Expression pattern of IAPP and prohormone convertase 1/3 reveals a distinctive set of endocrine cells in the embryonic pancreas

The earliest endocrine cells in the developing pancreas make glucagon and are described as a cells. We show here that these cells express islet amyloid polypeptide and prohormone convertase 1/3 (PC 1/3), proteins that are not expressed by mature a cells, but are found in P cells. PC 1/3 converts proglucagon to the functionally distinct hormones glucagon-like peptide (GLP)-1 and GLP-2 rather than glucagon. Despite these differences, the early proglucagon-positive cells express, as do mature cc cells, the POU domain transcription factor Brn-4, and do not express the beta cell factor pdx-1. The early production of atypical peptide hormones by these cells suggests that they could play an important role locally or systemically in the development of the embryo. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.