrCP1 and β-TrCP2 interact with cyclin F and control cyclin F levels during mitosis A TSGXXS motif is necessary for β-TrCP1 and β-TrCP2 binding to cyclin F CKIIα phosphorylates cyclin F at S704 within the TSGXXS motif β-TrCP-mediated degradation of cyclin F promotes mitotic progression via B-Myb
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