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Jagged‐1 Enhances CaSR‐Induced Increase in [Ca 2+ ] cyt by Promoting Recruitment of STIM2 to ER‐PM Junctions
Author(s) -
Song Shanshan,
McDermott Kimberly M.,
Makino Ayako,
Yuan Jason X.J.
Publication year - 2016
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.30.1_supplement.768.3
Subject(s) - extracellular , calcium sensing receptor , hek 293 cells , transfection , chemistry , endoplasmic reticulum , receptor , cyclopiazonic acid , microbiology and biotechnology , g protein coupled receptor , biophysics , calcium , biochemistry , biology , calcium metabolism , organic chemistry , gene
Calcium‐sensing receptor (CaSR) is a G protein‐coupled receptor (GPCR) that can be activated by extracellular Ca 2+ . Activation of CaSR results in an increase in cytosolic free Ca 2+ concentration ([Ca 2+ ] cyt ) due to inositol l,4,5‐trisphosphate (IP 3 )‐dependent Ca 2+ release and diacyglycerol (DAG)‐mediated Ca 2+ influx. STIM2 is a Ca 2+ sensor protein located in the endoplasmic reticulum (ER) that forms clusters at ER‐plasma membrane (PM) junctions when [Ca 2+ ] is reduced in the ER and has been proposed to regulate Ca 2+ entry at low concentration of agonist stimulation. Jagged‐1 (Jag‐1) is a ligand of Notch receptors and has been reported to enhance store‐operated Ca 2+ entry (SOCE) in human pulmonary arterial smooth muscle cells (PASMC). Here, we examined whether activation of Notch promotes recruitment of STIM2 to ER‐PM junctions and thus enhances extracellular Ca 2+ ‐mediated increase in [Ca 2+ ] cyt through CaSR. Addition of extracellular Ca 2+ induced increases in [Ca 2+ ] cyt in HEK cells transiently transfected with CaSR . Treatment of CaSR ‐transfected HEK cells with Jag‐1 (for 30 min) significantly increased the amplitude of CaSR‐mediated increase in [Ca 2+ ] cyt . Furthermore, the extracellular Ca 2+ ‐induced increase in [Ca 2+ ] cyt was also significantly enhanced in HEK cells transfected with STIM2 . Passive depletion of intracellularly stored Ca 2+ in ER by cyclopiazonic acid (CPA), an ER Ca 2+ pump inhibitor, induced the formation of STIM2 clusters in ER‐PM junctions in STIM2 ‐transfected HEK cells. Activation of CaSR by extracellular Ca 2+ in CaSR ‐overexpressed HEK also resulted in STIM2 clustering. Together, these results suggest that activation of Notch functionally enhances CaSR‐mediated increases in [Ca 2+ ] cyt by promoting recruitment of STIM2 to the ER‐PM junctions and enhancing store‐operated Ca 2+ entry. Support or Funding Information This study was supported by NIH grants (HL115014, HL066012 and HL098053).