Transcriptomics reveals the regulatory mechanisms of circRNA in the muscle tissue of cows with ketosis postpartum.

The transition period from late pregnancy to early lactation in dairy cows involves significant metabolic changes to cope with the challenges related to energy metabolism. Muscle tissue, as the largest energy-metabolizing tissue in dairy cows, plays a crucial role in energy metabolism. Furthermore, circular RNAs (circRNAs) have been shown to play key roles in various biological events. However, the regulatory mechanisms of energy metabolism and muscle cells mediated by circRNAs in the muscle tissue of ketotic dairy cows remain unclear. Here, we identified a total of 5103 circRNAs in the muscle tissue of ketosis-affected cows. Among these, compared to healthy cows, 57 circRNAs were differentially expressed in the muscle tissue of ketosis-affected cows, with 39 upregulated and 18 downregulated. Functional enrichment analysis based on the source genes of circRNAs indicated that circ-30,628 is closely related to carbon metabolism, and circ-CoQ is associated with mitochondrial energy metabolism. Given the sponge effect of circRNAs on miRNAs, we further predicted the network relationships of downstream miRNAs and mRNAs of circ-30,628 and circ-CoQ, and found that their downstream target genes are involved in signaling pathways such as MAPK, Wnt, FoxO, and autophagy, which is associated with the proliferation, differentiation, energy metabolism, oxidative stress, and mitochondrial function of muscle cells. In summary, these findings provide a theoretical basis for understanding the functions of circRNAs regulating energy metabolism in the muscle tissue of ketosis-affected cows, thereby reducing the accumulation of ketone bodies to prevent the occurrence of ketosis in dairy cows.