Disease-associated mutations prevent GPR56-collagen III interaction.

Area of Science:

• Neuroscience
• Molecular Biology
• Genetics

Background:

• G protein-coupled receptor 56 (GPR56) is an adhesion GPCR implicated in brain development.
• Mutations in GPR56 are linked to bilateral frontoparietal polymicrogyria (BFPP), a severe human brain malformation.
• Collagen III has been identified as the ligand for GPR56 in the developing brain.

Purpose of the Study:

• To identify and characterize a novel functional domain within the N-terminal fragment of GPR56 (GPR56(N)).
• To investigate the role of this domain in GPR56 ligand binding and its association with BFPP.
• To determine the impact of disease-associated mutations and glycosylation on GPR56-collagen III interaction.

Main Methods:

• Utilized the N-terminal fragment of GPR56 (GPR56(N)) as a molecular probe.
• Investigated the function of a newly discovered ligand binding domain within GPR56(N).
• Analyzed the effects of four disease-associated mutations and two N-glycosylation sites on ligand binding and protein expression.

Main Results:

• A novel ligand binding domain was identified in GPR56(N), containing four disease-associated mutations.
• Glycosylation of GPR56 is not essential for collagen III binding.
• Each of the four identified mutations completely abrogated the ligand binding capability of GPR56 to collagen III.

Conclusions:

• The identified ligand binding domain is crucial for GPR56's interaction with its ligand, collagen III.
• Disease-associated mutations in this domain primarily cause BFPP by preventing GPR56-collagen III binding.
• These findings provide critical insights into the molecular mechanisms underlying GPR56-related brain malformations.