Interacting hepatic PAI-1/tPA gene regulatory pathways influence impaired fibrinolysis severity in obesity
Ze Zheng, … , José A. López, Ira Tabas
Ze Zheng, … , José A. López, Ira Tabas
Published July 13, 2020
Citation Information: J Clin Invest. 2020;130(8):4348-4359. https://doi.org/10.1172/JCI135919.
View: Text | PDF
Research Article Hematology Metabolism

Interacting hepatic PAI-1/tPA gene regulatory pathways influence impaired fibrinolysis severity in obesity

Abstract

Fibrinolysis is initiated by tissue-type plasminogen activator (tPA) and inhibited by plasminogen activator inhibitor 1 (PAI-1). In obese humans, plasma PAI-1 and tPA proteins are increased, but PAI-1 dominates, leading to reduced fibrinolysis and thrombosis. To understand tPA–PAI-1 regulation in obesity, we focused on hepatocytes, a functionally important source of tPA and PAI-1 that sense obesity-induced metabolic stress. We showed that obese mice, like humans, had reduced fibrinolysis and increased plasma PAI-1 and tPA, due largely to their increased hepatocyte expression. A decrease in the PAI-1 (SERPINE1) gene corepressor Rev-Erbα increased PAI-1, which then increased the tPA gene PLAT via a PAI-1/LRP1/PKA/p-CREB1 pathway. This pathway was partially counterbalanced by increased DACH1, a PLAT-negative regulator. We focused on the PAI-1/PLAT pathway, which mitigates the reduction in fibrinolysis in obesity. Thus, silencing hepatocyte PAI-1, CREB1, or tPA in obese mice lowered plasma tPA and further impaired fibrinolysis. The PAI-1/PLAT pathway was present in primary human hepatocytes, and associations among PAI-1, tPA, and PLAT in livers from obese and lean humans were consistent with these findings. Knowledge of PAI-1 and tPA regulation in hepatocytes in obesity may suggest therapeutic strategies for improving fibrinolysis and lowering the risk of thrombosis in this setting.

Authors

Ze Zheng, Keiko Nakamura, Shana Gershbaum, Xiaobo Wang, Sherry Thomas, Marc Bessler, Beth Schrope, Abraham Krikhely, Rui-Ming Liu, Lale Ozcan, José A. López, Ira Tabas

×

Figure 4

Decreased Rev-Erbα in the livers of obese mice and in palmitate-treated primary human hepatocytes elevates both PAI-1 and tPA expression.

Options: View larger image (or click on image) Download as PowerPoint
Decreased Rev-Erbα in the livers of obese mice and in palmitate-treated ...
(A and B) Livers of lean and DIO mice were assayed for Rev-Erbα protein and β-actin loading control by immunoblot, with densitometric quantification shown, and for Nr1d1 mRNA. n = 5–6 mice/group. Data are represented as mean ± SEM. *P < 0.05; **P < 0.01, 2-tailed Student’s t test. (C) Lean and obese mice were injected intravenously with AAV8-TBG-Nr1d1 to increase Rev-Erbα expression in hepatocytes or with AAV8-TBG-LacZ control, as indicated. After 4 weeks, liver Serpine1 and Plat mRNA levels were measured. Horizontal lines in dot-density plots indicate mean values. n = 10 mice/group. *P < 0.05; **P < 0.01, 1-way ANOVA followed by Tukey’s test. (D) Human primary hepatocytes were transfected with a plasmid expressing Nr1d1 to increase expression of Rev-Erbα; transfection with empty vector (Vec) served as the control. After 24 hours, cells were treated with 100 μM palmitate for 16 hours and then assayed for Rev-Erbα protein by immunoblot and for SERPINE1 and PLAT mRNA by quantitative PCR (qPCR). n = 3 sets of cells/group. Data are represented as mean ± SEM. *P < 0.05, 1-way ANOVA followed by Tukey’s test.