BACKGROUND/AIMS: Stromal interacting molecule-1 (STIM1) aggregation and redistribution to plasma membrane to interact with Orai1 constitute the core mechanism of store-operated Ca2+ entry (SOCE). Previous study has revealed that calsequestrin-1 (CSQ1) regulates SOCE in HEK293 cells through interacting with STIM1 and inhibiting STIM1/Orai1 interaction. Here, we further investigate how CSQ1/STIM1 interaction affects SOCE. METHODS: Using confocal microscopy, STIM1 aggregation and co-localizations with CSQ1 or Orai1 upon Ca2+ store depletion by thapsigargin were measured and quantified by Imaris software in HeLa cells transfected with different CSQ1 mutants. The interactions of CSQ1/STIM1 and STIM1/Orai1, and internal Ca2+ changes were detected by co-immunoprecipitation and Fura2, respectively. RESULTS: Wt-CSQ1 overexpression significantly reduced STIM1 clustering in the perimembrane and cytosolic regions, whereas over-expression of a C-terminal amino acid 362-396 deletion mutant (C35) did not. Consistently, a significant depression of SOCE, increased CSQ1 monomerization and CSQ1/STIM1 interaction, and a reduced STIM1/Orai1 association were observed in wt-CSQ1 but not in C35-transfected cells. Additionally, mutant lacking C-terminal AA 388-396 deletion exerted weaker potency in inhibiting STIM1 aggregation and association with Orai1 than wt-CSQ1. CONCLUSIONS: Our results demonstrate that CSQ1 monomers suppress SOCE by interacting with STIM1 and attenuating STIM1 aggregation via its C-terminal amino acid 362-396.
BACKGROUND/AIMS: Stromal interacting molecule-1 (STIM1) aggregation and redistribution to plasma membrane to interact with Orai1 constitute the core mechanism of store-operated Ca2+ entry (SOCE). Previous study has revealed that calsequestrin-1 (CSQ1) regulates SOCE in HEK293 cells through interacting with STIM1 and inhibiting STIM1/Orai1 interaction. Here, we further investigate how CSQ1/STIM1 interaction affects SOCE. METHODS: Using confocal microscopy, STIM1 aggregation and co-localizations with CSQ1 or Orai1 upon Ca2+ store depletion by thapsigargin were measured and quantified by Imaris software in HeLa cells transfected with different CSQ1 mutants. The interactions of CSQ1/STIM1 and STIM1/Orai1, and internal Ca2+ changes were detected by co-immunoprecipitation and Fura2, respectively. RESULTS: Wt-CSQ1 overexpression significantly reduced STIM1 clustering in the perimembrane and cytosolic regions, whereas over-expression of a C-terminal amino acid 362-396 deletion mutant (C35) did not. Consistently, a significant depression of SOCE, increased CSQ1 monomerization and CSQ1/STIM1 interaction, and a reduced STIM1/Orai1 association were observed in wt-CSQ1 but not in C35-transfected cells. Additionally, mutant lacking C-terminal AA 388-396 deletion exerted weaker potency in inhibiting STIM1 aggregation and association with Orai1 than wt-CSQ1. CONCLUSIONS: Our results demonstrate that CSQ1 monomers suppress SOCE by interacting with STIM1 and attenuating STIM1 aggregation via its C-terminal amino acid 362-396.
Authors: Z I Krutetskaya; L S Milenina; A A Naumova; S N Butov; V G Antonov; A D Nozdrachev Journal: Dokl Biochem Biophys Date: 2018-03-14 Impact factor: 0.788
Authors: Antonio Michelucci; Simona Boncompagni; Laura Pietrangelo; Takahiro Takano; Feliciano Protasi; Robert T Dirksen Journal: J Gen Physiol Date: 2020-10-05 Impact factor: 4.086