MCOLN1 and depressive symptom measurement: To gain insight into the changes in TRPML1 expression in brain cells, we measured TRPML1 protein levels in cultured astrocytes, neurons, and microglial BV2 cells treated with dexamethasone (DXMS), which mimics the depression‐related stress response in vitro.[23] Western blotting revealed that TRPML1 protein levels were significantly decreased in cultured astrocytes treated with DXMS (1 μM) for 24 and 48 h, but no differences were observed in neurons or microglial BV2 cells (Figure 1L,M; Figure S2A, Supporting Information).