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Discover how PEPperPRINT Peptide Microarray products have been used in different fields of research.

Mus81-Mms4 endonuclease is an Esc2-STUbL-Cullin8 mitotic substrate impacting on genome integrity

Waizenegger, Anja; Urulangodi, Madhusoodanan; Lehmann, Carl P.; Reyes, Teresa Anne Clarisse; Saugar, Irene; Tercero, José Antonio; Szakal, Barnabas; Branzei, Dana
The Mus81-Mms4 nuclease is activated in G2/M via Mms4 phosphorylation to allow resolution of persistent recombination structures. However, the fate of the activated phosphorylated Mms4 remains unknown. Here we find that Mms4 is engaged by (poly)SUMOylation and ubiquitylation and targeted for proteasome degradation, a process linked to the previously described Mms4 phosphorylation cycle. Mms4 is a mitotic substrate for the SUMO-Targeted Ubiquitin ligase Slx5/8, the SUMO-like domain-containing protein Esc2, and the Mms1-Cul8 ubiquitin ligase. In the absence of these activities, phosphorylated Mms4 accumulates on chromatin in an active state in the next G1, subsequently causing abnormal processing of replication-associated recombination intermediates and delaying the activation of the DNA damage checkpoint. Mus81-Mms4 mutants that stabilize phosphorylated Mms4 have similar detrimental effects on genome integrity. Overall, our findings highlight a replication protection function for Esc2-STUbL-Cul8 and emphasize the importance for genome stability of resetting phosphorylated Mms4 from one cycle to another.

Detection of specific IgE against linear epitopes from Gal d 1 has additional value in diagnosing hen’s egg allergy in adults

Ehlers, Anna M.; Otten, Henny G.; Wierzba, Eva; Flügge, Ulrike; Le, Thuy-My; Knulst, André C.; Suer, Waltraud
Background Although hen’s egg allergy is more prevalent in children, up to 0.6% of adults from different European countries suffers from a persistent or newly-onset hen’s egg allergy, making accurate diagnosis in adults necessary. However, sensitisation to hen’s egg extracts, components and linear epitopes are solely studied in children. Methods Hen’s egg allergic (n=16) and tolerant (n=20) adults were selected by sensitisation towards recombinant components rGal d 1 and/or 3. Sensitisation profiles towards egg white and yolk extract and the native components Gal d 1, 2, 3 and 4 were respectively evaluated with the ImmunoCAP or the EUROLINE system. Characterisation of linear epitopes was performed with a peptide microarray containing 15mer peptides representing the entire sequence of mature Gal d 1 and 3. Results Overall, sIgE titres against hen’s egg extracts and single components overlapped largely between allergic and tolerant adults. Although the median sIgE/sIgG4 ratio to Gal d 1 was increased in allergic adults, the range was comparable between both groups. Clinically relevant sensitisation to Gal d 1 was confirmed by sIgE-binding to the linear epitopes aa30-41, aa39-50 or aa84-95 in 6/13 allergic adults, mainly suffering from objective symptoms. In comparison, these epitopes were recognized by 1/15 tolerant patient. Only a few linear epitopes were detected for Gal d 3, suggesting a greater importance of conformational epitopes for the recognition of Gal d 3. Conclusion and Clinical Relevance Specific IgE-binding to linear epitopes of Gal d 1 is highly specific in identifying hen’s egg allergic adults with objective symptoms.

Rapid response to pandemic threats: immunogenic epitope detection of pandemic pathogens for diagnostics and vaccine development using peptide microarrays

Heiss, Kirsten; Heidepriem, Jasmin; Fischer, Nico; Weber, Laura K; Dahlke, Christine; Jaenisch, Thomas; Loeffler, Felix F
J. Proteome Res..
Sep 2020
Emergence and re-emergence of pathogens bearing the risk of becoming a pandemic threat are on the rise. Increased travel and trade, growing population density, changes in urbanization, and climate have a critical impact on infectious disease spread. Currently, the world is confronted with the emergence of a novel coronavirus SARS-CoV-2, responsible for yet more than 500 000 deaths globally. Outbreaks caused by viruses such as SARS-CoV-2, HIV, Ebola, influenza, and Zika have increased over the last decade, underlining the urgent need for a rapid development of diagnostics and vaccines. Hence, the rational identification of biomarkers for diagnostic measures on the one hand, and antigenic targets for vaccine development on the other, are of utmost importance. Peptide microarrays can display large numbers of putative target proteins translated into overlapping linear (and cyclic) peptides. Using these highly diverse libraries, covering tens of thousands of peptides, allow for the in-depth analysis of antibody signatures in a multiplexed, high-throughput fashion. In this review, we highlight synthesis platforms that facilitate fast and highly flexible generation of high-density peptide microarrays. We further outline the multifaceted applications of these peptide array platforms for the development of serological tests and vaccines, to quickly encounter pandemic threats.

