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

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Systematic analysis of the RGS2 degron reveals characteristics of substrate recognition by the F-box protein FBXO44

McNabb, Harrison J.; Cho, Eugene; Pitman, Mary; Rushton, Phillip S.; Mobley, David; Sjögren, Benita
Journal of Biological Chemistry.
Nov 2025
10.1016/j.jbc.2025.110757
Regulator of G protein signaling 2 (RGS2) negatively modulates signaling downstream of G protein–coupled receptors by accelerating GTP hydrolysis at Gα subunits of heterotrimeric G proteins. Decreased RGS2 levels are implicated in numerous diseases, including cardiovascular disease and asthma. Thus, identifying selective means of enhancing RGS2 protein levels would be a viable therapeutic strategy. RGS2 is rapidly degraded through the ubiquitin–proteasomal pathway, and we previously identified F-box only protein 44 (FBXO44) as the substrate recognition component of the E3 ligase responsible for facilitating RGS2 degradation. As such, the RGS2–FBXO44 interaction is a potential target for pharmacological intervention. Detailed information on the FBXO44 recognition site (degron) in RGS2 will aid in structure-based small-molecule inhibitor design, as well as in identifying additional FBXO44 targets, which would help predict possible side effects of targeting this interaction. Thus, the goal of this study was to dissect the molecular properties for FBXO44 binding of the RGS2 degron. We used a peptide array utilizing systematic residue substitution, combined with AlphaFold modeling and molecular dynamics simulations, to identify several amino acid changes that altered binding both positively and negatively. Finally, we experimentally confirmed our results in cells through coimmunoprecipitation and proteasomal inhibition, using full-length RGS2. Altogether, these results provide structural insights into RGS2–FBXO44 binding, which will aid in structure-guided drug discovery efforts. It also provides a framework for building a consensus recognition motif for FBXO44, which could aid in identifying more substrates for this understudied F-box protein.

Anti-TRPV2 Autoantibody Linked to Sudden Infant Death Syndrome

Maguy, Ange; Tessier, Agnès; Mahendran, Yuvaraj; Denis, Manon; Lauzier, Benjamin; Charpentier, Flavien; Li, Jin
Jul 2025
10.1161/circulationaha.125.073748
As a leading cause of infant death, sudden infant death syndrome (SIDS) remains a perplexing diagnosis with no clear underlying biological substrate.1 In the past decade, studies have emerged demonstrating that circulating autoantibodies targeting cardiac antigens can underlie life-threatening arrhythmias.2 Because autoimmunity as a cause of SIDS has not yet been explored, we screened infant serum samples for the presence of autoantibodies targeting cardiac ion channels and examined how immunoglobulins may play a driving role in the pathogenesis of SIDS. Comparing cases of SIDS and accidental suffocation and strangulation in bed with healthy controls, we established the autoantibody profile of 47 serum samples using peptide microarray (Figure [A]), as previously described.2 Strikingly, only 1 single autoantibody targeting the transient receptor potential vanilloid 2 (TRPV2) channel (PTGPNATESVQPMEGQEDEG) was significantly associated with SIDS (P=0.028 versus controls, the default correction in limma). Collectively, we detected anti-TRPV2 autoantibodies in 84.6% of infants with SIDS compared with 50.0% in cases of accidental suffocation and strangulation in bed and 25.0% in controls.

Mapping autoantibody targets of full-length C-reactive protein in systemic lupus erythematosus: importance for neutrophil function and classical complement activation

Karlsson, Jesper; Wirestam, Lina; Duàn, Hanna; Ahmad, Suhana; Appelgren, Daniel; Enocsson, Helena; Wetterö, Jonas; Sjöwall, Christopher
Front. Immunol..
May 2025
10.3389/fimmu.2025.1578372
C-reactive protein (CRP) is an important pattern recognition molecule of innate immunity. Autoantibodies targeting CRP are common in patients with systemic lupus erythematosus (SLE) and the levels correlate with disease activity. The purpose of this study was to investigate binding sites of IgG autoantibodies on the full linear sequence of CRP and identify potential associations with clinical variables in well-characterized SLE patients; a secondary aim was to investigate the effect of an epitope-based synthesized peptide motif on neutrophil functions. The levels of anti-CRP and SLE-associated antibodies were assessed, and a microarray-based linear epitope mapping was performed to detect binding sites on the full CRP monomer. We observed that anti-CRP antibodies bind to a variety of linear epitopes with a higher prevalence in SLE compared to healthy blood donors. Eleven unique epitopes were identified, of which five were found exclusively in SLE. Furthermore, we show that patients with anticardiolipin IgG and/or anti-β2GPI IgG antibodies have a higher number of positive CRP epitopes, and some CRP autoantibody-specificities associate with antiphospholipid antibodies, disease activity, and classical complement activation. In addition, one identified motif was selected, synthesized, and used for studying neutrophil function. This peptide showed modulatory capacity on neutrophil oxidative burst and chemotaxis, but not on neutrophil extracellular trap formation. Our results implicate a wide variation of anti-CRP autoantibody binding motifs of the linear structure of CRP in SLE patients. Some epitopes have the potential to modify innate host responses of relevance to the pathogenesis of SLE.

