Fig. 4.

Depletion of lysosomal Ca²⁺ by activation of TRPML1 abrogates RANKL-induced [Ca²⁺]i oscillations and osteoclastogenesis. (A, B) BMMs from WT and TRPML1^−/− mice were cultured for 48 hours with (B) or without (A) RANKL stimulation (50 ng/mL). The cells were then exposed to the specific TRPML activator, ML-SA1 (20 μM), to selectively deplete lysosomal Ca²⁺. The columns are the mean±SD of Ca²⁺ oscillation frequency recorded in 7 experiments. (C) BMMs from WT and TRPML1^−/− mice were cultured with and without RANKL and in the presence or absence of 20 μM MA-SA1 for 3 days. The cultures were then stained for TRAP and TRAP+ MNCs were counted. The columns show the mean±SD from 3 experiments. (Scale bar = 200 μm). **p < 0.01.