CoChat
Sign Up
Cited by 119Muscle Physiology and DisordersPluripotent Stem Cells ResearchCongenital heart defects research

In vivo partial reprogramming of myofibers promotes muscle regeneration by remodeling the stem cell niche

Open access
Wang, Chao, Rabadan Ros, Ruben, Martinez-Redondo, Paloma, Ma, Zaijun, Shi, Lei, Xue, Yuan, Guillen-Guillen, Isabel, Huang, Ling +7 more·2021·Nature Communications
DOI 10.1038/s41467-021-23353-zPMC PMC8149870
Open this paper in CoChat — free accountOpen PDF

Abstract

Short-term, systemic expression of the Yamanaka reprogramming factors ( Oct-3/4 , Sox2 , Klf4 and c-Myc [OSKM]) has been shown to rejuvenate aging cells and promote tissue regeneration in vivo. However, the mechanisms by which OSKM promotes tissue regeneration are unknown. In this work, we focus on a specific tissue and demonstrate that local expression of OSKM, specifically in myofibers, induces the activation of muscle stem cells or satellite cells (SCs), which accelerates muscle regeneration in young mice. In contrast, expressing OSKM directly in SCs does not improve muscle regeneration. Mechanistically, expressing OSKM in myofibers regulates the expression of genes important for the SC microenvironment, including upregulation of p21, which in turn downregulates Wnt4 . This is critical because Wnt4 is secreted by myofibers to maintain SC quiescence. Thus, short-term induction of the Yamanaka factors in myofibers may promote tissue regeneration by modifying the stem cell niche.

AI snapshot

Written from the paper’s full text.

TL;DR

Myofiber-specific, short-term OSKM induction in mice activates satellite cells and accelerates muscle regeneration by inducing p21 and repressing the myofiber-secreted niche factor Wnt4; SC-specific OSKM induction does not improve regeneration. The effect is aging-independent and can be recapitulated by cyclic Wnt4 knockdown.

Key findings

  • Myofiber-specific OSKM induction before injury accelerated regeneration: Cre+ muscles had more eMHC+ myofibers at day 3, more Pax7+ cells, larger regenerated myofibers, more Pax7+MyoD+ myoblasts, and higher hindlimb grip strength at day 6; OSKM induction after injury did not accelerate regeneration.
  • OSKM in myofibers promoted SC activation/proliferation: Cre+ muscles had a 3-fold higher percentage of Pax7+BrdU+ cells; single Cre+ myofibers had 2-fold more Pax7+ cells and 3-fold more activated MyoD+ SCs, with quiescent MyoD− SCs decreased by half. Self-renewal was maintained after serial injuries.
  • SC-specific OSKM induction did not activate/proliferate SCs or improve regeneration; in cultured myoblasts, OSKM inhibited MyoD and miR-133a.
  • Mechanistically, Wnt4 was the only niche-related gene downregulated >2-fold; p21 was upregulated, p21 overexpression increased p21 60-fold and downregulated Wnt4 3-fold, ChIP showed 3-fold enrichment at the Wnt4 TATA-proximal region, and p21 inhibited a Wnt4 reporter 2-fold. Cyclic CasRx Wnt4 knockdown (gRNA1: 85% in vitro, 65% in vivo) recapitulated SC activation and regeneration. In 15-month-old mice, Cre+ muscles had 1.8-fold more Pax7+ cells, 2.8-fold more MyoD+ SCs, and 3-fold more BrdU+ SCs.

Methods

  • Generated myofiber-specific Acta1-Cre/4Fhet and SC-specific Pax7creER/4Fhet inducible OSKM mouse models; used young (6 weeks–4 months) and aging (12–15 months) mice, both male and female. Doxycycline was given in drinking water (1 mg/ml), often cyclically (2 days on/5 days off), with cardiotoxin injury, BrdU labeling, and tamoxifen for Pax7creER induction.
  • Readouts included RNA-seq of EDL/SOL muscles after 2.5 or 8.5 days Dox (DESeq2, WGCNA, GO/GSEA), qPCR, immunostaining/H&E, single myofiber isolation and culture, western blot, ChIP, luciferase assays, and AAV9-CasRx-mediated Wnt4 knockdown.
  • Statistical analysis used two-tailed unpaired Student’s t-test with p<0.05; RNA-seq OSKM/niche comparisons used n=2 biological samples, while many histology experiments used n=4–6 mice.

