Sushi domain-containing protein 4 (SUSD4) inhibits complement by disrupting the formation of the classical C3 convertase.

Research output: Contribution to journalArticle

Abstract

Recently discovered Sushi domain-containing protein 4 (SUSD4) contains several Sushi or complement control protein domains; therefore, we hypothesized that it may act as complement inhibitor. Two isoforms of human SUSD4, fused to the Fc part of human IgG, were recombinantly expressed in Chinese hamster ovary (CHO) cells. The secreted soluble isoform of SUSD4 (SUSD4b) inhibited the classical and lectin complement pathways by 50% at a concentration of 0.5 μM. This effect was due to the fact that 1 μM SUSD4b inhibited the formation of the classical C3 convertase by 90%. The membrane-bound isoform (SUSD4a) inhibited the classical and alternative complement pathways when expressed on the surface of CHO cells but not when expressed as a soluble, truncated protein. In all functional studies, we used known complement inhibitors as positive controls, while Coxsackie adenovirus receptor, which has no effect on complement, expressed with Fc tag, was a negative control. We also studied the mRNA expression of both isoforms of SUSD4 in a panel of human tissues using quantitative PCR and primarily found SUSD4a in esophagus and brain, while SUSD4b was highly expressed in esophagus, ovary, and heart. Overall, our results show that SUSD4 is a novel complement inhibitor with restricted expression.-Holmquist, E., Okroj, M., Nodin, B., Jirström, K. Blom, A. M. Sushi domain-containing protein 4 (SUSD4) inhibits complement by disrupting the formation of the classical C3 convertase.

Details

Authors
Organisations
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Cell and Molecular Biology
Original languageEnglish
Pages (from-to)2355-2366
JournalFASEB Journal
Volume27
Issue number6
Publication statusPublished - 2013
Publication categoryResearch
Peer-reviewedYes

Bibliographic note

The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Pathology, (Lund) (013030000), Protein Chemistry (013017510)

Related research output

Emelie Holmquist, 2015, Department of Medical protein chemistry. 71 p.

Research output: ThesisDoctoral Thesis (compilation)

View all (1)