Carbohydrate markers of ES cells

Abstract

Embryonic stem (ES) cells and induced pluripotent stem (iPS) cells are expected to play important roles in regenerative therapy. Cell surface markers, the epitopes of which are carbohydrates, are useful for distinguishing these pluripotent cells from other cells and following the process of their differentiation. The most established marker of mouse ES cells is SSEA-1. The epitope of SSEA-1 is Lewis X, namely Galβ1-4(Fucα1-3)GlcNAc. The markers of human ES cells are SSEA-3, SSEA-4, TRA-1-60 and TRA-1-81. SSEA-3 and SSEA-4 are antigens of globo-series glycolipids, while TRA-1-60 and TRA-1-81 are antigens related to keratan sulfate. iPS cells express the same set of carbohydrate markers found on ES cells of the same species. EG cells, pluripotent stem cells derived from primordial germ cells, express SSEA-1 both in humans and in mice. Embryoglycan, a high molecular weight, branched poly-N-acetyllactosamine of early embryonic cells, is expressed in mouse ES cells and in human and mouse embryonal carcinoma (EC) cells. Embryoglycan is a carrier of many carbohydrate markers, including SSEA-1. ES cells derived from mice deficient in Iβ1,6-N-acetylglucosaminyltransferase (IGnT) exhibited decreased synthesis of embryoglycan, loss of 4C9 antigen, and decreased adhesion to laminin-coated plates. The results raised the possibility that embryoglycan enhances integrin's actions.