Limitations

  • Stated: the authors cannot exclude that other cell types (macrophages, endothelial cells, fibroblasts) or ECM/exosome-mediated indirect effects contribute to SC activation; two possible explanations for maintained SC self-renewal (homeostatic mechanism vs. temporary niche modification) were not distinguished.
  • Stated: timing is important—post-injury OSKM did not accelerate regeneration—and systemic vs. myofiber-specific OSKM differ in induction level and p21 induction in SCs.
  • Evident: findings are in mice only; key RNA-seq comparisons for OSKM/niche genes used n=2 biological samples; and although both male and female mice were used, sex-specific effects were not analyzed.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1038/s41467-021-23353-z

Cites

55 of 55 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 39 cited sources checked · 0 supported · 0 flagged

  • Findingreasoning

    p21 downregulates Wnt4.

    “Mechanistically, expressing OSKM in myofibers regulates the expression of genes important for the SC microenvironment, including upregulation of p21, which in turn downregulates Wnt4.”
    Quote in the paperSubstantial claim
  • Findingown data

    Expressing OSKM directly in SCs does not improve muscle regeneration.

    “In contrast, expressing OSKM directly in SCs does not improve muscle regeneration.”
    Quote in the paperSubstantial claim
  • Findingown data

    Local expression of OSKM specifically in myofibers induces the activation of muscle stem cells or satellite cells (SCs) in young mice.

    “In this work, we focus on a specific tissue and demonstrate that local expression of OSKM, specifically in myofibers, induces the activation of muscle stem cells or satellite cells (SCs), which accelerates muscle regeneration in young mice.”
    Quote in the paperSubstantial claim
  • Findingown data

    Expressing OSKM in myofibers upregulates p21.

    “Mechanistically, expressing OSKM in myofibers regulates the expression of genes important for the SC microenvironment, including upregulation of p21, which in turn downregulates Wnt4.”
    Quote in the paperSubstantial claim
  • Findingown data

    Local expression of OSKM specifically in myofibers accelerates muscle regeneration in young mice.

    “In this work, we focus on a specific tissue and demonstrate that local expression of OSKM, specifically in myofibers, induces the activation of muscle stem cells or satellite cells (SCs), which accelerates muscle regeneration in young mice.”
    Quote in the paperSubstantial claim
  • May combine two claims. 35
  • Classified as probably not a substantial claim. 16
  • The quote only partly states this claim. 2

  • May combine two claims.

    Findingown data

    PCA of the RNA-seq data revealed a clear separation between Cre+ and Cre− samples, and the separation distance was wider in EDL muscles than in SOL muscles.

    “Principal component analysis (PCA) of the RNA-seq data revealed a clear separation between Cre+ and Cre− samples, and the separation distance was wider in EDL muscles than in SOL muscles (Fig. 1e), consistent with the levels of OSKM induction.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In SOL muscles, Oct4, Sox2, and c-Myc were induced, but Klf4 expression was similar between Cre+ and Cre− SOL muscles.

    “In SOL muscles, however, Oct4, Sox2, and c-Myc were induced, but the expression of Klf4 was similar between Cre+ and Cre− SOL muscles (Fig. 1d).”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    DE genes resulting from 2.5 or 8.5 days of treatment had similar distribution patterns when visualized using volcano plots.

    “Furthermore, DE genes resulting from 2.5 or 8.5 days of treatment had similar distribution patterns when visualized using volcano plots (Fig. 1g).”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingown data

    Eleven modules were identified, but only three were enriched for GO terms associated with biological processes.

    “Eleven modules were identified, but only three were enriched for GO terms associated with biological processes (Supplementary Fig. 2a, b).”
    Quote in the paperNot a substantial claim

  • The quote only partly states this claim.

    Findingown data

    Cre+ samples had more Pax7+ cells than Cre− samples at 3 days post CTX.

    “In addition, Cre+ samples had more Pax7+ cells than Cre− samples (Fig. 2e).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Cre+ muscles had a higher percentage of activated (MyoD+) SCs and a lower percentage of quiescent (MyoD−) SCs than Cre− muscles.

