HMGB1 Enhances the AGE-Induced Expression of CTGF and TGF-β via RAGE-Dependent Signaling in Renal Tubular Epithelial Cells.
OBJECTIVE
Advanced glycation end products (AGEs) induce epithelial mesenchymal transition (EMT) in renal proximal tubular epithelial cells (PTECs) by promoting the two EMT regulators, transforming growth factor beta (TGF-β) and connective tissue growth factor (CTGF). However, the exact signaling mechanism remains largely unclear.


METHODS
We investigated the promotion to high mobility group box 1 (HMGB1) in renal tubular epithelial HK-2 cells by AGE-BSA with quantitative PCR and western blot assay, and then determined the regulatory role of HMGB1 in the AGE-BSA-induced CTGF and TGF-β. In addition, the dependence of the receptor of advanced glycation end products (RAGE) was also examined in the CTGF and TGF-β promotion by AGEs and HMGB1 in HK-2 cells using the RNAi method.


RESULTS
It was demonstrated that AGEs induced translocation and release of HMGB1 from tubular epithelial HK-2 cells, and the released HMGB1 enhanced the promotion to CTGF and TGF-β by AGEs in HK-2 cells. On the other side, the HMGB1 knockdown by siRNA attenuated the AGE-BSA-induced expression of TGF-β. Moreover, the CTGF and TGF-β promotion in HK-2 cells by AGEs and HMGB1 was RAGE-dependent.


CONCLUSIONS
Our results indicated that AGEs induced HMGB-1 and promoted the CTGF and TGF-β in renal epithelial HK-2 cells RAGE-dependently. And there was a synergism between AGEs and HMGB1 in the RAGE signaling activation. The in vitro data suggested that the AGE-RAGE and HMGB-1-RAGE signaling might play an important role in the promotion of CTGF and TGF-β in the renal fibrosis process of diabetic nephropathy.
Department of Nephrology, The Second Xiangya Hospital, Central South University, Changsha, Hunan, PR China.
Meichu
M
Cheng
Hong
H
Liu
Dongshan
D
Zhang
Yinghong
Y
Liu
Chang
C
Wang
Fuyou
F
Liu
Junxiang
J
Chen
D002460:Cell Line; D055513:Connective Tissue Growth Factor / Q000378:metabolism*; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects; D017127:Glycation End Products, Advanced / Q000494:pharmacology*; D024243:HMGB1 Protein / Q000378:metabolism*; D006801:Humans; D007687:Kidney Tubules, Proximal / Q000187:drug effects / Q000378:metabolism*; D000067759:Receptor for Advanced Glycation End Products / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D016212:Transforming Growth Factor beta / Q000378:metabolism*
C526317:CCN2 protein, human; D017127:Glycation End Products, Advanced; D024243:HMGB1 Protein; D000067759:Receptor for Advanced Glycation End Products; D016212:Transforming Growth Factor beta; D055513:Connective Tissue Growth Factor