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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.

Peptide Epitopes of NC16A BP180 in the Diagnostics of Bullous Pemphigoid

Lytton, Simon D.; Wagger, Christine; Meyersburg, Damian; Mussnig, Birgit; Lang, Roland; Maglie, Roberto; Anzengruber, Florian; Antiga, Emiliano; Hall, Russell P.; Bauer, Johann W.
JID Innovations.
Nov 2025
10.1016/j.xjidi.2025.100415

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.

High-throughput identification of immunoreactive peptides and corresponding proteins from Anaplasma platys and Ehrlichia canis using peptide microarray chips

Llanes, Alejandro; Madesh, Swetha; Brangulis, Kalvis; Rajeev, Sreekumari
Front Cell Infect Microbiol.
Jan 2025
10.3389/fcimb.2025.1671309
INTRODUCTION: Anaplasma platys and Ehrlichia canis are rickettsial pathogens infecting dogs, with a worldwide distribution. Both species are obligate intracellular pathogens and colonize bone marrow-derived cells, with coinfections frequently reported in dogs. Although E. canis immunodominant proteins have been thoroughly characterized, very few high-throughput studies have been conducted to identify immunogenic proteins from Anaplasma spp. In this study, we used a methodology based on peptide microarray chips to identify immunoreactive peptides, either shared or species-specific, in the complete theoretical proteomes of both pathogens. METHODS: B-cell epitopes were predicted in the corresponding proteins from both species and ranked for synthesis on the peptide microarrays. These microarrays were screened with serum samples from antibody-positive dogs, as well as negative control sera from unexposed dogs. Additionally, we assessed the feasibility of integrating evidence gathered at the level of individual peptides to identify potentially immunogenic proteins contributing to the patterns of immunoreactivity observed on microarrays. RESULTS: Screening of peptide microarrays resulted in complex antibody reactivity patterns against thousands of peptides. After discarding peptides with cross-reactivity to negative control sera, we identified over 1,200 immunoreactive peptides, including ~80 peptides shared between the two species with almost identical sequences. Despite screening linear peptides, we were able to identify proteins previously reported as immunodominant in E. canis, some of which contain predominantly conformational epitopes. DISCUSSION: Our results suggest that a high-throughput strategy based on peptide microarrays is an effective approach for the rapid identification of immunoreactive peptides and the underlying immunogenic proteins. This study provides a foundation for developing novel diagnostic tools and vaccine candidates against A. platys and E. canis, including potential combined or multivalent formulations targeting both pathogens.

High-resolution mapping of linear epitopes from LiNTPDase2: Advancing leishmaniasis detection using optimized protein and peptide antigens

Castro, Raissa Barbosa De; Badaró De Moraes, João Victor; De Souza, Anna Cláudia Alves; Favarato, Evandro Silva; Voorwald, Fabiana Azevedo; Dos Santos, Fabiane Matos; Bressan, Gustavo Costa; Vasconcellos, Raphael De Souza; Fietto, Juliana Lopes Rangel
Diagnostic Microbiology and Infectious Disease.
Oct 2024
10.1016/j.diagmicrobio.2024.116448
Visceral Leishmaniasis, caused by Leishmania infantum, is a tropical neglected disease and the most dangerous form of Leishmaniasis. It occurs zoonotically, with domestic transmission posing risks to humans as dogs have high susceptibility and are natural reservoirs of the parasite. Given their epidemiological role, improvements are needed in diagnosing Canine Visceral Leishmaniasis (CVL). Thus, we mapped linear epitopes from the rLiNTPDase2 antigen through peptide microarray and identified six positive epitopes. Validation through peptide ELISA revealed three promising peptides with accuracies of 78.6%, 85.92%, and 79.59%. Their combination yielded 97.58% accuracy. Negative epitopes were also found, which interacted with CVL-negative and Chagas Disease positive samples. Their removal from the rLiNTPDase2 sequence resulted in the rNT2.neg, which obtained enhanced specificity over rLiNTPDase2. The rNT2.neg validation achieved 87.50% sensitivity, 90.55% specificity, and 93.5% accuracy within 127 CVL-positive and 96 CVL-negative samples. Therefore, three peptides and rNT2.neg show significant promise for CVL diagnosis.