Identification of Tripeptide Modulators of ACE2 Activity Using a High Throughput Screen (Abstract ID: 165381)

Walker, David F.; Karamyan, Vardan T.
The Journal of Pharmacology and Experimental Therapeutics.
Mar 2025
10.1016/j.jpet.2024.100697
Angiotensin converting enzyme 2 (ACE2) works in the renin angiotensin aldosterone system to decrease circulating levels of angiotensin II by removing the C-terminal phenylalanine and converting it to angiotensin (1-7). In addition, ACE2 has received increased interest in research due to its role in COVID-19 pathogenesis, as the binding site and cell entry gate for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). While ACE2 inhibitors have been primarily used as pharmacological tools to study the renin-angiotensin system, small molecule ACE2 enhancers (aka activators) are highly desired because of their hypothesized therapeutic potential. This study was designed to identify peptide-based enhancers of ACE2. First, binding of human recombinant ACE2 to all possible tripeptides composed of the 20 proteinogenic amino acids, was evaluated using a proprietary immunofluorescence-based peptide microarray. Binding of 6xHis-tagged ACE2 to the 8000 tripeptides immobilized on a microchip was evaluated at 10 µg/ml and 100 µg/ml concentrations of the peptidase using a DyLight680-conjugated anti-6xHis-tag antibody. Hemagglutinin (HA) immobilized on the microchip served as a positive control peptide in the microarray and it was tracked using a DyLight800-conjugated anti-HA antibody. The read-out was performed with an Innopsys InnoScan 710-IR Microarray Scanner at scanning gains of 50/10 (red/green). In the result of the microarray a number of tripeptides were identified as potential ACE2 binders. Among them, 22 tripeptides were selected to represent several the most pronounced binders as well as a number of structurally similar tripeptides that did not show appreciable binding to ACE2 to serve as negative control. The effect of the selected peptides (at 1, 10 and 100 µM) on activity of human recombinant ACE2 was tested in a continuous enzymatic assay using a fluorogenic substrate. Contrary to our expectation, none of the peptides affected the activity of ACE2 in a significant manner. These results suggest that the selected peptides do not alter activity of ACE2, but they do not exclude the possibility that some of the peptides may still bind to the peptidase. Our subsequent experiments will apply differential scanning fluorometry (DSF) to determine whether these peptides physically interact with recombinant ACE2.

Paediatric autoimmune uveitis is associated with intraocular antibodies against Epstein–Barr virus Nuclear Antigen 1 (EBNA-1)

Hendrikse, Jytte; Bont, Louis J.; Schellekens, Peter A.W.J.F.; De Groot-Mijnes, Jolanda D.F.; De Boer, Joke H.; Kuiper, Jonas J.W.
eBioMedicine.
Mar 2025
10.1016/j.ebiom.2025.105681
**Background** Non-infectious uveitis is an immune-mediated disease characterized by vision-threatening inflammation within the eye. Increasing evidence indicates that microbial agents promote non-infectious uveitis, but the natural history of immune responses to pathogens in patients remains unexplored. We determined intraocular antibodies against pathogens in paediatric uveitis. **Methods** We used peptide microarrays containing 3760 linear B-cell epitopes from 196 human pathogens to profile IgG levels in eye fluid biopsies and paired serum samples from 18 Dutch paediatric patients and 6 age-matched controls. We compared intensities of single epitopes and clusters based on overlapping amino acid sequence of peptides. Next-generation sequencing data was obtained to determine the HLA-DRB1∗15:01 genotype. **Findings** Intraocular antibody profiles largely matched serum profiles and were characterized by high IgG against the conserved PALTAVET-motif of enterovirus family members, as well as broad epitope reactivity against Epstein–Barr virus (EBV). The aqueous humour of patients showed elevated levels of antibodies against peptides containing the RRPFFHPV-motif of Epstein–Barr Virus Nuclear Antigen 1 [EBNA-1]. Antibody levels against the RRPFFHPV-motif of EBNA1 were significantly higher in individuals that carry the HLA-DRB1∗15:01 risk allele of paediatric uveitis. **Interpretation** Intraocular antibodies against an immunogenic epitope of EBV showed an association with paediatric uveitis, particularly HLA-DRB1∗15:01 positive uveitis, indicating a potential link between EBV-specific immune responses and autoimmune uveitis. **Funding** Funding for this research was received from Fischer Stichting (UZ2022-3), ODAS (2021-02), LSBS and ANVVB.

