Heparin-binding Sites in Granulocyte-Macrophage Colony-stimulating Factor

Abstract

The biological activity of granulocyte-macrophage colony-stimulating factor (GM-CSF) is modulated by the sulfated glycosaminoglycans (GAGs) heparan sulfate and heparin. However, the molecular mechanisms involved in such interactions are still not completely understood. We have proposed previously that helix C, one of the four α-helices of human GM-CSF (hGM-CSF), contains a GAG-binding site in which positively charged residues are spatially positioned the sulfate of the and of residues and in helix of a molecular the have a of GM-CSF in which residues in helix of the factor and by the residues in and the and that the The that the of a site in the of the in helix of heparin. of the of and completely a helix of a of residues in the of the of GM-CSF the that is of the molecular of the of the biological activity of The biological activity of granulocyte-macrophage colony-stimulating factor (GM-CSF) is modulated by the sulfated glycosaminoglycans (GAGs) heparan sulfate and heparin. However, the molecular mechanisms involved in such interactions are still not completely understood. We have proposed previously that helix C, one of the four α-helices of human GM-CSF (hGM-CSF), contains a GAG-binding site in which positively charged residues are spatially positioned the sulfate of the and of residues and in helix of a molecular the have a of GM-CSF in which residues in helix of the factor and by the residues in and the and that the The that the of a site in the of the in helix of heparin. of the of and completely a helix of a of residues in the of the of GM-CSF the that is of the molecular of the of the biological activity of colony-stimulating factor (GM-CSF) granulocyte-macrophage colony-stimulating human granulocyte-macrophage colony-stimulating human is a that and of such and The of the human of that is a which a the of human GM-CSF the molecular interactions involved in and the mechanisms of by such GM-CSF and of in However, of that is not the involved in the glycosaminoglycans (GAGs) have in the of factor in the of in GM-CSF and activity by heparan a and a the biological of The GM-CSF and the GM-CSF of a one heparan sulfate of is factor a and the of in the of GM-CSF is the sulfate in the GM-CSF are still in the of the of GM-CSF involved in the that have the and a a of have that in are not by a We have previously by a that the and sulfate in the of molecular the which the of a GAG-binding site in site is in helix of and contains residues and that and the charged sulfate in have a of GM-CSF in which residues in helix and by the residues in and and the a of helix of in the of and that the in helix of GM-CSF in the of in of the of the biological of GM-CSF are the of and helix of and human GM-CSF and and helix of GM-CSF by of the a in a of in the in the of of of and and of human and are in in a of the a in and of the a of of the a in by and of and a and The the by the and in the the previously a the the the The the the the and the are in of the a The and the and and in the The a in the the in and the The and and and the The and of by the and the of by of the and and by by a of factor and The of GM-CSF the and of and of and by and by and the a a by of in the in the the The of and in and and biological activity of in a the in a in the in the of the a of and in and a in the and the a in by in and of of by the in the of and by a in of by the and The The the a a residues of the The and and and the have previously that the of heparan sulfate and the of molecular by that proposed the of a GAG-binding site in helix of the of the of that residues that are helix of and are by residues and in the is in the that of molecular human GM-CSF and is that GM-CSF of of GM-CSF the of and in the of helix of the of helix in a in which residues by residues of the of the that and in in the of of not that the in the not the helix of helix of a of the the of the the of the a The and the of that the residues in the in a the of the residues that by the human a the of and the and the the of the and the of the that of residues of the in the of the the that and the of helix of the of the of helix of GM-CSF heparin. the a in which residues by the residues in that and in the of not in the helix of the that the the human helix the helix that the human helix the of and in of the the of the of the and of and the the a of in which residues in helix of the factor by the residues in and and in and by previously the of and human GM-CSF The and of and by and of and the molecular in of and The are and of a The of in the of is of of and and in the the in and that the not the of and of the that and and in the are in and of and and of C, activity of and a the of the and of the which is GM-CSF and of a of a that the in in the by is not the of the of GM-CSF of and and GM-CSF of the the the and biological of and the of heparin. the of the of of and and that the of the residues in helix the of the of heparin. which the residues in helix C, the the and in the of the that not that the and is previously and by in the of and heparin. and in and the previously the by the of GM-CSF GM-CSF contains a in helix of the the of in the of of residues in in the that a in the and by the in of the of not in However, of of in not the of that the of of We