Mouse Mincle: Characterization as a Model for Human Mincle and Evolutionary Implications

Abstract

Mincle, the macrophage-inducible C-type lectin also known as CLEC-4E, binds to the mycobacterial glycolipid trehalose dimycolate and initiates a signaling cascade by serving as a receptor for Mycobacterium tuberculosis and other pathogenic mycobacterial species. Studies of the biological functions of human mincle often rely on mouse models, based on the assumption that the biological properties of the mouse receptor mimic those of the human protein. Experimental support for this assumption has been obtained by expression of the carbohydrate-recognition domain of mouse mincle and characterization of its interaction with small molecule analogs of trehalose dimycolate. The results confirm that the ligand-binding properties of mouse mincle closely parallel those of the human receptor. These findings are consistent with the conservation of key amino acid residues that have been shown to form the ligand-binding site in human and cow mincle. Sequence alignment reveals that these residues are conserved in a wide range of mammalian species, suggesting that mincle has a conserved function in binding ligands that may include endogenous mammalian glycans or pathogen glycans in addition to trehalose dimycolate.

Contribution of MINCLE–SYK Signaling to Activation of Primary Human APCs by Mycobacterial Cord Factor and the Novel Adjuvant TDB

“…In our experimental system, the glycolipids were coated onto the cell culture plate, suggesting that the interaction with the CLR takes place at the cell surface. Recent structural data of MINCLE-trehalose cocrystals indicate that ligand binding is sensitive to acidic pH, making a phagolysosomal localization of the MINCLE-TDB/TDM interaction rather unlikely (68)(69)(70). Stabilization of expression of murine Mincle by Mcl has recently been suggested as potential mechanism for phagosomal ligand binding (71).…”

Rational design of adjuvants targeting the C-type lectin Mincle

“…At least three of these four binding sites must be occupied for effective recognition of the ligand, but interactions with the secondary glucose-binding site seem to be weaker than those induced by binding with the second hydrophobic groove; note the relative ability of GlcC14C18 vs. TMB vs. GlcMB/C22 to stimulate reporter cell lines. Key amino acid residues forming the ligand-binding site in human (14) and bovine (13) Mincle are conserved in a wide range of mammalian species, including mouse, suggesting that the receptor binding properties are conserved (33). Accordingly, only subtle differences in ligand binding between the human and mouse receptors were observed.…”

Trehalose diester glycolipids are superior to the monoesters in binding to Mincle, activation of macrophages in vitro and adjuvant activity in vivo

“…Short soluble diester derivatives of trehalose have been shown to compete with 2.5–7-fold higher efficiency than the corresponding monoesters for binding to the mouse Mincle carbohydrate recognition domain, which is consistent with our finding that trehalose 6,6'-diesters display superior binding and activation as compared with the monoesters. 23 …”