Insulin-degrading enzyme regulates mRNA processing and in-teracts with the CCR4-NOT transcription complex

Insulin-degrading enzyme is zinc metallo protease degrading low molecular weight substrates including insulin. Ubiquitous expression, high evolutionary conservation, upregulation of Ide in stress situations, and various literature findings suggest a broader function of Ide in cell physiology and protein homeostasis that remains to be elucidated. We used proteomics and transcriptomics approaches searching for leads related to a broader role of Ide in protein homeostasis. We combined an analysis of the proteome and single-cell transcriptome of Ide+/+ and Ide-/- pancreatic islet cells with an examination of the interactome of human cytosolic Ide using proximity biotinylation. We observe an upregulation of pathways related to RNA processing and translation in Ide+/+ relative to Ide-/- islet cells. Corroborating these results and providing a potential mechanistic explanation, proximity biotinylation reveals interaction of Ide with several subunits of CCR4-NOT, a key complex and mRNA deadenylase regulating protein expression "from birth to death". We propose a speculative model in which Ide and CCR4-NOT cooperate to control and limit protein expression in proteotoxic and met-abolic stress situations through cooperation between their deadenylase and protease functions.