The Discovery Of Nuclear Receptors Mlrh-isomers Of Transcriptional Regulation

Nuclear receptor mouse liver receptor homolog-1 (mLRH-1, also known as mFTF, NR5A2) is an ortholog of human B1 binding factor (hB1F, also known as CPF), a transcriptional factor discovered by our lab. LRH-1 is a member of the FTZ-F1 subfamily of the nuclear receptor superfamily. Accumulating data on the biological function of LRH-1 has shown in recent years that it plays important roles in regulating a wide range of biological processes such as the bile acid biosynthesis and the liver specific gene regulatory network. Moreover, mLRH-1 has been proved to be a key transcriptional factor in the early stage of embryonic development, however, little is known about the regulatory mechanism of its expression during this period. We identified an isoform of mLRH-1 from mouse embryonic stem cells, and studied the regulation of its expression.Chapter 1: identification and characterization of an variant of mlrh-1 mRNA (mlrh-1v2)We found that the mRNA of mlrh-1 in ES cells was different at its 5' end from the known one (mlrh-1 v1, or v1) with RT-PCR. Consequently we confirmed the existence of a novel variant (mlrh-1v2, or v2) by RT-PCR with the primers designed based on an EST related to the mlrh-1 gene. The protein product (mLRH-1-V2) of mlrh-1 v2 may lack the first 61 amino acids at the N-terminal .Electrophoresis mobility shift assay (EMSA) and reporter assays proved that mLRH-1V2 can bind to the conserved LRH-1 target sequence and is also a transcriptional activator.