title: A cathepsin L-specific inhibitor preferentially inhibits degradation of autophagosomal LC3 and GABARAP in HeLa and Huh-7 cells.
abstract: CAA0225 ((2S,3S)-oxirane-2,3-dicarboxylic acid 2-[((S)-1-benzylcarbamoyl-2-phenyl-ethyl)-amide] 3-{[2-(4-hydroxy-phenyl)-ethyl]-amide}) is a cathepsin L-specific inhibitor recently selected out by extensive screening of a series of new epoxysuccinyl peptides. CAA0225 inhibited rat liver cathepsin L with IC(50) values of 1.9 nM, but not rat liver cathepsin B (IC(50), >1,000-5,000 nM). We compared effects of CAA0225 on autophagy with those of CA-074 that was previously developed as a cathepsin B-specific inhibitor. In HeLa and Huh-7 cells cultured under nutrient-deprived conditions both CAA0225 and CA-074 significantly and comparably inhibited degradation of long-lived proteins. Meanwhile, CAA0225 effectively inhibited degradation of LC3-II and GABARAP, whereas CA-074-OMe had only a marginal effect on their levels. Therefore, cathepsin L does not seem to play a general role in the degradation of proteins in the lumen of autophagosomes, but is involved more specifically in the degradation of autophagosomal membrane markers.
authors.affiliation: Juntendo University School of Medicine, Department of Biochemistry, Tokyo, Japan. upfield@juntendo.ac.jp
authors.forename: Takashi
authors.initials: T
authors.lastname: Ueno
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Takahashi
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D000818:Animals; D051017:Apoptosis Regulatory Proteins; D001343:Autophagy / Q000187:drug effects; D001593:Benzyl Compounds / Q000494:pharmacology*; D056668:Cathepsin L / Q000037:antagonists & inhibitors*; D004151:Dipeptides; D004852:Epoxy Compounds; D005027:Ethylene Oxide / Q000031:analogs & derivatives* / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D010588:Phagosomes / Q000187:drug effects / Q000378:metabolism; D010649:Phenylalanine / Q000031:analogs & derivatives; D011480:Protease Inhibitors / Q000494:pharmacology*; D011499:Protein Processing, Post-Translational / Q000187:drug effects*; D051381:Rats; D013379:Substrate Specificity / Q000187:drug effects
chemical_list: C540134:(2S,3S)-oxirane-2,3-dicarboxylic acid 2-(((S)-1-benzylcarbamoyl-2-phenyl-ethyl)-amide) 3-((2-(4-hydroxy-phenyl)-ethyl)-amide); D048868:Adaptor Proteins, Signal Transducing; D051017:Apoptosis Regulatory Proteins; D001593:Benzyl Compounds; D004151:Dipeptides; D004852:Epoxy Compounds; C116741:GABARAP protein, human; C477012:MAP1LC3A protein, human; D008869:Microtubule-Associated Proteins; D011480:Protease Inhibitors; D010649:Phenylalanine; D056668:Cathepsin L; D005027:Ethylene Oxide