Differentiated cells maintain specific programs while retain the ability to respond to environmental changes. In epithelial cells the execution of specific functions pairs the capacity to respond to stimuli that may cause dramatic variations of gene expression (e.g. in the epithelial-to-mesenchymal transition (EMT) and in the reverse MET). Epigenetic mechanisms are one powerful way to allow the execution of transient or stable complex cellular programs. In particular DNA methylation, primarily orchestrated by the DNA methyltransferases (DNMTS) 1, 3a and 3b, plays a major role in these phenomena. We previously extensively characterized the mechanisms involved in TGFβ1-mediated EMT of hepatocytes, identifying a simple cross-regulatory circuitry between HNF4α and Snail, which expression was found to be mutually exclusive because of their direct reciprocal repression. These findings, relevant for the comprehension of the EMT and of the reverse process MET in hepatocytes, are also pivotal for the maintenance of liver stemness and of a stable epithelial phenotype. More recently, we explored regulative microRNAs, founding that the stemness inhibiting miRs-200a, b, c and miR-34a are epistatic elements in the Snail/HNF4α circuitry . Here, we integrated Snail/HNF4α circuitry in TGFβ-induced EMT of hepatocytes with the DNMT3a and the microRNA 29 family members. We found that: (i) TGFβ treatment strongly up-regulates the DNMT3a in hepatocytes; (ii) DNA methylation is required for TGFβ-mediated EMT and for Snail induction; (iii) DNMT3a levels inversely correlate with the expression of miR-29 family, known to target this enzyme in other cell systems. Furthermore, starting from our bioinformatic analysis revealing putative Snail and HNF4α binding sites on miRs-29 promoters, we investigated a possible regulation of these miRs by both these transcriptional factors showing the recruitment of HNF4α as a transcriptional activator in normal hepatocytes in vitro and in vivo while Snail works as a repressor after TGFβ-induced EMT.
Role of DNMT3s and miR-29 family members in TGF-β mediated EMT / Battistelli, C.; Cicchini, Carla; De Nonno, V.; Ciafrè, S. A.; Amicone, Laura; Tripodi, Marco. - (2013). (Intervento presentato al convegno TEMTIA 2013 The 6th International EMT Meeting tenutosi a Alicante, Spain nel November 13-16, 2013).
Role of DNMT3s and miR-29 family members in TGF-β mediated EMT
C. Battistelli;CICCHINI, Carla;AMICONE, Laura;TRIPODI, Marco
2013
Abstract
Differentiated cells maintain specific programs while retain the ability to respond to environmental changes. In epithelial cells the execution of specific functions pairs the capacity to respond to stimuli that may cause dramatic variations of gene expression (e.g. in the epithelial-to-mesenchymal transition (EMT) and in the reverse MET). Epigenetic mechanisms are one powerful way to allow the execution of transient or stable complex cellular programs. In particular DNA methylation, primarily orchestrated by the DNA methyltransferases (DNMTS) 1, 3a and 3b, plays a major role in these phenomena. We previously extensively characterized the mechanisms involved in TGFβ1-mediated EMT of hepatocytes, identifying a simple cross-regulatory circuitry between HNF4α and Snail, which expression was found to be mutually exclusive because of their direct reciprocal repression. These findings, relevant for the comprehension of the EMT and of the reverse process MET in hepatocytes, are also pivotal for the maintenance of liver stemness and of a stable epithelial phenotype. More recently, we explored regulative microRNAs, founding that the stemness inhibiting miRs-200a, b, c and miR-34a are epistatic elements in the Snail/HNF4α circuitry . Here, we integrated Snail/HNF4α circuitry in TGFβ-induced EMT of hepatocytes with the DNMT3a and the microRNA 29 family members. We found that: (i) TGFβ treatment strongly up-regulates the DNMT3a in hepatocytes; (ii) DNA methylation is required for TGFβ-mediated EMT and for Snail induction; (iii) DNMT3a levels inversely correlate with the expression of miR-29 family, known to target this enzyme in other cell systems. Furthermore, starting from our bioinformatic analysis revealing putative Snail and HNF4α binding sites on miRs-29 promoters, we investigated a possible regulation of these miRs by both these transcriptional factors showing the recruitment of HNF4α as a transcriptional activator in normal hepatocytes in vitro and in vivo while Snail works as a repressor after TGFβ-induced EMT.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
