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.
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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

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Figure 3

The increase in hepatocyte PAI-1 drives the increase in hepatocyte tPA in obesity.

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The increase in hepatocyte PAI-1 drives the increase in hepatocyte tPA i...
(A) Serpine1fl/fl mice were fed a high-fat diet for 4 months and then injected intravenously with either AAV8-TBG-Cre or control AAV8-TBG-LacZ. After 4 weeks, liver Plat mRNA and plasma tPA protein concentrations were measured. Horizontal lines in the dot-density plots indicate mean values. n = 11 mice/group. *P < 0.05; **P < 0.01, 2-tailed Student’s t test. (B) Human primary hepatocytes were treated for 16 hours with 100 μM palmitate (PALM) in BSA solution, or BSA solution control. The cells were assayed for PLAT and SERPINE1 mRNA, and the media were assayed for tPA and PAI-1 protein concentration. (C) Human primary hepatocytes were transfected with siSERPINE1 or scrambled control (Scr). After 24 hours, cells were treated with 100 μM palmitate for an additional 16 hours and then assayed for PLAT and SERPINE1 mRNA. In B and C, results are shown as mean ± SEM. n = 3 sets of cells/group. *P < 0.05; **P < 0.01, 2-tailed Student’s t test. (D) Liver specimens from the subjects described in Supplemental Table 1 were assayed for PAI‑1/GAPDH densitometric ratio by immunoblot, as shown in Supplemental Figure 3C, and for PLAT mRNA. These data were then subjected to correlation analysis, as described in the legend for Figure 2B.