Hepatitis B Virus-induced hFGL2 Transcription Is Dependent on c-Ets-2 and MAPK Signal Pathway

doi:10.1074/jbc.M806769200

Hepatitis B Virus-induced hFGL2 Transcription Is Dependent on c-Ets-2 and MAPK Signal Pathway^*

^‡Department of Infectious Disease and ^¶Department of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China and the ^§University Health Network, University of Toronto, Toronto, Ontario M5G 2N2, Canada

¹ To whom co-correspondence may be addressed: Dept. of Pediatrics, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Ave., Wuhan 430030, China. Tel./Fax: 86-27-83662393; E-mail: xpluo{at}tjh.tjmu.edu.cn. ² To whom correspondence may be addressed: Dept. of Infectious Disease, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Ave., Wuhan 430030, China. Tel./Fax: 86-27-83662391; E-mail: qning{at}tjh.tjmu.edu.cn.

Abstract

Fibrinogen-like protein 2 (FGL2)/fibroleukin plays a pivotal role in the pathogenesis of experimental and human fulminant and chronic viral hepatitis. To define the transcription factor(s) and upstream signal transduction pathways involved in the transcription of human FGL2 (hFGL2) in response to hepatitis B (HB) virus, hepatitis B core (HBc), hepatitis B virus S protein (HBs), or hepatitis B virus X protein (HBx) protein, expression plasmids were cotransfected with an hFGL2 promoter luciferase reporter construct into Chinese hamster ovary and HepG2 cells, respectively. HBc and HBx proteins, but not HBs protein, enhanced hFGL2 transcription in both cell lines. A strong regulatory region from -712 to -568 (relative to the transcriptional starting site) was shown to be responsible for hFGL2 gene transcription in response to both HBc and HBx proteins. c-Ets-2 was shown to be translocated to the nucleus in association with hFGL2 expression in response to both HBc and HBx proteins. Short hairpin RNA (shRNA) interference of c-Ets-2 expression inhibited hFGL2 gene transcription by 64.8 and 60.0% in response to HBc and HBx, respectively. c-Ets-2 protein was highly expressed in peripheral blood mononuclear cells from patients with severe chronic hepatitis B (CHB) in contrast to patients with mild CHB. Increased phosphorylation of ERK and JNK was detected in peripheral blood mononuclear cells from patients with severe CHB. ERK inhibitor PD098059 or ERK shRNA abolished the nuclear c-Ets-2 DNA binding activity and hFGL2 induction in response to HBc, whereas JNK inhibitor SP600125 or JNK shRNA abolished the nuclear c-Ets-2 DNA binding activity and hFGL2 induction in response to HBx. In conclusion, HBc and HBx proteins enhance transcription of hFGL2 through c-Ets-2 dependent on MAPK signal pathways.

Footnotes

↵3 The abbreviations used are: HBV, hepatitis B virus; HBc, hepatitis B virus core protein; HBs, hepatitis B virus S protein; HBx, hepatitis B virus X protein; CHO, Chinese hamster ovary; EMSA, electrophoretic mobility shift assays; ERK, extracellular signal-regulated kinase; PBMC, peripheral blood mononuclear cell; MAPK, mitogen-activated protein kinase; JNK, c-Jun N-terminal kinase; RT, reverse transcription; shRNA, short hairpin RNA; CHB, chronic hepatitis B; PBS, phosphate-buffered saline; PI3K, phosphatidylinositol 3-kinase; IL, interleukin; IFN, interferon; TNF, tumor necrosis factor; ChIP, chromatin immunoprecipitation; IP, immunoprecipitation; IHC, immunohistochemistry.
↵* This work was supported by the National Science Fund of China Grants 30571643 and 30672380, National Key Basic Research Program of China Grants 2005CB522901 and 2007CB512904, and 11th Five-Year Plan Key Project Grants 2006BAI05A07 and 2008ZX10202. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵ The on-line version of this article (available at http://www.jbc.org) contains supplemental Fig. 1.
- Received September 2, 2008.
- Revision received September 16, 2008.
The American Society for Biochemistry and Molecular Biology, Inc.