title: Monomeric gremlin is a novel vascular endothelial growth factor receptor-2 antagonist.
abstract: Angiogenesis plays a key role in various physiological and pathological conditions, including inflammation and tumor growth. The bone morphogenetic protein (BMP) antagonist gremlin has been identified as a novel pro-angiogenic factor. Gremlin promotes neovascular responses via a BMP-independent activation of the vascular endothelial growth factor (VEGF) receptor-2 (VEGFR2). BMP antagonists may act as covalent or non-covalent homodimers or in a monomeric form, while VEGFRs ligands are usually dimeric. However, the oligomeric state of gremlin and its role in modulating the biological activity of the protein remain to be elucidated.Here we show that gremlin is expressed in vitro and in vivo both as a monomer and as a covalently linked homodimer. Mutagenesis of amino acid residue Cys141 prevents gremlin dimerization leading to the formation of gremlinC141A monomers. GremlinC141A monomer retains a BMP antagonist activity similar to the wild-type dimer, but is devoid of a significant angiogenic capacity. Notably, we found that gremlinC141A mutant engages VEGFR2 in a non-productive manner, thus acting as receptor antagonist. Accordingly, both gremlinC141A and wild-type monomers inhibit angiogenesis driven by dimeric gremlin or VEGF-A165. Moreover, by acting as a VEGFR2 antagonist, gremlinC141A inhibits the angiogenic and tumorigenic potential of murine breast and prostate cancer cells in vivo.In conclusion, our data show that gremlin exists in multiple forms endowed with specific bioactivities and provide new insights into the molecular bases of gremlin dimerization. Furthermore, we propose gremlin monomer as a new inhibitor of VEGFR2 signalling during tumor growth.
authors.affiliation: Experimental Oncology and Immunology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, 25123, Italy.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Grillo
authors.affiliation: Experimental Oncology and Immunology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, 25123, Italy.
authors.forename: Cosetta
authors.initials: C
authors.lastname: Ravelli
authors.affiliation: Experimental Oncology and Immunology, Department of Molecular and Translational Medicine, National Institute of Neurosciences, University of Brescia, Brescia, 25123, Italy.
authors.forename: Michela
authors.initials: M
authors.lastname: Corsini
authors.affiliation: Biomolecular Research, Molecular Cell Biology, Paul Scherrer Institut, Villigen, 5232, Switzerland.
authors.forename: Kurt
authors.initials: K
authors.lastname: Ballmer-Hofer
authors.affiliation: Center of Genomics Science of IIT@SEMM, Milan, 20139, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Zammataro
authors.affiliation: Glycores2000, Milan, 20155, Italy.
authors.forename: Pasqua
authors.initials: P
authors.lastname: Oreste
authors.affiliation: Glycores2000, Milan, 20155, Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Zoppetti
authors.affiliation: Experimental Oncology and Immunology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, 25123, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Tobia
authors.affiliation: Experimental Oncology and Immunology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, 25123, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Ronca
authors.affiliation: Experimental Oncology and Immunology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, 25123, Italy.|Experimental Oncology and Immunology, Department of Molecular and Translational Medicine, National Institute of Neurosciences, University of Brescia, Brescia, 25123, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Presta
authors.affiliation: Experimental Oncology and Immunology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, 25123, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Mitola
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D064593:Heterografts; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000737:chemistry / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D009369:Neoplasms / Q000378:metabolism*; D009389:Neovascularization, Pathologic / Q000378:metabolism*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000037:antagonists & inhibitors*
chemical_list: C486399:GREM1 protein, human; D036341:Intercellular Signaling Peptides and Proteins; C000588866:KDR protein, human; D040301:Vascular Endothelial Growth Factor Receptor-2
keywords: BMP; VEGFR2 antagonist; angiogenesis; gremlin; oligomerization