Sepsis is a life-threatening inflammatory response to infection, often accompanied by skeletal muscle atrophy. A previous study demonstrated that the administration of microRNA-140 (miR-140) attenuated lipopolysaccharides (LPS)-induced muscle atrophy, whereas miR-140 knockdown with siRNA promoted atrophy. Therefore, we investigated whether miR-140 is involved in LPS-induced muscle atrophy using a genetic model, miR-140-/- mice. We found that a single injection of LPS induced atrophy both in slow-twitch and fast-twitch muscles. The muscle weights and fiber cross-sectional areas were significantly reduced in both the wild-type (WT) and miR-140-/- mice, with no difference between genotypes. The expression of several proteolysis markers, muscle-specific RING-finger 1 (MuRF1) and MAFbx/atrogin-1, increased in both groups after LPS injection. The ubiquitinated proteins in the miR-140-/- mice were similar to those in the WT mice. Therefore, the deletion of miR-140 did not affect sepsis-induced muscle atrophy.
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