tailieunhanh - Báo cáo khóa học: Surface nucleolin participates in both the binding and endocytosis of lactoferrin in target cells

Lactoferrin (Lf), a multifunctional molecule present in mammalian secretions and blood, plays important roles in host defense and cancer. Indeed, Lf has been reported to inhibit the proliferation of cancerous mammary gland epi-thelial cells and manifest a potent antiviral activity against human immunodeficiency virus and human cytomegalo-virus. The Lf-binding sites on the cell surface appear to be proteoglycans and other as yet undefined protein(s). | Eur. J. Biochem. 271 303-317 2004 FEBS 2003 doi Surface nucleolin participates in both the binding and endocytosis of lactoferrin in target cells Dominiaue Learand1. Keveen Viaié1 Elias A Said2. Elisabeth Elass1 Marvse Masson1 Marie-Christine Slomianny1 Mathieu Carpentier1 Jean-Paul Briand3 Joel Mazurier1 and Ara G. Hovanessian2 1 Unite de Glycobiologie Structurale et Fonctionnelle et Unite Mixte de Recherche n 8576 du CNRS Institut Federatif de Recherche n 118 Universite des Sciencss et Technologies de LíUe Villeneuve d Ascq France 2Unite de Virologie et Immunologie Cellulaire URA 1930 CNRS Paris France 3Institut de Biologie Moleculaire et Cellulaire UPR 9021 CNRS Strasbourg France Lactoferrin Lf a multifunctional molecule present in mammalian secretions and blood plays important roles in host defense and cancer. Indeed Lf has been reported to inhibit the proliferation of cancerous mammary gland epithelial cells and manifest a potent antiviral activity against human immunodeficiency virus and human cytomegalovirus. The Lf-binding sites on the cell surface appear to be proteoglycans and other as yet undefined protein s . Here we isolated a Lf-binding 105 kDa molecular mass protein from cell extracts and identified it as human nucleolin. Medium-affinity interactions w 240 nM between Lf and purified nucleolin were further illustrated by surface plasmon resonance assays. The interaction of Lf with the cell surface-expressed nucleolin was then demonstrated through competitive binding studies between Lf and the anti-human immunodeficiency virus pseudopeptide HB-19 which binds specifically surface-expressed nucleolin independently of proteoglycans. Interestingly binding competition studies between HB-19 and various Lf derivatives in proteoglycan-deficient hamster cells suggested that the nucleolin-binding site is located in both the N- and C-terminal lobes of Lf whereas the basic N-terminal region is dispensable. On intact cells Lf .