Limits...
Caveolin-1 alters the pattern of cytoplasmic Ca2+ oscillations and Ca2+-dependent gene expression by enhancing leukotriene receptor desensitization.

Yeh YC, Tang MJ, Parekh AB - J. Biol. Chem. (2014)

Bottom Line: Here, we show that the scaffolding protein caveolin-1 has a profound effect on receptor-driven Ca(2+) signals and downstream gene expression.Mutagenesis studies revealed that these effects required a functional scaffolding domain within caveolin-1.Our results reveal that caveolin-1 is a bimodal regulator of receptor-dependent Ca(2+) signaling, which fine-tunes the spatial and temporal profile of the Ca(2+) rise and thereby its ability to activate the NFAT pathway.

View Article: PubMed Central - PubMed

Affiliation: From the Department of Physiology, Anatomy, and Genetics, University of Oxford, Parks Road, Oxford OX1 3PT, United Kingdom and.

Show MeSH

Related in: MedlinePlus

Caveolin-1 expression increases agonist-evoked Ca2+ release from internal stores.A, cytoplasmic Ca2+ oscillations to LTC4 (applied in the presence of 2 mm external Ca2+) are compared between a WT cell and one expressing caveolin-1-GFP (Cav1) (dotted trace). B, the number of oscillations/100-s bin (recording period) is compared for the conditions shown. GFP denotes expression of GFP alone. Each data point is the mean of between 21 and 30 cells from three independent experiments. C–E, the peak amplitude of the first Ca2+ oscillation (C), average area of the oscillations (D), and mean duration of the oscillations (E) are compared among WT (26 cells), GFP-expressing (34 cells), and caveolin-1-GFP-expressing cells (39 cells). For D and E, the area and duration of each oscillation was measured, and then the data were pooled together. F, store-operated Ca2+ influx measured following stimulation with LTC4 in Ca2+-free solution for 600 s followed by readmission of external Ca2+ was compared between the two conditions. G, the graph compares the rundown of Ca2+ oscillations among WT (24 cells), GFP-expressing (29 cells), and caveolin-1-expressing cells (26 cells) when cells were stimulated with LTC4 in the absence of external Ca2+ as shown in F. H, the amplitude of the first Ca2+ oscillation, evoked by LTC4 in Ca2+-free solution, is compared. I, the rates of store-operated Ca2+ entry, measured by differentiating the Ca2+ rise following readmission of 2 mm Ca2+ as in F, are compared for the conditions shown (each bar denotes >25 cells from three independent experiments).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4067216&req=5

Figure 1: Caveolin-1 expression increases agonist-evoked Ca2+ release from internal stores.A, cytoplasmic Ca2+ oscillations to LTC4 (applied in the presence of 2 mm external Ca2+) are compared between a WT cell and one expressing caveolin-1-GFP (Cav1) (dotted trace). B, the number of oscillations/100-s bin (recording period) is compared for the conditions shown. GFP denotes expression of GFP alone. Each data point is the mean of between 21 and 30 cells from three independent experiments. C–E, the peak amplitude of the first Ca2+ oscillation (C), average area of the oscillations (D), and mean duration of the oscillations (E) are compared among WT (26 cells), GFP-expressing (34 cells), and caveolin-1-GFP-expressing cells (39 cells). For D and E, the area and duration of each oscillation was measured, and then the data were pooled together. F, store-operated Ca2+ influx measured following stimulation with LTC4 in Ca2+-free solution for 600 s followed by readmission of external Ca2+ was compared between the two conditions. G, the graph compares the rundown of Ca2+ oscillations among WT (24 cells), GFP-expressing (29 cells), and caveolin-1-expressing cells (26 cells) when cells were stimulated with LTC4 in the absence of external Ca2+ as shown in F. H, the amplitude of the first Ca2+ oscillation, evoked by LTC4 in Ca2+-free solution, is compared. I, the rates of store-operated Ca2+ entry, measured by differentiating the Ca2+ rise following readmission of 2 mm Ca2+ as in F, are compared for the conditions shown (each bar denotes >25 cells from three independent experiments).

Mentions: Endogenous levels of caveolin-1 were virtually undetectable in Western blots from RBL-1 cells (data not shown), so we overexpressed the GFP-tagged protein to study its impact on Ca2+ oscillations. In non-transfected (wild type) cells, stimulation with LTC4 evoked a series of cytoplasmic Ca2+ oscillations (Fig. 1A), which decreased slightly over time due to receptor desensitization (Fig. 1B) (6). Expression of caveolin-1-GFP substantially altered the pattern of the Ca2+ oscillations (Fig. 1A, dotted trace). The amplitudes of the initial Ca2+ oscillations evoked by LTC4 were now considerably larger than in non-transfected cells (Fig. 1, A and C), but the oscillations ran down more quickly and so were fewer in number over a 600 to 700-s recording period (Fig. 1B). Analysis of the various oscillatory parameters revealed that the total Ca2+ rise associated with each oscillation (area under the spike) was significantly larger in cells expressing caveolin-1-GFP (Fig. 1D); this reflected both an increase in the amplitude of each Ca2+ oscillation (Fig. 1C) as well as an increase in duration (Fig. 1E). Cytoplasmic Ca2+ during each oscillation was therefore elevated for a longer time in the presence of caveolin-1-GFP.


