Glucagon-like peptide 1 (1–37) converts intestinal epithelial cells into insulin-producing cells

Abstract

Glucagon-like peptide (GLP) 1 is produced through posttranslational processing of proglucagon and acts as a regulator of various homeostatic events. Among its analogs, however, the function of GLP-1-(1-37), synthesized in small amounts in the pancreas, has been unclear. Here, we find that GLP-1-(1-37) induces insulin production in developing and, to a lesser extent, adult intestinal epithelial cells in vitro and in vivo, a process mediated by upregulation of the Notch-related gene ngn3 and its downstream targets, which are involved in pancreatic endocrine differentiation. These cells became responsive to glucose challenge in vitro and reverse insulin-dependent diabetes after implantation into diabetic mice. Our findings suggest that efficient induction of insulin production in intestinal epithelial cells by GLP-1-(1-37) could represent a new therapeutic approach to diabetes mellitus.A t the end of gastrulation, the mouse endoderm exists as a one-cell layer covering the mesoderm and ectoderm of the embryo. Gut development begins with the invagination of the most anterior and posterior endoderm at embryonic day 8.5 (E8.5), leading to the formation of two open-ended tubes. This anterior and posterior migration, in combination with embryonic twisting, closes the midgut and forms a primitive gut tube. Pseudostratified immature epithelium is found in the gut by E15, and subsequent remodeling of the gut endoderm between E15 and E19 leads to the production of nascent villi with a monolayer of epithelial cells. During the first 2 postnatal wk, the intervillus epithelium develops into crypts, which contain a dividing epithelial stem cell population. Crypt cell progenies differentiate into the nonproliferative four principal epithelial cell lineages: enterocytes (columnar cells), goblet cells, enteroendocrine cells, and Paneth cells (1).Generation of these cell types requires a number of processes regulated by various signaling molecules and transcription factors. Like neuronal development in the central nervous system, the Notch signaling pathway is involved in endodermal endocrine differentiation (2-5). In this signaling system, ligands bind to Notch receptors and activate their intracellular domains, leading to interaction with the DNA-binding protein RBP-J k . This protein in turn activates expression of the basic helix-loophelix Hes genes (6, 7), which, in turn, repress expression of downstream target genes, including neurogenin (ngn) and Math-1 (8, 9). Decreased Hes repression results in cell differentiation to a primary fate. In the developing pancreases of mice lacking RBP-J k or a Notch ligand, Delta-like gene 1 (Dll1), differentiation of pancreatic endocrine cells was accelerated (10, 11). Overexpression of ngn3 or the intracellular domain of Notch3 (a repressor of Notch signaling) (12) also resulted in a similar pancreatic phenotype (2). Deletion of Hes-1 leads to pancreatic hypoplasia caused by increased endocrine differentiation from pancreatic progenitors and to abnormal endocrine differentiation of the stoma...

EGF signaling activates proliferation and blocks apoptosis of mouse and human intestinal stem/progenitor cells in long-term monolayer cell culture

“…[28][29] Information regarding PCR primers is presented in Supplementary Tables 1 and 2 and in our previous papers. 27,29,30 Immunostaining Frozen sections of intestinal tissues were fixed by 4% paraformaldehyde for 5 min at 4 1C.…”

“…[28][29] Information regarding PCR primers is presented in Supplementary Tables 1 and 2 and in our previous papers. 27,29,30 Immunostaining Frozen sections of intestinal tissues were fixed by 4% paraformaldehyde for 5 min at 4 1C. After washing in PBS and blocking, tissue sections were incubated with primary antibodies against EGFR (Santa Cruz), EGF (Chemicon), E-cadherin (E-cad) (BD Biosciences), BrdU (Amersham), and cleaved caspase-3 (Cell signaling).…”

“…After washing and blocking, these paraffin sections were incubated with an anti-BrdU antibody. Cultured cells were fixed as described previously 29 and incubated with primary antibodies against E-cad, Zo-1 (Zymed), Villin (Santa Cruz), Musashi-1 (Chemicon), serotonin (Immunostar), chromogranin A (Santa Cruz), gastrin (Santa Cruz), secretin (Chemicon), somatostatin (Affiniti Research Products), gastric inhibitory polypeptide (GIP) (Chemicon), synaptophysin (Dako), lysozyme (Dako), Ki-67 (Abcam), and b-galactosidase (Promega). After washing, paraffin sections were incubated with a horseradish peroxidaseconjugated secondary antibody (1:500; Dako), and frozen sections and cultured cells were incubated with Alexa 488-and/or Alexa 555-conjugated secondary antibodies (1:200; Molecular Probes) with DAPI.…”

In vitro cultivation and differentiation of fetal liver stem cells from mice

“…Liver progenitor cells and intestinal epithelial cells could be converted into insulin-producing cells with specific culture conditions [5,[7][8][9]. Purified hepatic oval stem cells possess the capacity to trans-differentiate into functional endocrine cells, including insulin-producing cells [10].…”

Activation of GLP-1 and gastrin signalling induces in vivo reprogramming of pancreatic exocrine cells into beta cells in mice

“…Among the many humoral factors that regulate pancreas development, glucagon-like peptide-1 (GLP-1) and its analogue, exendin-4, have been reported to affect beta cell differentiation under in vitro and ex vivo conditions [7][8][9]. In addition, previous in vivo studies showed that the co-activation of GLP-1 and gastrin signalling increased the number of beta cells in mouse models of diabetes [10][11][12].…”