Transforming growth factor beta (TGF-β) is activated by the CtBP2-p300-AP1 transcriptional complex in chronic renal failure

• Published in: International journal of biological sciences 2020, Vol.16 (2), p.204-215
• Main Authors: Zhou, Ping, Wan, Xiaoxiao, Zou, Yan, Chen, Zhi, Zhong, Aimin
• Format: Article
• Language: English
• Subjects: Activation; Activator protein 1; Binding sites; Biopsy; Biotechnology; c-Fos protein; c-Jun protein; Cancer; Chromatin; Downstream effects; Event-related potentials; Gene expression; Growth factors; Histone acetyltransferase; IL-1β; Immunoprecipitation; Inhibitors; Interleukin 1; Kidney diseases; Kidneys; Kinases; Lymphocytes B; Mass spectrometry; Mass spectroscopy; NF-κB protein; Pathogenesis; Proteins; Receptors; Renal failure; Research Paper; RNA polymerase; Signaling; Transcription factors; Transforming growth factor-b; Transforming growth factor-b1
• ISSN: 1449-2288; 1449-2288
• DOI: 10.7150/ijbs.38841

Chronic renal failure (CRF), also known as chronic kidney disease (CKD), is a common renal disorder characterized by gradual kidney dysfunction. Molecular dissection reveals that transforming growth factor beta (TGF-β) plays a central role in the pathogenesis of CRF. However, the mechanism underlying TGF-β upregulation has not been demonstrated. Here, we verified that the elevated level of TGF-β was associated with the severity of CRF stages and the activation of TGF-β-mediated signaling in 120 renal biopsies from CRF patients. By analyzing the promoter region of the gene, we identified one AP-1 (activator protein 1) and four NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) binding sites. Knockdown of two AP-1 subunits ( and ) or blockage of AP-1 signaling with two inhibitors T-5224 and SR11302 could cause the downregulation of , whereas knockdown of two NF-κB subunits ( and ) or blockage of NF-κB signaling with two inhibitors TPCA1 and BOT-64 could not change the expression of . Using mass spectrometry and coimmunoprecipitation analyses, we found that both c-Jun and c-FOS formed a complex with CtBP2 (C-terminal binding protein 2) and histone acetyltransferase p300. Our data demonstrated that induction of CtBP2 by recombinant IL-1β (interleukin-1 beta) led to the upregulation of and the activation of TGF-β downstream signaling, while knockdown of resulted in the reversed effects. Using chromatin immunoprecipitation assays, we revealed that the CtBP2-p300-AP1 complex specifically bound to the promoter of and that knockdown or blockage of CtBP2 significantly decreased the occupancies of the p300 and AP-1 subunits. Our results support a model in which the CtBP2-p300-AP1 transcriptional complex activates the expression of , increasing its production and extracellular secretion. The secreted TGF-β binds to its receptors and initiates downstream signaling.