    “Co-staining for Pax7 and MyoD showed that Cre+ muscles had a higher percentage of activated (MyoD+) SCs and a lower percentage of quiescent (MyoD−) SCs than Cre− muscles (Fig. 3d, f).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    H&E staining did not reveal any morphological differences between Cre+ and Cre− muscle sections and the myofibers in Cre− and Cre+ muscles lacked central nuclei.

    “H&E staining did not reveal any morphological differences between Cre+ and Cre− muscle sections and the myofibers in Cre− and Cre+ muscles lacked central nuclei (Supplementary Fig. 5a).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    The GO biological process term most enriched in shared upregulated genes was related to cytoskeleton organization, whereas downregulated genes were related to oxidative phosphorylation.

    “The GO biological process term most enriched in these upregulated genes was related to cytoskeleton organization, whereas downregulated genes were related to oxidative phosphorylation (Fig. 1h).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    OSKM expression was induced in the TA muscle following 2 days of Dox treatment, with OSKM levels returning back to control levels following 5 days of withdrawal.

    “OSKM expression was induced in the TA muscle following 2 days of Dox treatment, with OSKM levels returning back to control levels following 5 days of withdrawal (Fig. 2a).”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingown data

    The 202 downregulated genes were enriched in GO biological process terms related to cellular response to stimulus, whereas the 181 upregulated genes were not enriched for a specific GO biological process term.

    “These 202 downregulated genes were enriched in GO biological process terms related to cellular response to stimulus (Supplementary Fig. 3b), whereas the 181 upregulated genes were not enriched for a specific GO biological process term.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Regenerated myofibers in Cre+ muscles were larger than those observed in Cre− muscles, with more myofibers that were 30-40 μm and fewer that were 10-20 μm in diameter.

    “Consistently, regenerated myofibers in Cre+ muscles were larger than those observed in Cre− muscles, with more myofibers that were 30–40 µm and fewer that were 10–20 µm in diameter (Fig. 2h).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    At 30 days post-injury, the number of Pax7+ cells and the percentage of Pax7+MyoD− SCs were comparable between Cre+ and Cre− muscles.

    “At 30 days post-injury, the number of Pax7+ cells and the percentage of Pax7+MyoD− SCs were comparable between Cre+ and Cre− muscles (Fig. 4h, i).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Muscle structure was restored and there were no eMHC+ myofibers in Cre+ and Cre− muscles at 30 days post-injury.

    “Muscle structure was restored and there were no eMHC+ myofibers in Cre+ and Cre− muscles (Fig. 4j).”
    Quote in the paperNot a substantial claim

  • The quote only partly states this claim.

    Findingown data

    Myofiber sizes were comparable between Cre+ and Cre− muscles at 30 days post-injury.

    “Fibrosis was similarly low in Cre+ and Cre− muscles (Fig. 4k), and myofiber sizes were comparable between Cre+ and Cre− muscles (Fig. 4l).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    The percentage of eMHC+ regenerating myofibers and myofiber sizes were comparable between Cre+ and Cre− muscles after serial injury.

    “The percentage of eMHC+ regenerating myofibers and myofiber sizes were comparable between Cre+ and Cre− muscles (Fig. 5c, d).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Regenerated myofibers in Cre+ muscles were larger than those observed in Cre− muscle, with more myofibers that were 50-60 μm in diameter.

    “In addition, regenerated myofibers in Cre+ muscles were larger than those observed in Cre− muscle, with more myofibers that were 50–60 µm in diameter (Fig. 4f).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The percentage of quiescent (MyoD−) SCs was decreased by half in Cre+ myofibers compared to Cre− myofibers, and there was no difference in the percentage of MyoD+Pax7− cells.

    “Conversely, the percentage of quiescent (MyoD−) SCs was decreased by half in Cre+ myofibers compared to Cre− myofibers, and there was no difference in the percentage of MyoD+Pax7− cells (Fig. 3h, j).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    p21 was induced in the SCs of systemic 4F muscles but not in the SCs of Acta-Cre/4Fhet mice.

    “In addition, p21 was induced in the SCs of systemic 4F muscles but not in the SCs of Acta-Cre/4Fhet mice (Supplementary Fig. 9 g).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In 15-month-old myofiber-specific 4F mice, Cre+ muscles had 1.8-fold more Pax7+ cells and 2.8-fold more activated (MyoD+) SCs than Cre− muscles.

