Valproate induced hepatic steatosis by enhanced fatty acid uptake and triglyceride synthesis.

Bai X¹, Hong W¹, Cai P¹, Chen Y¹, Xu C¹, Cao D², Yu W¹, Zhao Z², Huang M¹, Jin J³.

Author information

1School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, China.2School of Chinese Materia Medica, Guangzhou University of Chinese Medicine, Guangzhou, China.3School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, China. Electronic address: jinjing@mail.sysu.edu.cn.

Abstract

Steatosis is the characteristic type of VPA-induced hepatotoxicity and may result in life-threatening hepatic lesion. Approximately 61% of patients treated with VPA have been diagnosed with hepatic steatosis through ultrasound examination. However, the mechanisms underlying VPA-induced intracellular fat accumulation are not yet fully understood. Here we demonstrated the involvement of fatty acid uptake and lipogenesis in VPA-induced hepatic steatosis in vitro and in vivo by using quantitative real-time PCR (qRT-PCR) analysis, western blotting analysis, fatty acid uptake assays, Nile Red staining assays, and Oil Red O staining assays. Specifically, we found that the expression of cluster of differentiation 36 (CD36), an important fatty acid transport, and diacylglycerol acyltransferase 2 (DGAT2) were significantly up-regulated in HepG2 cells and livers of C57B/6J mice after treatment with VPA. Furthermore, VPA treatment remarkably enhanced the efficiency of fatty acid uptake mediated by CD36, while this effect was abolished by the interference with CD36-specific siRNA. Also, VPA treatment significantly increased DGAT2 expression as a result of the inhibition of mitogen-activated protein kinase kinase (MEK) – extracellular regulated kinase (ERK) pathway; however, DGAT2 knockdown significantly alleviated VPA-induced intracellular lipid accumulation. Additionally, we also found that sterol regulatory element binding protein-1c (SREBP-1c)-mediated fatty acid synthesis may be not involved in VPA-induced hepatic steatosis. Overall, VPA-triggered over-regulation of CD36 and DGAT2 could be helpful for a better understanding of the mechanisms underlying VPA-induced hepatic steatosis and may offer novel therapeutic strategies to combat VPA-induced hepatotoxicity.

KEYWORDS:

CD36; DGAT2; Fatty acid; Hepatic steatosis; SREBP-1c; Valproate