The heparin/heparan sulfate sequence that interacts with cyclophilin B contains a 3-O-sulfated N-unsubstituted glucosamine residue.
Many of the biological functions of heparan sulfate (HS) proteoglycans can be attributed to specialized structures within HS moieties, which are thought to modulate binding and function of various effector proteins. Cyclophilin B (CyPB), which was initially identified as a cyclosporin A-binding protein, triggers migration and integrin-mediated adhesion of peripheral blood T lymphocytes by a mechanism dependent on interaction with cell surface HS. Here we determined the structural features of HS that are responsible for the specific binding of CyPB. In addition to the involvement of 2-O,6-O, and N-sulfate groups, we also demonstrated that binding of CyPB was dependent on the presence of N-unsubstituted glucosamine residues (GlcNH2), which have been reported to be precursors for sulfation by 3-O-sulfotransferases-3 (3-OST-3). Interestingly, 3-OST-3B isoform was found to be the main 3-OST isoenzyme expressed in peripheral blood T lymphocytes and Jurkat T cells. Moreover, down-regulation of the expression of 3-OST-3 by RNA interference potently reduced CyPB binding and consequent activation of p44/42 mitogen-activated protein kinases. Altogether, our results strongly support the hypothesis that 3-O-sulfation of GlcNH2 residues could be a key modification that provides specialized HS structures for CyPB binding to responsive cells. Given that 3-O-sulfation of GlcNH2-containing HS by 3-OST-3 also provides binding sites for glycoprotein gD of herpes simplex virus type I, these findings suggest an intriguing structural linkage between the HS sequences involved in CyPB binding and viral infection.
Vanpouille
Christophe
C
Unité de Glycobiologie Structurale et Fonctionnelle, Unité Mixte de Recherche Number 8576 du CNRS, Institut de Recherche Fédératif No. 147, Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq, France.
Deligny
Audrey
A
Delehedde
Maryse
M
Denys
Agnès
A
Melchior
Aurélie
A
Liénard
Xavier
X
Lyon
Malcolm
M
Mazurier
Joël
J
Fernig
David G
DG
Allain
Fabrice
F
D001665:Binding Sites; D002460:Cell Line; D021983:Cyclophilins / Q000737:chemistry / Q000378:metabolism*; D005944:Glucosamine / Q000737:chemistry; D006493:Heparin / Q000737:chemistry / Q000378:metabolism*; D006497:Heparan Sulfate / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D019169:Jurkat Cells; D019696:Peptidylprolyl Isomerase / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D013431:Sulfates; D013601:T-Lymphocytes
D021983:Cyclophilins; D005944:Glucosamine; D006493:Heparin; D006497:Heparan Sulfate; D019696:Peptidylprolyl Isomerase; D013431:Sulfates; C081786:cyclophilin B