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 5

PAI-1 induces CREB1 phosphorylation, which then induces tPA expression in hepatocytes.

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PAI-1 induces CREB1 phosphorylation, which then induces tPA expression i...
(A) Livers of lean and obese mice were assayed for p-CREB1 and total CREB1 by immunoblot (n = 3 mice/group). (B) 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, livers were assayed for p-CREB1 and total CREB1 by immunoblot, with densitometric quantification shown. Data are shown as mean ± SEM. *P < 0.05, 2-tailed Student’s t test. (C) Human primary hepatocytes were transfected with siSERPINE1 or scrambled control. After 24 hours, cells were treated with 100 μM palmitate for 16 hours, followed by assay of phosphorylated and total CREB1 by immunoblot, with densitometric quantification shown. Data are represented as mean ± SEM. *P < 0.05, 2-tailed Student’s t test. (D and E) Human primary hepatocytes were transfected with siCREB1 or scrambled control. After 24 hours, cells were treated for 8 hours with 1 μg rPAI-1/mL culture medium or vehicle control (Veh). Cells were then assayed for phosphorylated and total CREB1 by immunoblot and for PLAT mRNA by qPCR. n = 3 sets of cells/group. Data are represented as mean ± SEM. *P < 0.05, 1-way ANOVA followed by Tukey’s test. (F) Nuclear extracts from the livers of lean or obese mice were subjected to ChIP assay using anti-CREB1 or control IgG (Ctrl-IgG). The proximal promoter region containing the CREB1-binding sequence in the Plat gene was amplified by qPCR and normalized to the values obtained from input DNA. n = 3 mice/group. Data are represented as mean ± SEM. *P < 0.05; **P < 0.01, 1-way ANOVA followed by Tukey’s test.