Discovery of a novel STING-binding peptide associated with reduced cGAMP-induced inflammatory gene expression.
Peptide-1 shows potential in reducing STING-mediated inflammatory signaling in cellular models, but its clinical relevance remains to be determined.
Where it sits
this study against the rest of the cyclic glycine-proline (cgp) corpusSummary and findings
A peptide library was screened to identify STING-binding peptides, with Peptide-1 showing the highest affinity. Peptide-1 reduced cGAMP-induced IFN-β and IL-6 expression in macrophages without cytotoxicity. The study suggests potential for Peptide-1 in modulating inflammatory responses.
Abstract
cGAMP-induced STING activation contributes to inflammatory and interferon-related signalling, making STING a relevant target for inhibitor development. In this study, a 59,319-sequence peptide library was screened against STING by molecular docking, and four top-ranked peptides were selected for evaluation. MST analysis demonstrated that Peptides 1-4 bound to recombinant STING, with Peptide-1 showing the highest affinity (<i>K</i><sub>d</sub> = 0.15 ± 0.01 μM). Docking and simulation analyses suggested that binding was mediated by hydrogen bonding and hydrophobic contacts. Molecular dynamics, MM/PBSA, and free energy landscape analyses suggested stable binding with favourable calculated energetics. Peptide-1 showed no apparent cytotoxicity up to 10 μM in RAW264.7 macrophages and primary BMDMs, while dose-dependently reducing cGAMP-induced IFN-β and IL-6 expression at both protein and mRNA levels. This inhibitory effect was accompanied by reduced STING and IRF3 phosphorylation. Collectively, these findings suggest that Peptide-1 may bind STING and attenuate cGAMP-induced IFN-β and IL-6 expression.
Background
The study addresses the role of STING in inflammatory and interferon-related signaling, which is relevant for developing inhibitors to modulate these pathways. Prior research has identified STING as a key player in immune responses, but effective inhibitors are still under exploration. This study aims to identify peptides that can bind STING and potentially reduce inflammatory signaling.
Methods
A peptide library of 59,319 sequences was screened using molecular docking to identify candidates that bind STING. Four peptides were selected for further evaluation using MST analysis to determine binding affinity. Peptide-1 showed the highest affinity with a Kd of 0.15 ± 0.01 μM. The study also involved molecular dynamics simulations and cytotoxicity assays in RAW264.7 macrophages and primary BMDMs.
Results
Peptide-1 demonstrated the highest binding affinity to STING among the tested peptides. It reduced cGAMP-induced IFN-β and IL-6 expression at both protein and mRNA levels in a dose-dependent manner. The peptide also decreased phosphorylation of STING and IRF3, indicating a potential mechanism of action. No cytotoxicity was observed up to a concentration of 10 μM.
Interpretation
The findings suggest that Peptide-1 could serve as a potential modulator of STING-mediated inflammatory responses. While the binding affinity and reduction in inflammatory markers are promising, the study's reliance on cellular models limits the ability to draw conclusions about clinical efficacy. Further research, particularly in vivo studies, is needed to assess the therapeutic potential of Peptide-1.
Key findings
- Peptide-1 Kd = 0.15 ± 0.01 μM
- No cytotoxicity up to 10 μM in RAW264.7 macrophages
- Reduced IFN-β and IL-6 expression dose-dependently
- Reduced STING and IRF3 phosphorylation
Limitations
- cellular model only, no in vivo data
- short-term effects not indicative of long-term outcomes
- no clinical data to support therapeutic claims
- limited to specific cell types