title: Dual Exosite-binding Inhibitors of Insulin-degrading Enzyme Challenge Its Role as the Primary Mediator of Insulin Clearance in Vivo.
abstract: Insulin-degrading enzyme (IDE, insulysin) is the best characterized catabolic enzyme implicated in proteolysis of insulin. Recently, a peptide inhibitor of IDE has been shown to affect levels of insulin, amylin, and glucagon in vivo. However, IDE(-/-) mice display variable phenotypes relating to fasting plasma insulin levels, glucose tolerance, and insulin sensitivity depending on the cohort and age of animals. Here, we interrogated the importance of IDE-mediated catabolism on insulin clearance in vivo. Using a structure-based design, we linked two newly identified ligands binding at unique IDE exosites together to construct a potent series of novel inhibitors. These compounds do not interact with the catalytic zinc of the protease. Because one of these inhibitors (NTE-1) was determined to have pharmacokinetic properties sufficient to sustain plasma levels >50 times its IDE IC50 value, studies in rodents were conducted. In oral glucose tolerance tests with diet-induced obese mice, NTE-1 treatment improved the glucose excursion. Yet in insulin tolerance tests and euglycemic clamp experiments, NTE-1 did not enhance insulin action or increase plasma insulin levels. Importantly, IDE inhibition with NTE-1 did result in elevated plasma amylin levels, suggesting the in vivo role of IDE action on amylin may be more significant than an effect on insulin. Furthermore, using the inhibitors described in this report, we demonstrate that in HEK cells IDE has little impact on insulin clearance. In total, evidence from our studies supports a minimal role for IDE in insulin metabolism in vivo and suggests IDE may be more important in helping regulate amylin clearance.
authors.affiliation: From the Discovery Chemistry Research and Technologies, durham_timothy_barrett@lilly.com.
authors.forename: Timothy B
authors.initials: TB
authors.lastname: Durham
authors.affiliation: From the Discovery Chemistry Research and Technologies.
authors.forename: James L
authors.initials: JL
authors.lastname: Toth
authors.affiliation: From the Discovery Chemistry Research and Technologies.
authors.forename: Valentine J
authors.initials: VJ
authors.lastname: Klimkowski
authors.affiliation: Endocrine Discovery.
authors.forename: Julia X C
authors.initials: JX
authors.lastname: Cao
authors.affiliation: Endocrine Discovery.
authors.forename: Angela M
authors.initials: AM
authors.lastname: Siesky
authors.affiliation: Endocrine Discovery.
authors.forename: Jesline
authors.initials: J
authors.lastname: Alexander-Chacko
authors.affiliation: Endocrine Discovery.
authors.forename: Ginger Y
authors.initials: GY
authors.lastname: Wu
authors.affiliation: From the Discovery Chemistry Research and Technologies.
authors.forename: Jeffrey T
authors.initials: JT
authors.lastname: Dixon
authors.affiliation: From the Discovery Chemistry Research and Technologies.
authors.forename: James E
authors.initials: JE
authors.lastname: McGee
authors.affiliation: From the Discovery Chemistry Research and Technologies.
authors.forename: Yong
authors.initials: Y
authors.lastname: Wang
authors.affiliation: From the Discovery Chemistry Research and Technologies.
authors.forename: Sherry Y
authors.initials: SY
authors.lastname: Guo
authors.affiliation: From the Discovery Chemistry Research and Technologies.
authors.forename: Rachel Nicole
authors.initials: RN
authors.lastname: Cavitt
authors.affiliation: From the Discovery Chemistry Research and Technologies.
authors.forename: John
authors.initials: J
authors.lastname: Schindler
authors.affiliation: Translational Science and Technologies, and.
authors.forename: Stefan J
authors.initials: SJ
authors.lastname: Thibodeaux
authors.affiliation: Drug Disposition, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana 46285.
authors.forename: Nathan A
authors.initials: NA
authors.lastname: Calvert
authors.affiliation: From the Discovery Chemistry Research and Technologies.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Coghlan
authors.affiliation: Endocrine Discovery.
authors.forename: Dana K
authors.initials: DK
authors.lastname: Sindelar
authors.affiliation: Endocrine Discovery.
authors.forename: Michael
authors.initials: M
authors.lastname: Christe
authors.affiliation: Endocrine Discovery.
authors.forename: Vladislav V
authors.initials: VV
authors.lastname: Kiselyov
authors.affiliation: Endocrine Discovery.
authors.forename: M Dodson
authors.initials: MD
authors.lastname: Michael
authors.affiliation: Endocrine Discovery.
authors.forename: Kyle W
authors.initials: KW
authors.lastname: Sloop
mesh_terms: D000818:Animals; D001665:Binding Sites; D018360:Crystallography, X-Ray; D004791:Enzyme Inhibitors / Q000493:pharmacokinetics / Q000494:pharmacology*; D057809:HEK293 Cells; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D007339:Insulysin / Q000037:antagonists & inhibitors* / Q000737:chemistry; D008958:Models, Molecular; D059748:Proteolysis
chemical_list: D004791:Enzyme Inhibitors; D007328:Insulin; D007339:Insulysin
keywords: Insulin-degrading enzyme; amylin; cryptidase; diabetes; exosite; glucagon; glucose metabolism; insulin; insulysin; protease inhibitor