scholarly journals Acetylation of PAX7 controls muscle stem cell self-renewal and differentiation potential in mice

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Marie-Claude Sincennes ◽  
Caroline E. Brun ◽  
Alexander Y. T. Lin ◽  
Tabitha Rosembert ◽  
David Datzkiw ◽  
...  
Keyword(s):  
Stem Cell ◽  
Target Genes ◽  
Cell Function ◽  
Metabolic Adaptation ◽  
Acetyl Coa ◽  
Differentiation Potential ◽  
Muscle Stem Cell ◽  
Binding Motifs ◽  
Muscle Stem Cells ◽  
Stem Cell Divisions

AbstractMuscle stem cell function has been suggested to be regulated by Acetyl-CoA and NAD+ availability, but the mechanisms remain unclear. Here we report the identification of two acetylation sites on PAX7 that positively regulate its transcriptional activity. Lack of PAX7 acetylation reduces DNA binding, specifically to the homeobox motif. The acetyltransferase MYST1 stimulated by Acetyl-CoA, and the deacetylase SIRT2 stimulated by NAD +, are identified as direct regulators of PAX7 acetylation and asymmetric division in muscle stem cells. Abolishing PAX7 acetylation in mice using CRISPR/Cas9 mutagenesis leads to an expansion of the satellite stem cell pool, reduced numbers of asymmetric stem cell divisions, and increased numbers of oxidative IIA myofibers. Gene expression analysis confirms that lack of PAX7 acetylation preferentially affects the expression of target genes regulated by homeodomain binding motifs. Therefore, PAX7 acetylation status regulates muscle stem cell function and differentiation potential to facilitate metabolic adaptation of muscle tissue.

scholarly journals Empowering Muscle Stem Cells for the Treatment of Duchenne Muscular Dystrophy

2021 ◽  
pp. 1-14
Author(s):  
Romina L. Filippelli ◽  
Natasha C. Chang
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Duchenne Muscular Dystrophy ◽  
Muscular Dystrophy ◽  
Cell Function ◽  
Critical Role ◽  
Membrane Integrity ◽  
Muscle Membrane ◽  
Muscle Stem Cell ◽  
Muscle Stem Cells

Duchenne muscular dystrophy (DMD) is a devastating and debilitating muscle degenerative disease affecting 1 in every 3,500 male births worldwide. DMD is progressive and fatal; accumulated weakening of the muscle tissue leads to an inability to walk and eventual loss of life due to respiratory and cardiac failure. Importantly, there remains no effective cure for DMD. DMD is caused by defective expression of the <i>DMD</i> gene, which encodes for dystrophin, a component of the dystrophin glycoprotein complex. In muscle fibers, this protein complex plays a critical role in maintaining muscle membrane integrity. Emerging studies have shown that muscle stem cells, which are adult stem cells responsible for muscle repair, are also affected in DMD. DMD muscle stem cells do not function as healthy muscle stem cells, and their impairment contributes to disease progression. Deficiencies in muscle stem cell function include impaired establishment of cell polarity leading to defective asymmetric stem cell division, reduced myogenic commitment, impaired differentiation, altered metabolism, and enhanced entry into senescence. Altogether, these findings indicate that DMD muscle stem cells are dysfunctional and have impaired regenerative potential. Although recent advances in adeno-associated vector and antisense oligonucleotide-mediated mechanisms for gene therapy have shown clinical promise, the current therapeutic strategies for muscular dystrophy do not effectively target muscle stem cells and do not address the deficiencies in muscle stem cell function. Here, we discuss the merits of restoring endogenous muscle stem cell function in degenerating muscle as a viable regenerative medicine strategy to mitigate DMD.

Stem Cell Function, Self-Renewal, Heterogeneity, and Regenerative Potential in Skeletal Muscle Stem Cells

2012 ◽  
Vol 2 (1) ◽  
pp. 11-21
Author(s):  
Silvia Cristini ◽  
Giulio Alessandri ◽  
Francesco Acerbi ◽  
Daniela Tavian ◽  
Eugenio A. Parati ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Stem Cells ◽  
Stem Cell ◽  
Cell Function ◽  
Self Renewal ◽  
Muscle Stem Cells ◽  
Skeletal Muscle Stem Cells

Stem Cell Function, Self-Renewal, Heterogeneity, and Regenerative Potential in Skeletal Muscle Stem Cells

2012 ◽  
Vol 2 (1) ◽  
pp. 11-21
Author(s):  
Silvia Cristini ◽  
Giulio Alessandri ◽  
Francesco Acerbi ◽  
Daniela Tavian ◽  
Eugenio A. Parati ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Stem Cells ◽  
Stem Cell ◽  
Cell Function ◽  
Self Renewal ◽  
Muscle Stem Cells ◽  
Skeletal Muscle Stem Cells

