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 3

SAB expression in male mice determines the susceptibility to APAP-induced liver injury in a JNK-dependent fashion.

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SAB expression in male mice determines the susceptibility to APAP-induce...
WT C57BL/6N male mice received Ad-lacZ or Ad-SAB. (A) Fourteen days later, SAB expression was analyzed by immunoblotting, and (B) APAP (150 mg/kg) was given i.p., and H&E staining was performed and serum ALT levels were determined after 24 hours. Original magnification, ×10. Scale bars: 100 μm. n = 3/group. ALT: *P < 0.05 versus Ad-lacZ–injected SabiΔHep mice, by unpaired, 2-tailed Student’s t test. Data are presented as the mean ± SD. (C) Sabfl/fl or SabiΔHep mice received 0.05 5 × 109 to approximately 5 × 109 IU Ad-lacZ or Ad-SAB. Fourteen days later, SAB expression was determined by immunoblotting. Immunoblot is representative of 3 separate experiments. n = 3/group. *P < 0.05 versus SabiΔHep + Ad-lacZ, by 1-way ANOVA with Bonferroni’s correction. Data are presented as the mean ± SEM. (D) Mice received APAP (300 mg/kg, i.p.), and 24 hours later, liver sections were stained with H&E, and the necrotic area (percentage) was measured. Serum ALT (± SEM) (U/L) was measured. Scale bars: 100 μm. n = 3 mice/group. ALT: *P < 0.05, versus Ad-lacZ–injected Sabfl/fl mice; **P < 0.05, versus Ad-lacZ–injected SabiΔHep mice, by unpaired, 2-tailed Student’s t test. Data are presented as the mean ± SD. (E and F) Jnk1/2fl/fl mice received AAV8-TBG-GFP (n = 3), AAV8-TBG-Cre (n = 5), or AAV8-TBG-Cre plus Ad-SAB (n = 3). Fourteen days later, JNK and SAB expression levels were determined by immunoblotting, or mice were treated with APAP to analyze liver injury and serum ALT levels. Scale bars: 100 μm. ALT: *P < 0.05, versus AAV8-TBG-GFP, by unpaired, 2-tailed Student’s t test. Data are presented as the mean ± SD.