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Publication Abstract from PubMed

Although cyclophilins are attractive targets for probing biology and therapeutic intervention, no subtype-selective cyclophilin inhibitors have been described. We discovered novel cyclophilin inhibitors from the in vitro selection of a DNA-templated library of 256,000 drug-like macrocycles for cyclophilin D (CypD) affinity. Iterated macrocycle engineering guided by ten X-ray co-crystal structures yielded potent and selective inhibitors (half maximal inhibitory concentration (IC50) = 10 nM) that bind the active site of CypD and also make novel interactions with non-conserved residues in the S2 pocket, an adjacent exo-site. The resulting macrocycles inhibit CypD activity with 21- to >10,000-fold selectivity over other cyclophilins and inhibit mitochondrial permeability transition pore opening in isolated mitochondria. We further exploited S2 pocket interactions to develop the first cyclophilin E (CypE)-selective inhibitor, which forms a reversible covalent bond with a CypE S2 pocket lysine, and exhibits 30- to >4,000-fold selectivity over other cyclophilins. These findings reveal a strategy to generate isoform-selective small-molecule cyclophilin modulators, advancing their suitability as targets for biological investigation and therapeutic development.

Discovery and molecular basis of subtype-selective cyclophilin inhibitors.,Peterson AA, Rangwala AM, Thakur MK, Ward PS, Hung C, Outhwaite IR, Chan AI, Usanov DL, Mootha VK, Seeliger MA, Liu DR Nat Chem Biol. 2022 Nov;18(11):1184-1195. doi: 10.1038/s41589-022-01116-1. Epub, 2022 Sep 26. PMID:36163383^[3]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.