Thy-1 as a regulator of cell-cell and cell-matrix interactions in axon regeneration, apoptosis, adhesion, migration, cancer, and fibrosis

Thy-1 (CD90) is a 25-37 kDa glycosylphosphatidylinositol (GPI)-anchored glycoprotein expressed on many cell types, including T cells, thymocytes, neurons, endothelial cells, and fibroblasts. Activation of Thy- 1 can promote T cell activation, and this role of Thy- 1 is reviewed elsewhere. Thy- 1 also affects numerous nonimmunologic biological processes, including cellular adhesion, neurite outgrowth, tumor growth, migration, and cell death. In reviewing the nonimmunologic functions of Thy- 1, we discuss the phenotype of the Thy- 1 null mouse, signaling pathways modulated by Thy- 1, the role of the GPI anchor in Thy- 1 localization to lipid rafts and signaling, and regulation of Thy- 1 expression. Thy- 1 is an important regulator of cell-cell and cell-matrix interactions, with important roles in nerve regeneration, metastasis, inflammation, and fibrosis.