Fibrogenic Activity of MECP2 Is Regulated by Phosphorylation in Hepatic Stellate Cells

Abstract

Background & AimsMethyl-CpG binding protein 2, MECP2, which binds to methylated regions of DNA to regulate transcription, is expressed by hepatic stellate cells (HSCs) and is required for development of liver fibrosis in mice. We investigated the effects of MECP2 deletion from HSCs on their transcriptome and of phosphorylation of MECP2 on HSC phenotype and liver fibrosis.MethodsWe isolated HSCs from Mecp2–/y mice and wild-type (control) mice. HSCs were activated in culture and used in array analyses of messenger RNAs and long noncoding RNAs. Kyoto Encyclopedia of Genes and Genomes pathway analyses identified pathways regulated by MECP2. We studied mice that expressed a mutated form of Mecp2 that encodes the S80A substitution, MECP2S80, causing loss of MECP2 phosphorylation at serine 80. Liver fibrosis was induced in these mice by administration of carbon tetrachloride, and liver tissues and HSCs were collected and analyzed.ResultsMECP2 deletion altered expression of 284 messenger RNAs and 244 long noncoding RNAs, including those that regulate DNA replication; are members of the minichromosome maintenance protein complex family; or encode CDC7, HAS2, DNA2 (a DNA helicase), or RPA2 (a protein that binds single-stranded DNA). We found that MECP2 regulates the DNA repair Fanconi anemia pathway in HSCs. Phosphorylation of MECP2S80 and its putative kinase, HIPK2, were induced during transdifferentiation of HSCs. HSCs from MECP2S80 mice had reduced proliferation, and livers from these mice had reduced fibrosis after carbon tetrachloride administration.ConclusionsIn studies of mice with disruption of Mecp2 or that expressed a form of MECP2 that is not phosphorylated at S80, we found phosphorylation of MECP2 to be required for HSC proliferation and induction of fibrosis. In HSCs, MECP2 regulates expression of genes required for DNA replication and repair. Strategies to inhibit MECP2 phosphorylation at S80 might be developed for treatment of liver fibrosis.

Epigenetic silencing of LncRNA ANRIL enhances liver fibrosis and HSC activation through activating AMPK pathway

“…Currently, it is known that epigenetic modifications of liver fibrosis‐related genes in liver fibrosis development . Epigenetic provides to a heritable modulation in gene expression that does not alter the DNA itself .…”

“…Currently, it is known that epigenetic modifications of liver fibrosis-related genes in liver fibrosis development. [4][5][6] Epigenetic provides to a heritable modulation in gene expression that does not alter the DNA itself. 7,8 Epigenetic influences generally refer to aberrant DNA methylation and non-coding RNA (ncRNA) modifications.…”

Epigenetics in Liver Fibrosis: Could HDACs be a Therapeutic Target?

“…For instance, MeCP2 induces the expression of ASH1, a histone methyltransferase that induces transcriptional activation of profibrogenic genes via H3K4 methylation [ 56 ]. Furthermore, a very recent study demonstrated that HIPK2-mediated Ser80 phosphorylation of MeCP2 is required for HSC transdifferentiation [ 57 ]. Mutation of Ser80 to alanine reduces the affinity of MeCP2 to multiple gene promoter sequences, therefore this post-translational modification is also important for DNA binding [ 58 ].…”

MeCP2‐421‐mediated RPE epithelial‐mesenchymal transition and its relevance to the pathogenesis of proliferative vitreoretinopathy

“…34,35 Phosphorylated MeCP2-421 and MeCP2-80 are the two major event in keeping homeostasis of cell function under normal condition that is called Yin and Yang. 34,35 It is shown that inhibition of phosphorylated MeCP2-80 increased neuronal activity, and MeCP2-80 phosphorylation reduced hepatic stellate cells proliferation and liver fibrosis 36 ; in contrast to MeCP2-80 phosphorylation, the neuronal activity and gene activation are associated with phosphorylation of MeCP2-421. 34,37 In our study, the increased P-MeCP2 421 instead of P-MeCP2-80 was seen in the human PVR membranes; more likely, the balance between P-MeCP2-80 and P-MeCP421 was lost in the process of development of PVR.…”