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Abstract: PO2011

Podocyte-Derived Testican 2 Promotes In Vitro Glomerular Angiogenesis

Session Information

Category: Health Maintenance, Nutrition, and Metabolism

  • 1300 Health Maintenance, Nutrition, and Metabolism

Authors

  • Wen, Donghai, Massachusetts General Hospital, Boston, Massachusetts, United States
  • Ngo, Debby, Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States
  • Humphreys, Benjamin D., Washington University in Saint Louis, Saint Louis, Missouri, United States
  • Pollak, Martin R., Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States
  • Gerszten, Robert, Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States
  • Wilson, James G., Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States
  • Rhee, Eugene P., Massachusetts General Hospital, Boston, Massachusetts, United States
Background

In addition to their fundamental role in clearance, the kidneys release select molecules into the circulation, but whether any of these anabolic functions provides insight on kidney function is unknown.

Methods

Using aptamer-based proteomics, we characterized arterial (A) to renal venous (V) gradients for >1,300 proteins in 22 human individuals who underwent invasive sampling. To localize testican-2, immunohistochemistry, immunofluorescence, immunogold electron microscopy and single cell RNA sequencing in human kidney tissue were used. Functional effects of testican-2 were tested on cultured primary human glomerular endothelial cells (HGEC).

Results

Although most of the proteins that changed significantly decreased from A to V, consistent with renal clearance, several were found to increase, the most significant of which was testican-2 (V/A = 1.40, P = 1.5 x 10-9). Imaging and single cell RNA sequencing demonstrated testican-2 expression in human podocytes. Testican-2 promoted angiogenesis and migration in cultured HGEC, but not proliferation. Further, testican-2 upregulated MMP-2/MMP-9 activity in the culture media of HGEC.

Conclusion

Testican-2 is a circulating protein that is synthesized in the human podocyte. Testican-2 promotes angiogenesis in cultured HGEC, which may be mediated by upregulating MMP-2/MMP-9 activity and increased endothelial cell migration.

(A) Volcano plot showing median V/A ratio for all 1317 proteins detected by aptamer in 22 individuals, with P values plotted on the y axis. (B) Violin plot demonstrating podocyte-specific SPOCK2 expression (encodes testican-2), with NPHS2 as positive control. (C) Tube formation of primary HGECs treated with vehicle, testican-2, or VEGF.

Funding

  • NIDDK Support