Expression microarray studies of patients13, 14 and mouse models15, 16 have confirmed the importance of inflammatory response genes and specific developmental

pathways. Interestingly, one of these studies identified a small set of genes known to be regulated by DNA methylation as increased in livers from BA patients.14 Methylation of cytosine at CpG residues leads to repression of gene expression,17 and changes in DNA methylation can be elicited by drugs, toxins, viruses,18, 19 and genetic defects.20 DNA hypomethylation has been implicated as playing a causative role in autoimmune disorders such as systemic lupus erythematosis.21 DNA hypomethylation has also been shown to inhibit neuronal development22 and lymphocyte differentiation.23 We were intrigued that others Romidepsin cost had observed up-regulation of normally methylated genes in BA, that DNA hypomethylation affects development of specific cell types, and that changes in DNA methylation can be elicited by viruses, toxins, and genetic changes. Thus, we hypothesized that inhibition of DNA methylation may be

involved in the pathogenesis of BA. We have established several models of abnormal intrahepatic biliary development in zebrafish, including morpholino antisense oligonucleotide (MO)-mediated knockdown of Jagged and Notch family members24 and vps33b,25 which phenocopy biliary defects in patients with Alagille syndrome and arthrogryposis-renal dysfunction-cholestasis (ARC) syndrome, PARP inhibitor selleck chemical respectively. Additionally, MO-mediated knockdown of the transcription factors hnf626 and oc327 lead to developmental biliary defects, similar to targeted deletions of the orthologous genes in mice.28, 29 The pronounced conservation of molecular pathways regulating vertebrate biliary development led us to use zebrafish to examine whether induced changes in DNA methylation might play a role in mediating developmental biliary defects. AGS; Alagille

syndrome; ARC, arthrogryposis-renal dysfunction-cholestasis; azaC, 5-azacytidine; BA, biliary atresia; CF, cystic fibrosis; IFNγ, interferon-γ; MO, morpholino oligonucleotide; RRV, rhesus rotavirus; TGF-β, transforming growth factor β. Procedures for mutagenesis and screening for dtp are reported.30 Wildtype TLF strain fish were used for all morpholino injections and drug treatments. Fish were cared for in accordance with the Institutional Animal Care and Use Committees of both the Children’s Hospital of Philadelphia and the University of Pennsylvania. Zebrafish cytokeratin immunostainings were performed as described.24, 26 2F1131 stainings were performed on paraformaldehyde-fixed tissue at a dilution of 1:500 and processed as cytokeratin immunostainings. Electron microscopy specimens were prepared and examined as described.24 Methylcytosine stainings and human cytokeratin stainings were performed using antibodies purchased from Abcam (see below for protocol details).