    “Cre+ muscles had 1.8-fold more Pax7+ cells and 2.8-fold more activated (MyoD+) SCs than Cre− muscles (Supplementary Fig. 8b-d).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In 15-month-old myofiber-specific 4F mice, myofibers in Cre+ muscles were larger than those observed in Cre− muscle, with more myofibers that were 30-40 μm and fewer myofibers that were 10-20 μm in diameter.

    “Moreover, myofibers in Cre+ muscles were larger than those observed in Cre− muscle, with more myofibers that were 30–40 µm and fewer myofibers that were 10–20 µm in diameter (Supplementary Fig. 8 l).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    In SC-specific OSKM induction, the number of Pax7+ cells, as well as the percentages of MyoD+ and BrdU+ SCs, were all comparable between Cre+ and Cre− muscles.

    “The number of Pax7+ cells, as well as the percentages of MyoD+ and BrdU+ SCs were all comparable between Cre+ and Cre− muscles (Supplementary Fig. 6e–g), indicating that SC-specific OSKM induction did not lead to the activation and proliferation of SCs.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Expression of four genes (Itga7, Sdc4, Wnt2b, and Wnt4) was altered on average over two-fold, and among these, Wnt4 was the only one that was downregulated.

    “Expression of four of these genes (Itga7, Sdc4, Wnt2b, and Wnt4) was altered on average over two-fold, and among these, Wnt4 was the only one that was downregulated (Fig. 6a).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Electroporation of the CAG-3xFLAG-p21 plasmid increased p21 expression 60-fold and downregulated Wnt4 levels 3-fold compared with the control plasmid (CAG-Td).

    “Electroporation of the CAG-3xFLAG-p21 plasmid increased p21 expression 60-fold, and downregulated Wnt4 levels 3-fold, compared with the control plasmid (CAG-Td) (Fig. 6g).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In isolated myofibers, p21 and Wnt4 were significantly upregulated and downregulated, respectively, in Cre+ myofibers compared to Cre− myofibers.

    “The expression of p21 and Wnt4 were significantly upregulated and downregulated, respectively, in Cre+ myofibers compared to Cre− myofibers (Fig. 6e).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In TA muscles of Acta1-Cre/4Fhet mice, p21 expression was upregulated and Wnt4 expression was downregulated in Cre+ muscles following Dox treatment, and returned to control levels following Dox withdrawal.

    “Levels of p21 and Wnt4 expression were upregulated and downregulated in Cre+ muscles, respectively, following Dox treatment, and returned to control levels (i.e., levels seen in Cre− samples) following Dox withdrawal (Fig. 6c).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Both myofiber-specific and systemic OSKM induction increased the activation of SCs.

    “Both myofiber-specific and systemic OSKM induction increased the activation of SCs.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Partial reprogramming by short-term expression of reprogramming factors ameliorated aging hallmarks without tumor formation.

    “Our lab showed that partial reprogramming by short-term expression of reprogramming factors ameliorated aging hallmarks without tumor formation8, opening a possible application of this approach in vivo.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [8] Ocampo, A. et al. In vivo amelioration of age-associated hallmarks by partial reprogramming. Cell 167, e1712 (2016). 1719-1733. source

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Premisecitation

    The regenerative capacity of SCs is influenced by both intrinsic modulators and the extrinsic microenvironment.

    “The regenerative capacity of SCs is influenced by both intrinsic modulators and the extrinsic microenvironment13–15.”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [13] Blau, H. M., Cosgrove, B. D. & Ho, A. T. The central role of muscle stem cells in regenerative failure with aging. Nat. Med. 21, 854–862 (2015). source

      Not checked in the free run.

    • cites [14] Sousa-Victor, P. et al. Geriatric muscle stem cells switch reversible quiescence into senescence. Nature 506, 316–321 (2014). source

      Not checked in the free run.

    • cites [15] Brack, A. S. & Munoz-Canoves, P. The ins and outs of muscle stem cell aging. Skelet. Muscle 6, 1 (2016). source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationown data

    Fast-twitch muscles are a more appropriate model for evaluating the effects of OSKM on muscle regenerative capacity.

    “These results suggest that fast-twitch muscles are a more appropriate model for evaluating the effects of OSKM on muscle regenerative capacity.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Premisecitation

    Muscle regeneration is primarily mediated by muscle stem cells or satellite cells (SCs), which reside in a characteristic niche located between the basal lamina and plasma membrane of myofibers.

