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Updated: Aug 7, 2026
Induction and Analysis of Epithelial to Mesenchymal Transition
Published on: August 27, 2013
Role of connective tissue growth factor (CTGF) module 4 in regulating epithelial mesenchymal transition (EMT) in HK-2
Bi-Cheng Liu1, Jian-Dong Zhang, Xiao-Liang Zhang
1Institute of Nephrology, Zhong Da Hospital, Southeast University, No. 87 Ding Jia Qiao Road, Nanjing 210009, China. liubc64@yahoo.com.cn
Background:
Recent studies have suggested that connective tissue growth factor (CTGF) plays a key role in tissue fibrosis including renal scarring. While studies showed several forms of CTGF with 10-38 kDa in the body fluids, little is known about these small molecule species. We investigated the effect of a 10 kDa CTGF molecule consisting of module 4, on the epithelial mesenchymal transition (EMT) in human proximal tubular cell line (HK-2).
Methods:
HK2 cells were cultured in DMEM medium. The response of cytokeratin (CK) and vimentin (VIM) mRNA and protein expression to the stimulation of rhCTGF(C) were observed by real-time PCR and immunocytochemistry. At the same time, the morphologic changes were observed by microscopy, and expression of alpha-smooth muscle actin (alpha-SMA) and fibronectin (FN) was detected by laser confocal microscope. These effects were compared with CTGF N-terminal [rhCTGF(N)], consisting of module 1-3, and observed in a condition with the addition of anti-CTGF antibody.
Results:
RhCTGF(C) induced striking changes in epithelial cells, including changes in cellular morphology, loss of CK, gain VIM and alpha-SMA, and increased levels of fibronectin. Cocultured with anti-CTGF antibody could abrogate most of these effects, while cells treated with rhCTGF(N) showed no significant phenotypic changes comparing to control group.
Conclusions:
Our results suggest that module 4 could induce HK-2 cells EMT, whereas the residual fragment has no similar effect in spite of consisting of 3 modules of CTGF molecule.
Insights
Connective tissue growth factor (CTGF) module 4 induces epithelial mesenchymal transition (EMT) in kidney cells, a key process in renal scarring. Other CTGF fragments did not show similar effects.
Area of Science:
- Nephrology
- Cell Biology
- Molecular Biology
Background:
- Connective tissue growth factor (CTGF) is implicated in renal scarring and fibrosis.
- Small CTGF molecules (10-38 kDa) in body fluids are poorly understood.
- This study focuses on a 10 kDa CTGF molecule containing module 4.
Purpose of the Study:
- To investigate the effect of a 10 kDa CTGF molecule (module 4) on epithelial mesenchymal transition (EMT) in human proximal tubular HK-2 cells.
- To compare the effects of CTGF module 4 with the N-terminal fragment (modules 1-3).
Main Methods:
- HK-2 cells were stimulated with recombinant human CTGF module 4 (rhCTGF(C)).
- Changes in cytokeratin (CK), vimentin (VIM), alpha-smooth muscle actin (alpha-SMA), and fibronectin (FN) expression were assessed via real-time PCR and immunocytochemistry.
- Morphological changes were observed, and effects were compared with rhCTGF(N) and in the presence of anti-CTGF antibody.
Main Results:
- rhCTGF(C) induced significant EMT in HK-2 cells, characterized by altered morphology, decreased CK, increased VIM, alpha-SMA, and fibronectin.
- Anti-CTGF antibody treatment largely reversed these effects.
- The N-terminal fragment (rhCTGF(N)) did not induce significant phenotypic changes.
Conclusions:
- CTGF module 4 is sufficient to induce EMT in human proximal tubular cells.
- The N-terminal fragment of CTGF, despite containing three modules, does not induce EMT.
- These findings highlight the specific role of CTGF module 4 in renal fibrosis mechanisms.
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