• ATX/LPA/LPARs axis components are present in skeletal muscle. • LPA injection to skeletal muscle induces expression of CCN2 and ECM proteins, being prevented by an antagonist of LPA 1 and LPA 3 and in LPA 1 -KO mice. • LPA induces ERK 1/2 phosphorylation in WT muscle but not in LPA 1 -KO mice. • LPA augments the number of FAPs, the primary cellular source of myofibroblasts responsible for ECM synthesis. • The ATX/LPA/LPARs might be a promising therapeutic approach for patients suffering pathological conditions in which skeletal muscle fibrosis occurs. Several common chronic diseases, muscular dystrophies (MDs), and aging lead to progressive fibrous connective tissue (fibrosis) accumulation in skeletal muscle. Cumulative past evidence points to the role of signaling lipids such as lysophosphatidic acid (LPA) and its receptors (LPARs) in different models of fibrosis. However, the potential contribution of these molecules to the fibrotic process in skeletal muscle has not been explored. Here, we show the expression of ATX/LPA/LPARs axis components in skeletal muscle, which suggests their potential relevance for the biology of this tissue. We investigated if the skeletal muscle responds to the stimulus of intramuscular (IM) LPA injections, finding an early induction of the pro-fibrotic factor connective tissue growth factor/Cellular Communication Network factor 2 (CCN2) and extracellular matrix (ECM) proteins. Also, we found that LPA induces an increase in the number of fibro/adipogenic progenitors (FAPs), which are the primary cellular source of myofibroblasts. These effects were for the most part prevented by the inhibitor Ki16425, which inhibits the LPA receptors LPA 1 and LPA 3 , as well as in the LPA 1 -KO mice. We also evaluated the in vivo activation of extracellular signal-regulated kinases (ERK 1/2), AKT, c-Jun N-terminal kinase (JNK), and Yes-asocciated protein 1 (YAP) in response to LPA. Our results show that LPA induces ERK 1/2 phosphorylation in WT muscle, but not in LPA 1 -KO mice. Treatment with the ERK 1/2 inhibitor U0126 prevented the induction of fibronectin in response to LPA, suggesting that this pathway is involved in LPA-induced fibrosis. Altogether, these results demonstrate that ATX/LPA/LPARs constitute a pro-fibrotic axis and suggest a possible role in muscular diseases. [ABSTRACT FROM AUTHOR]