The antibody repertoire of autoimmune sensory neuronopathies targets pathways of the innate and adaptative immune system. An autoantigenomic approach.

Moritz, Christian P.; Tholance, Yannick; Boutahar, Nadia; Borowczyk, Coralie; Berger, Anne-Emmanuelle; Paul, Stéphane; Antoine, Jean-Christophe; Camdessanché, Jean-Philippe
Journal of Translational Autoimmunity.
Jan 2025
10.1016/j.jtauto.2025.100277
Sensory neuronopathies (SNN) encompasses diverse etiologies, with autoimmunity playing a major role through both cellular and humoral responses. To investigate the humoral autoantibody repertoire in autoimmune SNN, we conducted a retrospective cohort study using large Human Proteome-wide protein microarrays (HuProt 3.1, HuProt 4.0, ProtoArrays). We specifically focused on immune system pathways within the repertoire of targeted antigens (the autoantigenome). We included 131 participants: 44 patients with non-paraneoplastic autoimmune SNN (12 with anti-FGFR3 and/or anti-AGO antibodies), 8 with paraneoplastic SNN and 79 controls. Results were validated in an independent cohort of 16 SNN patients. Overrepresentation of immune-system-related proteins was assessed via the Reactome database, and serum levels of IFN-γ and IL-6 were measured using the Bio-Plex Pro™ Reagent Kit. Autoimmune SNN sera interact with more immune system proteins than healthy controls (ProtoArrays: 271/863 vs. 14/863, HuProt: 112/1694 vs. 39/1694, both p<0.0001). Overrepresentation was observed in all immune sub-pathways, including innate, adaptive immune responses, and cytokine signaling. Anti-FGFR3-positive SNN patients were more reactive with immune system proteins than negative ones. The independent SNN cohort validated the finding of overrepresentatively targeted immune system pathways. Validation with dot blot and ELISA confirmed reactivity to TRIM21 and IL-6, and identified anti-IFN-γ-positive SNN patients. IFN-γ levels correlated weakly with levels of anti-IFN-γ antibodies (Pearson’s r = 0.22, p=0.03). We conclude that the antibody repertoire of autoimmune SNN targets pathways of the innate and adaptative immune system, potentially reflecting key disease-related immune pathways and highlighting the systemic role of immune dysregulation in SNN.

Molecular mimicry, genetic homology, and gene sharing proteomic “molecular fingerprints” using an EBV (Epstein-Barr virus)-derived microarray as a potential diagnostic method in autoimmune disease

Dreyfus, David H.; Farina, Antonella; Farina, Giuseppina Alessandra
Immunol Res.
Dec 2018
10.1007/s12026-018-9045-0
EBV (Epstein-Barr Virus) and other human DNA viruses are associated with autoimmune syndromes in epidemiologic studies. In this work, immunoglobulin G response to EBV-encoded proteins which share regions with human immune response proteins from the human host including ZEBRA (BZLF-1 encoded protein), BALF-2 recombinase expressed primarily during the viral lytic replication cycle, and EBNA-1 (Epstein-Barr Virus Nuclear Antigen) expressed during the viral latency cycle respectively were characterized using a laser-printed micro-array (PEPperprint.com). IgG response to conserved “A/T hooks” in EBV-encoded proteins such as EBNA-1 and the BALF-2 recombinase related to host DNA-binding proteins including RAG-1 recombinase and histones, and EBV-encoded virokines such as the IL-10 homologue BCRF-1 suggest further directions for clinical research. The author suggests that proteomic “molecular fingerprints” of the immune response to viral proteins shared with human immune response genes are potentially useful in early diagnosis and monitoring of autoantibody production and response to therapy in EBV-related autoimmune syndromes.

