Cell Adhesion Mediated by Endocan/ESM‑1 and Neutralization by Mouse Endocan/|
ESM‑1 Antibody. Recombinant Mouse Endocan/ESM‑1 (Catalog # 1999-EC), immobilized onto a microplate, supports the adhesion of the Jurkat human acute T cell leukemia cell line in a dose-dependent manner (orange line). Adhesion elicited by Recombinant Mouse Endocan/ESM‑1 (25 µg/mL) is neutralized (green line) by increasing concentrations of Rat Anti-Mouse Endocan/ESM‑1 Monoclonal Antibody (Catalog # MAB1999). The ND50 is typically 0.75‑3.5 µg/mL.
Endocan (endothelial cell proteoglycan), also known as endothelial-cell specific molecule-1 (ESM-1), is a 50 kDa monomeric, secreted, cysteine-rich proteoglycan identified initially in endothelial cells of the kidney and lung (1). Mouse Endocan is synthesized as a 184 amino acid (aa) precursor that contains a 21 aa signal sequence and a 20 kDa, 163 aa mature region (2). The N-terminal 2/3 of the molecule contains 18 cysteine residues and there are no potential N-linked glycosylation sites. Based on human Endocan, there are at least two potential O-linked glycosylation sites, one of which will likely be utilized on Ser at position # 136 of the mature molecule (3). The posttranslational modification is approximately 30 kDa in size. It consists of a single dermatan sulfate chain that contains 4-O sulfated N-acetyl galactosamine with alpha -iduronate. This chain is suggested to bind HGF and contribute to HGF mitogenic activity (4). Mature mouse Endocan shares 96% and 74% aa identity with rat and human Endocan, respectively. In human, there is a potential for an alternate splice variant. It shows a deletion of aa 82-131, a range which would not remove the dermatan sulfate attachment site (4). It is not known if such a splice form exists in mouse. Endocan is expressed by endothelial cells, adipocytes, bronchial epithelium and distal renal tubular epithelium (1, 5, 6). It is upregulated by TNF-alpha and VEGF, (1, 7) and is known to bind to LFA-1 (integrin alpha L beta 2) on the surface of PBMCs, blocking LFA-1 interaction with ICAM-1 (8). Normal circulating levels of Endocan are approximately 1 ng/mL (6).