Knockdown of miR-23, miR-27, and miR-24 Alters Fetal Liver Development and Blocks Fibrosis in Mice.

MicroRNAs (miRNAs) regulate cell fate selection and cellular differentiation. miRNAs of the miR23b polycistron (miR-23b, miR-27b, and miR-24) target components of the TGF-β signaling pathway and affect murine bile ductular and hepatocyte cell fate selection in vitro. Here we show that miR-23b polycistron miRNAs directly target murine Smad4, which is required for TGF-β signaling.

Triple Staining Including FOXA2 Identifies Stem Cell Lineages Undergoing Hepatic and Biliary Differentiation in Cirrhotic Human Liver.

Recent investigations have reported many markers associated with human liver stem/progenitor cells, "oval cells," and identified "niches" in diseased livers where stem cells occur. However, there has remained a need to identify entire lineages of stem cells as they differentiate into bile ducts or hepatocytes. We have used combined immunohistochemical staining for a marker of hepatic commitment and specification (FOXA2 [Forkhead box A2]), hepatocyte maturation (Albumin and HepPar1), and features of bile ducts (CK19 [cytokeratin 19]) to identify lineages of stem cells differentiating toward the hepatocytic or bile ductular compartments of end-stage cirrhotic human liver.

Small RNAs derived from lncRNA RNase MRP have gene-silencing activity relevant to human cartilage-hair hypoplasia.

Post-transcriptional processing of some long non-coding RNAs (lncRNAs) reveals that they are a source of miRNAs. We show that the 268-nt non-coding RNA component of mitochondrial RNA processing endoribonuclease, (RNase MRP), is the source of at least two short (∼20 nt) RNAs designated RMRP-S1 and RMRP-S2, which function as miRNAs. Point mutations in RNase MRP cause human cartilage-hair hypoplasia (CHH), and several disease-causing mutations map to RMRP-S1 and -S2.

Overexpression of miR-21 promotes an in vitro metastatic phenotype by targeting the tumor suppressor RHOB.

Metastasis is a multistep process that involves the deregulation of oncogenes and tumor suppressors beyond changes required for primary tumor formation. RHOB is known to have tumor suppressor activity, and its knockdown is associated with more aggressive tumors as well as changes in cell shape, migration, and adhesion. This study shows that oncogenic microRNA, miR-21, represses RHOB expression by directly targeting the 3' untranslated region.

MicroRNA-23b cluster microRNAs regulate transforming growth factor-beta/bone morphogenetic protein signaling and liver stem cell differentiation by targeting Smads.

Unlabelled: Transforming growth factor-beta / bone morphogenetic protein (TGFbeta/BMP) signaling has a gradient of effects on cell fate choice in the fetal mouse liver. The molecular mechanism to understand why adjacent cells develop into bile ducts or grow actively as hepatocytes in the ubiquitous presence of both TGFbeta ligands and receptors has been unknown. We hypothesized that microRNAs (miRNAs) might play a role in cell fate decisions in the liver.

Elevated expression of the miR-17-92 polycistron and miR-21 in hepadnavirus-associated hepatocellular carcinoma contributes to the malignant phenotype.

Alterations in microRNA (miRNA) expression in both human and animal models have been linked to many forms of cancer. Such miRNAs, which act directly as repressors of gene expression, have been found to frequently reside in fragile sites and genomic regions associated with cancer. This study describes a miRNA signature for human primary hepatitis B virus-positive human hepatocellular carcinoma.

Clonal, cultured, murine fetal liver hepatoblasts maintain liver specification in chimeric mice.

Unlabelled: Recent studies have shown a pluripotential nature of stem cells that were previously thought to be committed to specific lineages. HBC-3 cells are a clonal fetal murine hepatoblast cell line derived from an e9.5 murine embryo, and these cells can be induced to form hepatocytes and bile ducts in vitro and when transplanted into adult mouse livers.

A mammalian microRNA expression atlas based on small RNA library sequencing.

MicroRNAs (miRNAs) are small noncoding regulatory RNAs that reduce stability and/or translation of fully or partially sequence-complementary target mRNAs. In order to identify miRNAs and to assess their expression patterns, we sequenced over 250 small RNA libraries from 26 different organ systems and cell types of human and rodents that were enriched in neuronal as well as normal and malignant hematopoietic cells and tissues. We present expression profiles derived from clone count data and provide computational tools for their analysis.

