Screening for and validation of a hepatic fibrosis-related pathway induced by insulin-like growth factor-binding protein-related protein 1.
OBJECTIVE
Our previous studies characterized insulin-like growth factor-binding protein-related protein 1 (IGFBPrP1) as a molecule that promotes hepatic fibrogenesis, but its mechanism has not been fully elucidated. Here, we have investigated the effect of IGFBPrP1 on gene expression in the hepatic fibrosis-related pathway.


METHODS
Sprague-Dawley rats received injections of an adenovirus carrying IGFBPrP1 or EGFP cDNA into their tail veins. In hepatic preparations, hepatic stellate cell activation was determined by α-smooth muscle actin expression and hepatic fibrosis by Sirius red staining and hydroxyproline content analysis. IGFBPrP1-inducible genes of the hepatic fibrosis-related pathway were assessed by PCR array. Expression of IGFBPrP1 and transforming growth factor β1 (TGFβ1) and array results were evaluated by quantitative real-time PCR and western blotting.


RESULTS
IGFBPrP1-overexpressing rats showed an increase in α-smooth muscle actin expression and collagen and hydroxyproline content in the liver. The PCR array results indicated that some genes were upregulated and some were downregulated in Ad-IGFBPrP1-infected rats. Among these, Egr1, MAP2K2 (MEK2) and MAPK3 (ERK1) expression increased, whereas PTEN and Hhip mRNA expression decreased. Egr1 protein levels increased and peaked 2 weeks after infection and then decreased gradually. PTEN protein decreased gradually in Ad-IGFBPrP1-infected rats with a concurrent increase in the degree of hepatic fibrosis. TGFβ1 levels increased during hepatic fibrosis development in liver tissues.


CONCLUSIONS
Egr1, PTEN, Hhip, MAP2K2 (MEK2) and MAPK3 (ERK1) were identified as candidate genes of the IGFBPrP1-induced hepatic fibrosis-related pathway. IGFBPrP1 promoted hepatic fibrosis mainly by enhancing the TGFβ1 expression that it triggered.
aDepartment of Gastroenterology and Hepatology bExperimental Center of Science and Research, The First Clinical Hospital of Shanxi Medical University cKey Laboratory of Cell Physiology, Provincial Department of the Ministry of Education, Shanxi Medical University, Taiyuan, Shanxi Province, China.
XiaoHong
X
Guo
HaiYan
H
Zhang
QianQian
Q
Zhang
XiuQing
X
Li
LiXin
L
Liu
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D005786:Gene Expression Regulation / Q000502:physiology; D005822:Genetic Vectors; D018969:Insulin-Like Growth Factor Binding Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D008099:Liver / Q000378:metabolism; D008103:Liver Cirrhosis / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D020935:MAP Kinase Signaling System / Q000235:genetics / Q000502:physiology; D008297:Male; D012333:RNA, Messenger / Q000235:genetics; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology; D014161:Transduction, Genetic; D053773:Transforming Growth Factor beta1 / Q000378:metabolism / Q000502:physiology
D018969:Insulin-Like Growth Factor Binding Proteins; D012333:RNA, Messenger; D053773:Transforming Growth Factor beta1; C102529:insulin-like growth factor binding protein-related protein 1