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Control of TRPML1 Channel Activity and Lysosome Trafficking by Acid Ceramidase in Mouse Coronary Arterial Endothelial Cells
Author(s) -
Li Guangbi,
Yuan Xinxu,
Huang Dandan,
Camus Sarah,
Li PinLan
Publication year - 2021
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2021.35.s1.04045
Subject(s) - lysosome , microbiology and biotechnology , ceramide , chemistry , acid sphingomyelinase , sphingomyelin , sphingosine , biology , medicine , biochemistry , endocrinology , enzyme , membrane , apoptosis , receptor
Previous studies have demonstrated that lysosomal acid ceramidase (AC) regulates lysosome‐multivesicular body (MVB) interaction and exosome release in mouse coronary arterial endothelial cells (CAECs). However, it remains unknown how exosome secretion is controlled by AC. In this study, we tested a hypothesis that enhancement of lysosome trafficking by AC activity increases lysosome‐MVB interaction determining MVB fate to promote exosome release, which may be attributed to its action on lysosomal TRPML1 channel‐mediated Ca 2+ release in CAECs. By GCaMP3 Ca 2+ imaging, we found that ML‐SA1 as a TRPML1 channel agonist remarkably increased lysosomal Ca 2+ release through TRPML1 channel in WT/WT CAECs. In Asah1 fl/fl /EC cre CAECs, however, ML‐SA1 failed to influence TRPML1 channel‐mediated Ca 2+ release. As an AC product, sphingosine remarkably increased lysosomal Ca 2+ release through TRPML1 channel in both WT/WT and Asah1 fl/fl /EC cre CAECs. With whole‐lysosome patch clamp recording, we detected ML‐SA1‐induced Ca 2+ currents in a dose‐dependent manner through the membrane of lysosomes isolated from WT/WT CAECs, while intact lysosomes isolated from Asah1 fl/fl /EC cre CAECs had evidently blunted opening of TRPML1 channels in response to ML‐SA1. Different effects of AC associated sphingolipids on TRPML1 channel activity were also examined in lysosomes isolated from WT/WT CAECs. It was found that sphingomyelin inhibited, but sphingosine enhanced lysosomal TRPML1 channel activity. Ceramide did not alter this lysosomal channel activity. In lysosomes isolated from Asah1 fl/fl /EC cre CAECs, only sphingosine increased ML‐SA1‐induced TRPML1 channel‐mediated Ca 2+ release. Using confocal microscopy for measurement of lysosomes movement, we demonstrated that lysosomal TRPML1 channel activation by ML‐SA1 in CAECs markedly enhanced lysosome trafficking toward nucleus, which was blocked by genetic deletion of AC. These results suggest that AC‐mediated sphingolipid metabolism controls lysosomal TRPML1 channel‐mediated Ca 2+ release and lysosome trafficking in CAECs, which may contribute to the regulation of lysosome‐MVB interaction and exosome release by AC (supported by NIH grant DK120491).