Open AccessTRP‐ML1 functions as a lysosomal NAADP‐sensitive Ca 2+ release channel in coronary arterial myocytes
Author(s) -
Zhang Fan,
Jin Si,
Yi Fan,
Li PinLan
Publication year - 2009
Publication title -
journal of cellular and molecular medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.44
H-Index - 130
eISSN - 1582-4934
pISSN - 1582-1838
DOI - 10.1111/j.1582-4934.2008.00486.x
Subject(s) - transient receptor potential channel , chemistry , lysosome , biophysics , endoplasmic reticulum , myocyte , microbiology and biotechnology , intracellular , biochemistry , biology , receptor , enzyme
Nicotinic acid adenine dinucleotide phosphate (NAADP) is a potent intracellular Ca 2+ signalling second messenger, but the mechanism of NAADP‐induced Ca 2+ release is still poorly understood. The present study tested the hypothesis that NAADP induces Ca 2+ release from the lysosomal store via a TRP‐ML1 (transient receptor potential‐mucolipin 1)‐mediated Ca 2+ release channel in coronary arterial myocytes (CAMs). RT‐PCR and Western blot analyses demonstrated that TRP‐ML1 was present in CAMs, and fluorescence resonance energy transfer (FRET) detection revealed that the TRP‐ML1 was closely associated with some lysosomal proteins in these CAMs. ET‐1, a well‐known NAADP stimulator, was found to induce a local Ca 2+ burst from lysosomes followed by a global Ca 2+ release. This lysosome‐associated Ca 2+ release was significantly inhibited in the TRP‐ML1 siRNA pre‐treated CAMs by 46.8 ± 12.6% in the local Ca 2+ burst and 73.3 ± 14.9% in the global Ca 2+ wave. In the reconstituted lysosomal channels from CAMs, NAADP activated Ca 2+ release channels at concentrations of 1–1000 nM, but neither activators (1 μM IP 3 , 5 μM Rya) nor blockers (100 μM 2‐APB, 50 μM Rya) of sarcoplasmic reticulum (SR) Ca 2+ release channels had effect on the channel activity. Moreover, TRP‐ML1 gene silencing reduced this NAADP‐sensitive Ca 2+ release channel activity in lysosomes by 71.5 ± 18.5%. Immunoprecipitation or blockade of TRP‐ML1 by anti‐TRP‐ML1 antibodies almost abolished NAADP‐induced activation of lysosomal Ca 2+ channels (to 14.0 ± 4.4% of control). These results for the first time provide direct evidence that an NAADP‐sensitive Ca 2+ release channel is characteristic of TRP‐ML1 channels.