Disease relevance of MSR1

• The type I macrophage scavenger receptor binds to gram-positive bacteria and recognizes lipoteichoic acid [1].

High impact information on MSR1

• We report here that lipid IVA binding and subsequent metabolism to a less active form by macrophage-like RAW 264.7 cells is mediated by the macrophage scavenger receptor [2].
• The macrophage scavenger receptor is a trimeric membrane glycoprotein with unusual ligand-binding properties which has been implicated in the development of atherosclerosis [3].
• AGE proteins are taken up by macrophages via the AGE receptor, which is similar to the macrophage scavenger receptor (MSR) [4].
• The growth-stimulating effect of Ox-LDL on murine resident peritoneal macrophages was inhibited by maleylated bovine serum albumin (maleyl-BSA), a non-lipoprotein ligand for MSR but a poor carrier of lyso-PC, while maleyl-BSA itself failed to induce macrophage growth even in the presence of lyso-PC [5].
• Furthermore, the Ox-LDL-induced cell growth of peritoneal macrophages obtained from MSR knockout mice was significantly weaker than that of macrophages obtained from their wild-type littermates [5].

Biological context of MSR1

• Furthermore, these results suggest that MSR ligands can block cytokine induction by plasmid DNA whether or not the plasmid contains extended runs of dG [6].
• Macrophage scavenger receptor is a trimerized membrane protein that binds ligands and undergoes internalization by endocytosis [7].
• The macrophage scavenger receptor exhibits a pH-dependent conformational change around the carboxy-terminal half of the alpha-helical coiled coil domain, which has a representative amino acid sequence of a (defgabc)n heptad [8].
• In a 24-h culture, silica (250 microg/ml) induced significant cell injury (necrosis and apoptosis) in transfected cells (MSR II) but not in the control cells (KA-7) [9].
• It is a single polypeptide chain of 1413 amino acids consisting of 11 non-identical repeats of a 110 amino acid consensus sequence, homologous to the macrophage scavenger receptor cysteine rich (SRCR) domain [10].

Anatomical context of MSR1

• Northern blot analysis using the cDNA for the macrophage scavenger receptor revealed that these CHO cells did not express this receptor [11].
• Studies with oligonucleotides indicate that dG sequences can directly stimulate B cells as well as enhance the activity of immunostimulatory CpG motifs because of interaction with the macrophage scavenger receptor (MSR); this receptor can bind a variety of polyanions including dG sequences [6].
• Transient expression of full-length, native type II MSR in COS-1 cells conferred adhesion to denatured type I collagens, whereas expression of a truncated receptor lacking the distal portion of the collagenous domain did not [12].
• Immunoelectron microscopic studies using both AGE-BSA conjugated with gold particles and anti-(bovine MSR) antibody (D2) revealed co-localization of gold particles and the reactive sites for the antibody at coated pits of plasma membranes as well as in endosomes [13].

Associations of MSR1 with chemical compounds

• Role of the buried glutamate in the alpha-helical coiled coil domain of the macrophage scavenger receptor [8].
• These domains resemble motifs of the LDL receptor (two copies), complement component Clr (two copies), the metalloprotease meprin (one copy), and the macrophage scavenger receptor (one copy) [14].
• These results indicate that the electrostatic interaction of oxLDL with some component(s) of the heparin-bound fraction might interfere with the endocytic uptake of oxLDL by the macrophage scavenger receptor [15].
• This effect was specific to silica, as a control particle titanium dioxide had no cytotoxic effects on the MSR II cells at equal particle mass concentrations [9].
• Furthermore, silica-induced apoptosis in the MSR II cells could be eliminated by preincubating the cells with SR-A II antagonists: polyinosinic acid or maleylated bovine serum albumin [9].

Other interactions of MSR1

• Complexes of a modified low-molecular-weight heparin with protamine are predominantly cleared by a macrophage scavenger receptor-mediated process in rats [16].

References