title: Cloning and tissue distribution of novel splice variants of the ovine ghrelin gene.
abstract: BACKGROUND
  The ghrelin axis is involved in the regulation of metabolism, energy balance, and the immune, cardiovascular and reproductive systems. The manipulation of this axis has potential for improving economically valuable traits in production animals, and polymorphisms in the ghrelin (GHRL) and ghrelin receptor (GHSR) genes have been associated with growth and carcass traits. Here we investigate the structure and expression of the ghrelin gene (GHRL) in sheep, Ovis aries.
  
  
  RESULTS
  We identify two ghrelin mRNA isoforms, which we have designated Δex2 preproghrelin and Δex2,3 preproghrelin. Expression of Δex2,3 preproghrelin is likely to be restricted to ruminants, and would encode truncated ghrelin and a novel C-terminal peptide. Both Δex2 preproghrelin and canonical preproghrelin mRNA isoforms were expressed in a range of tissues. Expression of the Δex2,3 preproghrelin isoform, however, was restricted to white blood cells (WBC; where the wild-type preproghrelin isoform is not co-expressed), and gastrointestinal tissues. Expression of Δex2 preproghrelin and Δex2,3 preproghrelin mRNA was elevated in white blood cells in response to parasitic worm (helminth) infection in genetically susceptible sheep, but not in resistant sheep.
  
  
  CONCLUSIONS
  The restricted expression of the novel preproghrelin variants and their distinct WBC expression pattern during parasite infection may indicate a novel link between the ghrelin axis and metabolic and immune function in ruminants.
authors.forename: Moira
authors.initials: M
authors.lastname: Menzies
authors.forename: Inge
authors.initials: I
authors.lastname: Seim
authors.forename: Peter
authors.initials: P
authors.lastname: Josh
authors.forename: Shivashankar H
authors.initials: SH
authors.lastname: Nagaraj
authors.forename: Michael
authors.initials: M
authors.lastname: Lees
authors.forename: Carina
authors.initials: C
authors.lastname: Walpole
authors.forename: Lisa K
authors.initials: LK
authors.lastname: Chopin
authors.forename: Michelle
authors.initials: M
authors.lastname: Colgrave
authors.forename: Aaron
authors.initials: A
authors.lastname: Ingham
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D005786:Gene Expression Regulation; D020022:Genetic Predisposition to Disease; D054439:Ghrelin / Q000235:genetics / Q000378:metabolism*; D006188:Haemonchiasis / Q000235:genetics / Q000378:metabolism / Q000662:veterinary*; D006189:Haemonchus; D007962:Leukocytes / Q000378:metabolism; D008969:Molecular Sequence Data; D020033:Protein Isoforms; D012756:Sheep; D012757:Sheep Diseases / Q000235:genetics / Q000378:metabolism*
chemical_list: D054439:Ghrelin; D020033:Protein Isoforms