Discovery of Stable and Permeable N‑Methylated Cyclic Peptides to Block the Endocytosis of GluA2 AMPAR for Ischemic Stroke Therapy

The
membrane-permeable peptide Tat-GluA2-3Y exhibits
therapeutic potential by competitively binding BRAG2 to disrupt GluA2
endocytosis. However, their poor in vivo stability
has become a barrier to clinical application. To address this limitation,
we systematically designed a series of N-methylated
cyclic peptides derived from GluA2-3Y and identified
the optimal peptide, c10c-G1V3, which exhibited high
binding affinity for BRAG2 (Kd = 7.37
μM) and potent neuroprotective activity in both the OGD-induced
cell model (cell viability: 85.97%) and the Glu-induced cell model
(cell viability: 76.34%) at 10 μM. Mechanistically, c10c-G1V3 markedly attenuated Glu-induced intracellular reactive oxygen species
accumulation. Notably, it displayed superior plasma stability and
favorable in vivo pharmacokinetic properties compared
to Tat-GluA2-3Y. In SD rat tMCAO models, 8 mg/kg c10c-G1V3 reduced infarct volume comparably to that of Tat-GluA2-3Y. Collectively, these findings establish c10c-G1V3 as a promising candidate for the development of
novel therapeutics against an ischemic stroke.