Establishment of a cell line derived from a mouse fetal liver that has the characteristic to promote the hepatic maturation of mouse embryonic stem cells by a coculture method.

Stromal cells residing in murine fetal livers have the ability to promote the hepatic maturation of murine embryonic stem cells (ESCs) and hepatic progenitor cells (HPCs) 3848 in vitro. These stromal cells were isolated as the CD49f(+/-)CD45(-)Thy1(+)gp38(+) cell fraction. The present study established a murine fetal liver stromal cell line that induced hepatic maturation in mouse ESCs and HPCs. A transgene containing a temperature-sensitive SV40 large T antigen was transfected into the primary fetal liver stromal cells. These immortalized cells, which were named as the gp38-positive and Thy1-positive murine liver stromal (MLSgt) cells, induced both mouse ESCs and HPCs to differentiate into mature hepatocyte-like cells using a coculture method. Since MLSgt is not a cloned cell line, one clone, MLSgt20, was selected as a line with the characteristic to induce hepatic differentiation, which was comparable to its parental stromal cells. The ESC-derived endoderm cells cocultured with the MLSgt20 cells expressed mature hepatocyte-specific gene markers, including glucose-6-phosphatase, tyrosine aminotransferase, tryptophan 2,3-dioxgenase, and cytochrome P450 (CYP1a1, Cyp1b1, Cyp1a2, and Cyp3a11). In addition, these cells also exhibited hepatic functions, such as glycogen storage and ammonia metabolism. Transmission electron microscopy showed that the cocultured ESCs expressed the morphologic features of mature hepatocytes. In conclusion, a cell line was established that has the characteristic to promote the hepatic maturation of mouse ESCs and HPCs by a coculture method.

Fusion between CIC and DUX4 up-regulates PEA3 family genes in Ewing-like sarcomas with t(4;19)(q35;q13) translocation.

Ewing's family tumors (EFTs) are highly malignant tumors arising from bone and soft tissues that exhibit EWS-FLI1 or variant EWS-ETS gene fusions in more than 85% of the cases. Here we show that CIC, a human homolog of Drosophila capicua which encodes a high mobility group box transcription factor, is fused to a double homeodomain gene DUX4 as a result of a recurrent chromosomal translocation t(4;19)(q35;q13). This translocation was seen in two cases of soft tissue sarcoma diagnosed as Ewing-like sarcoma. CIC-DUX4 exhibits a transforming potential for NIH 3T3 fibroblasts, and as a consequence of fusion with a C-terminal fragment of DUX4, CIC acquires an enhanced transcriptional activity, suggesting that expression of its downstream targets might be deregulated. Gene expression analysis identified the ETS family genes, ERM/ETV5 and ETV1, as potential targets for the gene product of CIC-DUX4. Indeed, CIC-DUX4 directly binds the ERM promoter by recognizing a novel target sequence and significantly up-regulates its expression. This study clarifies the function of CIC and its role in tumorigenesis, as well as the importance of the PEA3 subclass of ETS family proteins in the development of EFTs arising through mechanisms different from those involving EWS-ETS chimeras. Moreover, the study identifies the role of DUX4 that is closely linked to facioscapulohumeral muscular dystrophy in transcriptional regulation.