Genetic Background Alters Gene Expression in Small Intestine, Liver and Bone Marrow in Response to Dietary Phosphorus in Young Pigs

Abstract

Phosphorus (P) is essential to bone growth, however, little research focused on the genetic mechanisms controlling P utilization. Understanding the interactions between genetics and dietary P that optimize bone integrity could provide novel interventions for osteoporosis. We utilized 36 female pigs from 2 genetic lines known to differ in bone structure (lighter-boned or heavier-boned) to examine the interactions between genetic background and dietary P. Pigs were fed a P adequate, P deficient or P repletion diet for 2 wk. At the completion of the trial, RNA was isolated from liver, small intestine and bone marrow for quantification of gene expression by real-time PCR. Gene expression data was analyzed with sire line, diet and their interaction considered as fixed effects. Differential expression (P < .1) of parathyroid hormone receptor (PTHR), estrogen receptor alpha (ESR1), insulin-like growth factor 1 (IGF1), IGF binding proteins 3 and 5 (IGFBP3 and IGFBP5) message was seen in the small intestine. In liver tissue, the expression of ESR1, vitamin D receptor (VDR), PTHR, growth hormone receptor (GHR), IGFBP3, IGFBP5, calcitonin receptor and oxytocin receptor was affected (P < .1) by either dietary P or the interaction between dietary P and genetic background. Differential expression (P < .1) of peroxisome proliferator activated receptor gamma 2 (pPARG2) and ESR1 message was also seen in the bone marrow due to the interactions of diet and genetic background. Understanding these differences could lead to novel treatments for osteoporosis and aid in the development of tests for identifying those at risk for this disease. Acknowledgements This research was funded in part by Sygen International.