the of by the of a a of the a of a of have that of the molecular of the not a of the and of the is that the of the of the of in is which in in the and in the of the of of by in and of are of the of the in not in the of the a not in the The in and the the the in the of and in the of of GM-CSF a of in the activity of GM-CSF and the of the of helix of GM-CSF heparin. the of helix and a in which by by in in the of the helix C, helix a in the of not the helix not and in the of the the the the of helix a activity of the However, The of the in the of helix the have that in in the of not that of the of helix of The helix The and in the by a in by the and of the of in the of GM-CSF have a of the and heparin. and in and of the a of in that that the in helix not the of the of and in and the previously the The a of in in and that of the the in the of the that the of the of the sulfated heparan sulfate and in the of the biological activity of GM-CSF However, GAG-binding in GM-CSF have We have proposed previously the of a site in helix of human GM-CSF We have that of residues and in helix of a in the of that a in helix of is involved in the of in the of in of not in the of the of such in the of the of the of GM-CSF a of and human GM-CSF in is are GM-CSF and which the of helix of in are by residues in helix of the of residues in the of by which that GM-CSF not human GM-CSF that and by of of residues in helix of the of the of a the of helix of the that have in the residues and which in interactions charged sulfate in the of and of which are in helix of human and and residues a in helix of the by and and are in the helix and are the that is and human and helix and However, the of human and helix and that residues a in the of the and that by of the in GM-CSF which have the of that of residues the of heparin. residues proposed a the of the that positively charged and in the of human GM-CSF is positioned in the residues in helix C, and of the of that the residues are of is and the of the the residues are is the the of the residues are in the of a in the of the The of interactions the and the sulfate of heparin. the that a GAG-binding site is in human GM-CSF and that the by and is the of of human GM-CSF and the residues in and and and and and and of the the are by in of the the and residues and are in and in and and in the a of the the in of the The the and The is in GM-CSF and the that is of the of of GM-CSF that is involved in in GM-CSF is that a that residues the of biological of of of GM-CSF in a The mechanisms involved in the of the biological of by are still The have by and the in of the of in the factor by which and of the such We have previously that a by the is in heparan sulfate the GM-CSF and and in the GM-CSF in the of GM-CSF and the in that of residues in the of the the of a in that the the of GM-CSF and the of in which in the GM-CSF and in the the GM-CSF and heparan sulfate are We have proposed previously that the charged by the of such and in the a the of the have the and the that GM-CSF that the GM-CSF and is that the GM-CSF the of and of is that of the activity of by mechanisms by in a the of by of the of the of in the of have by the by the of is one of the which in the and in in the molecular of the in the of have a of of the of GM-CSF the that the molecular and the of and the of are GM-CSF which is the of the of and human biological are that are human GM-CSF are not by GM-CSF the that the in the of the a in the of a GAG-binding site in GM-CSF the the residues in helix the of in a of colony-stimulating factor (GM-CSF) granulocyte-macrophage colony-stimulating human granulocyte-macrophage colony-stimulating human is a that and of such and The of the human of that is a which a the of human GM-CSF the molecular interactions involved in and the mechanisms of by such GM-CSF and of in However, of that is not the involved in the glycosaminoglycans (GAGs) have in the of factor in the of in GM-CSF and activity by heparan a and a the biological of The GM-CSF and the GM-CSF of a one heparan sulfate of is factor a and the of in the of GM-CSF is the sulfate in the GM-CSF are still in the of the of GM-CSF involved in the that have the and a a of have that in are not by a We have previously by a that the and sulfate in the of molecular the which the of a GAG-binding site in site is in helix of and contains residues and that and the charged sulfate in have a of GM-CSF in which residues in helix and by the residues in and and the a of helix of in the of and that the in helix of GM-CSF in the of in of the of the biological of GM-CSF are the of and helix of and human GM-CSF and and helix of GM-CSF by of the a in a of in the in the of of of and and of human and are in in a of the a in and of the a of of the a in by and of and a and The the by the and in the the previously a the the the The the the the and the are in of the a The and the and and in the The a in the the in and the The and and and the The and of by the and the of by of the and and by by a of factor and The of GM-CSF the and of and of and by and by and the a a by of in the in the the The of and in and and biological activity of in a the in a in the in the of the a of and in and a in the and the a in by in and of of by the in the of and by a in of by the and The The the a a residues of the The and and and the the of and helix