Enigmatic GPCR finds a stimulating drug

Area of Science:

• Neuroscience
• Cell Biology
• Pharmacology

Background:

• GPR17 is an orphan G protein-coupled receptor vital for oligodendrocyte differentiation and central nervous system myelination.
• Existing knowledge on GPR17 agonists, such as uracil nucleotides and cysteinyl leukotrienes, is limited and debated.
• Developing specific modulators for GPR17 is essential for understanding its role and potential therapeutic applications.

Purpose of the Study:

• To identify novel small molecule activators of the GPR17 receptor.
• To characterize the signaling pathways activated by these molecules.
• To investigate the role of GPR17 in oligodendrocyte differentiation and myelination.

Main Methods:

• A signaling pathway-unbiased screen was employed to discover GPR17 activators.
• Recombinant GPR17-expressing cell lines and primary rat oligodendrocytes were used to assess receptor activation and downstream signaling (Gαi and Gαq pathways).
• Experiments involved heterozygous and GPR17 knockout mice to evaluate the in vivo effects on myelination.

Main Results:

• Two small molecule activators of GPR17 were identified, with MDL29951 being further characterized.
• MDL29951 demonstrated GPR17-dependent activation of Gαi- and Gαq-signaling pathways in cell lines and primary oligodendrocytes.
• MDL29951 did not activate known P2Y or cysteinyl leukotriene receptors, confirming its specificity.
• MDL29951 treatment reduced myelination in primary oligodendrocytes from heterozygous mice but not in those from GPR17 knockout mice.

Conclusions:

• MDL29951 is a specific small-molecule agonist of GPR17, validating its role in oligodendrocyte differentiation and myelination.
• The findings support the development of GPR17 antagonists as a therapeutic strategy for demyelinating diseases.
• This research provides a valuable tool for further investigation into GPR17 function in the central nervous system.