Pancreatic PYY but not PPY expression is responsive to short-term nutritional state and the pancreas constitutes the major site of PYY mRNA expression in chickens

Angus M.A Reid,Peter W Wilson,Sarah D Caughey,Laura M Dixon,Rick B D'Eath,Victoria Sandilands,Timothy Boswell,Ian C Dunn

doi:10.1016/j.ygcen.2017.07.002

Abstract

PP-fold peptides such as peptide YY (PYY) and pancreatic polypeptide (PPY) are known to play key roles in vertebrate energy homeostasis. Until recently, no gene sequence was available for avian PYY and therefore a gap in knowledge of regulation of its expression exists in avian species. Here we further evidence the mRNA sequence for chicken PYY and show that the pancreas is the major site of its mRNA expression, with a secondary peak of expression around the distal jejunum, in contrast to mammals where the large intestine is the major site of PYY expression. We also demonstrate that pancreatic PYY expression is responsive to short-term and long-term nutritional state, increasing within hours of feeding, in contrast to intestinal PYY which does not fluctuate to the same extent, and pancreatic PPY which appears to be primarily determined by long-term energy state. Both pancreatic PYY and PPY expression were found to exhibit ontogeny, being evenly distributed throughout the pancreas in young (2wk) chicks but having a decreasing splenic to duodenal gradient by adolescence (12wk).

Highlights

Peptide YY (PYY) is one of three known members of the PP-fold family of proteins, along with neuropeptide Y (NPY) and pancreatic polypeptide (PPY) (Cerda-Reverter and Larhammar, 2000)
The close agreement of our 50 rapid amplification of cDNA ends (RACE) product sequencing with 2017 data from Aoki et al provides convincing evidence that the transcriptional start site (TSS) for chicken PYY is approximately 38bp upstream of the translational start codon
The structure of chicken PYY ligand differs from mammalian PYY, offering a unique opportunity to study the evolution of the ligand in tetrapods, and the effects of proteolytic cleavage on receptor specificity and action in vivo

Summary

Introduction

Peptide YY (PYY) is one of three known members of the PP-fold family of proteins, along with neuropeptide Y (NPY) and pancreatic polypeptide (PPY) (Cerda-Reverter and Larhammar, 2000). The structure and function of the PYY gene is relatively welldocumented in mammals (Batterham and Bloom, 2003; McGowan and Bloom, 2004; Ueno et al, 2008); very little transcriptional work has been reported in avian species. This is due to the lack of a gene sequence, despite early elucidation of the peptide sequence (Conlon and Oharte, 1992) and relatively high conservation of the peptide (Blomqvist et al, 1992).

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Conclusion