ZFIN ID: ZDB-PUB-150924-9
Deviant development of pancreatic beta cells from embryonic exposure to PCB-126 in zebrafish
Timme-Laragy, A.R., Sant, K.E., Rousseau, M.E., diIorio, P.J.
Date: 2015
Source: Comparative biochemistry and physiology. Toxicology & pharmacology : CBP   178: 25-32 (Journal)
Registered Authors: diIorio, Philip
Keywords: Ahr, Nrf2, embryo, endocrine, gene expression, insulin, islet, time-lapse
MeSH Terms:
  • Animals
  • Animals, Genetically Modified/embryology
  • Embryo, Nonmammalian/drug effects
  • Embryo, Nonmammalian/embryology
  • GA-Binding Protein Transcription Factor/genetics
  • Gene Expression Regulation, Developmental/drug effects
  • Ghrelin/genetics
  • Glucagon/genetics
  • Homeodomain Proteins/genetics
  • Insulin-Secreting Cells/drug effects*
  • Insulin-Secreting Cells/physiology
  • Polychlorinated Biphenyls/adverse effects*
  • Trans-Activators/genetics
  • Transcription Factors/genetics
  • Zebrafish/embryology*
  • Zebrafish Proteins/genetics
PubMed: 26393762 Full text @ Comp. Biochem. Physiol. C Toxicol. Pharmacol.
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ABSTRACT
Exposures to co-planar PCBs and dioxins have been associated with diabetes in epidemiologic studies. Individuals may be predisposed to diseases such as diabetes as a result of exposure to environmental contaminants during early life, resulting in dysmorphic pancreatic islets or metabolically fragile β-cells. We tested the hypothesis that embryonic exposure to a model Ahr-ligand, PCB-126 would cause structural and/or functional alterations to the developing primary pancreatic islet in the zebrafish (Danio rerio). To assess β-cell development, transgenic zebrafish embryos (Tg(ins:GFP) and Tg(ins:mcherry) were exposed to nominal concentrations of 2 or 5 nM PCB-126 or DMSO from 24-48 hours post fertilization (hpf), and imaged via time-lapse microscopy from 80-102 hpf. We identified defects including hypomorphic islets, altered islet migration, islet fragmentation, and formation of ectopic β-cells. As we recently showed the transcription factor Nrf2a is protective in PCB-126 embryotoxicity, we then assessed the transcriptional function of the islets in wildtype and nrf2a(fh318/fh318) mutant embryos. We measured gene expression of preproinsulin a, somatostatin2, pdx1, ghrelin, and glucagon. Expression of preproinsulin a increased with PCB treatment in wildtype embryos, while expression of all measured pancreas genes was altered by the nrf2a mutant genotype, suggesting mis-regulation of the glucose homeostasis axis in those embryos, independent of PCB treatment. This study shows that embryonic exposure to PCB-126 can result in deviant development of the pancreatic islet and suggests that Nrf2a plays a role in regulating glucose homeostasis during development.
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