Enhancement of TEX264-Mediated ER-Phagy Contributes to the Therapeutic Effect of Glycycoumarin against APA Hepatotoxicity in Mice

Abstract

Acetaminophen (APA)-induced hepatotoxicity is coupled with the activation of autophagy. We sought to determine whether selective autophagy of the endoplasmic reticulum (ER), termed ER-phagy, is involved in APA hepatotoxicity and to explore its potential as a therapeutic target for APA-induced liver injury (AILI). APA (300 or 600 mg/kg) was administered to male C57BL/6N mice, with and without rapamycin, glycycoumarin (GCM) and N-acetylcysteine (NAC). The results demonstrated that ER-phagy accompanied with ER stress was activated after APA overdose. The dynamic changes of LC3 and TEX264 revealed that ER-phagy was induced as early as 6 h and peaked at 24 h following the APA injection. A delayed treatment with GCM, but not rapamycin, considerably attenuated a liver injury and, consequently, reduced its mortality. This is probably due to the inhibition of ER stress and the acceleration of liver regeneration via enhanced ER-phagy. Unlike the impaired hepatocyte proliferation and more severe liver injury in mice that received prolonged treatment with NAC, liver recovery is facilitated by repeated treatment with GCM. These findings suggest that TEX264-mediated ER-phagy is a compensatory mechanism against ER stress provoked by an APA overdose. A delayed and prolonged treatment with GCM enhances ER-phagy, thus serving as a potential therapeutic approach for patients presenting at the late stage of AILI.

Pharmacological Activities and Pharmacokinetics of Glycycoumarin

“…Yan et al ( 2018 ) found that 1 was able to attenuate acetaminophen-induced mitochondrial oxidative stress and c-jun N -terminal kinase (JNK) pathway activation through sustained activation of autophagy, thereby avoiding liver injury. Endoplasmic reticulum phagocytosis, which accompanies endoplasmic reticulum stress, is activated when APAP is overdosed, and treatment with 1 enhances TEX264-mediated endoplasmic reticulum phagocytosis, thereby inhibiting endoplasmic reticulum stress and promoting liver regeneration, significantly reducing liver injury and, thus, its mortality (Yan et al 2021 ). Glycycoumarin ( 1 ) is a potential replacement for N -acetyl cysteine as a therapeutic agent for patients with advanced acetaminophen-induced acute liver injury.…”

Cajaninstilbene Acid Ameliorates Acetaminophen-Induced Liver Injury Through Enhancing Sestrin2/AMPK-Mediated Mitochondrial Quality Control

“…In line with the changes detected by western blot, the number of mitophagic vacuoles (mitophagosomes and mitolysosomes) and LC3 puncta per hepatocyte increased after CSA treatment, when compared with that of APAP-treated alone, as illustrated by TEM (Figure 6B) and immunohistochemical analysis (Figure 6D). Moreover, the continuous decrease in p62 expression verified the unobstructed autophagic flux (Figure 6C), ruling out the possibility that the increase in PINK1, Parkin and LC3-II was caused by blocked autophagy (Yan et al, 2021). To test the involvement of mitophagy, primary hepatocytes were treated with CQ to block the autophagy before CSA treatment.…”

“…Liver tissues were processed as described previously ( Yan et al, 2021 ). The ultrathin sections (70 nm thick) were double stained with uranyl acetate and lead citrate, and viewed under a transmission electron microscope (HT7700, Tokyo, Japan) at 80.0 kV.…”