The proneural genes NEUROD1 and NEUROD2 are expressed during human trophoblast invasion.

During early human pregnancy, extravillous trophoblast cells invade the maternal tissue of the uterus in a way similar to invasion by cancer cells. However, the process of trophoblast invasion is regulated in a time and place restricted way, in contrast to cancer invasion. We screened first trimester placental tissue enriched by extravillous invasive trophoblasts for the expression of proneural basic helix-loop-helix (bHLH) transcription factors, which are important controllers of cell fate. Surprisingly, the presence of NEUROD1, NEUROD2 and ATH2 transcripts was found by reverse transcriptase polymerase chain reaction (RT-PCR) analysis in first trimester placentabed. Of these genes, the proneural genes NEUROD1 and NEUROD2 are expressed in different subsets of invasive trophoblasts. NEUROD1 expression is found in interstitial and endovascular invasive cells, while NEUROD2 expression is observed mainly in endovascular invasive cells, respectively. These data suggest that in addition to the involvement of proneural genes in neuron, neurendocrine and pancreas differentiation, these genes are involved in trophoblast differentation during progression of invasion.