Connexin 31 (GJB3) deficiency in mouse trophoblast stem cells alters giant cell differentiation and leads to loss of oxygen sensing.

The nonphysiological placental oxidative environment has been implicated in many complications during human pregnancy. Oxygen tension can influence a broad spectrum of molecular changes leading to alterations in trophoblast cell lineage development. In this study, we report that mouse wild-type trophoblast stem cells (TSCs) react to low oxygen (3%) with an enhanced differentiation into the giant cell pathway, indicated by a downregulation of the early stem cell markers Eomes and Cdx2 as well as by a significant upregulation of Tfap2c and the differentiation markers Tpbpa and Prl3d1. Here we demonstrated that connexin 31/GJB3-deficient TSCs failed to stabilize HIF-1A under low oxygen, resulting in nonresponsiveness of different marker genes, such as Cdx2 and Eomes and Tfap2c and Tpbpa. Moreover, connexin 31-deficient TSCs revealed a shift in giant cell differentiation from Prl3d1 expressing parietal giant cells to Ctsq, Prl3b1, and Prl2c2-positive giant cells, probably sinusoidal and canal lining trophoblast giant cells. Thus, loss of connexin 31 led to different giant cell subtypes which bypass the progenitor regulators Tfap2c and Tpbpa under low oxygen conditions.

The transcription factor TCFAP2C/AP-2gamma cooperates with CDX2 to maintain trophectoderm formation.

In mammals, cell lineage specification is established at the blastocyst stage. At this stage, transcription factor Cdx2 represses pluripotency genes, thus promoting extraembryonic trophoblast fate. Recently, transcription factor Gata3 was shown to act in a parallel pathway in promoting trophoblast cell fate, suggesting that there are more factors working in the trophoblast lineage. Here, we report that the transcription factor Tcfap2c is expressed at a high level in the trophectoderm and is able to induce trophoblast fate in embryonic stem cells. Trophoblast fate induced by Tcfap2c does not require Cdx2 and vice versa, suggesting that the molecules act in alternative pathways. However, both Tcfap2c and Cdx2 are required for the upregulation of Elf5, a marker of trophoblast stem cell maintenance, suggesting that both factors are required for stable trophoblast induction. Tcfap2c-induced trophoblast-like cells are stable in long-term culture, indicating that they are capable of self-renewal. Tcfap2c-controlled trophoblast maintenance involves the induction of Cdx2 and the repression of the pluripotency factor Nanog. Tcfap2c-induced trophoblast-like cells differentiate to trophoblast derivatives in vitro and contribute to the trophectoderm in blastocysts in vivo. Taken together, these observations suggest that Tcfap2c and Cdx2 cooperate to override the pluripotency program and establish the extraembryonic trophoblast maintenance program in murine embryos.

Influence of methyl jasmonate on podophyllotoxin and 6-methoxypodophyllotoxin accumulation in Linum album cell suspension cultures.

The accumulation of podophyllotoxin (PTOX) and 6-methoxypodophyllotoxin (6MPTOX) was enhanced about twofold in the suspension culture of Linum album line 2-5 aH following the addition of methyl jasmonate (MeJas) to the cultivation medium, reaching 7.69+/-1.45 mg/g dry weight and 1.11+/-0.09 mg/g dry weight, respectively. There was no increase in 6MPTOX accumulation following the addition of MeJas to suspension cells of L. album line X4SF, whereas PTOX accumulation was enhanced about tenfold to 0.49+/-0.10 mg/g dry weight. Phenylalanine ammonia-lyase activity increased immediately after the addition of MeJas to a cell suspension culture of line X4SF, reaching a maximum between 4 h and 1 day after elicitation, while cinnamyl alcohol dehydrogenase activity and the lignin content of the cells were not affected.