LAUSR

Significance Enteroendocrine cells control key physiological processes such as appetite and insulin secretion through the secretion of neurotransmitters and peptide hormones. The bioactive peptides are subject to complex proteolytic processing essential for their activation or inactivation. Moreover, alternative processing allows for the generation of different peptides from the same precursor protein. We use human organoid cultures combined with CRISPR-Cas9–mediated loss of function and peptidomics to assay the peptide spectrum of gut proteases. We identify substrates of these enzymes and identify the production of intestinal glucagon in organoids. A more complete understanding of hormone processing could allow a rational design of therapeutic interventions targeting these proteases.