Bivalent chromatin accommodates survivin and BRG1/SWI complex to activate DNA damage response in CD4+ cells

Chandrasekaran, Venkataragavan; Andersson, Karin M. E.; Erlandsson, Malin; Li, Shuxiang; Olsson, Torbjörn Nur; Garcia-Bonete, Maria-Jose; Malmhäll-Bah, Eric; Johansson, Pegah; Katona, Gergely; Bokarewa, Maria I.
Cell Commun Signal.
Sep 2024
10.1186/s12964-024-01814-4
Background: Bivalent regions of chromatin (BvCR) are characterized by trimethylated lysine 4 (H3K4me3) and lysine 27 on histone H3 (H3K27me3) deposition which aid gene expression control during cell differentiation. The role of BvCR in post-transcriptional DNA damage response remains unidentified. Oncoprotein survivin binds chromatin and mediates IFNγ effects in CD4+ cells. In this study, we explored the role of BvCR in DNA damage response of autoimmune CD4+ cells in rheumatoid arthritis (RA). Methods: We performed deep sequencing of the chromatin bound to survivin, H3K4me3, H3K27me3, and H3K27ac, in human CD4+ cells and identified BvCR, which possessed all three histone H3 modifications. Protein partners of survivin on chromatin were predicted by integration of motif enrichment analysis, computational machine-learning, and structural modeling, and validated experimentally by mass spectrometry and peptide binding array. Survivin-dependent change in BvCR and transcription of genes controlled by the BvCR was studied in CD4+ cells treated with survivin inhibitor, which revealed survivin-dependent biological processes. Finally, the survivin-dependent processes were mapped to the transcriptome of CD4+ cells in blood and in synovial tissue of RA patients and the effect of modern immunomodulating drugs on these processes was explored. Results: We identified that BvCR dominated by H3K4me3 (H3K4me3-BvCR) accommodated survivin within cis-regulatory elements of the genes controlling DNA damage. Inhibition of survivin or JAK-STAT signaling enhanced H3K4me3-BvCR dominance, which improved DNA damage recognition and arrested cell cycle progression in cultured CD4+ cells. Specifically, BvCR accommodating survivin aided sequence-specific anchoring of the BRG1/SWI chromatin-remodeling complex coordinating DNA damage response. Mapping survivin interactome to BRG1/SWI complex demonstrated interaction of survivin with the subunits anchoring the complex to chromatin. Co-expression of BRG1, survivin and IFNγ in CD4+ cells rendered complete deregulation of DNA damage response in RA. Such cells possessed strong ability of homing to RA joints. Immunomodulating drugs inhibited the anchoring subunits of BRG1/SWI complex, which affected arthritogenic profile of CD4+ cells. Conclusions: BvCR execute DNA damage control to maintain genome fidelity in IFN-activated CD4+ cells. Survivin anchors the BRG1/SWI complex to BvCR to repress DNA damage response. These results offer a platform for therapeutic interventions targeting survivin and BRG1/SWI complex in autoimmunity.

Identification of Schistosoma haematobium and Schistosoma mansoni linear B-cell epitopes with diagnostic potential using in silico immunoinformatic tools and peptide microarray technology

