The long noncoding RNAMeg3regulates myoblast plasticity and muscle regeneration through epithelial-mesenchymal transition

Abstract

statement Muscle differentiation and regeneration are regulated by an evolutionarily conserved long noncoding RNA that restricts gene expression to coordinate cell state transitions Abstract Formation of skeletal muscle is among the most striking examples of cellular plasticity in animal tissue development, where mononucleated, lineage-restricted progenitor cells are reprogrammed by epithelial-mesenchymal transition (EMT) to produce multinucleated myofibers. While some mediators of EMT have been shown to function in muscle formation, the regulation of this process in this tissue remains poorly understood. The long noncoding RNA (lncRNA) Meg3 is processed from the >200 kb Dlk1-Dio3 polycistron that we have previously shown is involved in skeletal muscle differentiation and regeneration. Here, we demonstrate that Meg3 regulates EMT in myoblast differentiation and skeletal muscle regeneration. Chronic inhibition of Meg3 in C2C12 myoblasts promoted aberrant EMT activation, and suppressed cell state transitions required for fusion and myogenic differentiation. Furthermore, adenoviral Meg3 knockdown compromised muscle regeneration, which was accompanied by abnormal mesenchymal gene expression and interstitial cell proliferation in the regenerating milieu. Transcriptomic and pathway analyses of Meg3-depleted C2C12 myoblasts and injured skeletal muscle revealed a significant dysregulation of EMT-related genes, and identified TGFβ as a key upstream regulator. Importantly, chemical inhibition of TGFβR1, as well as its downstream effectors ROCK1/2 and p38 MAPK, restored many aspects of myogenic differentiation in Meg3depleted myoblasts in vitro. Thus, Meg3 regulates myoblast identity to maintain proper cell state for progression into differentiation. Benetatos L, Hatzimichael E, Londin E, Vartholomatos G, Loher P, Rigoutsos I, Briasoulis E. (2013) The microRNAs within the DLK1-DIO3 genomic region: involvement in disease pathogenesis. Cell Mol Life Sci. 70(5):795-814. Benetatos L, Vartholomatos G, Hatzimichael E (2014). DLK1-DIO3 imprinted cluster in induced pluripotency: landscape in the mist. Cell Mol Life Sci. 71(22):4421-30. Buckingham M, Rigby PW (2014). Gene regulatory networks and transcriptional mechanisms that control myogenesis. Dev Cell. 28(3):225-38. Burks TN, Cohn RD. (2011) Role of TGF-β signaling in inherited and acquired myopathies. Skelet Muscle. 1(1):19. Campbell K, Casanova J. (2016) A common framework for EMT and collective cell migration. Development. 143(23):4291-4300. Caretti G, Di Padova M, Micales B, Lyons GE, Sartorelli V. (2004) The Polycomb Ezh2 methyltransferase regulates muscle gene expression and skeletal muscle differentiation. Genes Dev. 18(21):2627-38. Castel D, Baghdadi MB, Mella S, Gayraud-Morel B, Marty V, Cavaillé J, Antoniewski C, Tajbakhsh S (2018). Small-RNA sequencing identifies dynamic microRNA deregulation during skeletal muscle lineage progression. Sci Rep. 8(1):4208. Chal J, Pourquié O (2017). Making muscle: skeletal myogenesis in vivo and in vitro. . (2018). MEG3 affects the pro...

Histone H3K27 methyltransferase EZH2 interacts with MEG3-lncRNA to directly regulate integrin signaling and endothelial cell function

“…Similar, context-specific, MEG3 action has previously been described in regulation of TGF-β gene in cancer cells [14]. Although we find similarities in ChIRP targets between our datasets (overlap of 2933 hits upon correlation), we did not observe the same pattern of MEG3 targeting TGF-β in ECs, implying portentous context specificity of MEG3 actions and interactors, akin to its role in myoblast identity [30]. Our results, however, suggest a novel mechanism of MEG3 ability to inactivate ECs, linking integrin-mediated EC adhesion via ITGA4 to endure PRC2-associated chromatin changes in the nucleus; whereby epigenetic inhibition of PRC2 could derepress key genes, to enable efficient endothelial cell migration and adhesion during conditions like vascular injury and hypoxia.…”

“…4d). Data from one other public dataset also shows that ITGA4 is a direct target of MEG3 [30,31]. We next performed chromatin immunoprecipitation-qPCR to quantify the levels of EZH2 and H3K27me3 repressive mark and observed enrichment of EZH2 and H3K27me3 in the promoter region of ITGA4 in control HUVECs.…”

The Long Noncoding RNA MEG3 Retains Epithelial-Mesenchymal Transition by Sponging miR-146b-5p to Regulate SLFN5 Expression in Breast Cancer Cells

“…Studies show that the expression or dysfunction of long noncoding RNAs (lncRNAs) is correlated to many serious diseases, such as degenerative neurological diseases, cardiovascular diseases, and cancer [10][11][12][13]. Various lncRNAs play roles in regulating EMT and tumor progression in a variety of tumors, but the mechanisms are different [14].…”