Caveolin-1 alters the pattern of cytoplasmic Ca2+ oscillations and Ca2+-dependent gene expression by enhancing leukotriene receptor desensitization.

Yeh YC, Tang MJ, Parekh AB - J. Biol. Chem. (2014)

Caveolin-1 expression increases agonist-evoked Ca2+ release from internal stores.A, cytoplasmic Ca2+ oscillations to LTC4 (applied in the presence of 2 mm external Ca2+) are compared between a WT cell and one expressing caveolin-1-GFP (Cav1) (dotted trace). B, the number of oscillations/100-s bin (recording period) is compared for the conditions shown. GFP denotes expression of GFP alone. Each data point is the mean of between 21 and 30 cells from three independent experiments. C–E, the peak amplitude of the first Ca2+ oscillation (C), average area of the oscillations (D), and mean duration of the oscillations (E) are compared among WT (26 cells), GFP-expressing (34 cells), and caveolin-1-GFP-expressing cells (39 cells). For D and E, the area and duration of each oscillation was measured, and then the data were pooled together. F, store-operated Ca2+ influx measured following stimulation with LTC4 in Ca2+-free solution for 600 s followed by readmission of external Ca2+ was compared between the two conditions. G, the graph compares the rundown of Ca2+ oscillations among WT (24 cells), GFP-expressing (29 cells), and caveolin-1-expressing cells (26 cells) when cells were stimulated with LTC4 in the absence of external Ca2+ as shown in F. H, the amplitude of the first Ca2+ oscillation, evoked by LTC4 in Ca2+-free solution, is compared. I, the rates of store-operated Ca2+ entry, measured by differentiating the Ca2+ rise following readmission of 2 mm Ca2+ as in F, are compared for the conditions shown (each bar denotes >25 cells from three independent experiments).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4067216&req=5

Figure 1: Caveolin-1 expression increases agonist-evoked Ca2+ release from internal stores.A, cytoplasmic Ca2+ oscillations to LTC4 (applied in the presence of 2 mm external Ca2+) are compared between a WT cell and one expressing caveolin-1-GFP (Cav1) (dotted trace). B, the number of oscillations/100-s bin (recording period) is compared for the conditions shown. GFP denotes expression of GFP alone. Each data point is the mean of between 21 and 30 cells from three independent experiments. C–E, the peak amplitude of the first Ca2+ oscillation (C), average area of the oscillations (D), and mean duration of the oscillations (E) are compared among WT (26 cells), GFP-expressing (34 cells), and caveolin-1-GFP-expressing cells (39 cells). For D and E, the area and duration of each oscillation was measured, and then the data were pooled together. F, store-operated Ca2+ influx measured following stimulation with LTC4 in Ca2+-free solution for 600 s followed by readmission of external Ca2+ was compared between the two conditions. G, the graph compares the rundown of Ca2+ oscillations among WT (24 cells), GFP-expressing (29 cells), and caveolin-1-expressing cells (26 cells) when cells were stimulated with LTC4 in the absence of external Ca2+ as shown in F. H, the amplitude of the first Ca2+ oscillation, evoked by LTC4 in Ca2+-free solution, is compared. I, the rates of store-operated Ca2+ entry, measured by differentiating the Ca2+ rise following readmission of 2 mm Ca2+ as in F, are compared for the conditions shown (each bar denotes >25 cells from three independent experiments).
Mentions: Endogenous levels of caveolin-1 were virtually undetectable in Western blots from RBL-1 cells (data not shown), so we overexpressed the GFP-tagged protein to study its impact on Ca2+ oscillations. In non-transfected (wild type) cells, stimulation with LTC4 evoked a series of cytoplasmic Ca2+ oscillations (Fig. 1A), which decreased slightly over time due to receptor desensitization (Fig. 1B) (6). Expression of caveolin-1-GFP substantially altered the pattern of the Ca2+ oscillations (Fig. 1A, dotted trace). The amplitudes of the initial Ca2+ oscillations evoked by LTC4 were now considerably larger than in non-transfected cells (Fig. 1, A and C), but the oscillations ran down more quickly and so were fewer in number over a 600 to 700-s recording period (Fig. 1B). Analysis of the various oscillatory parameters revealed that the total Ca2+ rise associated with each oscillation (area under the spike) was significantly larger in cells expressing caveolin-1-GFP (Fig. 1D); this reflected both an increase in the amplitude of each Ca2+ oscillation (Fig. 1C) as well as an increase in duration (Fig. 1E). Cytoplasmic Ca2+ during each oscillation was therefore elevated for a longer time in the presence of caveolin-1-GFP.

Bottom Line: Here, we show that the scaffolding protein caveolin-1 has a profound effect on receptor-driven Ca(2+) signals and downstream gene expression.Mutagenesis studies revealed that these effects required a functional scaffolding domain within caveolin-1.Our results reveal that caveolin-1 is a bimodal regulator of receptor-dependent Ca(2+) signaling, which fine-tunes the spatial and temporal profile of the Ca(2+) rise and thereby its ability to activate the NFAT pathway.

View Article: PubMed Central - PubMed

Affiliation: From the Department of Physiology, Anatomy, and Genetics, University of Oxford, Parks Road, Oxford OX1 3PT, United Kingdom and.

Show MeSH
Related in: MedlinePlus