Nutrient supply alters transcriptome regulation in adipose tissue of pre-weaning Holstein calves

Abstract

Performance of dairy cows can be influenced by early life nutrient supply. Adipose tissue is diet sensitive and an important component in that process as it is involved in the regulation of energetic, reproductive and immunological functions. However, it is not clear how early life nutrition alters the molecular regulation of adipose tissue in calves and potentially adult individuals. This study aimed at determining how differences in pre-weaning nutrient supply alter gene expression profiles and physiology in omental adipose tissue. A total of 12 female Holstein calves were fed two levels of milk replacer supply: a restricted amount of 11.72 MJ of metabolizable energy (ME) intake per day (n = 6) or an enhanced amount of 1.26 MJ ME intake per kg of metabolic body weight (BW0.75), resulting in supply from 17.58 to 35.17 MJ ME intake per day (n = 6). All calves had ad libitum access to a commercial calf starter and water. Analysis of the transcriptome profiles at 54 ± 2 days of age revealed that a total of 396 out of 19,968 genes were differentially expressed (DE) between groups (p < 0.001, FDR < 0.1). The directional expression of DE genes through Ingenuity Pathway Analysis showed that an enhanced nutrient supply alters adipose tissue physiology of pre-weaned calves. Several biological functions were increased (Z-score > +2), including Lipid Metabolism (Fatty Acid Metabolism), Cell Cycle (Entry into Interphase, Interphase, Mitosis and Cell Cycle Progression), Cellular Assembly and Organization (Cytoskeleton Formation and Cytoplasm Development) and Molecular Transport (Transport of Carboxylic Acid). These changes were potentially orchestrated by the activation/inhibition of 17 upstream regulators genes. Our findings indicate that adipose tissue of calves under an enhanced nutrient supply is physiologically distinct from restricted calves due to an increased development/expansion rate and also a higher metabolic activity through increased fatty acid metabolism.

Fig 1. Molecular and cellular functions in DE genes in adipose tissue.

The likelihood of the association between the genes in the dataset and a biological function is represented as–log (p-value), with larger bars being more significant than shorter bars. The vertical line indicates the cut-off for significance (p-value of 0.05).

Fig 2. Effects of DE genes in Fatty Acid Metabolism.

Values under gene symbols represent direction expression of DE genes (fold change). Relationship lines in orange indicate that genes showed a directional expression compatible with an increased function. Yellow lines indicate that the gene expression is compatible with a decreased function. Gray lines mean that the genes are involved in this function, but literature results in Ingenuity Knowledge Base do not indicate whether they increase or decrease Fatty Acid Metabolism.

Fig 3. Effects of DE genes in Mitosis.

Values under gene symbols represent direction expression of DE genes (fold change). Relationship lines in orange indicate that genes showed a directional expression compatible with an increased function. Yellow lines indicate that the gene expression is compatible with a decreased function. Gray lines mean that the genes are involved in this function, but literature results in Ingenuity Knowledge Base do not indicate whether they increase or decrease Fatty Acid Metabolism.

Fig 4. Predicted impact of upstream regulators controlling DE genes on adipose tissue biological functions.

Only upstream regulators with overlap p-value < 0.05 and Z-score > +2 or < -2 are displayed.