alpha2,6-Sialylation promotes binding of placental protein 14 via its Ca2+-dependent lectin activity: insights into differential effects on CD45RO and CD45RA T cells.
Glycobiology
; 16(3): 173-83, 2006 Mar.
Article
em En
| MEDLINE
| ID: mdl-16269626
ABSTRACT
Placental protein 14 (PP14; glycodelin) is a pregnancy-associated immunoregulatory protein that is known to inhibit T cells via T-cell receptor desensitization. The recent demonstration of PP14 as lectin has provided insight into how it may mediate its CD45 glycoprotein-dependent T-cell inhibition. In this study, we have investigated PP14's lectin-binding properties in detail. Significantly, PP14 reacts with N-acetyllactosamine (LacNAc) as was also found for members of the galectin family, such as the potent immunoregulatory protein, galectin-1. However, in contrast to galectin-1, PP14's binding is significantly enhanced by alpha2,6-sialylation and also by the presence of cations. This was demonstrated by preferential binding to fetuin as compared with its desialylated variant asialofetuin (ASF) and by using free alpha2,6- versus alpha2,3-sialylated forms of LacNAc in competitive inhibition and direct solid-phase binding assays. Interestingly, from immunological point of view, PP14 also binds differentially to CD45 isoforms known to differ in their degree of sialylation. PP14 preferentially inhibits CD45RA+, as compared with CD45RO+ T cells, and preferentially co-capped this variant CD45 on the T-cell surface. Finally, we demonstrate that PP14 promotes CD45 dimerization and clustering, a phenomenon that may regulate CD45 activity.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteínas da Gravidez
/
Sistema ABO de Grupos Sanguíneos
/
Glicoproteínas
/
Linfócitos
/
Cálcio
/
Antígenos Comuns de Leucócito
/
Ácido N-Acetilneuramínico
/
Lectinas
Limite:
Female
/
Humans
/
Pregnancy
Idioma:
En
Revista:
Glycobiology
Assunto da revista:
BIOQUIMICA
Ano de publicação:
2006
Tipo de documento:
Article
País de afiliação:
Israel