Analysis of Rex1 (zfp42) expression and function in murine embryonic stem cells.

摘要

Reduced Expression-1 (Rex1), also known as zfp42, is a zinc finger transcription factor discovered in F9 embryonal carcinoma stem cell. Rex1 expression has since been observed primarily in undifferentiated cell types, including embryonic stem cells, embryonic germ cells and induced pluripotent cells. Upon all-trans retinoic acid induced differentiation of murine embryonic stem cells, Rex1 mRNA levels decrease several fold. Rex1 is widely used as a marker of stem cells, however, little is known about its role in these cells. To characterize the function(s) of Rex1 more extensively, Rex1 homozygous null ES cell lines were generated. We also evaluated gene expression in a Wt line that overexpresses Rex1 and in a Rex1 -/- line in which Rex1 expression was restored.;Rex1 is a downstream target of retinoic acid, an agent of differentiation. Upon culture of Rex1-/- cells in the presence of retinoic acid, Rex1-/- cells exhibited distinct differences as compared to wild-type cells. Rex1-/- cells express lower transcript levels of the stem cell markers Oct4, Nanog and Sox2. Conversely, they show increased levels of genes normally expressed in differentiated cells. These genes include the endoderm markers LamB1 and Gata4, the ectoderm markers Nestin and Pax6, and the mesoderm markers Brachyury and PDGFR beta. Thus, the disruption of the Rex1 gene enhanced the expression of ectoderm, mesoderm and endoderm markers as compared to wild type (Wt) cells. We propose that Rex1 acts to reduce retinoic acid induced differentiation in ES cells.;In order to elucidate further the potential functions of Rex1 and to identify potential Rex1 targets, microarray analyses were performed on Wt and Rex1-/- cells cultured in the presence or absence of LIF. These data suggest that Rex1 influences differentiation and cell cycle regulation. Disruption of the Rex1 gene also resulted in differential expression of transcripts involved in cancer progression.