    “Muscle regeneration is primarily mediated by muscle stem cells or satellite cells (SCs), which reside in a characteristic niche located between the basal lamina and plasma membrane of myofibers12.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [12] Mauro, A. Satellite cell of skeletal muscle fibers. J. Biophys. Biochem. Cytol. 9, 493 (1961). source

      Not checked in the free run.

  • May combine two claims.

    Interpretationown data

    Partial reprogramming via OSKM can remodel the SC niche to induce SC activation and proliferation and accelerate muscle regeneration.

    “We conclude that partial reprogramming via OSKM can remodel the SC niche to induce SC activation and proliferation and accelerate muscle regeneration.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationown data

    Cre+ samples had an expansion of myoblasts without changing the SC number.

    “In contrast, the number of Pax7+MyoD− SCs was comparable in Cre− and Cre+ samples (Fig. 2i), indicating Cre+ samples had an expansion of myoblasts without changing the SCs number.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationown data

    Partial reprogramming of myofibers induced the activation and proliferation of SCs.

    “Together, these results suggest that partial reprogramming of myofibers induced the activation and proliferation of SCs.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationown data

    Partial reprogramming of myofibers induced the activation and proliferation of SCs and the expansion of myoblasts.

    “Collectively, these results prove that partial reprogramming of myofibers induced the activation and proliferation of SCs and the expansion of myoblasts.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Oct4 represses the expression of MyoD.

    “OSKM inhibited the expression of MyoD and miR-133a (Supplementary Fig. 7b), which is consistent with the finding that Oct4 represses the expression of MyoD18.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [18] Watanabe, S. et al. MyoD gene suppression by Oct4 is required for reprogramming in myoblasts to produce induced pluripotent stem cells. Stem Cells 29, 505–516 (2011). source

      Not checked in the free run.

  • May combine two claims.

    Interpretationown data

    Myofiber-specific OSKM induction promotes SC activation and proliferation and accelerates muscle regeneration independent of aging.

    “Together, these results indicate that myofiber-specific OSKM induction promotes SC activation and proliferation and accelerates muscle regeneration independent of aging.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Premisecitation

    In mouse keratinocytes, p21 inhibits Wnt4 expression by binding to the TATA-proximal region of the Wnt4 promoter in association with E2F-1.

    “In mouse keratinocytes, p21 inhibits Wnt4 expression by binding to the TATA-proximal region of the Wnt4 promoter in association with E2F transcription factor 1 (E2F-1)24, and levels of p21 expression were negatively correlated with Wnt4 expression in our RNA-seq analysis (Fig. 6b).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [24] Devgan, V., Mammucari, C., Millar, S. E., Brisken, C. & Dotto, G. P. p21WAF1/Cip1 is a negative transcriptional regulator of Wnt4 expression downstream of Notch1 activation. Genes Dev. 19, 1485–1495 (2005). source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Itga7 is a laminin-binding protein that connects myofibers to the basal lamina to maintain sarcolemma integrity.

    “Integrin subunit alpha 7 (Itga7) is a laminin-binding protein that connects myofibers to the basal lamina to maintain sarcolemma integrity20.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [20] Mayer, U. et al. Absence of integrin alpha 7 causes a novel form of muscular dystrophy. Nat. Genet. 17, 318–323 (1997). source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Loss of Wnt4 in myofibers induces the activation of SCs and accelerates muscle regeneration.

    “Loss of Wnt4 in myofibers induces the activation of SCs and accelerates muscle regeneration23.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [23] Eliazer, S. et al. Wnt4 from the niche controls the mechano-properties and quiescent state of muscle stem cells. Cell Stem Cell 25, 654–665.e4 (2019). source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Sdc4 is expressed in SCs and is required for SC activation.

    “Syndecan-4 (Sdc4) is expressed in SCs and is required for SC activation21,22, but a role for Sdc4 in myofibers remains elusive.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [21] Bentzinger, C. F. et al. Fibronectin regulates Wnt7a signaling and satellite cell expansion. Cell Stem Cell 12, 75–87 (2013). source

      Not checked in the free run.

