Potential role of miR-155-5p in fat deposition and skeletal muscle development of chicken.

miR-155 has multiple functions in many physiological and pathological processes. However, little is known about the expression characteristics of avian miR-155. In the present study, partial pri-miR-155 sequences were cloned from AA+ broiler, Sanhuang broiler and Hy-Line Brown layer, respectively. Stem-loop qRT-PCR was performed to detect the miR-155-5p spatiotemporal expression profiles of each chicken breed, and the target genes of miR-155-5p were predicted in Gene Oncology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. The results showed that the partial pri-miR-155 sequences of different breeds of chicken were high conserved. The expression patterns of miR-155-5p between broiler and layer were basically similar, and miR-155-5p was expressed highly in immune related tissues (spleen, thymus and bursa). In the same old chicken (14 days old), miR-155-5p expression activity of fat tissue all had higher level in the three chicken breeds, but the expression activities in skeletal muscle of broilers were significantly lower than that of layer (P<0.05). In different development stages of Hy-Line Brown layer, miR-155-5p expression activities in skeletal muscle of 14-day-old and 10-month-old layers were significantly lower than that of 24-month-old layer (P<0.05). Fat related target genes (ACOX1, ACOT7, FADS1, SCD and HSD17B12) and skeletal muscle related target genes (CCNT2, DMD, CFL2, MAPK14, FLNB, ZBTB18 and CDK5) of miR-155-5p were predicted, respectively. The results indicate that miR-155-5p may be an important factor inhibiting the fat deposition and skeletal muscle development in chicken.