Progranulin directly binds to the CRD2 and CRD3 of TNFR extracellular domains

We previously reported that PGRN directly bound to TNF receptors (TNFR) in vitro and in chondrocytes (Tang, et al., Science, 2011). Here we report that PGRN also associated with TNFR in splenocytes, and inhibited the binding of TNF alpha to immune cells. Proper folding of PGRN is essential for its binding to TNFR, as DTT treatment abolished its binding to TNFR. In contrast, the binding of PGRN to Sortilin was enhanced by DTT. Protein interaction assays with mutants of the TNFR extracellular domain demonstrated that CRD2 and CRD3 of TNFR are important for the interaction with PGRN, similar to the binding to TNF alpha. Taken together, these findings provide the molecular basis underlying PGRN/TNFR interaction and PGRN-mediated anti-inflammatory activity in various autoimmune diseases and conditions. Structured summary of protein interactions: TNFR1 physically interacts with PGRN by two hybrid (View interaction) TNFR2 physically interacts with PGRN by anti bait coimmunoprecipitation (View interaction) TNF alpha binds to TNFR1 by surface plasmon resonance (View interaction) TNFR1 binds to PGRN by pull down (View interaction) TNFRSF1B and PGRN bind by surface plasmon resonance (View interaction) TNFR1 binds to PGRN by solid phase assay (View interaction) PGRN binds to Sortilin by solid phase assay (View interaction) TNFR2 binds to PGRN by pull down (View interaction) PGRN binds to TNFR2 by solid phase assay (1, 2) PGRN binds to TNFR1 by surface plasmon resonance (View interaction) TNF alpha binds to TNFR2 by surface plasmon resonance (View interaction) TNFR2 physically interacts with PGRN by two hybrid (View interaction) (C) 2013 Federation of European Biochemical Societies. Published by Elsevier B. V. All rights reserved.