    • cites [22] Cornelison, D. D. et al. Essential and separable roles for Syndecan-3 and Syndecan-4 in skeletal muscle development and regeneration. Genes Dev. 18, 2231–2236 (2004). source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Deletion of collagen VI or laminin-α1 (ECM components) or myofiber-specific deletion of O-fucosyltransferase 1 gene (Pofut1) impairs the self-renewal of SCs, leading to the shrinkage of the SC pool after multiple muscle injuries.

    “Deletion of collagen VI or laminin-α1 (ECM components) or myofiber-specific deletion of O-fucosyltransferase 1 gene (Pofut1) impairs the self-renewal of SCs36–38, leading to the shrinkage of the SC pool after multiple muscle injuries.”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [36] Rayagiri, S. S. et al. Basal lamina remodeling at the skeletal muscle stem cell niche mediates stem cell self-renewal. Nat. Commun. 9, 1075 (2018). source

      Not checked in the free run.

    • cites [37] Urciuolo, A. et al. Collagen VI regulates satellite cell self-renewal and muscle regeneration. Nat. Commun. 4, 1964 (2013). source

      Not checked in the free run.

    • cites [38] Zygmunt D. A. et al. Deletion of Pofut1 in mouse skeletal Myofibers induces muscle aging-related phenotypes in cis and in trans. Mol. Cell. Biol. 37, e00426–16 (2017). source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Reprogramming factors have been shown to promote axon regeneration through intrinsic rejuvenation of retinal ganglion cells.

    “Reprogramming factors have been shown to promote axon regeneration through intrinsic rejuvenation of retinal ganglion cells10.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [10] Lu, Y. et al. Reprogramming to recover youthful epigenetic information and restore vision. Nature 588, 124–129 (2020). source

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    Our results suggest an aging-independent effect of reprogramming factors on muscle regeneration through remodeling of the extrinsic niche but not by regulating the intrinsic modulators of SCs.

    “In contrast, our results suggest an aging-independent effect of reprogramming factors on muscle regeneration through remodeling of the extrinsic niche but not by regulating the intrinsic modulators of SCs.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    The increase in activated SCs accelerated muscle regeneration, which may partly explain the previous observation that muscle regeneration was promoted in aging systemic 4F mice.

    “The increase in activated SCs accelerated muscle regeneration, which may partly explain our previous observation that muscle regeneration was promoted in aging systemic 4F mice8.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [8] Ocampo, A. et al. In vivo amelioration of age-associated hallmarks by partial reprogramming. Cell 167, e1712 (2016). 1719-1733. source

      Not checked in the free run.

    • Rests on an assumption: SC activation is required for muscle regeneration.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning

    Longer time may be required to observe the effect of OSKM on SC number in naturally aging mice.

    “The aging process is much slower in WT mice compared to progeria mice and longer time may be required to observe the effect of OSKM on SC number in naturally aging mice.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: The aging process is much slower in WT mice compared to progeria mice.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Intrinsic modulators control SC-initiated postnatal myogenesis.

    “Intrinsic modulators control SC-initiated postnatal myogenesis29.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [29] Dumont, N. A., Wang, Y. X. & Rudnicki, M. A. Intrinsic and extrinsic mechanisms regulating satellite cell function. Development 142, 1572–1581 (2015). source

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Premisecitation

    Self-renewal of SCs is maintained by the SC niche, including, but not limited to ECM components and myofibers.

    “Self-renewal of SCs is maintained by the SC niche, including, but not limited to ECM components and myofibers34,35.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [34] Kuang, S., Gillespie, M. A. & Rudnicki, M. A. Niche regulation of muscle satellite cell self-renewal and differentiation. Cell Stem Cell 2, 22–31 (2008). source

      Not checked in the free run.

    • cites [35] Yin, H., Price, F. & Rudnicki, M. A. Satellite cells and the muscle stem cell niche. Physiol. Rev. 93, 23–67 (2013). source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    OSKM induction triggers complex cellular changes.

    “OSKM induction triggers complex cellular changes1–3.”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [1] Takahashi, K. et al. Induction of pluripotent stem cells from adult human fibroblasts by defined factors. Cell 131, 861–872 (2007). source

      Not checked in the free run.

    • cites [2] Takahashi, K. & Yamanaka, S. Induction of pluripotent stem cells from mouse embryonic and adult fibroblast cultures by defined factors. Cell 126, 663–676 (2006). source

      Not checked in the free run.

    • cites [3] Polo, J. M. et al. A molecular roadmap of reprogramming somatic cells into iPS cells. Cell 151, 1617–1632 (2012). source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing). May combine two claims.

