title: Quantitative assessment of Pdx1 promoter activity in vivo using a secreted luciferase reporter system.
abstract: The luciferase reporter system is useful for the assessment of various biological processes in vivo. The transcription factor pancreatic and duodenal homeobox 1 (Pdx1) is critical for the formation and the function of pancreatic β-cells. A novel reporter system using secreted Gaussia princeps luciferase (GLuc) under the control of a Pdx1 promoter was generated and activated in rat and mouse β-cell lines. This Pdx1-GLuc construct was used as a transgene for the generation of reporter mice to monitor Pdx1 promoter activity in vivo via the measurement of secreted GLuc activity in a small aliquot of blood. Significantly increased plasma GLuc activity was observed in Pdx1-GLuc mice. Analysis of Pdx1-GLuc mice by bioluminescence imaging, GLuc reporter assays using homogenates of various organs, and immunohistochemistry revealed that GLuc expression and activity were exponentially higher in pancreatic β-cells than in pancreatic non-β-cells, the duodenum, and other organs. In addition, GLuc activity secreted into the culture medium from islets isolated from Pdx1-GLuc mice correlated with the number of islets. The transplantation of Pdx1-GLuc islets into severe combined immunodeficiency mice elevated their plasma GLuc activity. Conversely, a partial pancreatectomy in Pdx1-GLuc mice reduced plasma GLuc activity. These results suggest that a secreted luciferase reporter system in vivo enables not only the monitoring of promoter activity but also a quantitative and minimally invasive assessment of physiological and pathological changes in small cell masses, such as pancreatic β-cells.
authors.affiliation: Department of Metabolic Disorders, Diabetes Research Center, National Center for Global Health and Medicine, Tokyo 162-8655, Japan. kyasuda@ri.ncgm.go.jp.
authors.forename: Wataru
authors.initials: W
authors.lastname: Nishimura
authors.forename: Koki
authors.initials: K
authors.lastname: Eto
authors.forename: Atsushi
authors.initials: A
authors.lastname: Miki
authors.forename: Motohito
authors.initials: M
authors.lastname: Goto
authors.forename: Miho
authors.initials: M
authors.lastname: Kawaguchi
authors.forename: Takao
authors.initials: T
authors.lastname: Nammo
authors.forename: Haruhide
authors.initials: H
authors.lastname: Udagawa
authors.forename: Masaki
authors.initials: M
authors.lastname: Hiramoto
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Shimizu
authors.forename: Tadashi
authors.initials: T
authors.lastname: Okamura
authors.forename: Toshiyoshi
authors.initials: T
authors.lastname: Fujiwara
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Yasuda
authors.forename: Kazuki
authors.initials: K
authors.lastname: Yasuda
mesh_terms: D000818:Animals; D002460:Cell Line; D033342:Copepoda / Q000201:enzymology; D015870:Gene Expression; D017930:Genes, Reporter; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D007515:Islets of Langerhans / Q000378:metabolism; D008156:Luciferases / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D011401:Promoter Regions, Genetic / Q000502:physiology*; D051381:Rats; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*
chemical_list: D018398:Homeodomain Proteins; D015534:Trans-Activators; C084010:pancreatic and duodenal homeobox 1 protein; D008156:Luciferases