Regulatory T-cell deficiency leads to pathogenic bullous pemphigoid antigen 230 autoantibody and autoimmune bullous disease

Haeberle, Stefanie; Wei, Xiaoying; Bieber, Katja; Goletz, Stephanie; Ludwig, Ralf J.; Schmidt, Enno; Enk, Alexander H.; Hadaschik, Eva N.
Journal of Allergy and Clinical Immunology.
Dec 2018
10.1016/j.jaci.2018.04.006
Background Autoimmune bullous diseases/dermatoses (AIBDs) are severe autoantibody-mediated skin diseases. The pathogenic relevance of autoreactive CD4+ T cells for the induction of autoantibody production remains to be fully evaluated. Scurfy mice lack functional regulatory T (Treg) cells, experience spontaneous activation of autoreactive CD4+ T cells, and display severe erosive skin lesions suggestive of AIBDs. Objective We sought to determine whether AIBDs develop in Treg cell–deficient scurfy mice. Methods Histology, indirect immunofluorescence (IF) microscopy, direct IF, and ELISA were used to prove the presence of AIBDs in scurfy mice. Monoclonal autoantibodies from sera of scurfy mice were screened by using indirect IF on murine skin, and immunoprecipitation and mass spectrometry were used for target antigen identification, followed by confirmation in modified human embryonic kidney cells and murine keratinocytes. Pathogenicity was determined by injecting the autoantibody into neonatal mice and transferring scurfy CD4+ T cells into nu/nu mice. Results Autoantibodies against different known autoantigens of AIBDs spontaneously develop in scurfy mice. Histology reveals subepidermal blisters, and direct IF of skin of scurfy mice shows a predominant linear staining pattern. The mAb 20B12 shows a linear staining pattern in indirect IF, recognizes the murine hemidesmosomal protein bullous pemphigoid antigen 230 (BP230) as the target antigen, and cross-reacts with human BP230. Purified mAb 20B12 induces subepidermal blisters in neonatal mice. Transfer of scurfy CD4+ T cells is sufficient to induce antibodies with reactivity to AIBD autoantigens and subepidermal blisters in the skin of recipient T cell–deficient nu/nu mice. Conclusion We show that the absence of Treg cells leads to AIBDs by pathogenic autoantibodies targeting BP230.

Potential therapeutic antibodies targeting specific adiponectin isoforms in rheumatoid arthritis

Lee, Yeon-Ah; Hahm, Dae-Hyun; Kim, Jung Yeon; Sur, Bonjun; Lee, Hyun Min; Ryu, Chun Jeih; Yang, Hyung-In; Kim, Kyoung Soo
Arthritis Res Ther.
Oct 2018
10.1186/s13075-018-1736-3
Background Different adiponectin isoforms appear to be differentially involved in the pathogenesis of various diseases. The purpose of this study was to generate monoclonal antibodies (mAbs) specific to different adiponectin isoforms and investigate whether these mAbs have potential as therapeutic agents for such diseases. Methods Hybridoma cells producing monoclonal antibodies were generated and screened using enzyme-linked immunosorbent assay and Western blotting for the production of mAbs recognizing human adiponectin isoforms. Results The mAb from hybridoma clone KH7–41 recognized both the middle molecular weight (MMW) (hexamer) and low molecular weight (LMW) (trimer) isoforms of adiponectin in human serum, whereas the KH7–33 mAb detected only MMW (hexamer) adiponectin. The KH4–8 clone recognized both the high molecular weight (HMW) (multimer) and MMW adiponectin isoforms. However, in mouse and rat sera, the abovementioned antibodies recognized only the MMW isomer. These mAbs also recognized adiponectin in various human tissues, such as lung, kidney, and adipose tissues, although the three mAbs had different staining intensities. The mAb from clone KH4–8 effectively inhibited increases in interleukin-6 (IL-6) and IL-8 expression in recombinant adiponectin-stimulated human osteoblasts and human umbilical vein endothelial cells. Also, the mAbs KH7–33 and KH4–8 significantly ameliorated rheumatic symptoms in a collagen-induced arthritis mouse model. This result suggests that these mAb treatments may ameliorate adiponectin-mediated inflammatory response. Conclusions mAbs against human adiponectin isomers can potentially be developed as therapeutic antibodies to target specific detrimental isoforms of adiponectin while maintaining the functions of beneficial isoforms.

