Expression of mitochondrial membrane–linked SAB determines severity of sex-dependent acute liver injury
Sanda Win, … , Tin A. Than, Neil Kaplowitz
Sanda Win, … , Tin A. Than, Neil Kaplowitz
Published December 2, 2019; First published September 5, 2019
Citation Information: J Clin Invest. 2019;129(12):5278-5293. https://doi.org/10.1172/JCI128289.
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Research Article Hepatology

Expression of mitochondrial membrane–linked SAB determines severity of sex-dependent acute liver injury

Abstract

SH3 domain–binding protein that preferentially associates with Btk (SAB) is an outer-membrane docking protein for JNK-mediated impairment of mitochondrial function. Deletion of Sab in hepatocytes inhibits sustained JNK activation and cell death. The current study demonstrates that an increase in SAB expression enhanced the severity of acetaminophen-induced (APAP-induced) liver injury. Female mice were resistant to liver injury and exhibited markedly decreased hepatic SAB protein expression compared with male mice. The mechanism of SAB repression involved a pathway from ERα to p53 expression that induced miR34a-5p. miR34a-5p targeted the Sab mRNA coding region, thereby repressing SAB expression. Fulvestrant or p53 knockdown decreased miR34a-5p and increased SAB expression in female mice, leading to increased injury from APAP and TNF/galactosamine. In contrast, an ERα agonist increased p53 and miR34a-5p, which decreased SAB expression and hepatotoxicity in male mice. Hepatocyte-specific deletion of miR34a also increased the severity of liver injury in female mice, which was prevented by GalNAc-ASO knockdown of Sab. Similar to mice, premenopausal women expressed elevated levels of hepatic p53 and low levels of SAB, whereas age-matched men expressed low levels of p53 and high levels of SAB, but there was no difference in SAB expression between the sexes in the postmenopausal stage. In conclusion, SAB expression levels determined the severity of JNK-dependent liver injury. Female mice expressed low levels of hepatic SAB protein because of the ERα/p53/miR34a pathway, which repressed SAB expression and accounted for the resistance to liver injury seen in these females.

Authors

Sanda Win, Robert W.M. Min, Christopher Q. Chen, Jun Zhang, Yibu Chen, Meng Li, Ayako Suzuki, Manal F. Abdelmalek, Ying Wang, Mariam Aghajan, Filbert W.M. Aung, Anna Mae Diehl, Roger J. Davis, Tin A. Than, Neil Kaplowitz

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Figure 4

ERα antagonist overcomes resistance to Ad-SAB expression and APAP-induced liver injury in female mice.

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ERα antagonist overcomes resistance to Ad-SAB expression and APAP-induce...
(A) Female mice received Ad-lacZ or Ad-SAB, and SAB protein levels were analyzed. (B) Female mice were treated with fulvestrant (Fulv) (2 or 5 mg/kg) once per week for 3 weeks, and SAB expression was determined by immunoblotting. n = 3 mice/group. *P < 0.05 versus vehicle (Veh), by 1-way ANOVA with Bonferroni’s correction. (C) Female littermates received a total of 3 doses of fulvestrant (2 mg/kg), 1 dose before and 2 doses (1 and 2 weeks) after Ad-lacZ or Ad-SAB (1 × 109 IU) tail-vein injection. SAB expression in isolated mitochondria was determined by immunoblotting. (D) Mice were treated with APAP (300 mg/kg, i.p.). H&E staining was performed, and serum ALT levels were measured 24 hours later. Scale bars: 100 μm. n = 3 mice/group. *P < 0.05, versus Ad-lacZ, by unpaired, 2-tailed Student’s t test. (E) Male mice were treated with PPT for 2 weeks, and mitochondria SAB levels were determined. (F and G) Male mice were treated with APAP or GalN/TNF, and H&E staining was performed and ALT levels determined 6 hours (GalN/TNF) or 24 hours (APAP) later. Scale bars: 100 μm. n = 3 mice/group. *P < 0.05, versus vehicle, by unpaired, 2-tailed Student’s t test. (H) Male mice were treated with PPT (5 mg/kg) or vehicle for 2 weeks, and SAB expression in PMHs was determined. (I and J) PMHs from vehicle- or PPT-treated male mice were treated with APAP (5 mM) or actinmycin D (0.5 μg/mL) and TNF (20 ng/mL), respectively. JNK activation in whole-cell lysates was determined by immunoblotting with anti–p-JNK. Immunoblot is representative of 3 separate experiments. *P < 0.05 versus vehicle, by 1-way ANOVA with Bonferroni’s correction. Cell death was determined with SYTOX Green staining. n = 5 experiments. *P < 0.05 versus vehicle, by unpaired, 2-tailed Student’s t test. Data are presented as the mean ± SEM.