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. 2022 Mar 17;13:1439. doi: 10.1038/s41467-022-29150-6

Fig. 1. Loss of primary cilia in MuSCs impairs muscle regeneration and strength recovery.

Fig. 1

a Pax7-specific Ift88 conditional knockout mice (Pax7CreERT2;IFT88f/f, IFT88−/−), heterozygous mice (Pax7CreERT2;IFT88+/f, IFT88+/−) or control littermates (Pax7CreERT2;IFT88+/+, control, con) were treated with tamoxifen (TAM) at 8 weeks of age. Myofibers were isolated and stained for ciliary markers. b Representative confocal images of control and IFT88−/− myofibers showing IFT88 and FOP staining in PAX7+ MuSCs. All cells stain positive for the centrosomal marker FOP. Scale bars: 10 μm. DAPI, blue; PAX7, white; FOP, green; IFT88, red. White arrowheads indicate the presence of IFT88 in the primary cilium on the surface of MuSCs. Blue arrowheads indicate MuSCs lacking cilia. Quantification in Supplementary Fig. 1b. c, d Visualization of MuSC cilia using detyrosinated tubulin to stain the ciliary axoneme and FOP to visualize the ciliary base. All cells stain positive for the centrosomal marker FOP. Absence of detyrosinated tubulin is scored as no cilia. c Percent of short (<1 µM) and long (>1 µM) cilia on Pax7+ MuSCs quantified from isolated myofibers of control, IFT88+/− and IFT88−/− mice (n = 75 control, 79 IFT88+/−, 81 IFT88−/− total myofibers were analyzed from 4 independent mice per genotype; average percent of ciliated MuSCs per mouse is shown, individual data points in Supplementary Fig. 1c). d Representative confocal images of uninjured/resting EDL myofibers of control and IFT88−/− mice showing cilia immunostaining in Pax7+ MuSCs. Scale bars: 10 μm. DAPI, blue; PAX7, white; FOP, green; detyrosinated tubulin, red. e–i Control, IFT88+/− and IFT88−/− mice were injured with notexin and analysis was performed 7 or 14 days post-injury (n = 3 control mice; n = 4 IFT88+/− and IFT88−/−; two legs per mouse). e Experimental scheme. f Plantar flexion tetanic torque of control, IFT88+/− and IFT88−/− mice on day 7 and day 14 post-injury (values normalized to baseline torque). g Representative Gastrocnemius (GA) cross-section at 14 days post-injury from control and IFT88−/− mice. DAPI, blue; LAMININ, green. Bar=50 µm. h Myofiber cross-sectional areas (CSA) in control, IFT88+/− and IFT88−/− GAs (n = 3 for control, n = 6 for IFT88+/− and n = 6 for IFT88−/−). i Mean CSA. *P < 0.05, **P < 0.01, ***P < 0.001 ****P < 0.0001. ANOVA test with Fisher’s LSD test for multiple comparisons (c, f, h, i). Source data are provided as a Source Data file. Means+s.e.m.