Interleukin-8 modifies the expression profile of microRNA in rat primary skeletal muscle cells

In the present study we examined the expression profile of microRNA in rat primary skeletal muscle cells (RSkMC) treated with IL-8, a chemokine and an angiogenic factor, which is released in visceral adipose tissue, but also found in contracting skeletal muscles. The miRNA microarray analysis revealed increased expression of 5 miRNA species, which were not yet described in skeletal muscle, in RSkMC exposed to IL-8 (1 ng/ml) for 11 days of differentiation. In order to verify the microarray data, qRT-PCR analysis was performed to quantify miRNA expression. We confirmed the increased expression of miR-154-3p (fold change =1.91), miR-541-5p (fold change =1.36), miR-376c-3p (fold change =1.84), and miR-338-3p (fold change =1.6), whereas let-7a-1-3p did not show a significant change in expression, in comparison to control group. Using Target Scan database we found potential targets for all miRNAs with expression modified by IL-8 and focused our further interest on genes and pathways involved in skeletal muscle hypertrophy, that is: myocilin, PKB/Akt and FoxO3. We compared the miRNA expression profiles of RSkMC exposed to IL-8 (1 ng/ml) for 11 days of differentiation to control group (untreated samples). Three microarrays were done for each experimental condition.