TY - JOUR
T1 - Thyrotropin increases hepatic triglyceride content through upregulation of SREBP-1c activity
AU - Yan, Fang
AU - Wang, Qi
AU - Lu, Ming
AU - Chen, Wenbin
AU - Song, Yongfeng
AU - Jing, Fei
AU - Guan, Youfei
AU - Wang, Laicheng
AU - Lin, Yanliang
AU - Bo, Tao
AU - Zhang, Jie
AU - Wang, Tingting
AU - Xin, Wei
AU - Yu, Chunxiao
AU - Guan, Qingbo
AU - Zhou, Xinli
AU - Gao, Ling
AU - Xu, Chao
AU - Zhao, Jiajun
N1 - Publisher Copyright:
© 2014 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.
PY - 2014/12/1
Y1 - 2014/12/1
N2 - Background & Aims Hallmarks of non-alcoholic fatty liver disease (NAFLD) are increased triglyceride accumulation within hepatocytes. The prevalence of NAFLD increases steadily with increasing thyrotropin (TSH) levels. However, the underlying mechanisms are largely unknown. Here, we focused on exploring the effect and mechanism of TSH on the hepatic triglyceride content. Methods As the function of TSH is mediated through the TSH receptor (TSHR), Tshr-/- mice (supplemented with thyroxine) were used. Liver steatosis and triglyceride content were analysed in Tshr-/- and Tshr+/+ mice fed a high-fat or normal chow diet, as well as in Srebp-1c-/- and Tshr-/-Srebp-1c-/- mice. The expression levels of proteins and genes involved in liver triglyceride metabolism was measured. Results Compared with control littermates, the high-fat diet induced a relatively low degree of liver steatosis in Tshr-/- mice. Even under chow diet, hepatic triglyceride content was decreased in Tshr-/- mice. TSH caused concentration- and time-dependent effects on intracellular triglyceride contents in hepatocytes in vitro. The activity of SREBP-1c, a key regulator involved in triglyceride metabolism and in the pathogenesis of NAFLD, was significantly lower in Tshr-/- mice. In Tshr-/-Srebp-1c-/- mice, the liver triglyceride content showed no significant difference compared with Tshr+/+Srebp-1c-/- mice. When mice were injected with forskolin (cAMP activator), H89 (inhibitor of PKA) or AICAR (AMPK activator), or HeG2 cells received MK886 (PPARα inhibitor), triglyceride contents presented in a manner dependent on SREBP-1c activity. The mechanism, underlying TSH-induced liver triglyceride accumulation, involved that TSH, through its receptor TSHR, triggered hepatic SREBP-1c activity via the cAMP/PKA/PPARα pathway associated with decreased AMPK, which further increased the expression of genes associated with lipogenesis. Conclusions TSH increased the hepatic triglyceride content, indicating an essential role for TSH in the pathogenesis of NAFLD.
AB - Background & Aims Hallmarks of non-alcoholic fatty liver disease (NAFLD) are increased triglyceride accumulation within hepatocytes. The prevalence of NAFLD increases steadily with increasing thyrotropin (TSH) levels. However, the underlying mechanisms are largely unknown. Here, we focused on exploring the effect and mechanism of TSH on the hepatic triglyceride content. Methods As the function of TSH is mediated through the TSH receptor (TSHR), Tshr-/- mice (supplemented with thyroxine) were used. Liver steatosis and triglyceride content were analysed in Tshr-/- and Tshr+/+ mice fed a high-fat or normal chow diet, as well as in Srebp-1c-/- and Tshr-/-Srebp-1c-/- mice. The expression levels of proteins and genes involved in liver triglyceride metabolism was measured. Results Compared with control littermates, the high-fat diet induced a relatively low degree of liver steatosis in Tshr-/- mice. Even under chow diet, hepatic triglyceride content was decreased in Tshr-/- mice. TSH caused concentration- and time-dependent effects on intracellular triglyceride contents in hepatocytes in vitro. The activity of SREBP-1c, a key regulator involved in triglyceride metabolism and in the pathogenesis of NAFLD, was significantly lower in Tshr-/- mice. In Tshr-/-Srebp-1c-/- mice, the liver triglyceride content showed no significant difference compared with Tshr+/+Srebp-1c-/- mice. When mice were injected with forskolin (cAMP activator), H89 (inhibitor of PKA) or AICAR (AMPK activator), or HeG2 cells received MK886 (PPARα inhibitor), triglyceride contents presented in a manner dependent on SREBP-1c activity. The mechanism, underlying TSH-induced liver triglyceride accumulation, involved that TSH, through its receptor TSHR, triggered hepatic SREBP-1c activity via the cAMP/PKA/PPARα pathway associated with decreased AMPK, which further increased the expression of genes associated with lipogenesis. Conclusions TSH increased the hepatic triglyceride content, indicating an essential role for TSH in the pathogenesis of NAFLD.
KW - Hepatic steatosis
KW - Peroxisome proliferator-activated receptor α
KW - Sterol regulatory element-binding protein 1c
KW - Thyrotropin (TSH)
KW - Triglyceride
UR - https://www.scopus.com/pages/publications/84922762830
U2 - 10.1016/j.jhep.2014.06.037
DO - 10.1016/j.jhep.2014.06.037
M3 - 文章
C2 - 25016220
AN - SCOPUS:84922762830
SN - 0168-8278
VL - 61
SP - 1358
EP - 1364
JO - Journal of Hepatology
JF - Journal of Hepatology
IS - 6
ER -