Lipin1 restores nNOS sarcolemmal localization and improves fatigue resistance in Duchenne muscular dystrophy

In Duchenne muscular dystrophy (DMD), nNOS is mislocalized from the sarcolemmal membrane and exhibits reduced expression and activity, impairing vasomodulation and contributing to increased muscle fatigue. Identification of upstream regulators that restore nNOS localization and function may provide therapeutic strategies to improve muscle performance in dystrophic muscle. In this study, we investigated the role of lipin1 in regulating nNOS expression, sarcolemmal localization, and NOS activity in skeletal muscle. Lipin1 deficiency significantly reduced nNOS expression and total NOS enzymatic activity, whereas lipin1 overexpression enhanced these parameters. Skeletal muscle-specific lipin1 knockout mice (lipin1Myf5cKO) exhibited increased muscle fatigue, consistent with impaired nNOS-dependent muscle function. In contrast, transgenic lipin1 restoration in dystrophic muscle (mdx:lipin1Tg/0) restored nNOS expression and sarcolemmal localization and improved fatigue resistance. Our findings suggest that lipin1 promotes nNOS sarcolemmal localization, potentially through stabilization of membrane-associated protein complexes, and enhances nNOS expression through a lipin1/DAG/PKD/CREB signaling axis. Collectively, these findings identify lipin1 as an important regulator of nNOS expression and localization in skeletal muscle and support lipin1 restoration as a potential therapeutic strategy for DMD.