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 1

Hepatocyte tPA is increased in DIO mice, but a larger increase in hepatocyte PAI-1 causes a net impairment of fibrinolysis.

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Hepatocyte tPA is increased in DIO mice, but a larger increase in hepato...
(A–C) Chow-fed mice (Lean) or DIO mice were injected intravenously with AAV8-H1-shPlat (shPlat) to silence the tPA gene Plat in hepatocytes or with control AAV8-H1-Scr (Ctrl). After 4 weeks, the following parameters were measured: (A) liver Plat mRNA; (B) plasma tPA protein concentration and plasma tPA activity; (C) fibrinolytic activity measured by euglobulin clot-lysis assay; and (D) time to occlusive carotid arterial thrombosis induced by rose bengal/laser photochemical injury. Horizontal lines in the dot-density plots indicate mean values. n = 10 mice/group. *P < 0.05; **P < 0.01, 1-way ANOVA followed by Tukey’s test. (E) Samples of human liver and omental white adipose tissue (WAT) from the subjects described in Supplemental Table 1 were assayed for SERPINE1 mRNA, and the plasma from these subjects was assayed for PAI-1 concentration. The graph shows plots of the indicated correlations, which were analyzed by linear regression, with the r2 and P values indicated in the graph. (F–I) Serpine1fl/fl mice were fed a high-fat diet for 4 months and then injected intravenously with AAV8-TBG-Cre (Cre) to target the PAI-1 gene Seprine1 in hepatocytes or with control AAV8-TBG-LacZ (LacZ). After 4 weeks, the following parameters were measured: (F) liver Serpine1 mRNA and plasma PAI-1 protein concentration; (G) plasma tPA activity measured by enzymatic assay; (H) plasma fibrinolytic activity measured by the euglobulin clot-lysis assay; and (I) tail-bleeding time and time to occlusive carotid arterial thrombosis induced by rose bengal/laser photochemical injury. n = 11 mice/group. *P < 0.05; **P < 0.01, 2-tailed Student’s t test.