CLEC4F Is an Inducible C-Type Lectin in F4/80-Positive Cells and Is Involved in Alpha-Galactosylceramide Presentation in Liver

Abstract

CLEC4F, a member of C-type lectin, was first purified from rat liver extract with high binding affinity to fucose, galactose (Gal), N-acetylgalactosamine (GalNAc), and un-sialylated glucosphingolipids with GalNAc or Gal terminus. However, the biological functions of CLEC4F have not been elucidated. To address this question, we examined the expression and distribution of murine CLEC4F, determined its binding specificity by glycan array, and investigated its function using CLEC4F knockout (Clec4f−/−) mice. We found that CLEC4F is a heavily glycosylated membrane protein co-expressed with F4/80 on Kupffer cells. In contrast to F4/80, CLEC4F is detectable in fetal livers at embryonic day 11.5 (E11.5) but not in yolk sac, suggesting the expression of CLEC4F is induced as cells migrate from yolk cells to the liver. Even though CLEC4F is not detectable in tissues outside liver, both residential Kupffer cells and infiltrating mononuclear cells surrounding liver abscesses are CLEC4F-positive upon Listeria monocytogenes (L. monocytogenes) infection. While CLEC4F has strong binding to Gal and GalNAc, terminal fucosylation inhibits CLEC4F recognition to several glycans such as Fucosyl GM1, Globo H, Bb3∼4 and other fucosyl-glycans. Moreover, CLEC4F interacts with alpha-galactosylceramide (α-GalCer) in a calcium-dependent manner and participates in the presentation of α-GalCer to natural killer T (NKT) cells. This suggests that CLEC4F is a C-type lectin with diverse binding specificity expressed on residential Kupffer cells and infiltrating monocytes in the liver, and may play an important role to modulate glycolipids presentation on Kupffer cells.

Tissue-Resident Macrophage Enhancer Landscapes Are Shaped by the Local Microenvironment

“…Many genes coding for TFs were uniquely expressed in specific macrophage populations, including Sall1 in microglia and Spi-c in red pulp macrophages (Figures 1B and 1C). Other population-specific genes included Clec4f in Kupffer cells (Yang et al, 2013), Car4 in lung macrophages, and Tgfb2 in peritoneal macrophages (Figure 1C). Differentially expressed genes clustered into 11 groups by their expression patterns across samples (Figure 1B).…”

Human CLEC18 Gene Cluster Contains C-type Lectins with Differential Glycan-binding Specificity

“…ND, not determined. nant fusion proteins as described previously (8,14,16). To understand whether the presence of exon B (encoding "LVWL-SAAMG") affects the glycan-binding ability, we inserted the 9 amino acids into CLEC18A CTLD to generate pCLEC18B.Fc.…”

“…However, the fusion proteins did not bind any glycans spotted on the glass slides, because the signals are weak (relative fluorescence units Ͻ 10,000) and the coefficient variation is high (CV Ͼ 50%) (supplemental Data 1, A-C). Thus, we further tested their binding ability to F3 polysaccharides isolated from medicinal fungi Ganoderma lucidum (GLPS-F3), followed by a glycan competition assay to determine binding specificity as described previously (14,16).…”

Acquiring Kupffer Cells in Mice Using a MACS-Based Method

“…Although F4/80 is agreed to be the specific marker for KCs [11,12], it is also expressed on CD11c þ dendritic cells [13e15]. However, these 2 markers provide us the potential to acquire KCs by MACS.…”