Analysis of hepatic gene expression in chickens with hormonally‐induced lean and fat phenotypes

Abstract

The purpose of this project was to use microarray analysis to unravel the genetic circuits controlling deposition and metabolism of fat in a hormonally-induced obesity model. The abdominal fat content and free fatty acid levels of four-week-old chickens were dramatically altered after chronic infusion (two weeks) of exogenous corticosterone (CS) or thyroid hormone (T3), producing a fat and lean phenotype, respectively. Our Del-Mar 14K Chicken Integrated Systems Microarray (Geo Platform GPL1731) was used to identify differentially expressed hepatic genes (i.e., 1.4-fold difference). In the contrast of fat (CS) and lean (T3) phenotypes, 136 genes were up-regulated by CS, whereas 64 genes were up-regulated by T3. An additional study was designed to examine gene response to acute hormone infusion (six days) of CS or T3, alone or in combination. Both studies revealed several transcription factors (Spot14, CEBP2, etc.), metabolic enzymes (malic enzyme, fatty acid synthase, etc.) and transport proteins (LFABP, adipophilin, etc.) that control lipogenic (CS induced) and lipolytic (T3 induced) pathways. This project provides new insight into genetic control of metabolic disorders, such as diabetes and obesity. This work was supported by a USDA Training Grant (2004-38411-14734) and by a USDA-IFAFS Animal Genome Program (00-52100-9614).