    Interpretationreasoning

    The identification of effective downstream targets of OSKM would restrict unwanted outcomes and benefit the development of new approaches to facilitate tissue regeneration.

    “The identification of their effective downstream targets would restrict unwanted outcomes and benefit the development of new approaches to facilitate tissue regeneration.”
    Quote in the paperNot a substantial claim
49 of 49

  • The paper relies on this without support.

    Young mice lack aging-related decline, so any OSKM-induced improvement in muscle regeneration in them cannot be attributed to rejuvenation of aged cells.

    “In addition, we chose young mice to investigate whether the improvement of regeneration can be achieved by OSKM induction regardless of its rejuvenating effect.”

  • The paper relies on this without support.

    The aging process is much slower in WT mice compared to progeria mice.

    “The aging process is much slower in WT mice compared to progeria mice and longer time may be required to observe the effect of OSKM on SC number in naturally aging mice.”

  • The paper relies on this without support.

    The intrinsic regulatory machinery is efficient in young SCs.

    “The intrinsic regulatory machinery is efficient in young SCs, therefore, further improvement of SC quality is limited.”

  • The paper relies on this without support.

    SC activation is required for muscle regeneration.

    “SCs activation is required for muscle regeneration, but the activation kinetics is delayed in aged SCs30.”
4 of 4

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • Expression of OSKM in myofibres, but not in MuSCs, promotes regeneration of old muscles.

    “The beneficial effects of OSKM on muscle function may be not cell autonomous: indeed expression of OSKM in myofibres, but not in MuSCs, promotes regeneration of old muscles232.”

    From Ageing and rejuvenation of tissue stem cells and their niches (2023) · cites this paper as [232]

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Fig. 2i is cited for the wrong experimental groups

    Minor

    The Wnt4-knockdown section cites Fig. 2i as evidence for a comparison between control and knockdown muscles. Earlier, the paper describes Fig. 2i as comparing Cre− and Cre+ muscles in the OSKM-induction experiment, not the Wnt4-knockdown groups.

1 of 1

Cites

Flagged first, then by citations

Cited by

Sorted by citations

Related

Authors
Wang, C., Rabadan Ros, R., Martinez-Redondo, P., Ma, Z., Shi, L., Xue, Y., Guillen-Guillen, I., Huang, L., Hishida, T., Liao, H.-K., Nuñez Delicado, E., Rodriguez Esteban, C., Guillen-Garcia, P., Reddy, P., & Izpisua Belmonte, J. C.
Affiliations
Salk Institute for Biological Studies (US)
ORCID
Venue
Nature Communications
Publisher
Springer Science and Business Media LLC
Published
2021-05-25
Volume
12
Issue
1
Pages
3094-3094
ISSN
2041-1723 (ISSN-L)
DOI
10.1038/s41467-021-23353-z
PMC
PMC8149870
OpenAlex
W3165546848
Cited by
119
References
55
Citations by year
2026: 16 · 2025: 24 · 2024: 27 · 2023: 28 · 2022: 17 · 2021: 7
FWCI
6.19
Type
journal article
Language
en
Open access
Licence
Locations
  • Nature Communications (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • RePEc: Research Papers in Economics (submittedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
Funders
This work was supported by Asociación de Futbolistas Españoles (AFE), Fundacion Pedro Guillen, Universidad Católica San Antonio de Murcia (UCAM), The Glenn Foundation, The Moxie Foundation and CIRM
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Muscle Physiology and Disorders
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Pluripotent Stem Cells Research
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Congenital heart defects research
Keywords
partial reprogramming, Yamanaka factors, OSKM, muscle regeneration, satellite cells, muscle stem cells, stem cell niche, muscle fibers, Wnt4, p21, stem cell quiescence, aging cells, local gene expression
MeSH terms
Kruppel-Like Factor 4, Animals, Cell Differentiation, Cells, Cultured, Female, Mice, Transgenic, Myofibrils, Regeneration, Gene Expression, Proto-Oncogene Proteins c-myc, Satellite Cells, Skeletal Muscle, Octamer Transcription Factor-3, Kruppel-Like Transcription Factors, Stem Cell Niche, SOXB1 Transcription Factors, Wnt4 Protein, Cellular Reprogramming

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-10.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-10.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review