title: Short-term effects of INGAP and Reg family peptides on the appearance of small β-cells clusters in non-diabetic mice.
abstract: The Reg3 peptides INGAP-PP and human Reg3α/β (HIP) have been hypothesized to stimulate β-cell neogenesis in the pancreas. Administration of INGAP-PP has been shown to cause an increase in β-cell mass in multiple animal models, reverse streptozotocin (STZ) induced diabetes in mice and reduces HbA1c levels in type 2 diabetic humans. In this study, we have examined the ability of the INGAP-PP and HIP peptides to induce β-cell formation in vivo in normal mice through short-term administration of the peptides. We assessed the peptides ability to induce an increase in extra-islet insulin-positive cell clusters by looking at β-cell number by point counting morphometry on pancreata that had been randomized using the smooth fractionator principle in non-diabetic NMRI mice after short-term injections of the peptides (5 d). Five day continuous BrdU labeling was used to determine if the new β-cells were derived from replicating β-cells. Real time quantitative RT-PCR and immuno-histochemistry was used to analyze changes in pancreatic transcription factor expression. A 1.5- to 2-fold increase in the volume of small extra-islet insulin-positive clusters post 5 d treatment with INGAP-PP and HIP as compared with mice treated with a non-peptide control or scrambled peptide (p<0.05) (n = 7) was found. Five day continuous BrdU infusion during the 5 d period showed little or no incorporation in islets or small insulin clusters. Five days of treatment with INGAP-PP or HIP, showed a tendency toward increased levels of pancreatic progenitor markers such as Ngn3, Nkx6.1, Sox9 and Ins. These are the first studies to compare and indicate that the human Reg3 α/β (HIP) peptide has similar bioactivity in vivo as INGAP by causing formation of small β-cell clusters in extra-islet pancreatic tissue after only 5 d of treatment. Upregulation of pancreatic transcription factors may be part of the mechanism of action.
authors.affiliation: Department of Beta Cell Regeneration; Hagedorn Research Institute; Gentofte, Denmark.
authors.forename: Rahul
authors.initials: R
authors.lastname: Kapur
authors.affiliation: Department of Beta Cell Regeneration; Hagedorn Research Institute; Gentofte, Denmark.
authors.forename: Tine Westergaard
authors.initials: TW
authors.lastname: Højfeldt
authors.affiliation: Department of Beta Cell Regeneration; Hagedorn Research Institute; Gentofte, Denmark.
authors.forename: Tine Westergaard
authors.initials: TW
authors.lastname: Højfeldt
authors.affiliation: Department of Incretin Biology; Hagedorn Research Institute; Gentofte, Denmark.
authors.forename: Sif Groth
authors.initials: SG
authors.lastname: Rønn
authors.affiliation: Department of Beta Cell Regeneration; Hagedorn Research Institute; Gentofte, Denmark.
authors.forename: Allan E
authors.initials: AE
authors.lastname: Karlsen
authors.affiliation: Department of Beta Cell Regeneration; Hagedorn Research Institute; Gentofte, Denmark.
authors.forename: R Scott
authors.initials: RS
authors.lastname: Heller
mesh_terms: D000818:Animals; D000951:Antigens, Neoplasm / Q000494:pharmacology*; D051792:Basic Helix-Loop-Helix Proteins / Q000032:analysis / Q000235:genetics; D014408:Biomarkers, Tumor / Q000494:pharmacology*; D002452:Cell Count; D005260:Female; D015870:Gene Expression; D018398:Homeodomain Proteins / Q000032:analysis / Q000235:genetics; D007328:Insulin / Q000032:analysis / Q000235:genetics; D050417:Insulin-Secreting Cells / Q000737:chemistry / Q000166:cytology* / Q000187:drug effects*; D037181:Lectins, C-Type; D051379:Mice; D009419:Nerve Tissue Proteins / Q000032:analysis / Q000235:genetics; D000073718:Pancreatitis-Associated Proteins; D055758:SOX9 Transcription Factor / Q000032:analysis / Q000235:genetics; D013997:Time Factors; D014157:Transcription Factors / Q000032:analysis; D015854:Up-Regulation
chemical_list: D000951:Antigens, Neoplasm; D051792:Basic Helix-Loop-Helix Proteins; D014408:Biomarkers, Tumor; D018398:Homeodomain Proteins; D007328:Insulin; D037181:Lectins, C-Type; D009419:Nerve Tissue Proteins; D000073718:Pancreatitis-Associated Proteins; D055758:SOX9 Transcription Factor; D014157:Transcription Factors; C407737:Neurog3 protein, mouse; C491328:Nkx6-1 protein, mouse; C000612141:REG3A protein, human; C527933:Sox9 protein, mouse