FIGURE 4.

Mannose supplementation increases amount of ICAM-1 and its appearance on cell surface of CDG-Ib cells. A, mannose supplementation as a therapeutic in CDG-Ib. The supplemented mannose enhances flux through the complementary metabolic pathway, which partially corrects Man-6-P deficiency due to deficient phosphomannose isomerase (PMI) activity and in turn fuels more glycan synthesis. B, FACS analysis of ICAM-1 alteration on the CDG-Ib cell surface when supplemented with increased amounts of mannose. CDG-Ib cells were treated with increasing amounts of mannose (25–100 μm) for 24 h. The cells were stained with phycoerythrin-conjugated anti-human ICAM-1 antibodies. Each error bar in the histogram represents the mean ± S.D. of duplicate determinations of independent experiments. C, Western blot analysis of ICAM-1 expression in CDG-Ib membranes when supplemented with increased amounts of mannose. CDG-Ib cells were treated with increasing amounts of mannose (25–200 μm) for 24 h. Membrane proteins were extracted and analyzed. Integrin α5 served as both a membrane fraction marker and a loading control.