PSII-B-27 - miRNA transcriptome of lamb skeletal muscle during hypertrophic growth from mid-gestation to market weight

The objective of this study was to characterize the miRNA transcriptome of the longissimus muscle during skeletal muscle hypertrophy. Longissimus samples were collected from Suffolk x Texel cross sheep at six developmental time points: Prenatal [gd 85 (PN1), 110 (PN2), and 133 (PN3)] and postnatal [preweaning (d 40; PW1), weaning (d 65; PW2), and maturity (57 kg; MKT)]. Total RNA was extracted for miRNA sequencing. Data were analyzed using a priori comparisons PN1 vs. PN2, PN2 vs. PN3, PN3 vs. PW1, PW1 vs. PW2, PW2 vs. MKT to examine stages of muscle hypertrophy. One hundred forty-two miRNAs were differentially expressed between the 5 comparisons made. The stage from PN3 to PW1 had the most differentially expressed miRNA (115). Examination of the differentially expressed miRNA also showed that 4 miRNA, miR-154a-3p, miR-3956-5p, miR-410-3p, and miR-431, had a log fold change greater than 3 and miR-22-3p had a log fold change greater than 4. Target genes of differentially expressed miRNA were identified and the functional associations of genes were assessed with GOseq. Between all 5 comparisons made, 195 terms were significantly enriched, 86 were from biological process, 42 were from cellular component, and 67 were from molecular function. The miRNA transcriptome of skeletal muscle changes with advancing development and the period from gd133 to d40 appears to have increased transcriptome alteration.