A184 DISCOVERY OF POTENTIAL LGR5 LIGANDS
Bibliographic record
Abstract
Abstract Background LGR5, an intestinal stem cell marker, is crucial in mediating R-spondin (RSPO) signaling, supporting canonical WNT signaling for tissue development and renewal. This pathway is pivotal in gastrointestinal (GI) disease, assisting wound healing and playing a role in cancer progression and chemoresistance. While modulating the WNT pathway holds therapeutic potential, directly targeting it risks disrupting cell differentiation and organ function. LGR5, whose activity complements but does not fully overlap with the WNT pathway, represents a safer target for therapeutic intervention. Aims This study seeks to identify novel ligands for LGR5, focusing on bioactive molecules in the gut lumen and secreted soluble factors from epithelial cells. In addition, RSPO-derived peptidomimetics were designed and assessed as potential LGR5 ligands. Methods Luminal lavages from mice intestines were subjected to size-exclusion chromatography, and their activity was tested using impedance assays in HEK293 cells expressing human LGR5 (HEK293/LGR5). Active fractions were further analyzed using pull-down assays and LC-MS/MS to identify LGR5 interacting proteins. Media from cultured IECs were also processed and evaluated for potential LGR5 ligands using LC-MS/MS. Protein-protein interactions (PPIs) were confirmed via immunoprecipitation (IP). Finally, RSPO peptidomimetics based on the FU2 domain, known to bind LGR5, were tested for their ability to modulate β-catenin activity through luciferase reporter assays. Results An isoform of Urotensin II (iUTS2) from the cell culture media and three proteins from intestinal luminal extracts were identified as potential LGR5 ligands. The interaction between iUTS2 and LGR5 was confirmed through IP. As a proof of concept, six RSPO peptidomimetics were designed and tested. Although none of the peptides fully replicated RSPO1 activity, three were found to enhance the effect of RSPO1 on WNT3a-induced β-catenin activity, indicating their potential as modulators of LGR5. Conclusions This study presents the first identification of potential endogenous and peptidomimetic LGR5 ligands. Although in the preliminary stages, these findings represent a significant step toward developing selective LGR5 ligands, offering insight into LGR5 receptor functions. Such discoveries hold promise for future LGR5-targeted therapies, which could restore tissue homeostasis in conditions like inflammatory bowel disease or impede cancer progression by preventing cell adaptation and dissemination. This work was funded by a CCC-GIA research grant (2022-2025) and NSERC (RGPIN-2019-05294). Funding Agencies CCCNSERC
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".