LOSS OF GLUTATHIONE PEROXIDASE 1 ATTENUATES COLITIS AND IS CRITICAL IN ACTIVATING EPITHELIAL REGENERATIVE RESPONSES

2021 ◽  
Vol 27 (Supplement_1) ◽  
pp. S27-S27
Author(s):  
Jared Hendren ◽  
Koral Kasnyik ◽  
Christopher Williams ◽  
Sarah Short
Keyword(s):  
Stem Cell ◽  
Glutathione Peroxidase ◽  
Target Genes ◽  
Cell Function ◽  
Intestinal Inflammation ◽  
Cellular Metabolism ◽  
Intestinal Injury ◽  
Gene Set Enrichment Analysis ◽  
Intestinal Cell ◽  
Glutathione Peroxidase 1

Abstract Many selenium-containing “selenoproteins” function as antioxidants, and work by our lab and others has demonstrated that selenoproteins often protect against intestinal inflammatory diseases, including colitis. Glutathione peroxidase 1 (GPx1) is a ubiquitous, mitochondrial and cytosolic selenoprotein which catalyzes the reduction of hydrogen peroxide by glutathione. Previously, we determined that despite its antioxidant role, loss of GPx1 greatly reduced disease severity in the dextran sodium sulfate (DSS) colitis model. Furthermore, GPx1 loss increased baseline intestinal cell proliferation, enhanced enteroid plating efficiency, and induced expression of stem cell-associated genes, such as Lgr5. Next, we aimed to determine the mechanism by which GPx1 modifies response to DSS. We observed that GPx1 is increased in colonic tissues from DSS-treated mice as compared to nontreated controls, suggesting that GPx1 may functionally contribute to intestinal injury responses. While GPx1 is expressed in both intestinal epithelial and immune cells, in situ hybridization to visualize Gpx1 identified epithelial cells as the most highly expressing cell type, with the greatest Gpx1 upregulation observed in wound-adjacent and regenerative crypts. Next, we investigated whether GPx1 loss affects stem cell function after injury. Here, we determined that both proliferation (p&lt;0.01) and Lgr5 expression (p&lt;0.05) were increased in the crypts of Gpx1-/- DSS-treated mice in comparison to WT controls. Similarly, organoids established from ulcerative colitis tissue displayed increased growth rates (p&lt;0.01), expression of stem cell and Wnt target genes such as AXIN2 (p&lt;0.0001) and LGR5 (p&lt;0.01), and proliferation (p&lt;0.05) following GPX1 knockdown. Together, these results indicate that GPx1 has an epithelial-cell autonomous role, and that its loss activates stem cell and proliferative responses which may both protect from intestinal injury and promote healing. Interestingly, recent research has highlighted the role of cellular metabolism in maintaining intestinal stem cell function, and GPx1 has previously been implicated in these processes. RNA-sequencing from DSS-treated mice and gene set enrichment analysis identified a positive association with oxidative phosphorylation-associated genes in Gpx1-/- mice (NES: 1.78; FDR q-val: 0.01), suggesting altered metabolism which may favor stem cell function. Further analysis of cellular metabolism using GPX1 knockdown colorectal cancer cells observed higher basal respiration (p&lt;0.0001) and ATP generation (p&lt;0.0001). Together, these results suggest that unlike other intestinal selenoproteins studied to date, loss of GPx1 augments stem cell injury responses to protect against intestinal inflammation, likely via augmenting epithelial regenerative responses.

Hairless regulates heterochromatin maintenance and muscle stem cell function as a histone demethylase antagonist

2021 ◽  
Vol 118 (37) ◽  
pp. e2025281118
Author(s):  
Ling Liu ◽  
Cristina Rodriguez-Mateo ◽  
Polly Huang ◽  
Albin Huang ◽  
Alexander Lieu ◽  
...  
Keyword(s):  
Cell Function ◽  
Expression Profiles ◽  
Gene Expression Profiles ◽  
Genotoxic Stress ◽  
Histone Demethylases ◽  
Muscle Stem Cell ◽  
Muscle Stem Cells ◽  
Histone 3 ◽  
Age Related ◽  
Regenerative Ability

