Discovery, characterization, and clinical development of the glucagon-like peptides Daniel J. Drucker, … , Joel F. Habener, Jens Juul Holst J Clin Invest. 2017;127(12):4217-4227. https://doi.org/10.1172/JCI97233. Harrington Prize Essay Endocrinology Gastroenterology The discovery, characterization, and clinical development of glucagon-like-peptide-1 (GLP-1) spans more than 30 years and includes contributions from multiple investigators, science recognized by the 2017 Harrington Award Prize for Innovation in Medicine. Herein, we provide perspectives on the historical events and key experimental findings establishing the biology of GLP-1 as an insulin-stimulating glucoregulatory hormone. Important attributes of GLP-1 action and enteroendocrine science are reviewed, with emphasis on mechanistic advances and clinical proof-of-concept studies. The discovery that GLP-2 promotes mucosal growth in the intestine is described, and key findings from both preclinical studies and the GLP-2 clinical development program for short bowel syndrome (SBS) are reviewed. Finally, we summarize recent progress in GLP biology, highlighting emerging concepts and scientific insights with translational relevance. Find the latest version: https://jci.me/97233/pdf The Journal of Clinical Investigation HARRINGTON PRIZE ESSAY Discovery, characterization, and clinical development of the glucagon-like peptides Daniel J. Drucker,1 Joel F. Habener,2 and Jens Juul Holst3 1Lunenfeld-Tanenbaum Research Institute, Mt. Sinai Hospital, University of Toronto, Toronto, Ontario, Canada. 2Laboratory of Molecular Endocrinology, Massachusetts General Hospital, Harvard University, Boston, Massachusetts, USA. 3Novo Nordisk Foundation Center for Basic Metabolic Research, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark. sequences of cloned recombinant cDNA copies of messenger RNAs. The Habener The discovery, characterization, and clinical development of glucagon-like- lab utilized this technology to elucidate peptide-1 (GLP-1) spans more than 30 years and includes contributions from proglucagon amino acid sequences from multiple investigators, science recognized by the 2017 Harrington Award cDNAs and genes isolated from angler- Prize for Innovation in Medicine. Herein, we provide perspectives on the fish in the early 1980s (3–5) and the rat historical events and key experimental findings establishing the biology proglucagon cDNA and gene sequences of GLP-1 as an insulin-stimulating glucoregulatory hormone. Important followed shortly thereafter (refs. 6, 7, Fig- attributes of GLP-1 action and enteroendocrine science are reviewed, with ure 1, and Figure 2). Corresponding pro- emphasis on mechanistic advances and clinical proof-of-concept studies. glucagon sequences from hamster, bovine, The discovery that GLP-2 promotes mucosal growth in the intestine is and human were identified by Graeme described, and key findings from both preclinical studies and the GLP-2 Bell and others in the early 1980s (8–10). clinical development program for short bowel syndrome (SBS) are reviewed. These sequences revealed that glucagon Finally, we summarize recent progress in GLP biology, highlighting emerging and re lated GLP sequences were encoded concepts and scientific insights with translational relevance. by larger protein precursors, termed pre- prohormones (Figure 2). The anglerfish preproglucagons (Figure 2A), isolated and characterized by Lund and Goodman (3–5), were interesting as there were two different The endocrine activity of the gastroin- second incretin hormone, GLP-1. We high- cDNAs encoded by separate (nonallelic) testinal tract has been studied for more light 3 decades of science from multiple genes and they each contained a glucagon- than a century, with gut hormones such as laboratories supporting the development related sequence, in addition to glucagon. secretin emerging from the seminal stud- of GLP-1– and GLP-2–based therapies. The two anglerfish glucagon–related pep- ies of Bayliss and Starling (1). The concept GLP-1 is now used for the treatment of tides resembled GIP, a glucoincretin hor- that the gut also controlled pancreatic type 2 diabetes (T2D) and obesity, whereas mone released from the gut into the circu- islet secretions was supported by experi- GLP-2 is used for the therapy of short bow- lation during meals, subsequently shown ments demonstrating that administration el syndrome (SBS). by Dupre and Brown in 1973 to augment of crude gut extracts lowered blood glu- glucose-dependent insulin secretion (11). cose in animals. The development of the Discovery of GLP-1 Unlike the two anglerfish preproglucagons, insulin radioimmunoassay enabled the Although GIP was isolated through classical each of which harbored glucagon and a