Transgenic overexpression of insulin‐like growth factor‐I (IGF‐I) in milk influences intestinal development and gene expression in piglets.

Abstract

Piglets suckling transgenic sows (TG) that overexpress IGF-I in milk have greater (p<0.05) ileal mucosal weight, protein and DNA content, villus height, disaccharidase activities and type 1 IGF receptor abundance at d21 postpartum than piglets suckling non-TG (CON) sows. Herein, porcine-specific microarrays were used to examine gene expression in ileal crypt and villus cells isolated by laser capture microdissection. Following amplification, mRNA samples were labeled with Cy dyes and hybridized onto microarrays and data were analyzed using the limma package in R. In piglets suckling TG, 2 villus and 3 crypt genes were up-regulated and 1 crypt gene was down-regulated at a FDR-adjusted p<0.05. Five villus and 8 crypt genes tended (p<0.1) to be up-regulated and 4 crypt and 2 villus genes down-regulated. Differentially expressed genes displayed the following biological processes: cell signaling, proliferation, transcription, translation, apoptosis, immune function, metabolism, and structure. Six genes were selected for quantitative real-time PCR and the directionality and fold-change differences were in agreement with microarray results. Coordinate up-regulation of an anti-proliferative gene and down-regulation of a cell cycle regulator in the crypts of piglets suckling TG support reduced proliferation as an adaptation to elevated milk IGF-I. Funded by: AG-00-35206-9537 and IL C-FAR Sentinel Program.