Abstract: PUB200
Fibroblast Growth Factor 23 (FGF-23) Regulates HK-2 Cell Proliferation, Migration, and Response to TGF-β1
Session Information
Category: Chronic Kidney Disease (Non-Dialysis)
- 308 CKD: Mechanisms of Tubulointerstitial Fibrosis
Authors
- Lawson, Jack S., Royal Veterinary College, London, United Kingdom
- Syme, Harriet M., Royal Veterinary College, London, United Kingdom
- Wheeler-Jones, Caroline Pd, Royal Veterinary College, London, United Kingdom
- Elliott, Jonathan, Royal Veterinary College, London, United Kingdom
Background
Plasma FGF-23 concentration increases early in the course of chronic kidney disease (CKD), and rises progressively with deteriorating renal function. Elevated FGF-23 is associated with progression of CKD, and may play a direct role in the development of renal injury and tubulointerstitial fibrosis. The aims of this study were to investigate the effects of FGF-23 on proliferation, migration, viability and pro-fibrotic gene expression in a human tubular epithelial cell line (HK-2), and to determine whether FGF-23 modulates the transcriptional and functional effects of TGF-β1.
Methods
HK-2 cells were incubated with FGF-23 (0.1-100 ng/ml) ± 10 ng/ml TGF-β1 for 72 h. ERK1/2 phosphorylation was measured by immunoblotting. Expression of E-cadherin, N-cadherin, connective tissue growth factor (CTGF), collagen 1α1 (col1α1) and TGF-β1 was assessed by RT-qPCR (normalised to GAPDH/RPS7). Cell migration was measured using a scratch wound healing assay, and proliferation and viability monitored by cell counting, crystal violet staining and measurement of caspase 3/7 activity. The MEK inhibitor PD184352 (1 μM) and the FGF receptor 1 (FGFR1) antagonist SU5402 (10 μM) were used to investigate involvement of MEK-ERK signalling and FGFR activation, respectively.
Results
FGF-23 increased ERK phosphorylation and stimulated cell proliferation, which was completely attenuated by PD184352. Scratch wound closure was stimulated by FGF-23 in a concentration dependent manner, and this was blocked by SU5402. TGF-β1 decreased wound closure, and this was partially ameliorated by FGF-23. FGF-23 suppressed col1α1 expression, and at 100 ng/ml partially inhibited TGF-β1-driven increases in col1α1, N-cadherin, and CTGF expression. FGF-23 and TGF-β1 each inhibited E-cadherin expression, but there was no additive inhibitory effect. FGF-23 did not modify TGF-β1 mRNA expression or TGF-β1-mediated caspase 3/7 activation.
Conclusion
FGF-23 stimulates migration and proliferation of HK-2 cells most likely through engagement of FGFR1 and MEK-ERK pathway activation, and partially reverses pro-fibrotic and anti-repair responses to TGF-β1. These results suggest FGF-23 facilitates tubular repair and regeneration processes. The relevance of these findings to progressive nephron loss in the CKD patient warrants further study to establish their translational potential.
Funding
- Commercial Support – Elanco Animal Health