Up-regulated expression of murine Mcl1/EAT, a bcl-2 related gene, in the early stage of differentiation of murine embryonal carcinoma cells and embryonic stem cells.

We have cloned a murine homologue of the human Mcl1/EAT gene, a Bcl-2 related gene. Sequence analysis revealed that murine Mcl1/EAT (mMcl1/EAT) has three Bcl-2 homology domains, two PEST sequences, and immediate response boxes (IRB). The presence of IRB indicates that mMcl1/EAT is an immediate-early gene. mMcl1/EAT increases dramatically with exposure to retinoic acid in murine embryonal carcinoma cell lines (F9 and PCC3) as well as embryonic stem cells, both of which are models of early embryogenesis.

Induction of mcl1/EAT, Bcl-2 related gene, by retinoic acid or heat shock in the human embryonal carcinoma cells, NCR-G3.

NCR-G3 cells were established from a testicular embryonal carcinoma and were differentiated into multi-lineages including trophectoderm cells by exposure to retinoic acid. The differentiated cells began to produce human chorionic gonadotropin (hCG), a trophectoderm-specific hormone, which was regulated at the mRNA level. As we assumed that genes responsible for differentiation were differentially expressed at the early stage of retinoic acid-induced differentiation, we prepared a cDNA library from retinoic acid-treated NCR-G3 cells. This cDNA library was then screened for genes whose expression was induced during the differentiation of these cells. From about 5 x 10(4) clones screened, three independent sequences were isolated. Sequencing analysis revealed that clone 1002 codes for mcl1/EAT, which has a Bcl-2 homology domain. The expression of mcl1/EAT, the Bcl-2 related gene, was increased at an early stage of the retinoic acid-induced differentiation and preceded the up-regulation of cytokeratin and hCG genes after ratinoic acid treatment. Furthermore, mcl1/EAT was also up-regulated by heat shock, which has recently been shown to induce the cells to differentiate.