Transcriptomic characterization of pancreatic duct cells in adult zebrafish

Transcriptomic characterization of pancreatic duct cells in adult zebrafish

David Bergemann, Estefañia Tarifeño, Aurélie Ghaye, Marianne Voz, Bernard Peers and Isabelle Manfroid*

Zebrafish Development and Disease Models laboratory, Giga-Research, University of Liège, Belgium

Loss of pancreatic beta cells is a hallmark of diabetes. To compensate the resulting deficit of insulin and maintain glucose homeostasis, beta cell replacement by transplantation or regeneration constitute promising strategies. Studies have shown beta cell neogenesis, though by mechanisms not fully understood. These beta cells can derive from replication of pre-existing beta cells1 or from conversion of alpha cells2. Besides these mechanisms, pancreatic ducts have also been hypothesized to contain progenitors/precursors for beta cell regeneration. However, the existence of such adult progenitors remains controversial.
Zebrafish has been extensively used as a model for embryogenesis and regeneration. Their beta cells are very similar in development and function to their mammalian counterpart. Indeed, as in mammals, beta cells control glucose homeostasis in adult zebrafish. But, in contrast to mammals, adult zebrafish display the remarkable capacity to spontaneously, efficiently and rapidly regenerate their beta cells after ablation. The origin of these new beta cells is unknown but strong evidences collected in larvae argue in favour of a ductal origin. First, larval pancreatic ducts give rise to endocrine cells in normal condition and in response to the absence of beta cells4. Second, mutant larvae of the ductal marker sox9b harbour defects specifically in duct formation, and beta cell regeneration is impaired5. Here we show that adult pancreatic duct cells can give rise to beta cells. To get insight into this process, we established the transcriptome of adult duct cells by RNA-Seq. Comparison with the transcriptome of the other pancreatic cells identified known and novel ductal markers. Adult duct cells are also characterized by strong expression of embryonic pancreatic progenitor markers (sox9b, pdx1, nkx6.1 and components of the Notch pathway...). Future comparative analyses with ductal cells isolated from zebrafish in different conditions of beta cell (neo)genesis will help identify novel important players in beta cell formation from the ducts as well as regulators of beta cell regeneration.

1. Dor Y et al.(2004) Adult pancreatic beta-cells are formed by self-duplication rather than stem-cell differentiation. Nature
2. Thorel F et al. (2010) Conversion of adult pancreatic alpha-cells to beta-cells after extreme beta-cell loss. Nature
3. Moss JB et al. (2009) Regeneration of the pancreas in adult zebrafish. Diabetes
4. Ninov N et al. (2013) Metabolic regulation of cellular plasticity in the pancreas. Curr. Biol.
5. Manfroid I et al. (2012) Zebrafish sox9b is crucial for hepatopancreatic duct development and pancreatic endocrine cell regeneration. Dev. Biol.