Glycosyltransferase GLT25D2 Acts as a Negative Regulator of Autophagy to Promote Acetaminophen-Induced Hepatotoxicity

Background: Acetaminophen (N-acetyl-para-aminophenol, APAP) overdose induces mitochondria damage and subsequent necrosis in hepatocytes, thereby causing liver injury. However, the glycosylation of proteins in APAP-induced hepatotoxicity remains enigmatic. Here, we have assessed the contribution of the collagen galactosyltransferase GLT25D2 gene to the development of APAP-induced hepatotoxicity. Methods: GLT25D2 knockout and C57 wild-type mice were treated with APAP overdose, followed by histological and biochemical evaluation of liver injury and autophagy. The mechanism of GLT25D2 action against APAP-induced hepatotoxicity was also explored in primary cultured hepatocytes. The serum and liver biopsy samples from drug-induced liver injury patients were further analyzed. Results: The GLT25D2 expression was significantly elevated in the early stage of liver injury in mice exposed to APAP, and knockout of GLT25D2 ameliorated the hepatocellular damage. Interestingly, knockout of GLT25D2 decreased the levels of proinflammatory cytokines (TNF-α, IL-6) and chemokines (CXCL-1, CXCL-10 and MIG), however, increased the levels of anti-inflammatory cytokines (IL-10, IL-22). Mechanistic investigations elucidated that (1) knockout of GLT25D2 enhanced autophagy, promoted autophagy flux in vitro, but blocked autophagy flux in vivo; (2) inhibition of autophagy by Atg 7 knockdown abrogated liver protection by GLT25D2 knockout; and (3) autophagy induced by GLT25D2 knockout seemed to be selective for damaged mitochondria in APAP-induced hepatotoxicity. Moreover, the expression of GLT25D2 was significantly downregulated in the serum and liver of patients with a drug-induced liver failure. Conclusions: The increased GLT25D2 expression suppressed autophagy to promote the occurrence and development of APAP-induced hepatotoxicity. Funding: This work was supported by grants from the National Natural Science Foundation of China (81770611, 81270532), the Natural Science Foundation of Beijing (7162085), Applied Research for the Clinical Characteristics of Capital (Z161100000516113), the High-level Technical Personnel Training Plan of the Beijing Health System (2013-3-075 and 2015-3-099), National Science and Technology Key Project on “Major Infectious Diseases such as HIV/AIDS, Viral Hepatitis Prevention and Treatment” (2017ZX10203201-005, 2017ZX10202203-006-001, 2017ZX10302201-004-002, 2017ZX10201201). Declaration of Interest: None. Ethical Approval: This study met the ethical guidelines of the 1975 Declaration of Helsinki, and the study protocol was approved by the Medical Ethics Committee of Beijing YouAn Hospital. Informed consent was obtained from all patients.