Expression of mitochondrial membrane–linked SAB determines severity of sex-dependent acute liver injury
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
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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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 6

p53 modulates hepatotoxicity through SAB expression.

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p53 modulates hepatotoxicity through SAB expression. Ten- to twelve-week...
Ten- to twelve-week-old littermate male or female mice received 7 doses of a scrambled control or p53-ASO (50 mg/kg, i.p.) over a 2-week period. (A and B) SAB and PHB1 expression levels were determined in the mitochondrial fraction. p53, acetyl-p53, SIRT1, ER-α, and GAPDH levels were determined in whole-liver extracts. Immunoblot is representative of 3 separate experiments. Expression of miR-34a-5p was quantitated by qPCR. The pound sign indicates the nonspecific band, and the arrow indicates the specific band for acetyl-p53. n = 5 mice/group. *P < 0.05 versus control ASO, by unpaired, 2-tailed Student’s t test. Data are presented as the mean ± SEM. (C) Scrambled control– or p53-ASO–treated PMHs from male mice were treated with DMSO (Veh) or PPT (10 μM) for 2 days. Immunoblot is representative of 3 separate experiments. n = 5 mice/group. *P < 0.05 versus vehicle control, by unpaired, 2-tailed Student’s t test. Data are presented as the mean ± SEM. (D and E) Scrambled control– or p53-ASO–treated Sabfl/fl and SabiΔHep male and female mice were fasted overnight and treated with APAP (150 or 300 mg/kg, i.p.) or GalN (800 mg/kg, i.p.) and TNF (6 or 12 μg/kg, i.p.), and 6 hours (GalN/TNF) and 24 hours (APAP) later, liver histology was performed and serum ALT levels determined. Representative H&E-stained images are shown. Scale bars: 100 μm. n = 3 mice in the control ASO–treated group; n = 5 mice in the p53-ASO–treated groups. *P < 0.05 versus the control ASO–treated group; **P < 0.05 versus the p53-ASO–treated Sabfl/fl group, by unpaired, 2-tailed Student’s t test. Data are presented as the mean ± SD.