Transcriptional and Pathway Analysis of Anterior Pituitary Gene Expression in Chickens Genetically Selected for High and Low Body Weight

Date: Monday, January 14, 2013
Room: Grand Exhibit Hall
Laura E Ellestad , University of Maryland, College Park, MD
Mardi S. Byerly , University of Maryland, College Park, MD
Jean Simon , INRA - UR83 Recherches Avicoles, Nouzilly, France
Larry A. Cogburn , University of Delaware, Newark, DE
Elisabeth Le Bihan-Duval , INRA - UR83 Recherches Avicoles, Nouzilly, France
Tom E. Porter , University of Maryland, College Park, MD
Many processes that control growth and metabolism are regulated by trophic hormones produced in the anterior pituitary gland. In this study, global gene expression patterns in the anterior pituitary were assessed at 1, 3, 5, and 7 weeks post-hatch in two lines of chickens genetically selected for high growth (HG) and low growth (LG). Birds in the HG line weighed more than those in the LG line by three weeks post-hatch and had higher percentage body fat by one week post-hatch (P≤0.05; n=8). Expression of 263 genes was significantly and substantially different between the two lines (P≤0.05; n=4; ³1.6-fold difference between the highest expression in one line and lowest expression in the other). Four anterior pituitary hormones were contained in this set of differentially expressed genes: thyroid-stimulating hormone β-subunit, luteinizing hormone β-subunit (LHβ), and follicle-stimulating hormone β-subunit (FSHβ) mRNA levels were higher in the HG line; and growth hormone (GH) mRNA was elevated in the LG line. Pathway analysis revealed differences in expression between HG and LG lines associated with molecular transport, endocrine system development and function, gene expression, and cell morphology, growth and proliferation. Potential alteration in pituitary function between the two lines was highlighted in a network containing LHβ, FSHβ, and GH, in addition to elements of several signaling pathways (e.g., adenylate cyclase, dexras1, and MAPK) and transcription factors (e.g. SMAD1). These results support the conclusion that differences in pituitary cell differentiation, proliferation and function contribute to the differences in growth between the two genetic lines.