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Differentiation shifts from a reversible to an irreversible heterochromatin state at the DM1 locus.

ABSTRACT: Epigenetic defects caused by hereditary or de novo mutations are implicated in various human diseases. It remains uncertain whether correcting the underlying mutation can reverse these defects in patient cells. Here we show by the analysis of myotonic dystrophy type 1 (DM1)-related locus that in mutant human embryonic stem cells (hESCs), DNA methylation and H3K9me3 enrichments are completely abolished by repeat excision (CTG2000 expansion), whereas in patient myoblasts (CTG2600 expansion), repeat deletion fails to do so. This distinction between undifferentiated and differentiated cells arises during cell differentiation, and can be reversed by reprogramming of gene-edited myoblasts. We demonstrate that abnormal methylation in DM1 is distinctively maintained in the undifferentiated state by the activity of the de novo DNMTs (DNMT3b in tandem with DNMT3a). Overall, the findings highlight a crucial difference in heterochromatin maintenance between undifferentiated (sequence-dependent) and differentiated (sequence-independent) cells, thus underscoring the role of differentiation as a locking mechanism for repressive epigenetic modifications at the DM1 locus.

SUBMITTER: Handal T

PROVIDER: S-EPMC11021500 | biostudies-literature | 2024 Apr

REPOSITORIES: biostudies-literature

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Differentiation shifts from a reversible to an irreversible heterochromatin state at the DM1 locus.

Handal Tayma T Juster Sarah S Abu Diab Manar M Yanovsky-Dagan Shira S Zahdeh Fouad F Aviel Uria U Sarel-Gallily Roni R Michael Shir S Bnaya Ester E Sebban Shulamit S Buganim Yosef Y Drier Yotam Y Mouly Vincent V Kubicek Stefan S van den Broek Walther J A A WJAA Wansink Derick G DG Epsztejn-Litman Silvina S Eiges Rachel R

Nature communications 20240416 1

Epigenetic defects caused by hereditary or de novo mutations are implicated in various human diseases. It remains uncertain whether correcting the underlying mutation can reverse these defects in patient cells. Here we show by the analysis of myotonic dystrophy type 1 (DM1)-related locus that in mutant human embryonic stem cells (hESCs), DNA methylation and H3K9me3 enrichments are completely abolished by repeat excision (CTG2000 expansion), whereas in patient myoblasts (CTG2600 expansion), repea ...[more]

PMID: 38627364

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Project description:AimsDifferentiation of cardiac fibroblasts (Fbs) into myofibroblasts (MyoFbs) is responsible for connective tissue build-up in myocardial remodelling. We examined MyoFb differentiation and reversibility.Methods and resultsAdult rat cardiac Fbs were cultured on a plastic substratum providing mechanical stress, with conditions to obtain different levels of Fb differentiation. Fb spontaneously differentiated to proliferating MyoFb (p-MyoFb) with stress fibre formation decorated with alpha-smooth muscle actin (α-SMA). Transforming growth factor-β1 (TGF-β1) promoted differentiation into α-SMA-positive MyoFb showing near the absence of proliferation, i.e. non-p-MyoFb. SD-208, a TGF-β-receptor-I (TGF-β-RI) kinase blocker, inhibited p-MyoFb differentiation as shown by stress fibre absence, low α-SMA expression, and high proliferation levels. Fb seeded in collagen matrices induced no contraction, whereas p-MyoFb and non-p-MyoFb induced 2.5- and four-fold contraction. Fb produced little collagen but high levels of interleukin-10. Non-p-MyoFb had high collagen production and high monocyte chemoattractant protein-1 and tissue inhibitor of metalloproteinases-1 levels. Transcriptome analysis indicated differential activation of gene networks related to differentiation of MyoFb (e.g. paxilin and PAK) and reduced proliferation of non-p-MyoFb (e.g. cyclins and cell cycle regulation). Dedifferentiation of p-MyoFb with stress fibre de-polymerization, but not of non-p-MyoFb, was induced by SD-208 despite maintained stress. Stress fibre de-polymerization could also be induced by mechanical strain release in p-MyoFb and non-p-MyoFb (2-day cultures in unrestrained 3-D collagen matrices). Only p-MyoFb showed true dedifferentiation after long-term 3-D cultures.ConclusionsFb, p-MyoFb, and non-p-MyoFb have a distinct gene expression, ultrastructural, and functional profile. Both reduction in mechanical strain and TGF-β-RI kinase inhibition can reverse p-MyoFb differentiation but not non-p-MyoFb.

