Macrocyclic and linear peptides promote LAR dimerization and neurite outgrowth

Area of Science:

• Neuroscience
• Molecular Biology
• Biochemistry

Background:

• Leucocyte common antigen-related protein (LAR), a type IIa receptor protein tyrosine phosphatase (RPTP), regulates crucial cellular processes including axon elongation and regeneration.
• LAR's activity is modulated by dimerization, with monomeric forms inhibiting and dimeric forms promoting axon growth, but controlling this dimerization has been challenging.

Purpose of the Study:

• To develop novel tools for controlling LAR dimerization to investigate its role in intracellular signaling.
• To identify high-affinity peptides that selectively modulate LAR dimerization.

Main Methods:

• Utilized the random non-standard peptides integrated discovery (RaPID) system, combining mRNA display with genetic code reprogramming.
• Performed peptide library screening to identify LAR-binding peptides.
• Assessed peptide-induced LAR dimerization using a split luciferase assay and evaluated effects on neurite outgrowth in cultured hippocampal neurons.

Main Results:

• Identified high-affinity macrocyclic (L6) and linear (D1L) peptides that bind and promote LAR dimerization in mouse and human cells with minimal off-target effects.
• Dimerized peptides, particularly D1L-derived dimers, showed enhanced LAR dimerization activity.
• Both monomeric and dimeric peptides stimulated neurite outgrowth in cultured hippocampal neurons.

Conclusions:

• De novo identified peptides (L6 and D1L) serve as selective modulators of LAR dimerization.
• These peptides provide valuable new tools for exploring LAR-mediated signaling pathways involved in axon growth and regeneration.