Functional Proteomics: Elucidation of Molecular Mechanisms of Physiological Variations of Fat Depots in Beef Cattle

Wednesday, July 23, 2014: 2:40 PM
2503 (Kansas City Convention Center)
Josue Moura Romao , Department of Agricultural, Food and Nutritional Science, University of Alberta,, Edmonton, AB, Canada
Maolong He , Agriculture and Agri-Food Canada, Lethbridge, AB, Canada
Tim A. McAllister , Agriculture and Agri-Food Canada, Lethbridge, AB, Canada
L. L Guan , Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada
Abstract Text:

Adipose tissue plays an important role in energetics, meat quality and animal productivity, but the factors that regulate fat metabolism in beef cattle are unclear.  Recent transcriptomics has identified hundreds of genes that may influence fat deposition in bovine adipocytes, but the phenotypic traits of fat are ultimately determined by the functional proteins that regulate adipogenesis and lipolysis. It is evident that gene expression does not always correspond to the levels of functional proteins produced due to differences in translation efficiency and post-translational modification. Using high throughput Label Free Quantification (LC-MS/MS), we have attempted to identify the global changes in protein expression in bovine subcutaneous and visceral fat depots of steers fed different diets at different stages of physiological maturity. Our results revealed that the proteomic profile of bovine adipocytes differs among fat depots, reflecting functional and physiological differences such as the higher metabolic activity of visceral fat. Changes in lipid profiles in the diet, altered proteomic profiles in subcutaneous fat and provide insight into mechanisms whereby the fatty acid composition of adipose tissue may be favourable altered. Moreover, proteomic changes in subcutaneous adipose tissue of feedlot cattle between 12and 15 months reflected increased adipocyte growth and proliferation, but fatty acid synthesis declined as steers approached finishing weight. These findings suggest that the rate of fatty acids synthesis is not static during growth, revealing a coordinated balance between subcutaneous fat mass and the cellular abundance of lipogenic proteins which regulate the rate and degree of fat deposition in beef cattle. Additional work suggested that miRNAs within bovine adipose tissue may play an important role in the controlling the expression of regulatory proteins within fat depots. Consequently, proteins and miRNAs may serve as markers for future selection of cattle based on their ability to generate favourable levels of adipose tissue with desirable fatty acid profiles within beef meat.

Keywords: fatty acid, beef meat, adipose tissue