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J Immunol. 2016 Sep 15;197(6):2229-38. doi: 10.4049/jimmunol.1501878. Epub 2016 Aug 17.

Folate Receptor β Regulates Integrin CD11b/CD18 Adhesion of a Macrophage Subset to Collagen.

Author information

1
Institute for Hygiene and Applied Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, 1090 Vienna, Austria;
2
Institute for Hygiene and Applied Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, 1090 Vienna, Austria; Laboratory of Molecular Immunology, Institute of Molecular Biology, Slovak Academy of Sciences, 845 51 Bratislava, Slovakia;
3
Department of Clinical Chemistry and Laboratory Medicine, Medical University of Vienna, 1090 Vienna, Austria;
4
Department of Surgery and Core Facility Flow Cytometry, Medical University of Vienna, 1090 Vienna, Austria; and.
5
EXBIO Praha, 252 42 Vestec, Czech Republic.
6
Institute for Hygiene and Applied Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, 1090 Vienna, Austria; hannes.stockinger@meduniwien.ac.at anna.repic@meduniwien.ac.at.

Abstract

Folate, also known as vitamin B9, is necessary for essential cellular functions such as DNA synthesis, repair, and methylation. It is supplied to the cell via several transporters and receptors, including folate receptor (FR) β, a GPI-anchored protein belonging to the folate receptor family. As FRβ shows a restricted expression to cells of myeloid origin and only a subset of activated macrophages and placental cells have been shown to express functional FRβ, it represents a promising target for future therapeutic strategies. In this study, we performed affinity purification and mass spectrometric analysis of the protein microenvironment of FRβ in the plasma membrane of human FRβ(+) macrophages and FRβ-transduced monocytic THP-1 cells. In this manner, we identified a novel role of FRβ: that is, we report functional interactions of FRβ with receptors mediating cellular adhesion, in particular the CD11b/CD18 β2 integrin heterodimer complement receptor type 3/Mac-1. This interaction results in impeded adhesion of FRβ(+) human primary macrophages and THP-1 cells to collagen in comparison with their FRβ(-) counterparts. We further show that FRβ is only expressed by human macrophages when differentiated with M-CSF. These findings thus identify FRβ as a novel CD11b/CD18 regulator for trafficking and homing of a subset of macrophages on collagen.

PMID:
27534550
DOI:
10.4049/jimmunol.1501878
[Indexed for MEDLINE]
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