TY - JOUR T1 - Identification and characterization of a new carboxylesterase 2 isozyme, mfCES2C, in the small intestine of cynomolgus monkeys JF - Drug Metabolism and Disposition JO - Drug Metab Dispos DO - 10.1124/dmd.119.089011 SP - dmd.119.089011 AU - Kayoko Ohura AU - Yoshiyuki Igawa AU - Maori Tanaka AU - Kana Matsumoto AU - Akiko Kasahara AU - Naoya Wada AU - Kazuishi Kubota AU - Yasuhiro Uno AU - Teruko Imai Y1 - 2019/01/01 UR - http://dmd.aspetjournals.org/content/early/2019/12/13/dmd.119.089011.abstract N2 - In contrast to a single human carboxylesterase 2 (CES2) isozyme, hCE2, three CES2 genes have been identified in cynomolgus monkeys, mfCES2A, mfCES2B and mfCES2C. While mfCES2A protein is expressed in several organs, mfCES2B is a pseudogene and the phenotype of the mfCES2C gene has not yet been clarified in tissues. In previous studies, we detected an unidentified esterase in the region of CES2 mobility on non-denaturing polyacrylamide gel electrophoresis (PAGE) analysis of monkey intestinal microsomes, which showed immunoreactivity for anti-mfCES2A antibody. The aim of the present study was to identify this unidentified esterase from monkey small intestine. The esterase was separated on non-denaturing PAGE gel and digested in-gel with trypsin. The amino acid sequences of fragmented peptides were analyzed by tandem mass spectrometry. The unidentified esterase was shown to be identical to mfCES2C (XP_015298642.1, predicted from the genome sequence data). mfCES2C consists of 559 amino acid residues and shows approximately 90% homology with mfCES2A (561 amino acid residues). In contrast to the ubiquitous expression of mfCES2A, mfCES2C is only expressed in the small intestine, kidney and skin. The hydrolytic properties of recombinant mfCES2C, expressed in HEK293 cells, with respect to p-nitrophenyl derivatives, 4-methylumbelliferyl acetate and irinotecan were similar to those of recombinant mfCES2A. However, mfCES2C showed a higher hydrolase activity for O-n-valeryl propranolol than mfCES2A. It is concluded that the previously unidentified monkey intestinal CES2 is mfCES2C, which shows different hydrolytic properties to mfCES2A, depending on the substrate.SIGNIFICANCE STATEMENT In the present paper, we determined that mfCES2C, a novel monkey CES2 isozyme, is expressed in the small intestine and kidney of the cynomolgus monkey. Interestingly, mfCES2C showed a relatively wide substrate specificity for ester-containing compounds. These findings may support the use of in vitro to in vivo extrapolation for the intestinal hydrolysis of ester drugs in the cynomolgus monkey in early stages of drug development. ER -