Skeletal muscle possesses remarkable regenerative ability because of the resident muscle stem cells (MuSCs). A prominent feature of quiescent MuSCs is a high content of heterochromatin. However, little is known about the mechanisms by which heterochromatin is maintained in MuSCs. By comparing gene-expression profiles from quiescent and activated MuSCs, we found that the mammalian Hairless (Hr) gene is expressed in quiescent MuSCs and rapidly down-regulated upon MuSC activation. Using a mouse model in which Hr can be specifically ablated in MuSCs, we demonstrate that Hr expression is critical for MuSC function and muscle regeneration. In MuSCs, loss of Hr results in reduced trimethylated Histone 3 Lysine 9 (H3K9me3) levels, reduced heterochromatin, increased susceptibility to genotoxic stress, and the accumulation of DNA damage. Deletion of Hr leads to an acceleration of the age-related decline in MuSC numbers. We have also demonstrated that despite the fact that Hr is homologous to a family of histone demethylases and binds to di- and trimethylated H3K9, the expression of Hr does not lead to H3K9 demethylation. In contrast, we show that the expression of Hr leads to the inhibition of the H3K9 demethylase Jmjd1a and an increase in H3K9 methylation. Taking these data together, our study has established that Hr is a H3K9 demethylase antagonist specifically expressed in quiescent MuSCs.

scholarly journals MLL1 is required for PAX7 expression and satellite cell self-renewal in mice

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Gregory C. Addicks ◽  
Caroline E. Brun ◽  
Marie-Claude Sincennes ◽  
John Saber ◽  
Christopher J. Porter ◽  
...  
Keyword(s):  
Satellite Cell ◽  
Satellite Cells ◽  
Transcriptional Activation ◽  
Cell Activation ◽  
Target Genes ◽  
Cell Function ◽  
Skeletal Muscle Regeneration ◽  
Differentiation Potential ◽  
Self Renewal

Abstract PAX7 is a paired-homeobox transcription factor that specifies the myogenic identity of muscle stem cells and acts as a nodal factor by stimulating proliferation while inhibiting differentiation. We previously found that PAX7 recruits the H3K4 methyltransferases MLL1/2 to epigenetically activate target genes. Here we report that in the absence of Mll1, myoblasts exhibit reduced H3K4me3 at both Pax7 and Myf5 promoters and reduced Pax7 and Myf5 expression. Mll1-deficient myoblasts fail to proliferate but retain their differentiation potential, while deletion of Mll2 had no discernable effect. Re-expression of PAX7 in committed Mll1 cKO myoblasts restored H3K4me3 enrichment at the Myf5 promoter and Myf5 expression. Deletion of Mll1 in satellite cells reduced satellite cell proliferation and self-renewal, and significantly impaired skeletal muscle regeneration. Pax7 expression was unaffected in quiescent satellite cells but was markedly downregulated following satellite cell activation. Therefore, MLL1 is required for PAX7 expression and satellite cell function in vivo. Furthermore, PAX7, but not MLL1, is required for Myf5 transcriptional activation in committed myoblasts.

scholarly journals Glucose Metabolism Drives Histone Acetylation Landscape Transitions that Dictate Muscle Stem Cell Function

Cell Reports ◽  
2019 ◽  
Vol 27 (13) ◽  
pp. 3939-3955.e6 ◽  
Author(s):  
Nora Yucel ◽  
Yu Xin Wang ◽  
Thach Mai ◽  
Ermelinda Porpiglia ◽  
Peder J. Lund ◽  
...  
Keyword(s):  
Stem Cell ◽  
Glucose Metabolism ◽  
Histone Acetylation ◽  
Cell Function ◽  
Muscle Stem Cell

ASXL2 Is a Novel Mediator of RUNX1-ETO Transcriptional Function and Collaborates with RUNX1-ETO to Promote Leukemogenesis

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 302-302
Author(s):  
Jean-Baptiste Micol ◽  
Nicolas Duployez ◽  
Alessandro Pastore ◽  
Robert Williams ◽  
Eunhee Kim ◽  
...  
Keyword(s):  
Stem Cell ◽  
Cell Line ◽  
Hematopoietic Stem Cell ◽  
Binding Sites ◽  
Target Genes ◽  
Cell Function ◽  
Rna Seq ◽  
Hematopoietic Stem

