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The poliovirus receptor CD155 mediates cell-to-matrix contacts by specifically binding to vitronectin
1Department of Tumor and Immunogenetics, Max-Delbrück-Center for Molecular Medicine, Robert-Rössle Strasse 10, Berlin, 13092, Germany.
Abstract:
The human receptor for poliovirus (CD155) is an immunoglobulin-like molecule with unknown normal function(s). Here we provide evidence that CD155 binds specifically to vitronectin with a dissociation constant (K(d)) of 72 nM as determined by surface plasmon resonance. Based on sequence homology to the CD155 gene, three poliovirus receptor-related genes (PRR1, PRR2, and PRR3) were cloned recently. PRR proteins were reported by others to mediate homophilic cell adhesion. Neither PRR1 nor PRR2 binds poliovirus and it is assumed that their physiological functions differ from that of CD155. Indeed, mPRR2 was found to bind to vitronectin only weakly, while its self-adhesion activity is characterized by a K(d) of 310 nM. Moreover, there is no evidence for CD155 self-adhesion. Both CD155 and vitronectin colocalize to follicular dendritic cells and B cells inside the germinal centers of secondary lymphoid tissue (tonsils)-an observation suggesting that the CD155/vitronectin interaction is required for the establishment of a proper immune response in this particular context.
Insights
The human poliovirus receptor (CD155) binds to vitronectin, a protein crucial for immune responses. This CD155-vitronectin interaction occurs in lymphoid tissues, suggesting a role in immune cell function.
Area of Science:
- Immunology
- Cell Biology
- Molecular Biology
Background:
- The normal function of the human poliovirus receptor (CD155), an immunoglobulin-like molecule, is not well understood.
- Three poliovirus receptor-related (PRR) genes (PRR1, PRR2, PRR3) have been identified, with PRR proteins previously reported to mediate homophilic cell adhesion.
Purpose of the Study:
- To investigate the binding interactions of CD155 and related proteins.
- To explore the potential physiological functions of CD155 beyond poliovirus binding.
- To determine the role of CD155-vitronectin interaction in the immune system.
Main Methods:
- Surface plasmon resonance was used to quantify the binding affinity between CD155 and vitronectin.
- Sequence homology was used to identify and clone poliovirus receptor-related genes.
- Immunohistochemistry was employed to examine the colocalization of CD155 and vitronectin in lymphoid tissues.
Main Results:
- CD155 specifically binds to vitronectin with a dissociation constant (K(d)) of 72 nM.
- PRR1 and PRR2 do not bind poliovirus, and mPRR2 binds vitronectin weakly (K(d) of 310 nM for self-adhesion).
- CD155 and vitronectin were found to colocalize on follicular dendritic cells and B cells within germinal centers of tonsils.
Conclusions:
- The specific binding of CD155 to vitronectin suggests a novel physiological role for CD155.
- The colocalization of CD155 and vitronectin in secondary lymphoid tissues indicates their interaction is important for immune responses.
- This interaction may be essential for the proper functioning of the immune system within germinal centers.