of and human GM-CSF and and helix of GM-CSF by of the a in a of in the in the of of of the a in and of the a of of the a in by and of and a and The the by the and in the the previously a the the the The the the the and the are in of the a The and the and and in the The a in the the in and the The and and and the The and of by the and the of by of the and and by by a of factor and The of GM-CSF the and of and of and by and by and the a a by of in the in the the The of and in and and The biological activity of in a the in a in the in the of the a of and in and a in the and the a in by in and of of by the in the of and by a in of by the and The The the a a residues of the The and and and the have previously that the of heparan sulfate and the of molecular by that proposed the of a GAG-binding site in helix of the of the of that residues that are helix of and are by residues and in the is in the that of molecular human GM-CSF and is that GM-CSF of of GM-CSF the of and in the of helix of the of helix in a in which residues by residues of the of the that and in in the of of not that the in the not the helix of helix of a of the the of the the of the a The and the of that the residues in the in a the of the residues that by the human a the of and the and the the of the and the of the that of residues of the in the of the the that and the of helix of the of the of helix of GM-CSF heparin. the a in which residues by the residues in that and in the of not in the helix of the that the the human helix the helix that the human helix the of and in of the the of the of the and of and the the a of in which residues in helix of the factor by the residues in and and in and by previously the of and human GM-CSF The and of and by and of is of of and and in the the in and that the not the of and of the that and and in the are in and of and and of C, activity of and a the of the and of the which is GM-CSF and of a of a that the in in the by is not the of the of GM-CSF of and and GM-CSF of the the the and biological of and the of heparin. the of the of of and and that the of the residues in helix the of the of heparin. which the residues in helix C, the the and in the of the that not that the and is previously and by in the of and heparin. and in and the previously the by the of GM-CSF GM-CSF contains a in helix of the the of in the of of residues in in the that a in the and by the in of the of not in However, of of in not the of that the of of We the of by the of a a of the a of a of have that of the molecular of the not a of the and of the is that the of the of the of in is which in in the and in the of the of of by in and of are of the of the in not in the of the a not in the The in and the the the in the of and in the of of GM-CSF a of in the activity of GM-CSF and the of the of helix of GM-CSF heparin. the of helix and a in which by by in in the of the helix C, helix a in the of not the helix not and in the of the the the the of helix a activity of the However, The of the in the of helix the have that in in the of not that of the of helix of The helix The and in the by a in by the and of the of in the of GM-CSF have a of the and heparin. and in and of the a of in that that the in helix not the of the of and in and the previously the The a of in in and that of the the in the of the that the of the of heparin. We have previously that the of heparan sulfate and the of molecular by that proposed the of a GAG-binding site in helix of the of the of that residues that are helix of and are by residues and in the is in the that of molecular human GM-CSF and is that GM-CSF of of GM-CSF the of and in the of helix of the of helix in a in which residues by residues of the of the that and in in the of of not that the in the not the helix of helix of a of the the The of the the of the a The and the of that the residues in the in a the of the residues that by the human a the of and the and the the of the and the of the that of residues of the in the of the the that and the of helix of We the of the of helix of GM-CSF heparin. the a in which residues by the residues in that and in the of not in the helix of the that the the human helix the helix that the human helix the of and in of the the of the of the and of and the the a of in which residues in helix of the factor by the residues in and and in and by previously the of and human GM-CSF The and of and by and The of is of of and and in the the in and that the not the of and of the that and and in the are in and of the which is GM-CSF and of a of a that the in in the by is not the of the of GM-CSF of and and GM-CSF of the the the and biological of and the of heparin. the of the of of and and that the of the residues in helix the of the of heparin. which the residues in helix C, the the and in the of the that not that the and is previously and by in the of GM-CSF GM-CSF contains a in helix of the the of in the of of residues in in the that a in the and by the in of the of not in However, of of in not the of that the of of We the of by the of a a of the a of a of have that of the molecular of the not a of the and of the is that the of the of the of in is which in in the and in the of the of of the of the in not in the of the a not of of GM-CSF a of in the activity of GM-CSF and the of the of helix of GM-CSF heparin. the of helix and a in which by by in