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Tindall, C.A.* ; Dommel, S.* ; Riedl, V.* ; Ulbricht, D.* ; Hanke, S.* ; Sträter, N.* ; Heiker, J.T.

Membrane phospholipids and polyphosphates as cofactors and binding molecules of SERPINA12 (Vaspin).

Molecules 25:1992 (2020)
Publ. Version/Full Text DOI
Open Access Gold
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Visceral adipose tissue derived serine protease inhibitor (vaspin) is a member of the serpin family and has been shown to have beneficial effects on glucose tolerance, insulin stability as well as adipose tissue inflammation, parameters seriously affected by obesity. Some of these effects require inhibition of target proteases such as kallikrein 7(KLK7) and many studies have demonstrated vaspin-mediated activation of intracellular signaling cascades in various cells and tissues. So far, little is known about the exact mechanism how vaspin may trigger these intracellular signaling events. In this study, we investigated and characterized the interaction of vaspin with membrane lipids and polyphosphates as well as their potential regulatory effects on serpin activity using recombinant vaspin and KLK7 proteins and functional protein variants thereof. Here, we show for the first time that vaspin binds to phospholipids and polyphosphates with varying effects on KLK7 inhibition. Vaspin binds strongly to monophosphorylated phosphatidylinositol phosphates (PtdInsP) with no effect on vaspin activation. Microscale thermophoresis (MST) measurements revealed high-affinity binding to polyphosphate 45 (K-D: 466 +/- 75 nM) and activation of vaspin in a heparin-like manner. Furthermore, we identified additional residues in the heparin binding site in fi-sheet A by mutating five basic residues resulting in complete loss of high-affinity heparin binding. Finally, using lipid overlay assays, we show that these residues are additionally involved in PtdInsP binding. Phospholipids play a major role in membrane trafficking and signaling whereas polyphosphates are procoagulant and proinflammatory agents. The identification of phospholipids and polyphosphates as binding partners of vaspin will contribute to the understanding of vaspins involvement in membrane trafficking, signaling and beneficial effects associated with obesity.
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Publication type Article: Journal article
Document type Scientific Article
Keywords Serpin ; Protease ; Cofactor ; Polyphosphates ; Phosphatidylinositol Phosphates ; Membrane Lipids; Visceral Adipose-tissue; Heparin-binding; Kallikrein 7; Beta-sheet; Protein-c; Kappa-b; Activation; Obesity; Inhibition; Domain
ISSN (print) / ISBN 1420-3049
e-ISSN 1420-3049
Journal Molecules
Quellenangaben Volume: 25, Issue: 8, Pages: , Article Number: 1992 Supplement: ,
Publisher MDPI
Publishing Place Basel
Reviewing status Peer reviewed
Institute(s) Helmholtz Institute for Metabolism, Obesity and Vascular Research (HI-MAG)