The objective of this study was to explore the roles of
arachidonic acid cytochrome P450ω
hydroxylase CYP4A14 in skeletal muscle regeneration after injury. Wild-type (WT) control mice and Cyp4a14 knockout (A14-/-) mice were used to establish the muscle injury and regeneration model by
intramuscular injection with
cardiotoxin (CTX) on the tibial anterior (TA) muscle. The TA muscles were harvested at the time points of 0, 3, 5 and 15 days after injury. The changes in skeletal muscle regeneration and
fibrosis were assessed by
wheat germ agglutinin (WGA) staining and Sirius Red staining. Immunohistochemical staining was used to observe the expression of proliferation-related
protein Ki-67 and macrophage marker
protein Mac-2. The
mRNA levels of regeneration and
inflammation associated genes were analyzed by real-time PCR. The results showed that the cross-section area (CSA) of regenerated myofibers in A14-/- mice was significantly smaller (P < 0.05), while the percentage of
fibrosis area was significantly higher than those in WT mice at 15 days after injury (P < 0.05). In A14-/- muscles, both the ratio of Ki-67 positive proliferating cells and the
mRNA levels of differentiation associated genes Myod1 and Myog were significantly lower than those in WT muscles (P < 0.05). At 3 days after injury, the
mRNA expression of inflammatory cells marker genes CD45 and CD11b and Mac-2 positive macrophages in A14-/- muscles were significantly lower than those in WT skeletal muscle (P < 0.05). Macrophages derived pro-regeneration
cytokines IL-1β,
IGF-1 and SDF-1 were also significantly decreased in A14-/- muscles (P < 0.05). These results suggest that
arachidonic acid cytochrome P450ω
hydroxylase CYP4A14 plays a critical role in skeletal muscle regeneration after injury.