PDGFRβ signaling restrains myocyte function to limit the regenerative capacity of skeletal muscle
Siwen Xue, Abigail M. Benvie, Jamie E. Blum, Benjamin D. Cosgrove, Anna E. Thalacker-Mercer, Daniel C. Berry
Siwen Xue, Abigail M. Benvie, Jamie E. Blum, Benjamin D. Cosgrove, Anna E. Thalacker-Mercer, Daniel C. Berry
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Research Article Development Muscle biology

PDGFRβ signaling restrains myocyte function to limit the regenerative capacity of skeletal muscle

Abstract

Muscle cell fusion is critical for the formation and maintenance of multinucleated myotubes during skeletal muscle development and regeneration. However, the molecular mechanisms directing cell-cell fusion are not fully understood. Here, we identified platelet-derived growth factor receptor β (PDGFRβ) signaling as a key modulator of myocyte function in adult muscle cells. Our findings demonstrated that genetic deletion of Pdgfrb enhanced muscle regeneration and increased myofiber size, whereas Pdgfrb activation impaired muscle repair. Inhibition of PDGFRβ activity promoted myonuclear accretion in both mouse and human myotubes, whereas PDGFRβ activation stalled myotube development by preventing cell spreading to limit fusion potential. Furthermore, PDGFRβ activity cooperated with TGF-β signaling to regulate myocyte size and fusion. Mechanistically, PDGFRβ signaling required STAT1 activation, and blocking STAT1 phosphorylation enhanced myofiber repair and size during regeneration. Collectively, PDGFRβ signaling acts as a regenerative checkpoint and represents a potential clinical target to improve skeletal muscle repair.

Authors

Siwen Xue, Abigail M. Benvie, Jamie E. Blum, Benjamin D. Cosgrove, Anna E. Thalacker-Mercer, Daniel C. Berry

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Figure 2

PDGFRβ activity regulates myotube development and muscle regeneration.

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PDGFRβ activity regulates myotube development and muscle regeneration. (...
(A) Experimental design: Muscle progenitor cells (MPCs) isolated from P30 male mice were differentiated and treated for 5 days with vehicle (0.1% DMSO), PDGF-BB (25 ng/mL), or SU16f (1 μM), and myotube formation was assessed. (B) Representative MyHC-stained images showing treatment-dependent differences in myotube formation. (C) Fusion index quantification from the cultures in B (n = 3 mice/group). (D) Quantification of myotube nuclear number and distribution from the cultures in B (n = 4 mice/group). (E) Differentiation index of low-density MyoGtdTomato progenitors treated with vehicle, PDGF-BB, or SU16f (n = 4 mice/group). (F) In vivo regeneration protocol: MyoGtdTomato mice received BaCl2 injury (1.2%), followed by daily injections of vehicle, PDGF-BB (50 ng/mouse), or SU16f (2 mg/kg) for 5 days. TA muscles were analyzed at 7 d.p.i. (G) Representative laminin and eMyHC immunostaining shows regeneration across treatment groups. (H) Quantification of injured myofiber CSA from the images in G (n = 5 mice/group). (I) Myonuclear numbers per injured myofiber from the images in G (n = 5 mice/group). (J) Quantification of eMyHC+ myofibers from the images in G (n = 5 mice/group). (K) Quantification of PAX7+ cells in regenerating TA muscle following the treatments described in F (n = 4 mice/group). Data represent the mean ± SEM. Statistical significance was determined by 1-way ANOVA (C, E, H, J, and K) or 2-way ANOVA (D and I) followed by multiple-comparison tests. Scale bars: 100 μm (B and G). Panels A and F were created using BioRender.