Molecular and Serological Tests for COVID-19. A Comparative Review of SARS-CoV-2 Coronavirus Laboratory and Point-of-Care Diagnostics

Kubina, Robert; Dziedzic, Arkadiusz
Validated and accurate laboratory testing for Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is a crucial part of the timely management of Coronavirus Disease 2019 (COVID-19) disease, supporting the clinical decision-making process for infection control at the healthcare level and detecting asymptomatic cases. This would facilitate an appropriate treatment, a prompt isolation and consequently deceleration of the pandemic. Various laboratory tests can identify the genetic material of SARS-CoV-2 that causes COVID-19 in specimens, or specific anti-viral antibodies in blood/serum. Due to the current pandemic situation, a development of point-of-care diagnostics (POCD) allows us to substantially accelerate taking clinical decisions and implement strategic planning at the national level of preventative measures. This review summarizes and compares the available POCD and those currently under development, including quantitative reverse transcription PCR (RT-qPCR), serology immunoassays (SIAs) and protein microarray method (PMM) designed for standard and rapid COVID-19 diagnosis.

Fibrinogen interaction with complement C3: a potential therapeutic target to reduce thrombosis risk

King, Rhodri J.; Schuett, Katharina; Tiede, Christian; Jankowski, Vera; John, Vicky; Trehan, Abhi; Simmons, Katie; Ponnambalam, Sreenivasan; Storey, Robert F.; Fishwick, Colin W.G.; McPherson, Michael J.; Tomlinson, Darren C.; Ajjan, Ramzi A.
Haematologica.
Apr 2020
Complement C3 binds fibrinogen and compromises fibrin clot lysis thereby enhancing thrombosis risk. We investigated the role of fibrinogen-C3 interaction as a novel therapeutic target to reduce thrombosis risk by analysing: i) consistency in the fibrinolytic properties of C3, ii) binding sites between fibrinogen and C3 and iii) modulation of fibrin clot lysis by manipulating fibrinogen-C3 interactions. Purified fibrinogen and C3 from the same individuals (n=24) were used to assess inter-individual variability in the anti-fibrinolytic effects of C3. Microarray screening and molecular modelling evaluated C3 and fibrinogen interaction sites. Novel synthetic conformational proteins, termed Affimers, were used to modulate C3-fibrinogen interaction and fibrinolysis. C3 purified from patients with type 1 diabetes showed enhanced prolongation of fibrinolysis compared with healthy control protein [195±105 and 522±166 seconds, respectively (p=0.04)], with consistent effects but a wider range (5-51% and 5-18% lysis prolongation, respectively). Peptide microarray screening identified 2 potential C3-fibrinogen interactions sites within fibrinogen β chain (residues 424-433, 435-445). One fibrinogen-binding Affimer was isolated that displayed sequence identity with C3 in an exposed area of the protein. This Affimer abolished C3-induced prolongation of fibrinolysis (728±25.1 seconds to 632±23.7 seconds, p=0.005) and showed binding to fibrinogen in the same region that is involved in C3-fibrinogen interactions. Moreover, it shortened plasma clot lysis of patients with diabetes, cardiovascular disease or controls by 7-11%. C3 binds fibrinogen β-chain and disruption of fibrinogen-C3 interaction using Affimer proteins enhances fibrinolysis, which represents a potential novel target tool to reduce thrombosis in high risk individuals.

