On the hypothesis that grazing of cattle prompts organs to secrete or internalize circulating microRNAs (c-miRNAs) in parallel with changes in energy metabolism, we aimed to clarify biological events in adipose, skeletal muscle, and liver tissues in grazing Japanese Shorthorn (JSH) steers by a transcriptomic approach. The subcutaneous fat (SCF), biceps femoris muscle (BFM), and liver in JSH steers after three months of grazing or housing were analyzed using microarray and qPCR, followed by gene

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... ontology (GO) and functional annotation analyses. The results of transcriptomics indicated that SCF was highly responsive to grazing compared to BFM and liver tissues. The 'Exosome', 'Carbohydrate metabolism' and 'Lipid metabolism' were extracted as the relevant GO terms in SCF and BFM, and/or liver from the >1.5-fold-altered mRNAs in grazing steers. The qPCR analyses showed a trend of upregulated gene expression related to exosome secretion and internalization (CHMP4A, VPS4B, VAMP7, CAV1) in the BFM and SCF, as well as upregulation of lipolysis-associated mRNAs (CPT1A, HSL, PLIN, ATGL, FABP4) and most of the microRNAs (miRNAs) in SCF. Moreover, gene expression related to fatty acid uptake and inter-organ signaling (FATP4 and ANGPTL) was upregulated in BFM, suggesting SCF-BFM organ crosstalk for energy metabolism. Meanwhile, expression of plasma exosomal miR-16a, miR-19b, miR-21-5p, and miR-142-5p was reduced. According to bioinformatic analyses, the c-miRNA target genes are associated with the terms 'Endosome', 'Caveola', 'Endocytosis', 'Carbohydrate metabolism', and with pathways related to environmental information processing and the endocrine system. Exosome and fatty acid metabolism-related gene expression was altered in SCF of grazing cattle, which could be regulated by miRNA such as miR-142-5p. These changes occurred coordinately in both the SCF and BFM, suggesting involvement of exosome in the SCF-BFM organ crosstalk to modulate energy metabolism.