in the of the helix C, helix a in the of not the helix not and in the of the the the the of helix a activity of the However, The of the in the of helix the have that in in the of not that of the and of the of in the of GM-CSF have a of the and heparin. and in and of the a of in that that the in helix not the of the in and that of the the in the of the that the of the of heparin. the sulfated heparan sulfate and in the of the biological activity of GM-CSF However, GAG-binding in GM-CSF have We have proposed previously the of a site in helix of human GM-CSF We have that of residues and in helix of a in the of that a in helix of is involved in the of in the of in of not in the of the of such in the of the of the of GM-CSF a of and human GM-CSF in is are GM-CSF and which the of helix of in are by residues in helix of the of residues in the of by which that GM-CSF not human GM-CSF that and by of of residues in helix of the of the of a the of helix of the that have in the residues and which in interactions charged sulfate in the of and of which are in helix of human and and residues a in helix of the by and and are in the helix and are the that is and human and helix and However, the of human and helix and that residues a in the of the and that by of the in GM-CSF which have the of that of residues the of heparin. residues proposed a the of the that positively charged and in the of human GM-CSF is positioned in the residues in helix C, and of the of that the residues are of is and the of the the residues are is the the of the residues are in the of a in the of the The of interactions the and the sulfate of heparin. the that a GAG-binding site is in human GM-CSF and that the by and is the of is in GM-CSF and the that is of the of of GM-CSF that is involved in in GM-CSF is that a that residues the of biological of of of GM-CSF in a The mechanisms involved in the of the biological of by are still The have by and the in of the of in the factor by which and of the such We have previously that a by the is in heparan sulfate the GM-CSF and and in the GM-CSF in the of GM-CSF and the in that of residues in the of the the of a in that the the of GM-CSF and the of in which in the GM-CSF and in the the GM-CSF and heparan sulfate are We have proposed previously that the charged by the of such and in the a the of the have the and the that GM-CSF that the GM-CSF and is that the GM-CSF the of and of is that of the activity of by mechanisms by in a the of by of the of the of in the of have by the by the of is one of the which in the and in in the molecular of the in the of have a of of the of GM-CSF the that the molecular and the of and the of are GM-CSF which is the of the of and human biological are that are human GM-CSF are not by GM-CSF the that the in the of the a in the of a GAG-binding site in GM-CSF the the residues in helix the of in a of the sulfated heparan sulfate and in the of the biological activity of GM-CSF However, GAG-binding in GM-CSF have We have proposed previously the of a site in helix of human GM-CSF We have that of residues and in helix of a in the of that a in helix of is involved in the heparin. of in the of in of not in the of the of such in the of the of the of GM-CSF a of and human GM-CSF in is are GM-CSF and which the of helix of in are by residues in helix of the of residues in the of by which that GM-CSF not human GM-CSF that and by of of residues in helix of the of the of a the of helix of the that have in the residues and which in interactions charged sulfate in the of and of which are in helix of human and and residues a in helix of the by and and are in the helix and are the that is and human and helix and However, the of human and helix and that residues a in the of the and that by of the in GM-CSF which have the of that of residues the of heparin. residues proposed a the of the that positively charged and in the of human GM-CSF is positioned in the residues in helix C, and of the of that the residues are of is and the of the the residues are is the the of the residues are in the of a in the of the The of interactions the and the sulfate of heparin. the that a GAG-binding site is in human GM-CSF and that the by and is the of is in GM-CSF and the that is of the of of GM-CSF that is involved in in GM-CSF is that a that residues the of biological The mechanisms involved in the of the biological of by are still The have by and the in of the of in the factor by which and of the such We have previously that a by the is in heparan sulfate the GM-CSF and and in the GM-CSF in the of GM-CSF and the in that of residues in the of the the of a in that the the of GM-CSF and the of in which in the GM-CSF and in the the GM-CSF and heparan sulfate are We have proposed previously that the charged by the of such and in the a the of the have the and the that GM-CSF that the GM-CSF and is that the GM-CSF the of and of is that of the activity of by mechanisms by in a the of by of the of the of in the of have by the by the of GM-CSF is one of the which in the and in in the molecular of the in the of have a of of the of GM-CSF the that the molecular and the of and the of are GM-CSF which is the of the of and human biological are that are human GM-CSF are not by GM-CSF the that the in the of the a in the of a GAG-binding site in GM-CSF the the residues in helix the of in a of