Cd44 Is a Major E-Selectin Ligand on Human Hematopoietic Progenitor Cells

作者：Charles J. Dimitroff, Jack Y. Lee, Shahin Rafii, Robert C. Fuhlbrigge, Robert Sackstein · 发表于：The Journal of Cell Biology · 年份：2001 · DOI：10.1083/jcb.153.6.1277 · 被引用次数：332 · 研究领域：Cell Adhesion Molecules Research、Immunotherapy and Immune Responses、Chemokine receptors and signaling

E-selectin plays a critical role in mediating tissue-specific homing of T cells into skin, and of primitive hematopoietic progenitor cells (HPCs) into bone marrow (BM). Though it is known that a glycoform of PSGL-1 (CLA) functions as the principal E-selectin ligand on human T lymphocytes, the E-selectin ligand(s) of human HPCs has not been identified. We used a shear-based adherence assay to analyze and define the E-selectin ligand activity of membrane proteins from human HPCs. Our data show that PSGL-1 expressed on human HPCs is an E-selectin ligand, and that HPCs also express a previously unrecognized E-selectin ligand, CD44. The E-selectin ligand activity of CD44 is conferred by the elaboration of sialylated, fucosylated binding determinants on N-glycans. This glycoform of CD44 is expressed on primitive CD34+ human HPCs, but not on more mature hematopoietic cells. Under physiologic flow conditions, this molecule mediates E-selectin-dependent rolling interactions over a wider shear range than that of PSGL-1, and promotes human HPC rolling interactions on E-selectin expressed on human BM endothelial cells. These findings offer new insights into the structural biology and physiology of CD44, and into the molecular basis of E-selectin-dependent adhesive interactions that direct homing of human HPC to BM.