Lysophosphatidic acid mediates skeletal muscle fibrosis in denervation via activation of YAP/TAZ
Meilyn Cruz-Soca, Adriana Córdova-Casanova, Jennifer Faundez-Contreras, Nicolás W. Martínez, Francesca Vaccaro-Rivera, Sebastián Bazaes-Astorga, Cristian Gutiérrez-Rojas, Felipe S. Gallardo, Daniela L. Rebolledo, Felipe A. Court, Jerold Chun, Carlos P. Vio, Soledad Matus, Juan Carlos Casar, Enrique Brandan
Meilyn Cruz-Soca, Adriana Córdova-Casanova, Jennifer Faundez-Contreras, Nicolás W. Martínez, Francesca Vaccaro-Rivera, Sebastián Bazaes-Astorga, Cristian Gutiérrez-Rojas, Felipe S. Gallardo, Daniela L. Rebolledo, Felipe A. Court, Jerold Chun, Carlos P. Vio, Soledad Matus, Juan Carlos Casar, Enrique Brandan
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Research Article Cell biology Muscle biology

Lysophosphatidic acid mediates skeletal muscle fibrosis in denervation via activation of YAP/TAZ

Abstract

Lysophosphatidic acid (LPA) is a bioactive lipid that signals through G protein–coupled receptors (LPA1–6) and regulates multiple cellular processes, including fibrosis. Although LPA signaling has been implicated in fibrotic diseases in several organs, its role in skeletal muscle remains unclear. Here, we show that LPA/LPA1 signaling promotes fibrogenesis after sciatic nerve transection. Denervation induces differential expression of LPA signaling axis components and a transient early increase in intramuscular LPA levels. Pharmacological inhibition of LPA1/3 with Ki16425, or genetic deletion of LPA1, reduces extracellular matrix accumulation and expansion of fibro/adipogenic progenitors (FAPs) in denervated muscle. Although LPA blockade suppresses atrophy-related gene expression, it does not fully preserve myofiber size. Mechanistically, denervation increases YAP/TAZ expression, nuclear localization in FAPs, and transcriptional activity, effects that are attenuated by LPA axis inhibition. Furthermore, pharmacological inhibition of YAP/TAZ with verteporfin reduces fibrosis after denervation, supporting their role as critical downstream mediators. Finally, transient denervation activates the LPA axis, promotes muscle fibrosis, reduces axonal density in the sciatic nerve, and increases neuromuscular junction instability, effects reversed by Ki16425. Together, these findings identify the LPA/LPA1/YAP/TAZ pathway as a key driver of denervation-induced muscle fibrosis and a potential therapeutic target in neuromuscular disorders.

Authors

Meilyn Cruz-Soca, Adriana Córdova-Casanova, Jennifer Faundez-Contreras, Nicolás W. Martínez, Francesca Vaccaro-Rivera, Sebastián Bazaes-Astorga, Cristian Gutiérrez-Rojas, Felipe S. Gallardo, Daniela L. Rebolledo, Felipe A. Court, Jerold Chun, Carlos P. Vio, Soledad Matus, Juan Carlos Casar, Enrique Brandan

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Figure 7

Inhibition of LPA1 and LPA3 reduces fibrosis and improves sciatic nerve integrity after transient denervation.

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Inhibition of LPA1 and LPA3 reduces fibrosis and improves sciatic nerve ...
Three-month-old C57Bl/6J mice were denervated by unilateral crush injury of the sciatic nerve. (A) RT-qPCR analysis showing fibronectin (Fn1) and Ccn2 expression in GST from crushed and contralateral control limbs at 4, 14, and 30 days (n = 4). *P < 0.05, **P < 0.01, with 2-tailed Student′s t test. Values are shown as mean ± SEM. (B) Three-month-old C57Bl/6J mice were treated with vehicle (DMSO) (n = 4) or Ki16425 (n = 4) for 3 days before unilateral sciatic denervation by crush. Skeletal muscles from both hindlimbs were collected 2 weeks after denervation. Ccn2 and Fn1 mRNA levels were measured by RT-qPCR. (C) GST homogenates were subjected to SDS-PAGE and immunoblot. Levels of fibronectin and PDGFRα were quantified (right). (D) Frozen-tissue GST cross-sections from crushed and contralateral controls were subjected to immunofluorescence for the detection of fibronectin (red). Scale bar: 100 μm. Quantification of fibronectin-positive area (right). (E) Representative immunofluorescence images of CCN2 (red). Scale bar: 100 μm. Quantification of CCN2-positive area (right). (F) RT-qPCR analysis showing Ccn1, Tagln2, and Ankrd1 expression in contralateral and crushed GST muscles. (G) Representative immunofluorescence images of neurofilament in sciatic nerve showing axonal abundance under different experimental conditions. Scale bar: 100 μm. Quantification of axonal density (axons/100 μm2) (right). *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001 with 1-way ANOVA test. Values are shown as mean ± SEM. (H) Representative images of neuromuscular junction staining showing nerves reaching skeletal muscle. For quantification, we classified postsynaptic clusters as non-innervated (a); close to a nerve (b); or with signs of reinnervation, presynaptic staining opposed to postsynaptic site (c). Scale bar: 50 μm. *P < 0.05 with 1-tailed t test. Values are shown as mean ± SEM.