Identification of an H-Ras nanocluster disrupting peptide
Candy Laura Steffen1, Ganesh Babu Manoharan1, Karolina Pavic1
1Cancer Cell Biology and Drug Discovery group, Department of Life Sciences and Medicine, University of Luxembourg, 4362, Esch-sur-Alzette, Luxembourg.
Abstract:
Hyperactive Ras signalling is found in most cancers. Ras proteins are only active in membrane nanoclusters, which are therefore potential drug targets. We previously showed that the nanocluster scaffold galectin-1 (Gal1) enhances H-Ras nanoclustering via direct interaction with the Ras binding domain (RBD) of Raf. Here, we establish that the B-Raf preference of Gal1 emerges from the divergence of the Raf RBDs at their proposed Gal1-binding interface. We then identify the L5UR peptide, which disrupts this interaction by binding with low micromolar affinity to the B- and C-Raf-RBDs. Its 23-mer core fragment is sufficient to interfere with H-Ras nanoclustering, modulate Ras-signalling and moderately reduce cell viability. These latter two phenotypic effects may also emerge from the ability of L5UR to broadly engage with several RBD- and RA-domain containing Ras interactors. The L5UR-peptide core fragment is a starting point for the development of more specific reagents against Ras-nanoclustering and -interactors.
Insights
Researchers identified the L5UR peptide, which disrupts galectin-1 (Gal1) binding to Raf Ras binding domains (RBDs). This peptide interferes with Ras nanoclustering, impacting cancer signalling pathways.
Area of Science:
- Oncology
- Molecular Biology
- Biochemistry
Background:
- Hyperactive Ras signaling drives most cancers.
- Ras proteins function within membrane nanoclusters, presenting a therapeutic target.
- Galectin-1 (Gal1) enhances H-Ras nanoclustering by interacting with Raf's Ras binding domain (RBD).
Purpose of the Study:
- To investigate the basis for Gal1's B-Raf preference.
- To identify novel inhibitors of Ras-Raf interactions within nanoclusters.
- To explore therapeutic strategies targeting Ras signaling.
Main Methods:
- Comparative analysis of Raf RBD sequences to understand Gal1 binding specificity.
- Identification and characterization of the L5UR peptide and its core fragment.
- Assays to measure L5UR's effect on H-Ras nanoclustering, Ras signaling, and cell viability.
Main Results:
- Gal1's B-Raf preference is attributed to divergence in Raf RBDs at the Gal1-binding interface.
- The L5UR peptide disrupts Gal1-Raf interaction with low micromolar affinity for B- and C-Raf-RBDs.
- The L5UR core fragment inhibits H-Ras nanoclustering, modulates Ras signaling, and reduces cell viability.
Conclusions:
- The L5UR peptide core fragment is a promising starting point for developing targeted Ras-nanoclustering inhibitors.
- Disrupting Ras-Raf interactions within nanoclusters offers a potential anti-cancer therapeutic strategy.
- L5UR's broader interactions suggest potential for targeting multiple Ras pathway components.
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