Vengesai, Arthur; Manuwa, Marble; Midzi, Herald; Mandeya, Masimba; Muleya, Victor; Mujeni, Keith; Chipako, Isaac; Mduluza, Takafira
PLoS Negl Trop Dis.
Aug 2024
10.1371/journal.pntd.0011887
Introduction: Immunoinformatic tools can be used to predict schistosome-specific B-cell epitopes with little sequence identity to human proteins and antigens other than the target. This study reports an approach for identifying schistosome peptides mimicking linear B-cell epitopes using in-silico tools and peptide microarray immunoassay validation. Method: Firstly, a comprehensive literature search was conducted to obtain published schistosome-specific peptides and recombinant proteins with the best overall diagnostic performances. For novel peptides, linear B-cell epitopes were predicted from target recombinant proteins using ABCpred, Bcepred and BepiPred 2.0 in-silico tools. Together with the published peptides, predicted peptides with the highest probability of being B-cell epitopes and the lowest sequence identity with proteins from human and other pathogens were selected. Antibodies against the peptides were measured in sera, using peptide microarray immunoassays. Area under the ROC curve was calculated to assess the overall diagnostic performances of the peptides. Results: Peptide AA81008-19-30 had excellent and acceptable diagnostic performances for discriminating S. mansoni and S. haematobium positives from healthy controls, with AUC values of 0.8043 and 0.7326 respectively for IgG. Peptides MS3_10186-123-131, MS3_10385-339-354, SmSPI-177-193, SmSPI-379-388, MS3-10186-40-49 and SmS-197-214 had acceptable diagnostic performances for discriminating S. mansoni positives from healthy controls with AUC values ranging from 0.7098 to 0.7763 for IgG. Peptides SmSPI-359-372, Smp126160-438-452 and MS3 10186-25-41 had acceptable diagnostic performances for discriminating S. mansoni positives from S. mansoni negatives with AUC values of 0.7124, 0.7156 and 0.7115 respectively for IgG. Peptide MS3-10186-40-49 had an acceptable diagnostic performance for discriminating S. mansoni positives from healthy controls, with an AUC value of 0.7413 for IgM. Conclusion: One peptide with a good diagnostic performance and nine peptides with acceptable diagnostic performances were identified using the immunoinformatic approach and peptide microarray validation. There is need for evaluation of the peptides with true negatives and a good standard positive reference.

Alzheimer’s disease risk associated with changes in Epstein-Barr virus nuclear antigen 1-specific epitope targeting antibody levels

Sim, Kyu-Young; An, Jaekyeung; Bae, So-Eun; Yang, Taewoo; Ko, Gwang-Hoon; Hwang, Jeong-Ryul; Choi, Kyu Yeong; Park, Jung Eun; Lee, Jung Sup; Kim, Byeong C.; Lee, Kun Ho; Park, Sung-Gyoo
Journal of Infection and Public Health.
Jul 2024
10.1016/j.jiph.2024.05.050
*Background* Alzheimer’s disease (AD) is a neurodegenerative disorder influenced by age, sex, genetic factors, immune alterations, and infections. Multiple lines of evidence suggest that changes in antibody response are linked to AD pathology. *Methods* To elucidate the mechanisms underlying AD development, we investigated antibodies that target autoimmune epitopes using high-resolution epitope microarrays. Our study compared two groups: individuals with AD (n = 19) and non-demented (ND) controls (n = 19). To validate the results, we measured antibody levels in plasma samples from AD patients (n = 96), mild cognitive impairment (MCI; n = 91), and ND controls (n = 97). To further explore the invlovement of EBV, we performed epitope masking immunofluorescence microscopy analysis and tests to induce lytic replication using the B95–8 cell line. *Results* In this study, we analyzed high-resolution epitope-specific serum antibody levels in AD, revealing significant disparities in antibodies targeting multiple epitopes between the AD and control groups. Particularly noteworthy was the significant down-regulation of antibody (anti-DG#29) targeting an epitope of Epstein-Barr virus nuclear antigen 1 (EBNA1). This down-regulation increased AD risk in female patients (odds ratio up to 6.6), but not in male patients. Our investigation further revealed that the down-regulation of the antibody (anti-DG#29) is associated with EBV reactivation in AD, as indicated by the analysis of EBV VCA IgG or IgM levels. Additionally, our data demonstrated that the epitope region on EBNA1 for the antibody is hidden during the EBV lytic reactivation of B95–8 cells. *Conclusion* Our findings suggest a potential relationship of EBV in the development of AD in female. Moreover, we propose that antibodies targeting the epitope (DG#29) of EBNA1 could serve as valuable indicators of AD risk in female.

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