title: Cationic Peptides and Peptidomimetics Bind Glycosaminoglycans as Potential Sema3A Pathway Inhibitors.
abstract: Semaphorin3A (Sema3A) is a vertebrate-secreted protein that was initially characterized as a repulsive-guidance cue. Semaphorins have crucial roles in several diseases; therefore, the development of Sema3A inhibitors is of therapeutic interest. Sema3A interacts with glycosaminoglycans (GAGs), presumably through its C-terminal basic region. We used different biophysical techniques (i.e., NMR, surface plasmon resonance, isothermal titration calorimetry, fluorescence, and UV-visible spectroscopy) to characterize the binding of two Sema3A C-terminus-derived basic peptides (FS2 and NFS3) to heparin and chondroitin sulfate A. We found that these peptides bind to both GAGs with affinities in the low-micromolar range. On the other hand, a peptoid named SICHI (semaphorin-induced chemorepulsion inhibitor), which is positively charged at physiological pH, was first identified by our group as being able to block Sema3A chemorepulsion and growth-cone collapse in axons at the extracellular level. To elucidate the direct target for the reported SICHI inhibitory effect in the Sema3A signaling pathway, we looked first to the protein-protein interaction between secreted Sema3A and the Nrp1 receptor. However, our results show that SICHI does not bind directly to the Sema3A sema domain or to Nrp1 extracellular domains. We evaluated a new, to our knowledge, hypothesis, according to which SICHI binds to GAGs, thereby perturbing the Sema3A-GAG interaction. By using the above-mentioned techniques, we observed that SICHI binds to GAGs and competes with Sema3A C-terminus-derived basic peptides for binding to GAGs. These data support the ability of SICHI to block the biologically relevant interaction between Sema3A and GAGs, thus revealing SICHI as a new, to our knowledge, class of inhibitors that target the GAG-protein interaction.
authors.affiliation: Departamento de Química Biológica y Modelización Molecular, Instituto de Química Avanzada de Catalunya, IQAC-CSIC, Barcelona, Spain.
authors.forename: Miriam
authors.initials: M
authors.lastname: Corredor
authors.affiliation: Departamento de Química Biológica y Modelización Molecular, Instituto de Química Avanzada de Catalunya, IQAC-CSIC, Barcelona, Spain.
authors.forename: Roman
authors.initials: R
authors.lastname: Bonet
authors.affiliation: Departamento de Química Biológica y Modelización Molecular, Instituto de Química Avanzada de Catalunya, IQAC-CSIC, Barcelona, Spain.
authors.forename: Alejandra
authors.initials: A
authors.lastname: Moure
authors.affiliation: Departamento de Química Biológica y Modelización Molecular, Instituto de Química Avanzada de Catalunya, IQAC-CSIC, Barcelona, Spain.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Domingo
authors.affiliation: Departamento de Química Biológica y Modelización Molecular, Instituto de Química Avanzada de Catalunya, IQAC-CSIC, Barcelona, Spain.
authors.forename: Jordi
authors.initials: J
authors.lastname: Bujons
authors.affiliation: Departamento de Química Biológica y Modelización Molecular, Instituto de Química Avanzada de Catalunya, IQAC-CSIC, Barcelona, Spain.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Alfonso
authors.affiliation: Servicio de Resonancia Magnética Nuclear, Instituto de Química Avanzada de Catalunya, IQAC-CSIC, Barcelona, Spain. Electronic address: yolanda.perez@iqac.csic.es.
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Pérez
authors.affiliation: Departamento de Química Biológica y Modelización Molecular, Instituto de Química Avanzada de Catalunya, IQAC-CSIC, Barcelona, Spain. Electronic address: angel.messeguer@iqac.csic.es.
authors.forename: Àngel
authors.initials: À
authors.lastname: Messeguer
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002151:Calorimetry; D002412:Cations; D004396:Coloring Agents / Q000737:chemistry; D006025:Glycosaminoglycans / Q000737:chemistry / Q000378:metabolism*; D006493:Heparin / Q000378:metabolism; D006801:Humans; D008751:Methylene Blue / Q000737:chemistry; D051379:Mice; D056004:Molecular Dynamics Simulation; D010455:Peptides / Q000737:chemistry / Q000378:metabolism*; D057786:Peptidomimetics / Q000737:chemistry / Q000378:metabolism*; D066244:Proton Magnetic Resonance Spectroscopy; D040121:Semaphorin-3A / Q000737:chemistry / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D020349:Surface Plasmon Resonance; D013696:Temperature
chemical_list: D002412:Cations; D004396:Coloring Agents; D006025:Glycosaminoglycans; D010455:Peptides; D057786:Peptidomimetics; D040121:Semaphorin-3A; D006493:Heparin; D008751:Methylene Blue