Abstract: TH-OR108
ADAM17 Induces Sustained Pro-Fibrotic EGFR Activation via a Positive Feedback Loop Involving YAP1-Dependent Transcription of Pro-AREG
Session Information
- Scarred for Life?
November 02, 2017 | Location: Room 394, Morial Convention Center
Abstract Time: 04:30 PM - 04:42 PM
Category: Chronic Kidney Disease (Non-Dialysis)
- 308 CKD: Mechanisms of Tubulointerstitial Fibrosis
Authors
- Kefalogianni, Eirini, Washington University in St. Louis, St. Louis, Missouri, United States
- Herrlich, Andreas, Washington University in St. Louis, St. Louis, Missouri, United States
Background
We recently showed that the cell-surface metalloprotease ADAM17 and its substrates, including in particular the epidermal growth factor receptor (EGFR) ligand pro-amphiregulin (pro-AREG) are highly upregulated after kidney injury and that inducible proximal tubule (PT)-specific knockout of ADAM17 confers protection against fibrosis in ischemic and obstructive kidney injury mouse models. To clarify the role and function of ADAM17 and its substrate AREG in PT cells in vivo, we have now genetically labeled (tdTomato) PT cells in ADAM17 wt or ADAM17 PT-KO mice and studied them after kidney ischemia-reperfusion injury (IRI). We have also examined the transcriptional regulation and function of pro-AREG in PT cells in vitro. Finally, we investigated the activation of these pathways in acute kidney injury (AKI) and chronic kidney disease (CKD) in human samples.
Methods
We used SLC34a1-Cre-ERt2;R26tdTomato;ADAM17fl/fl (PT-KO) and respective littermates and subjected them to unilateral IRI. tdTomato positive cells were isolated by FACS. ADAM17 and downstream pathways were studied in human and mouse PT cells in vitro and in human AKI and CKD samples.
Results
IRI induces the transcriptional upregulation of ADAM17 and pro-AREG in PT cells (tdTomato+ cells). This upregulation is diminished in PT cells lacking ADAM17, suggesting that a positive feedback loop exists in which ADAM17 activity drives not only the release of soluble active AREG but also the upregulation of pro-AREG. This positive feedback is also observed in vitro; soluble AREG causes sustained (profibrotic) activation of EGFR that requires Yap1-dependent upregulation of pro-AREG expression, followed by ADAM17-mediated release of soluble AREG. AREG is unique among other EGFR ligands in inducing a panel of proinflammatory and profibrotic cytokines in vitro. PT cells isolated from injured mice and lacking ADAM17 show diminished production of these factors as compared to controls. Finally, levels of urinary and serum soluble AREG are upregulated in human AKI and CKD samples, suggesting that this pathway is also active in human kidney disease.
Conclusion
Injury-induced ADAM17-dependent release of soluble AREG drives a profibrotic positive feedback loop of further AREG release via Yap1-dependent transcriptional upregulation of pro-AREG.
Funding
- NIDDK Support