Fig. 5

IL-1β does not measurably alter cell surface TrkB expression. a Cell surface TrkB was measured in a 1-hour timecourse in response to BDNF or BDNF + IL-1β. Following treatment, endocytosis was arrested and cells were biotinlyated (see Methods). Cell surface TrkB levels did not differ significantly among groups over 1 h. The average rate of endocytosis per 1 h was 53% for TrkB150 after treatment with BDNF vs 47% following treatment with BDNF + IL-1β, suggesting that IL-1β does not significantly alter endocytic kinetics of TrkB at 1 h. Rates ΔCS-TrkB95/hr: BDNF = –72 ± 9%, n = 2 independent experiments vs BDNF + IL-1β = –0.70 ± 10%, n = 2 independent experiments). Rates ΔCS-TrkB150/hr: BDNF = –72 ± 9%, n = 2 independent experiments vs BDNF + IL-1β = –0.70 ± 10%, n = 2 independent experiments). b Cell surface TrkB-full length (TrkB-FL) was measured in a 1-h timecourse in response to BDNF, BDNF + IL-1β, or BDNF + Dynasore, an inhibitor of dynamin. Dynasore, but not IL-1β, suppressed BDNF-induced TrkB internalization. Upper panel: the image of western blotting. Lower upper panel: quantification of western blotting data (mean ± SE, n = 2)