Fig. 4

Schematic of the regulation and potential roles of ER stress and FGF21 in lipid metabolism during pregnancy. Activation of the PERK, IRE and ATF6 ER stress pathways plays an important role in augmenting hepatic TG synthesis and deposition during early pregnancy. A sharp increase in hepatic FGF21 secretion is crucial in curbing the continuous increase in hepatic TG content during late pregnancy, and hepatic FGF21 secretion is associated with the COPII vesicle coat proteins sec23a.