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Connective tissue growth factor is a new ligand of epidermal growth factor receptor Free
Sandra Rayego-Mateos1, Raquel Rodrigues-Díez1, Jose Luis Morgado-Pascual1, Raul R. Rodrigues Díez1, Sebastian Mas3, Carolina Lavoz1, Matilde Alique1, Janos Pato2, Gyorgy Keri2,3, Alberto Ortiz4, Jesus Egido4, and Marta Ruiz-Ortega1,*
1Cellular Biology in Renal Diseases Laboratory, Universidad Autónoma de Madrid, 28040 Madrid, Spain
2Pathobiochemistry Research Group of Hungarian Academy of Sciences, Semmelweis University, H-1094 Budapest, Hungary
3Vichem Chemie Research Ltd., H-1022 Budapest, Hungary
4Renal Research Laboratory, IIS-Fundación Jiménez Díaz, Universidad Autónoma de Madrid, 28040 Madrid, Spain
*Correspondence to:Marta Ruiz-Ortega, E-mail:mruizo@fjd.es
J Mol Cell Biol, Volume 5, Issue 5, October 2013, 323-335,  https://doi.org/10.1093/jmcb/mjt030
Keyword: CCN2, receptors, EGFR, TrkA, renal, inflammation

Chronic kidney disease is reaching epidemic proportions worldwide and there is no effective treatment. Connective tissue growth factor (CCN2) has been suggested as a risk biomarker and a potential therapeutic target for renal diseases, but its specific receptor has not been identified. Epidermal growth factor receptor (EGFR) participates in kidney damage, but whether CCN2 activates the EGFR pathway is unknown. Here, we show that CCN2 is a novel EGFR ligand. CCN2 binding to EGFR extracellular domain was demonstrated by surface plasmon resonance. CCN2 contains four distinct structural modules. The carboxyl-terminal module (CCN2(IV)) showed a clear interaction with soluble EGFR, suggesting that EGFR-binding site is located in this module. Injection of CCN2(IV) in mice increased EGFR phosphorylation in the kidney, mainly in tubular epithelial cells. EGFR kinase inhibition decreased CCN2(IV)-induced renal changes (ERK activation and inflammation). Studies in cultured tubular epithelial cells showed that CCN2(IV) binds to EGFR leading to ERK activation and proinflammatory factors overexpression. CCN2 interacts with the neurotrophin receptor TrkA, and EGFR/TrkA receptor crosstalk was found in response to CCN2(IV) stimulation. Moreover, endogenous CCN2 blockade inhibited TGF-β-induced EGFR activation. These findings indicate that CCN2 is a novel EGFR ligand that contributes to renal damage through EGFR signalling.