Figure 4. The suppression in long-chain fatty acid uptake during differentiation of cytotrophoblasts to syncytiotrophoblast can be prevented with p38 MAPK inhibition.

(A-B) Trophoblast were cultured for 72h with and without 10μM SB203580 (p38 MAPK inhibitor), incubated with 2μM BODIPY-C12 (green) for 20min, fixed and immunolabeled with desmoplakin (red) to visualize intercellular junctions and fatty acid uptake using confocal microscopy. Nuclei are labeled blue (Hoechst) (A) Desmoplakin shows large syncytial aggreggates in control 72h cultures, representing syncytiotrophoblast (SCT). (B) 72h cultures treated with SB203580 show cytotrophoblast (CTB) have aggregated, but remain as discrete cells, as evidenced by clearly demarcated desmoplakin labeled intercellular junctions, and suggests SB203580 maintains the CTB phenotype in vitro and prevents CTB differentiation to SCT (C) Total uptake of BODIPY-C12 long-chain fatty acid in isolated primary human term trophoblast was measured after 20min of incubation using a plate reader. Uptake was measured at 8, 24, or 72h after initial plating with and without a differentiation blocker SB203580. Treatment with SB203580 had no detectable effect on total uptake of BODIPY-C12 at 8 or 24h time points in culture. Trophoblast at 8 and 24h represent CTB because the majority of cells have not syncytialized at these time points. However, by 72h when CTB have largely fused to become SCT, uptake of BODIPY-C12 is greater in cultures treated with SB203580. These data indicate blocking differentiation of CTB to SCT is sufficient to preserve greater levels of BODIPY-C12 long-chain fatty acid uptake. Data are Mean±SEM, n=8 placentas.