Role of placental fibrinogen-like protein 1 in gestational diabetes

In view of the increasing prevalence of gestational diabetes mellitus (GDM) and the increased risks of delivering a macrosomic infant, developing preeclampsia, and suffering a perinatal death due to GDM, GDM has emerged as a growing public health problem. Although the placenta was suggested to play a crucial role in the pathology of GDM, the mechanisms that induce the development of GDM are still obscure. Fibrinogen-like protein (FGL)-1 is a hepatokine that plays an important role in hepatogenesis, as well as in nonalcoholic fatty liver disease and diabetes. Although FGL-1 is also expressed by the placenta, the pathophysiological role of FGL-1 in GDM is still unknown. In this study, FGL-1 levels were evaluated in 45 subjects with (n = 16) or without (n = 29) GDM. We found that FGL-1 was mainly expressed by placental trophoblasts, and FGL-1 expression was significantly higher in subjects with GDM. FGL-1 increased trophoblast proliferation through an extracellular signal-regulated kinase 1/2-dependent pathway. In addition, plasma concentrations of FGL-1 were higher in subjects with GDM, and the increased circulating FGL-1 might contribute to systemic insulin resistance. FGL-1 disrupted the gluconeogenic action of insulin in HepG2 cells, and decreased insulin-induced glucose uptake by L6 myotubes. Taken together, placental FGL-1 possibly plays a role in the impairment of insulin function in the development of GDM, and it might be a novel biomarker for diagnosing GDM.