Interaction of the Warsaw breakage syndrome DNA helicase DDX11 with the replication fork-protection factor Timeless promotes sister chromatid cohesion

Cortone, Giuseppe; Zheng, Ge; Pensieri, Pasquale; Chiappetta, Viviana; Tatè, Rosarita; Malacaria, Eva; Pichierri, Pietro; Yu, Hongtao; Pisani, Francesca M.
PLoS Genet.
Oct 2018
10.1371/journal.pgen.1007622
Establishment of sister chromatid cohesion is coupled to DNA replication, but the underlying molecular mechanisms are incompletely understood. DDX11 (also named ChlR1) is a super-family 2 Fe-S cluster-containing DNA helicase implicated in Warsaw breakage syndrome (WABS). Herein, we examined the role of DDX11 in cohesion establishment in human cells. We demonstrated that DDX11 interacts with Timeless, a component of the replication fork-protection complex, through a conserved peptide motif. The DDX11-Timeless interaction is critical for sister chromatid cohesion in interphase and mitosis. Immunofluorescence studies further revealed that cohesin association with chromatin requires DDX11. Finally, we demonstrated that DDX11 localises at nascent DNA by SIRF analysis. Moreover, we found that DDX11 promotes cohesin binding to the DNA replication forks in concert with Timeless and that recombinant purified cohesin interacts with DDX11 in vitro. Collectively, our results establish a critical role for the DDX11-Timeless interaction in coordinating DNA replication with sister chromatid cohesion, and have important implications for understanding the molecular basis of WABS.

Combinatorial Synthesis of Macromolecular Arrays by Microchannel Cantilever Spotting (µCS)

Atwater, Jordyn; Mattes, Daniela S.; Streit, Bettina; von Bojničić-Kninski, Clemens; Loeffler, Felix F.; Breitling, Frank; Fuchs, Harald; Hirtz, Michael
Adv. Mater..
Aug 2018
10.1002/adma.201801632
Surface-bound microarrays of multiple oligo- and macromolecules (e.g., peptides, DNA) offer versatile options in biomedical applications like drug screening, DNA analysis, or medical diagnostics. Combinatorial syntheses of these molecules in situ can save significant resources in regard to processing time and material use. Furthermore, high feature densities are needed to enable high-throughput and low sample volumes as generally regarded in combinatorial chemistry. Here, a scanning-probe-lithography-based approach for the combinatorial in situ synthesis of macromolecules is presented in microarray format. Feature sizes below 40 µm allow for the creation of high-density arrays with feature densities of 62 500 features per cm2. To demonstrate feasibility of this approach for biomedical applications, a multiplexed array of functional protein tags (HA- and FLAG-tag) is synthesized, and selective binding of respective epitope recognizing antibodies is shown. This approach uses only small amounts of base chemicals for synthesis and can be further parallelized, therefore, opening up a route to flexible, highly dense, and cost-effective microarrays.

Autism-specific maternal autoantibodies produce behavioral abnormalities in an endogenous antigen-driven mouse model of autism

Jones, Karen L.; Pride, Michael C.; Edmiston, Elizabeth; Yang, Mu; Silverman, Jill L.; Crawley, Jacqueline N.; Van de Water, Judy
Mol Psychiatry.
Jun 2018
10.1038/s41380-018-0126-1
Immune dysregulation has been noted consistently in individuals with autism spectrum disorder (ASD) and their families, including the presence of autoantibodies reactive to fetal brain proteins in nearly a quarter of mothers of children with ASD versus <1% in mothers of typically developing children. Our lab recently identified the peptide epitope sequences on seven antigenic proteins targeted by these maternal autoantibodies. Through immunization with these peptide epitopes, we have successfully created an endogenous, antigen-driven mouse model that ensures a constant exposure to the salient autoantibodies throughout gestation in C57BL/6J mice. This exposure more naturally mimics what is observed in mothers of children with ASD. Male and female offspring were tested using a comprehensive sequence of behavioral assays, as well as measures of health and development highly relevant to ASD. We found that MAR-ASD male and female offspring had significant alterations in development and social interactions during dyadic play. Although 3-chambered social approach was not significantly different, fewer social interactions with an estrous female were noted in the adult male MAR-ASD animals, as well as reduced vocalizations emitted in response to social cues with robust repetitive self-grooming behaviors relative to saline treated controls. The generation of MAR-ASD-specific epitope autoantibodies in female mice prior to breeding created a model that demonstrates for the first time that ASD-specific antigen-induced maternal autoantibodies produced alterations in a constellation of ASD-relevant behaviors.

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