Exogenous TPRX1 homeoprotein modulates the gene expression of lineage-specific transcription factors in human embryonal carcinoma cells

Yuki Mori,Mizuki Sakuraoka,Takahiro Suzuki,Sho Sato,Saiko Sugawara,Misuzu Hiraide,Suguru Sato,Masayuki Kobayashi

doi:10.1080/13102818.2018.1447396

Abstract

ABSTRACTWe reported previously that EGAM1 homeoproteins (EGAM1 and EGAM1N), transcribed from the Crxos gene as splicing variants, are expressed in preimplantation mouse embryos and mouse embryonic stem (ES) cells. Exogenous expression of these proteins affects the maintenance of an undifferentiated state and the progression of differentiation in mouse ES cells. Human tetrapeptide-repeat homeobox 1 (TPRX1), a member of the eutherian totipotent cell homeobox (ETCHbox) genes, is an ortholog of Crxos. However, the roles of TPRX1 in the differentiation of human pluripotent cells are still unknown. Because the TPRX1 transcripts were undetectable in an undifferentiated state and during the progression of differentiation in wild-type human embryonal carcinoma NT2/D1 cells, it would be advantageous to clarify the relationship between the exogenous expression of TPRX1 and the induction of genes encoding lineage-specific transcription factors in pluripotent cells. The expression of GATA6 and FOXA2, crucial transcription factors for the formation of the primitive endoderm, was upregulated, whereas that of CDX2, a crucial transcription factor for the formation of the trophectoderm, was downregulated by enforced expression of TPRX1. Overall, we suggest that TPRX1 is capable of modulating the expression of lineage-specific transcription factors in pluripotent cells derived from humans.

Highlights

In mice, the pluripotent inner cell mass, the precursor cells of all fetal and adult cell lineages, and the trophectoderm, precursor cells of placental cell lineages, arise during preimplantation development between the morula stage and the blastocyst stage
We suggest that tetrapeptide-repeat homeobox 1 (TPRX1) is capable of modulating the expression of lineage-specific transcription factors in pluripotent cells derived from humans
In order to clarify the roles of orthologs for Crxos, we focused on the functions of TPRX1 in human embryonal carcinoma NT2/D1 cells, as a model of human pluripotent cells

Summary

Introduction

The pluripotent inner cell mass, the precursor cells of all fetal and adult cell lineages, and the trophectoderm, precursor cells of placental cell lineages, arise during preimplantation development between the morula stage and the blastocyst stage. We identified the structurally related homeoproteins EGAM1 (GenBank accession No AB472692, known as CRXOS isoform a) and EGAM1N (No AB472693, CRXOS isoform c) in preimplantation mouse embryos [3]. These homeoproteins encoded by the Crxos gene (Gene ID 546024) on chromosome 7 (Figure 1) are expressed as splicing variants in both mouse embryos and mouse ES cells. Maeso et al reported that ETCHbox (eutherian totipotent cell homeobox) genes, including TPRX1, ARGFX, LEUTX, DPRX and PARGFX, arose by tandem gene duplication from the retinally expressed CRX gene, followed by asymmetric sequence evolution in mammals [9] They argued the Crxos gene is an ortholog of ETCHbox genes, especially of TPRX1 (Figure 1), and suggested that ETCHbox. In order to clarify the roles of orthologs for Crxos, we focused on the functions of TPRX1 in human embryonal carcinoma NT2/D1 cells, as a model of human pluripotent cells

Materials and methods

Results and discussion

Conclusions