Project description:Aim: Differentiation of cardiac fibroblasts (Fb) into myofibroblasts (MyoFb) is responsible for connective tissue buildup in myocardial remodeling. We examined reversibility of MyoFb differentiation. Methods and Results: Adult rat cardiac Fb were cultured on a plastic substratum providing mechanical stress, with conditions to obtain different Fb phenotypes. Fb spontaneously differentiated to proliferating MyoFb (p-MyoFb) with stress fiber formation decorated with alpha-smooth muscle actin (M-NM-1-SMA). Transforming growth factor-M-NM-21 (TGF-M-NM-21) promoted terminal differentiation into M-NM-1-SMA positive MyoFb showing near absence of proliferation i.e. non-p-MyoFb (2-fold increase in cell number after 12 days vs 11-fold for p-MyoFb). SD-208, a TGF-M-NM-2-receptor-I kinase blocker, inhibited p-MyoFb differentiation as shown by stress fiber absence, low levels of M-NM-1-SMA protein expression, and high levels of proliferation (32-fold increase after 12 days). Fb seeded in collagen matrices induced no contraction, whereas p-MyoFb and non-p-MyoFb induced 2.5- and 4-fold contraction. Fb produced low levels of collagen and secreted high levels of IL-10. Non-p-MyoFb showed high collagen production and high MCP-1 and TIMP-1 secretion. Transcriptome analysis indicated differential gene expression between all phenotypes. Dedifferentiation of p-MyoFb, but not of non-p-MyoFb, was induced by SD-208 despite maintained stress, shown by stress fiber de-polymerization in 30% of p-MyoFb vs in 8% of non-p-MyoFb. Stress fiber de-polymerization could be induced by mechanical strain release in p-MyoFb and non-p-MyoFb (2 day culture in unrestrained 3-D collagen matrices). Only p-MyoFb showed true dedifferentiation after long-term 3-D culture. Conclusions: Both reduction in mechanical strain and TGF-M-NM-2-receptor-I kinase inhibition can reverse p-MyoFb differentiation but not in non-p-MyoFb. Fibroblasts isolated from each rat heart (n= 4) were cultured in specific conditions to obtain different fibroblast phenotypes: 1) spontaneously differentiation into proliferating myofibroblasts (code RC), 2) terminal differentiation into non-proliferating myofibroblasts with TGF-M-NM-21 (code RT) and 3) inhibition of myofibroblast differentiation with SD-208, a TGF-M-NM-2-receptor-I kinase blocker (code RS). RNA concentration and purity from a total of 12 samples were determined spectrophotometrically using the Nanodrop ND-1000 (Nanodrop Technologies) and RNA integrity was assessed using a Bioanalyser 2100 (Agilent). Using the Ambion WT Expression Kit, per sample, an amount of 100 ng of total RNA spiked with bacterial poly-A RNA positive controls (Affymetrix) was converted to double stranded cDNA in a reverse transcription reaction. Next the sample was converted and amplified to antisense cRNA in an in vitro transcription reaction which was subsequently converted to single stranded sense cDNA. Finally, samples were fragmented and labeled with biotin in a terminal labeling reaction according to the Affymetrix WT Terminal Labeling Kit. A mixture of fragmented biotinylated cDNA and hybridisation controls (Affymetrix) was hybridised on Affymetrix GeneChipM-BM-. Rat Gene 2.0 ST array followed by staining and washing in a GeneChipM-BM-. fluidics station 450 (Affymetrix) according to the manufacturerM-bM-^@M-^Ys procedures. To assess the raw probe signal intensities, chips were scanned using a GeneChipM-BM-. scanner 3000 (Affymetrix).

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Differentiation shifts from a reversible to an irreversible heterochromatin state at the DM1 locus.

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Differentiation shifts from a reversible to an irreversible heterochromatin state at the DM1 locus.

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