Decorporation and detoxification effects of TRPML1 agonist ML-SA5 on human renal proximal tubular epithelial cells exposed to uranyl acetate
10.3760/cma.j.cn112271-20231120-00179
- VernacularTitle:TRPML1激动剂ML-SA5对铀暴露人肾近端小管上皮细胞的促排解毒作用及机制
- Author:
Hongjing ZHANG
1
;
Ruiyun WANG
;
Yifei WANG
;
Xuxia ZHANG
;
Honghong CHEN
Author Information
1. 复旦大学上海医学院放射医学研究所，上海 200032
- Keywords:
Uranium;
TRPML1;
ML-SA5;
Lysosomal exocytosis;
HK-2 cell
- From:
Chinese Journal of Radiological Medicine and Protection
2024;44(7):549-554
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To study the role of ML-SA5, an agonist of the lysosomal Ca 2+ channel transient receptor potential mucolipin 1 (TRPML1), in promoting lysosomal exocytosis to facilitate intracellular uranium removal and alleviate uranium-induced cellular damage for human renal proximal tubule epithelial cells (HK-2) exposed to uranyl acetate. Methods:HK-2 cells were divided into the following groups to be exposed to uranyl acetate at either 0 or 300 μmol/L for 24 h, followed by treatment with ML-SA5 and/or the lysosomal exocytosis inhibitor vacuolin-1 for 0.5 h: control group (Ctrl group), ML-SA5 group (M group), vacuolin-1 group (V group), ML-SA5 plus vacuolin-1 group (M+ V group), uranium exposure group (U group), uranium exposure plus ML-SA5 group (U+ M group), uranium exposure plus vacuolin-1 group (U+ V group), and uranium exposure plus ML-SA5 plus vacuolin-1 group (U+ M+ V group). We localized lysosome-associated membrane protein-1 (LAMP-1) on the plasma membrane (surface LAMP-1) by immunofluorescence assay; measured intracellular uranium content by inductively coupled plasma mass spectrometry; measured the level of kidney injury molecule-1 (KIM-1) by immunofluorescence assay; measured the rate of cell death with Calcein-AM/PI double staining; determined the subcellular localization of transcription factor EB (TFEB) and the levels of LAMP-1 and TRPML1 proteins by immunofluorescence assay; and measured the number of lysosomes using LysoTracker probes.Results:Compared with the Ctrl group, the U group showed significant increases in the surface LAMP-1 protein level ( t = 12.86, P < 0.05), KIM-1 protein level ( t = 18.86, P < 0.05), cell death rate ( t = 38.53, P < 0.05), TFEB nuclear translocation ( t = 9.12, P < 0.05), the protein expression levels of TFEB’s downstream target genes LAMP-1 ( t = 16.47, P < 0.05) and TRPML1 ( t = 32.33, P < 0.05), and the number of lysosomes labeled with LysoTracker probes ( t = 7.75, P < 0.05). Compared with the U group, the U+ M group showed a significantly increased surface LAMP-1 level ( t = 3.33, P < 0.05) and significant decreases in the intracellular uranium level ( t = 5.01, P < 0.05), KIM-1 protein expression level ( t = 3.81, P < 0.05), and cell death rate ( t = 3.24, P < 0.05); all these effects in the U+ M group could be neutralized by the lysosomal exocytosis inhibitor vacuolin-1; and in addition, ML-SA5 significantly increased TFEB nuclear translocation ( t = 9.20, P < 0.05), the protein expression levels of LAMP-1 ( t = 3.05, P < 0.05) and TRPML1 ( t = 3.17, P < 0.05), and the number of lysosomes labeled with LysoTracker probes ( t = 3.13, P < 0.05). Conclusions:The TRPML1 agonist ML-SA5 can promote lysosomal exocytosis to enhance intracellular uranium clearance and reduce uranium-induced cellular damage/death in uranium-loaded HK-2 cells, through activating TFEB to up-regulate lysosome biogenesis and TRPML1 protein expression.
