Sγc is generated by proteolytic shedding of membrane-bound γc.
(A) On the surfaces of EL-4 cells, γc expression was detected by flow cytometry with an isotype-matched control mAb (white graph) or TUGm2 mAb (gray graph). (B) PMA induces the release of sγc by EL-4 cells. 2 × 106 cells/mL were cultured in the presence or absence of PMA (250 ng/mL), and at the time-points indicated the sγc concentrations in the culture supernatants were measured by ELISA. (C) Decreased expression of membrane-bound γc of EL-4 cells in the presence of PMA and re-expression after PMA withdrawal. In parallel to the sγc measurements in the supernatants (see B), cell surface expression of γc was analyzed by flow cytometry. Forty-eight hours after stimulation, the cells were washed and the re-occurrence of the γc was measured. Ratios of the mean fluorescence (MF) of stimulated cells divided by the MF of nonstimulated cells are depicted. (D) Expression of full-length transmembrane γc by transfected COS-7.1 cells. Graphs appear as described for panel A. (E) Enhanced release of sγc by COS-7.1/γc, but not control transfected COS-7.1, cells in the presence of PMA (300 ng/mL). (F) PMA dose-dependent decrease of the MF after staining the surface-bound γc on COS-7.1/γc cells.
