Functional proteome and microRNAome of beef cattle adipose tissue.

摘要

Adipose tissue plays an important role in the energetic balance, but it is also an important aspect of meat quality and animal productivity. However, the understanding on how fat metabolism is regulated in beef cattle is not clear. This research aimed at exploring how bovine adipose tissue is molecularly regulated by proteins and microRNAs (miRNAs) under different conditions. Study 1 detected a total of 244 miRNAs in subcutaneous and visceral adipose tissue of steers fed different diets (high or low fat content). Several miRNAs responded to dietary changes (miR-19a, -92a, -92b, -101, -103, -106, -142-5p, and 296) or fat depot (miR-196a and -2454), and were predicted to be involved in different aspects of lipid metabolism such as lipid synthesis and oxidation. Study 3 showed that the compositional structure of DNA that surrounded 155 miRNA genes was associated with miRNA expression and function as clustered miRNAs and highly conserved miRNAs were more highly expressed and had more predicted targets than non-clustered or less conserved miRNAs. Bovine miRNAs were shown to work collectively in regulatory networks with other miRNAs or with genes that host intronic miRNAs. Study 2 identified and quantified 682 proteins in bovine adipose tissue revealing that the proteomic profile differs between fat depots, indicating important functional and physiological differences such as a higher metabolic activity of visceral fat. Besides, fat depots also respond differently to diet, as subcutaneous fat seems to be more responsive to dietary changes. Study 4 showed that subcutaneous fat expansion in steers from 12 to 15 months of age (finishing) occurred concomitant with expression changes in 123 out of 627 proteins. Differentially expressed (DE) proteins were associated with several biological processes. Proteomic changes related to lipid metabolism indicated a reduction in the synthesis of fatty acids at the cellular level when steers were older. These findings improved our understanding on how adipose tissue is regulated. They may help the development of strategies to manipulate bovine adiposity that consider the specific molecular regulation and physiology of different fat depots and their response to dietary manipulation, as well as the different periods of development of beef cattle.