ASN's Mission

To create a world without kidney diseases, the ASN Alliance for Kidney Health elevates care by educating and informing, driving breakthroughs and innovation, and advocating for policies that create transformative changes in kidney medicine throughout the world.

learn more

Contact ASN

1401 H St, NW, Ste 900, Washington, DC 20005


The Latest on X

Kidney Week

Please note that you are viewing an archived section from 2022 and some content may be unavailable. To unlock all content for 2022, please visit the archives.

Abstract: SA-PO747

THSD7A Cleavage Is Mediated by the Proprotein Convertase Furin In Vitro

Session Information

Category: Glomerular Diseases

  • 1304 Glomerular Diseases: Podocyte Biology


  • Seifert, Larissa, Universitatsklinikum Hamburg-Eppendorf, Hamburg, Hamburg, Germany
  • Dehde, Silke, Universitatsklinikum Hamburg-Eppendorf, Hamburg, Hamburg, Germany
  • Lucas, Renke, Universitatsklinikum Hamburg-Eppendorf, Hamburg, Hamburg, Germany
  • Zahner, Gunther, Universitatsklinikum Hamburg-Eppendorf, Hamburg, Hamburg, Germany
  • Tomas, Nicola M., Universitatsklinikum Hamburg-Eppendorf, Hamburg, Hamburg, Germany

Thrombospondin type 1 domain-containing 7A (THSD7A) is a pathogenic autoantigen in membranous nephropathy (MN). It is prominently expressed on podocytes in humans and rodents, where it is located at the basal aspects of foot processes and it likely plays a role in podocyte adhesion. When expressed recombinantly e.g. in HEK cells, THSD7A is cleaved in the N-terminal region.


Purified, recombinantly expressed THSD7A was analyzed by mass spectrometry (MS). Following MS analysis, we applied site directed mutagenesis to further narrow down the cleavage site. We tried two additional approaches to confirm our data and identify the protease that we assumed to be responsible for the cleavage. First, we tested a specific inhibitor and second we added the recombinant commercial available protease to uncut protein, to see whether it is processed.


Mass spectrometry revealed a cleavage of THSD7A in the polybasic region of the fourth TSP-1 domain. The cleavage site was located between two cysteins forming a disulfide bond, leading to adherence of the fragments even after cleavage of the peptide backbone. The identified site corresponded to the cleavage motif of proprotein convertases (PCs). Base substitution of one Arginin to Alanin within the cleavage site completely abolished the proteolytic processing. Adding an inhibitor, which dominantly inhibits the PC furin, to the cell culture medium of THSD7A expressing HEK cells achieved the same effect. Conversely, adding recombinant furin to uncut THSD7A led to cleavage of the protein.


The PC furin cleaves THSD7A in the fourth TSP-1 domain in vitro. Whether this processing also occurs in vivo and is related to the biological function of THSD7A needs to be investigated.


  • Government Support – Non-U.S.