sin- description of the incretin effect, namely peptide purification and protein sequenc- gle glucagon-related peptide, the mammali- that glucose administered into the gut ing methodology, the discovery of the an preproglucagons all contained glucagon potentiated insulin secretion to a greater GLP-1 sequence stemmed from the appli- and two additional glucagon-related pep- extent than isoglycemic stimulation of cation of recombinant DNA approaches tides, designated GLP-1 and GLP-2 (Figure insulin secretion achieved through i.v. developed in the laboratories of Stanley 2B). Notably, the corresponding amino acid glucose administration. The first incretin Cohen, Paul Berg, and Herb Boyer in the sequences of the GLP-1s in the four mam- hormone, glucose-dependent insulinotro- early 1970s. This remarkable new techn- malian species were identical (12), with pic polypeptide (GIP), was isolated by John ology allowed for a rapid and accurate conservation of sequence implying as yet Brown in the 1970s (2). Here, we describe prediction of the amino acid sequences of unknown but potentially important biolog- the discovery and characterization of the proteins by the decoding of the nucleotide ical actions of GLP-1. Collectively, these findings further supported the evolving notion at the Conflict of interest: D.J. Drucker is supported by the Canada Research Chairs program and a BBDC-Novo Nordisk time that small peptide hormones are Chair in incretin biology, and has received speaking or consulting honorarium from Arisaph, Intarcia, Merck, Pfizer, synthesized in the form of larger prohor- and Novo Nordisk Inc. Mt. Sinai Hospital receives research support from GSK, Merck, and Novo Nordisk, for preclin- ical studies in the Drucker laboratory. J.J. Holst has served as a consultant or advisor to Novartis Pharmaceuticals, mones and that the final bioactive pep- Novo Nordisk, Merck Sharp & Dohme, and Roche and has received fees for lectures from Novo Nordisk, Merck Sharp tides are formed posttranslationally by & Dohme, and GlaxoSmithKline. selective enzymatic cleavages from the Reference information: J Clin Invest. 2017;127(12):4217–4227. https://doi.org/10.1172/JCI97233 prohormones (Figure 2B). Earlier studies jci.org Volume 127 Number 12 December 2017 4217 HARRINGTON PRIZE ESSAY The Journal of Clinical Investigation Figure 1. Historical timeline depicting seminal events in the discovery and development of gluca- gon-like peptide therapeutics. had demonstrated that insulin and para- GLP-1(7-37). Further, at the carboxyl- note, in addition to glucagon, the pancreas thyroid hormone are synthesized as pre- terminal region of the putative GLP-1 pep- contained a large peptide with immuno- prohormones. The hydrophobic amino tide resides a sequence RGRR predicting reactive determinants for both GLP-1 and terminal sequences, termed the pre- or a prohormone convertase–directed cleav- GLP-2 (but not glucagon), consistent with signal sequences, are cleaved from the age site followed by an amidation of the incompletely cleaved proglucagon (major nascent polypeptide chains during their penultimate arginine by a peptidylglycine proglucagon fragment [MPGF]) (Figure 3, translation on ribosomes, leaving the α-amidating monooxygenase (14) result- A and C, and ref. 19). In contrast to find- prohormones as the precursor of the ing in peptides of 36 and 30 amino acids, ings in pancreas, immunoreactive GLP-1 peptide hormones. The A and B chains GLP-1(1-36)amide and GLP-1(7-36)amide. peptides detected in gut extracts consisted of insulin and parathyroid hormone were The availability of the amino acid entirely of smaller peptides (refs. 15 and found to be cleaved from their respective sequences of GLP-1 and GLP-2 obtained 16, and Figure 3, B and C). These findings prohormones by the actions of specific from the decoding of the nucleotide indicated that the cleavage of proglucagon endopeptidases, prohormone conver- sequences based on the genetic code into small GLP-1–immunoreactive pep- tases, which cleave proteins at the sites allowed for the chemical synthesis of the tides was more efficient in the gut com- of two consecutive basic amino acids, predicted peptides, examination of their pared with pancreas. These observations arginine and lysine (13). These earlier biological activities, and preparation of were also consistent with the incretin con- findings of prohormone convertase spec- peptide-specific antisera. Daniel Drucker cept in which, in response to oral nutrients, ificity were applied to deduce potential joined the Habener laboratory in the sum- glucoincretin hormones such as GIP (and cleavage sites in proglucagon. mer of 1984, with the original intent of subsequently GLP-1) originate from the studying the molecular control of thyroid gut and