Autoantibody Signature in Cardiac Arrest

Maguy, Ange; Tardif, Jean-Claude; Busseuil, David; Ribi, Camillo; Li, Jin
Circulation.
Apr 2020
Background: Cardiac arrest is a tragic event that causes one death roughly every 90 seconds worldwide. Survivors generally undergo a work-up to identify the etiology of arrest. However, 5-10% of cardiac arrest remain unexplained. As cardiac arrhythmias mostly underlie cardiac arrest and increasing evidence strongly supports the involvement of autoantibodies in arrhythmogenesis, a large-panel autoantibody screening was performed in cardiac arrest patients. Methods: This is an observational, cross-sectional study of patients from the Montreal Heart Institute (MHI) hospital cohort, a single center registry of participants. A peptide microarray was designed to screen for IgG targeting epitopes from all known cardiac ion channels with extracellular domains. Plasma samples from 23 patients with unexplained cardiac arrest were compared to 22 cardiac arrest cases of ischemic origin and a group of 29 age-, sex- and BMI-matched healthy subjects. The false discovery rate (FDR), LASSO logistic regression and random forest methods were jointly carried out to find significant differential IgG responses. Results: The autoantibody against the pore domain of the L-type voltage-gated calcium channel (Ca v 1.2) was consistently identified as a biomarker of idiopathic cardiac arrest (P=0.002, FDR=0.007, classification accuracies ≥0.83). Functional studies on human induced pluripotent stem cell-derived cardiomyocytes demonstrated that the anti-Ca v 1.2 IgG purified from patients with idiopathic cardiac arrest is proarrhythmogenic by reducing the action potential duration through calcium channel inhibition. Conclusions: The present report addresses the concept of autoimmunity and cardiac arrest. Hitherto unknown autoantibodies targeting extracellular sequences of cardiac ion channels were detected. Moreover, the study identified an autoantibody signature specific to patients with cardiac arrest.

The Myc tag monoclonal antibody 9E10 displays highly variable epitope recognition dependent on neighboring sequence context

Schüchner, Stefan; Behm, Christian; Mudrak, Ingrid; Ogris, Egon
Sci. Signal..
Jan 2020
Epitope tags are short, linear antibody recognition sequences that enable detection of tagged fusion proteins by antibodies. Epitope tag position and neighboring sequences potentially affect its recognition by antibodies, and such context-dependent differences in tag binding may have a wide-ranging effect on data interpretation. We tested by Western blotting six antibodies that recognize the c-Myc epitope tag, including monoclonal antibodies 9E10, 4A6, 9B11, and 71D10 and polyclonal antibodies 9106 and A-14. All displayed context-dependent differences in their ability to detect N- or C-terminal Myc-tagged proteins. In particular, clone 9E10, the most cited Myc-tag antibody, displayed high context-dependent detection variability, whereas others, notably 4A6 and 9B11, showed much less context sensitivity in their detection of Myc-tagged proteins. The very high context sensitivity of 9E10 was further substantiated by peptide microarray analyses. We conclude that recently developed, purpose-made monoclonal antibodies specific for Myc have much more uniform reactivity in diverse assays and are much less context sensitive than is the legacy antibody 9E10.

Properties of Two Enterovirus Antibodies that are Utilized in Diabetes Research

Maccari, Giuseppe; Genoni, Angelo; Sansonno, Silvia; Toniolo, Antonio
Sci Rep.
Apr 2016
Human enteroviruses (EVs) comprise >100 different types. Research suggests a non-chance association between EV infections and type 1 diabetes. Immunohistochemical studies with the anti-EV antibody 5D-8.1 have shown that the EV capsid antigen is present in pancreatic islet cells of diabetic subjects. When it was noticed that 5D-8.1 may cross-react with human proteins, doubt was casted on the significance of the above histopathologic findings. To address this issue, properties of EV antibodies 5D-8.1 and 9D5 have been investigated using peptide microarrays, peptide substitution scanning, immunofluorescence of EV-infected cells, EV neutralization assays, bioinformatics analysis. Evidence indicates that the two antibodies bind to distinct non-neutralizing linear epitopes in VP1 and are specific for a vast spectrum of EV types (not for other human viruses). However, their epitopes may align with a few human proteins at low expected values. When tested by immunofluorescence, high concentrations of 5D-8.1 yelded faint cytoplasmic staining in uninfected cells. At reduced concentrations, both antibodies produced dotted staining only in the cytoplasm of infected cells and recognized both acute and persistent EV infection. Thus, the two monoclonals represent distinct and independent probes for hunting EVs in tissues of patients with diabetes or other endocrine conditions.

