Imprinted X-inactivation in extra-embryonic endoderm cell lines from mouse blastocysts

Abstract

The extra-embryonic endoderm lineage plays a major role in the nutritive support of the embryo and is required for several inductive events, such as anterior patterning and blood island formation. Blastocyst-derived embryonic stem (ES) and trophoblast stem (TS) cell lines provide good models with which to study the development of the epiblast and trophoblast lineages,respectively. We describe the derivation and characterization of cell lines that are representative of the third lineage of the blastocyst –extra-embryonic endoderm. Extra-embryonic endoderm (XEN) cell lines can be reproducibly derived from mouse blastocysts and passaged without any evidence of senescence. XEN cells express markers typical of extra-embryonic endoderm derivatives, but not those of the epiblast or trophoblast. Chimeras generated by injection of XEN cells into blastocysts showed exclusive contribution to extra-embryonic endoderm cell types. We used female XEN cells to investigate the mechanism of X chromosome inactivation in this lineage. We observed paternally imprinted X-inactivation, consistent with observations in vivo. Based on gene expression analysis, chimera studies and imprinted X-inactivation, XEN cell lines are representative of extra-embryonic endoderm and provide a new cell culture model of an early mammalian lineage.

Concise Review: Culture Mediated Changes in Fate and/or Potency of Stem Cells

“…Recent isolations of rodent MAPCs, which express the ESC-associated TF Oct4 (but not Nanog and Sox2) and the primitive endoderm specific genes Gata6, Gata4, Sox7, and Sox17, demonstrate that they can be detected after 2-4 months of in vitro culture [43,44]. As such, rodent MAPC resemble extraembryonic endoderm cells [45] and extraembryonic endoderm precursor cells [46]. In the initial report, we speculated that MAPC might be embryonic remnants or the result of dedifferentiation of a BM derived cell to a more potent cell.…”

Cell and molecular regulation of the mouse blastocyst

“…8A). ES cells have been derived from the epiblast lineage (Evans and Kaufman, 1981;Martin, 1981), trophoblast stem cells (TS cells) from the trophectoderm lineage (Tanaka et al, 1998), and extraembryonic endoderm (XEN) cells from the primitive endoderm lineage (Kunath et al, 2005). Like other stem cells, these cells can either self-renew or differentiate into lineage-specific cell types.…”

“…Each stem cell type also exhibits morphology, gene expression, and growth factor requirements characteristic of the lineage from which it derives. Importantly, all have been shown to contribute mainly to their lineage of origin in chimeras (Beddington and Robertson, 1989;Tanaka et al, 1998;Kunath et al, 2005). Stem cells from the blastocyst have provided a valuable tool for the genetic analysis of lineage-promoting factors and have confirmed the central importance of transcription factors in maintaining cell fates.…”

“…In fact, if outgrowths are cultured in non-ES cell culture conditions, stem cells from the PE lineage can be recovered. These stem cells, called XEN for extraembryonic endoderm, proliferate in culture and contribute only to the PE lineage when injected into blastocysts (Kunath et al, 2005).…”

L’embryogenèse précoce des mammifères

“…Les plus étudiées sont les cellules souches embryonnaires (ES) qui ont des caractéristiques épiblastiques [4,5]. Les cellules souches trophoblastiques (TS) [6] et Xen [7] ont été isolées plus récemment et représentent les lignées trophoblastiques et de l'EPr respectivement. Pour chacune de ces trois lignées, le caractère « souche » a été validé …”