(332) IGF-1 Mediates ID2 in Trophoblast Differentiation

In preeclampsia (PE), impaired trophoblast proliferation and differentiation is thought to cause abnormal placentation and consequent fetal growth restriction. Insulin-like growth factor 1 (IGF-1) promotes trophoblast proliferation and differentiation, however the mechanisms of these processes are not well understood. The IGF-1 receptor regulates inhibitor of DNA binding 2 (ID2), but it is unclear how. ID2 functions as a negative regulator of bHLH transcription factors. ID2 is involved in trophoblast differentiation and implicated in many processes disrupted in PE—placental development, vascular differentiation, and angiogenesis. We hypothesize that IGF-1 promotes trophoblast differentiation via ID2—a relationship that has not been tested before in trophoblasts.

Study Design:

Immortalized human first trimester trophoblast cells (HTR-8/SVneo) were treated with IGF-1 for 24 hours after serum starvation. ID2 and MKI67 (marker of proliferation Ki67) expression was quantified by qRT-PCR and Western blot. Treated cells were visualized for tube formation as an index of differentiation. A wound healing assay was used to visualize cell migration and CCK-8 was used to enzymatically quantify viable cells.

Results:

Cell viability, migration, and differentiation were significantly increased in high doses (100 and 1000 ng/mL) of IGF-1 compared to low doses (0 and 10 ng/mL). ID2 and MKI67 mRNA levels were significantly lower in high IGF-1 doses compared to lower doses. As IGF-1 increased from 0 to 100 ng/mL, ID2 protein increased significantly. But when IGF-1 increased from 100 to 1000 ng/mL, ID2 protein decreased significantly.

Conclusion:

These data suggest IGF-1 may regulate trophoblast proliferation and differentiation through ID2. Increased IGF-1 may increase differentiation by decreasing ID2 expression. Futures studies will investigate mechanisms by which IGF-1 influences ID2, and if there are ID2-independent pathways of IGF-1 trophoblast regulation.