Abstract Mutations in Addition of Sex Combs Like 1 (ASXL1) are common in patients with myeloid leukemias. More recently, mutations in ASXL2, a paralog of ASXL1 with ~40% shared amino acid homology, have been discovered to occur specifically in patients with acute myeloid leukemia (AML) patients bearing the RUNX1-ETO (AML1-ETO; RUNX1-RUNX1T1) translocation and are amongst the most common mutations in RUNX1-ETO AML (mutated in 20-25% of patients). Although ASXL1 is critical for Polycomb Repressive Complex 2 function in myeloid hematopoietic cells and loss of Asxl1 recapitulates key aspects of myelodysplastic syndrome (MDS), the function of ASXL2 in normal or malignant hematopoiesis is unknown. We therefore set out to perform a functional comparison of ASXL1and ASXL2on hematopoiesis and transcription and determine the functional basis for frequent mutations in RUNX1-ETO AML. In vitro analyses of ASXL2 insertion/deletion mutations revealed that these mutations resulted in substantial reduction of ASXL2 protein expression, stability, and half-life. We therefore generated Asxl2 conditional knockout (cKO) mice to delineate the effect of ASXL2 loss on hematopoiesis. Competitive (Fig. 1A) and noncompetitive transplantation revealed that Asxl2 or compound Asxl1/2 loss resulted in cell-autonomous, rapid defects of hematopoietic stem cell function, self-renewal, and number with peripheral blood leukopenia and thrombocytopenia but without any obvious MDS features- phenotypes distinct from Asxl1 cKO mice. Mice with heterozygous deletion of Asxl2 demonstrated an intermediate phenotype between control and homozygous cKO mice indicating a gene dosage effect of Asxl2 loss. RNA sequencing (RNA-seq) of hematopoietic stem/progenitor cells from Asxl2- and Asxl1-deficient mice revealed twenty-fold greater differentially expressed genes in Asxl2 cKO mice relative to Asxl1 cKO mice. Interestingly, genes differentially expressed with Asxl2 loss significantly overlapped with direct transcriptional targets of RUNX1-ETO, findings not seen in Asxl1 cKO mice (Fig. 1B). Asxl2 target genes appeared to also be targets of RUNX1, a key gene repressed by RUNX1-ETO to promote leukemogenesis. Consistent with this, genome-wide analysis of Asxl2 binding sites through anti-Asxl2 ChIP-seq revealed that Asxl2 binding sites substantially overlap with those of Runx1. Overall, the above data suggest that Asxl2 may be a critical mediator of RUNX1-ETO mediated leukemogenesis by affecting the expression of RUNX1 and/or RUNX1-ETO target genes. RNA-seq of primary RUNX1-ETO AML patient samples revealed that ASXL2-mutant RUNX1-ETO patients form a distinct transcriptional subset of RUNX1-ETO AML (Fig. 1C) suggesting a specific role of ASXL2 in leukemogenesis. To functionally interrogate the role of ASXL2 loss in RUNX1-ETO mediated leukemogenesis we first utilized an in vitro model with RNAi-mediated depletion of ASXL1 or ASXL2 in the SKNO1 cell line (the only ASXL-wildtype human RUNX1-ETO cell line). RNA-seq revealed distinct target genes dysregulated by ASXL1 versus ASXL2 loss in these cells without any significant overlap. Anti-ASXL2, RUNX1, and RUNX1-ETO ChIPSeq in SKNO1 cells revealed significant co-occupancy of ASXL2 with RUNX1 and RUNX1-ETO binding sites. Moreover, analysis of histone modification ChIPSeq revealed an enrichment in intergenic and enhancer H3K4me1 abundance following ASXL2 loss in SKNO1 cells. Next, to understand the in vivo effects of Asxl2 loss in the context of RUNX1-ETO, we performed retroviral bone marrow (BM) transplantation assays using RUNX1-ETO9a in Asxl2 cKO mice. In contrast to the failure of hematopoietic stem cell function with Asxl2 deletion alone, mice reconstituted with BM cells expressing RUNX1-ETO9a in Asxl2-deficient background had a shortened leukemia-free survival compared to Asxl2 -wildtype control. Overall, these data reveal that ASXL2 is required for hematopoiesis and has differing biological and transcriptional functions from ASXL1. Moreover, this work identifies ASXL2 as a novel mediator of RUNX1-ETOtranscriptional function and provides a new model of penetrant RUNX1-ETO AML based on genetic events found in a substantial proportion of t(8;21) AML patients. Further interrogation of the enhancer alterations generated by ASXL2 loss in RUNX1-ETO AML may highlight new therapeutic approaches for this subset of AML. Figure 1. Figure 1. Disclosures No relevant conflicts of interest to declare.

Rejuvenating Muscle Stem Cell Function: Restoring Quiescence and Overcoming Senescence

2016 ◽  
Vol 19 (2) ◽  
pp. 182-186 ◽  
Author(s):  
Andrew R. Mendelsohn ◽  
James W. Larrick
Keyword(s):  
Stem Cell ◽  
Cell Function ◽  
Muscle Stem Cell
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