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Abstract: PO1806

Can the Cross-Talk Between PDGF Receptor and Axl in Mesangial Cells Represent a Possible Therapeutic Target in IgA Nephropathy?

Session Information

Category: Glomerular Diseases

  • 1202 Glomerular Diseases: Immunology and Inflammation

Authors

  • Bian, Qi, Changhai Hospital, Changhai Hospital, Second Military Medical University/Naval Medical University, Shanghai, China
  • Huang, Zhi qiang, University of alabama at Birmingham, Birmingham, Alabama, United States
  • Anderson, Joshua Charles, University of alabama at Birmingham, Birmingham, Alabama, United States
  • Zhang, Xianwen, Long Hua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
  • Ebefors, Kerstin, University of Gothenburg, Gothenburg, Sweden
  • Nystrom, Jenny C., University of Gothenburg, Gothenburg, Sweden
  • Hall, Stacy D., University of alabama at Birmingham, Birmingham, Alabama, United States
  • Novak, Lea, University of alabama at Birmingham, Birmingham, Alabama, United States
  • Julian, Bruce A., University of alabama at Birmingham, Birmingham, Alabama, United States
  • Willey, Christopher D., University of alabama at Birmingham, Birmingham, Alabama, United States
  • Novak, Jan, University of alabama at Birmingham, Birmingham, Alabama, United States
Background

PDGF is involved in the pathogenesis of IgA nephropathy, namely in the activation of mesangial cells (MC). Our kinomic profiling revealed that receptor tyrosine kinase Axl and non-receptor tyrosine kinase ABL were the top upregulated protein-tyrosine kinases in MC stimulated by PDGF-AB. In this study, we describe crosstalk between Axl and a PDGF receptor (PDGFR-β) in human MC stimulated with PDGF.

Methods

Quiescent primary human MC were stimulated with PDGF-AB for 15 min. Cell lysates were analyzed with SDS-PAGE/Western blotting to probe for phospho-PDGFR-β, phospho-Axl, and down-stream signaling. Immunoprecipitation with antibodies specific for PDGFR-β or Axl was used to assess association of Axl and PDGFR-β. To test the role of Axl in crosstalk with PDGFR-β, the Axl/ABL inhibitor R428 and an Axl-specific siRNA knock-down (k/d) were used. Cellular proliferation was measured by BrdU incorporation ~20-h after PDGF-AB stimulation.

Results

PDGF-AB stimulated cellular proliferation of MC. PDGF-AB induced phosphorylation of multiple kinases, including Axl, PDGFR-β, Akt1, and ERK1/2 in MC. Immunoprecipitation experiments revealed association of Axl with PDGFR-β. The Axl/ABL inhibitor R428 inhibited PDGF-AB-induced phosphorylation of Axl, PDGFR-β, AKT1, and ERK1/2, and partially reduced PDGF-AB-induced MC proliferation. siRNA k/d of Axl reduced expression of Axl, but did not prevent PDGF-AB-induced phosphorylation of AKT1, ERK1/2 and PDGFR-β, and did not reduce proliferation of MC.

Conclusion

In summary, PDGF-AB induced multiple signaling events in cultured human MC that included crosstalk between PDGFR-β and Axl. MC cellular signaling induced by PDGF-AB was blocked by the Axl/ABL inhibitor R428 but not by Axl siRNA k/d. These findings suggest a role for the non-receptor tyrosine kinase ABL in a crosstalk between the two receptors. We postulate that the PDGFR-β/Axl/ABL pathway may represent a possible therapeutic target in the treatment of IgA nephropathy.

Funding

  • NIDDK Support