Serum peptide reactivities may distinguish neuromyelitis optica subgroups and multiple sclerosis

Metz, Imke; Beißbarth, Tim; Ellenberger, David; Pache, Florence; Stork, Lidia; Ringelstein, Marius; Aktas, Orhan; Jarius, Sven; Wildemann, Brigitte; Dihazi, Hassan; Friede, Tim; Brück, Wolfgang; Ruprecht, Klemens; Paul, Friedemann
Neurol Neuroimmunol Neuroinflamm.
Apr 2016
Objective: To assess in an observational study whether serum peptide antibody reactivities may distinguish aquaporin-4 (AQP4) antibody (Ab)–positive and -negative neuromyelitis optica spectrum disorders (NMOSD) and relapsing-remitting multiple sclerosis (RRMS). Methods: We screened 8,700 peptides that included human and viral antigens of potential relevance for inflammatory demyelinating diseases and random peptides with pooled sera from different patient groups and healthy controls to set up a customized microarray with 700 peptides. With this microarray, we tested sera from 66 patients with AQP4-Ab-positive (n = 16) and AQP4-Ab-negative (n = 19) NMOSD, RRMS (n = 11), and healthy controls (n = 20). Results: Differential peptide reactivities distinguished NMOSD subgroups from RRMS in 80% of patients. However, the 2 NMOSD subgroups were not well-discriminated, although those patients are clearly separated by their antibody reactivities against AQP4 in cell-based assays. Elevated reactivities to myelin and Epstein-Barr virus peptides were present in RRMS and to AQP4 and AQP1 peptides in AQP4-Ab-positive NMOSD. Conclusions: While AQP4-Ab-positive and -negative NMOSD subgroups are not well-discriminated by peptide antibody reactivities, our findings suggest that peptide antibody reactivities may have the potential to distinguish between both NMOSD subgroups and MS. Future studies should thus concentrate on evaluating peptide antibody reactivities for the differentiation of AQP4-Ab-negative NMOSD and MS.

Identification of Equine arteritis virus immunodominant B cell epitopes using a peptide microarray

Mayers, J.; Westcott, D.; Steinbach, F.
Journal of Equine Veterinary Science.
Apr 2016

Non-invasive glioblastoma immunoprofiling by printed peptide arrays

Mock, Andreas; Herold-Mende, Christel
OncoImmunology.
Feb 2016
Immune monitoring assays for patient stratification and treatment efficacy in clinical trials are in demand. We have recently described a cost-effective non-invasive assay to determine the immune status of glioblastoma patients. Profiling antitumor serum antibodies by customized printed peptide arrays identified response against a tenascin-C (TNC) peptide as a robust prognostic biomarker.

Autoantibodies specific to estrogen receptor alpha act as estrogen agonists and their levels correlate with breast cancer cell proliferation

Maselli, Angela; Capoccia, Sara; Pugliese, Patrizia; Raggi, Carla; Cirulli, Francesca; Fabi, Alessandra; Malorni, Walter; Pierdominici, Marina; Ortona, Elena
OncoImmunology.
Feb 2016
Estrogen receptors have recently been demonstrated at the cell surface. Unlike nuclear receptors, they are able to trigger rapid responses inside the cells. In this study, we evaluated the presence and the possible role of autoantibodies specific to estrogen receptor (anti-ER Abs) in the peripheral blood of breast cancer patients. Anti-ERα Abs were detectable in 22/48 (46%) patients’ sera and their levels positively correlated with the percentage of Ki-67-positive breast cancer cells. Anti-ERα Abs purified from breast cancer patients’ sera were able: (i) to recognize ERα epitopes expressed at the cell surface of ER-positive breast cancer cells, (ii) to trigger rapid extracellular signal-regulated kinase (ERK) phosphorylation, and (iii) to induce cell proliferation. Our results suggest that anti-ERα Abs can act as estrogen agonists playing a pathogenetic role as breast cancer-promoting factors. These autoantibodies could also be considered as possible peripheral blood biomarkers indicative of the breast cancer growth potential.

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