The zymogen granule protein 2 (GP2) binds to scavenger receptor expressed on endothelial cells I (SREC-I).
Bottom Line: Inhibition of SREC-I on moDCs with anti-SREC-I antibodies does not result in a decreased GP2 binding.Interaction of GP2 with SREC-I and uptake might have profound effects in antigen clearance and mediation of the immune response.In addition to SREC-I other presently unknown receptors for GP2 on DCs might be involved in this process.
Affiliation: Institute of Immunology, Center of Pathophysiology, Infectiology and Immunology, Medical University of Vienna, A-1090 Vienna, Austria.Show MeSH
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Mentions: Since SREC-I has been shown to be a receptor with endocytic capacity , we were interested whether GP2 is taken up after ligation. Therefore Bw-SREC-I cells were incubated with GP2-bio at 4 °C and washed. SA-PE staining of the cells was either performed after the washing step or following a one hour incubation step at 37 °C. After the one hour incubation step at 37 °C, GP2-bio was no longer accessible for binding of SA-PE, whereas immediate application of the secondary reagent and subsequent incubation for one hour at 37 °C still resulted in a strong fluorescence signal (Fig. 3A). These results clearly demonstrate efficient endocytic uptake of GP2 by the Bw-SREC-I cells. moDCs have been shown to bind and internalize the GP2 homologue THP . Therefore, we were also interested to test the interaction of GP2 with this cell type. moDCs were able to bind (Fig. 3B) and to internalize GP2-bio (Fig. 3C). Using the same approach as described before, we found that moDCs stained with SA-PE before the one hour incubation step retained surface staining with GP2-bio. In contrast, staining after incubation at 37 °C for one hour resulted in a complete loss of SA-PE binding, indicating uptake of GP2.
Affiliation: Institute of Immunology, Center of Pathophysiology, Infectiology and Immunology, Medical University of Vienna, A-1090 Vienna, Austria.