Hepatocyte growth factor preferentially activates the anti-inflammatory arm of NF-?B signaling to induce A20 and protect renal proximal tubular epithelial cells from inflammation

da Silva CG1, Maccariello ER, Wilson SW, Putheti P, Daniel S, Damrauer SM, Peterson CR, Siracuse JJ, Kaczmarek E, Ferran C
Source: J Cell Physiol
Publication Date: (2012)
Issue: 227(4): 1382-90
Research Area:
Basic Research
Cells used in publication:
Renal proximal tubule cells (RPTEC), human
Species: human
Tissue Origin: kidney
Inflammation induces the NF-?B dependent protein A20 in human renal proximal tubular epithelial cells (RPTEC), which secondarily contains inflammation by shutting down NF-?B activation. We surmised that inducing A20 without engaging the pro-inflammatory arm of NF-?B could improve outcomes in kidney disease. We showed that hepatocyte growth factor (HGF) increases A20 mRNA and protein levels in RPTEC without causing inflammation. Upregulation of A20 by HGF was NF-?B/RelA dependent as it was abolished by overexpressing I?Ba or silencing p65/RelA. Unlike TNFa, HGF caused minimal I?Ba and p65/RelA phosphorylation, with moderate I?Ba degradation. Upstream, HGF led to robust and sustained AKT activation, which was required for p65 phosphorylation and A20 upregulation. While HGF treatment of RPTEC significantly increased A20 mRNA, it failed to induce NF-?B dependent, pro-inflammatory MCP-1, VCAM-1, and ICAM-1 mRNA. This indicates that HGF preferentially upregulates protective (A20) over pro-inflammatory NF-?B dependent genes. Upregulation of A20 supported the anti-inflammatory effects of HGF in RPTEC. HGF pretreatment significantly attenuated TNFa-mediated increase of ICAM-1, a finding partially reversed by silencing A20. In conclusion, this is the first demonstration that HGF activates an AKT-p65/RelA pathway to preferentially induce A20 but not inflammatory molecules. This could be highly desirable in acute and chronic renal injury where A20-based anti-inflammatory therapies are beneficial.