In vivo detection of extrapancreatic insulin gene expression in diabetic mice by bioluminescence imaging

• Published in: PloS one Vol. 5; no. 2; p. e9397
• Main Authors: Chen, Xiaojuan, Larson, Courtney S, West, Jason, Zhang, Xiaomin, Kaufman, Dixon B
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 24.02.2010; Public Library of Science (PLoS)
• Subjects: Animal tissues; Animals; Bioluminescence; Cell Biology/Gene Expression; Cytology; Diabetes; Diabetes and Endocrinology/Endocrinology; Diabetes mellitus; Diabetes Mellitus, Experimental - chemically induced; Diabetes Mellitus, Experimental - genetics; Diabetes Mellitus, Experimental - metabolism; Enzymatic activity; Enzyme activity; Enzymes; Gene expression; Gene Expression - drug effects; Genes; Genetic engineering; Glucose; House mouse; Hyperglycemia; Imaging; Immunohistochemistry; Immunology; In vivo methods and tests; Insulin; Insulin - genetics; Life sciences; Liver; Liver - drug effects; Liver - enzymology; Liver - metabolism; Localization; Luciferase; Luciferases - genetics; Luciferases - metabolism; Luminescent Measurements - methods; Medicine; Metabolism; Mice; Mice, Transgenic; Monitoring methods; Pancreas; Pancreatic beta cells; Pharmacology; Radiology and Medical Imaging; Reverse Transcriptase Polymerase Chain Reaction; Ribonucleic acid; RNA; Rodents; Stem cells; Streptozocin; Streptozocin - toxicity; Surgery; Tissues; Toxins; Transcription factors; Transgenic animals; Transgenic mice; Transplants & implants; United States > US; Illinois; Chicago Illinois
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0009397

Extrapancreatic tissues such as liver may serve as potential sources of tissue for generating insulin-producing cells. The dynamics of insulin gene promoter activity in extrapancreatic tissues may be monitored in vivo by bioluminescence-imaging (BLI) of transgenic mice Tg(RIP-luc) expressing the firefly luciferase (luc) under a rat-insulin gene promoter (RIP). The Tg(RIP-luc) mice were made diabetic by a single injection of the pancreatic beta-cell toxin streptozotocin. Control mice were treated with saline. Mice were subject to serum glucose measurement and bioluminescence imaging daily. On day eight of the treatment, mice were sacrificed and tissues harvested for quantitative luciferase activity measurement, luciferase protein cellular localization, and insulin gene expression analysis. Streptozotocin-induced diabetic Tg(RIP-luc) mice demonstrated a dramatic decline in the BLI signal intensity in the pancreas and a concomitant progressive increase in the signal intensity in the liver. An average of 5.7 fold increase in the liver signal intensity was detected in the mice that were exposed to hyperglycemia for 8 days. Ex vivo quantitative assays demonstrated a 34-fold induction of the enzyme activity in the liver of streptozotocin-treated mice compared to that of the buffer-treated controls. Luciferase-positive cells with oval-cell-like morphology were detected by immunohistochemistry in the liver samples of diabetic mice, but not in that of non-treated control transgenic mice. Gene expression analyses of liver RNA confirmed an elevated expression of insulin genes in the liver tissue exposed to hyperglycemia. BLI is a sensitive method for monitoring insulin gene expression in extrapancreatic tissues in vivo. The BLI system may be used for in vivo screening of biological events or pharmacologic activators that have the potential of stimulating the generation of extrapancreatic insulin-producing cells.