Identification of hepatocytic and bile ductular cell lineages and candidate stem cells in bipolar ductular reactions in cirrhotic human liver.

Hepatocyte function and regeneration are severely compromised in severe liver disease, and a common sequela is cirrhosis. Structural changes caused by cirrhosis create a cellular environment conducive to the formation of ductular reactions (DRs). Ductular reactions are primarily composed of oval cells also known as "intermediate hepatobiliary cells".

Multi-miRNA hairpin method that improves gene knockdown efficiency and provides linked multi-gene knockdown.

A number of natural microRNA (miRNA) hairpins have been found in clusters of multiple identical or different copies, suggesting that effects of miRNAs can be enhanced and multiple genes can be regulated together by encoding multiple miRNA hairpins in a single transcript. Here, we report a simple and effective artificial multi-hairpin method that stimulates production of mature 22-nucleotide small RNAs from modified miRNA hairpins, improves gene knockdown over single-hairpin constructs, and provides linked multi-gene knockdowns.

Hit-and-run mechanism of HBV-mediated progression to hepatocellular carcinoma.

Aim And Background: Hepatitis B virus is implicated in the development of hepatocellular caracinoma. No oncogenes have been identified within the viral genome. Furthermore, it frequently fragments after integration into the hepatocyte genome.

cDNA microarray analysis of HBV transgenic mouse liver identifies genes in lipid biosynthetic and growth control pathways affected by HBV.

Hepatitis B virus (HBV) transgenic mice that replicate HBV in the liver generally do not exhibit gross liver pathology, while maintaining a high level (10(7) or greater) of viral titer in the blood. We have used this model to determine the minimum effects of HBV replication in the liver on cellular gene transcription, using cDNA microarrays. cDNA microarray data from sets of HBV versus control cDNA microarrays revealed a very small impact of HBV on the cellular transcriptome.

RNA expression microarrays (REMs), a high-throughput method to measure differences in gene expression in diverse biological samples.

We have developed RNA expression microarrays (REMs), in which each spot on a glass support is composed of a population of cDNAs synthesized from a cell or tissue sample. We used simultaneous hybridization with test and reference (housekeeping) genes to calculate an expression ratio based on normalization with the endogenous reference gene. A test REM containing artificial mixtures of liver cDNA and dilutions of the bacterial LysA gene cDNA demonstrated the feasibility of detecting transcripts at a sensitivity of four copies of LysA mRNA per liver cell equivalent.

Gene expression pattern in hepatic stem/progenitor cells during rat fetal development using complementary DNA microarrays.

To identify new and differentially expressed genes in rat fetal liver epithelial stem/progenitor cells during their proliferation, lineage commitment, and differentiation, we used a high throughput method-mouse complementary DNA (cDNA) microarrays-for analysis of gene expression. The gene expression pattern of rat hepatic cells was studied during their differentiation in vivo: from embryonic day (ED) 13 until adulthood. The differentially regulated genes were grouped into two clusters: a cluster of up-regulated genes comprised of 281 clones and a cluster of down-regulated genes comprised of 230 members.

Reduced hepatocyte proliferation is the basis of retarded liver tumor progression and liver regeneration in mice lacking N-acetylglucosaminyltransferase III.

Mice lacking N-acetylglucosaminyltransferase III (GlcNAc-TIII) exhibit slightly but significantly retarded liver tumor progression after a single injection of 10 micro g/g diethylnitrosamine (DEN) and continued administration of phenobarbital (PB) in drinking water. A key question is whether the absence of GlcNAc-TIII inhibits cell proliferation or induces apoptosis. Because PB aids tumor progression, we tested whether it diminished the difference in tumor progression between Mgat3(+/+) and Mgat3(Delta/Delta) mice.

Increase in de novo HBV DNA integrations in response to oxidative DNA damage or inhibition of poly(ADP-ribosyl)ation.

Chronic infection with hepatitis B virus (HBV) is associated with an increased risk for the development of cirrhosis and hepatocellular carcinoma (HCC). Although clonal HBV DNA integrations are detected in nearly all HCCs the role of these integrations in hepatocarcinogenesis is poorly understood. We have used a cloning protocol that allows studying the frequency and the natural history of HBV DNA integrations in cell culture.