A novel chimeric aequorin fused with caveolin-1 reveals a sphingosine kinase 1-regulated Ca²âº microdomain in the caveolar compartment.
Biochim Biophys Acta
; 1853(9): 2173-82, 2015 Sep.
Article
em En
| MEDLINE
| ID: mdl-25892494
ABSTRACT
Caveolae are plasma membrane invaginations enriched in sterols and sphingolipids. Sphingosine kinase 1 (SK1) is an oncogenic protein that converts sphingosine to sphingosine 1-phosphate (S1P), which is a messenger molecule involved in calcium signaling. Caveolae contain calcium responsive proteins, but the effects of SK1 or S1P on caveolar calcium signaling have not been investigated. We generated a Caveolin-1-Aequorin fusion protein (Cav1-Aeq) that can be employed for monitoring the local calcium concentration at the caveolae ([Ca²âº]cav). In HeLa cells, Cav1-Aeq reported different [Ca²âº] as compared to the plasma membrane [Ca²âº] in general (reported by SNAP25-Aeq) or as compared to the cytosolic [Ca²âº] (reported by cyt-Aeq). The Ca²âº signals detected by Cav1-Aeq were significantly attenuated when the caveolar structures were disrupted by methyl-ß-cyclodextrin, suggesting that the caveolae are specific targets for Ca²âº signaling. HeLa cells overexpressing SK1 showed increased [Ca²âº]cav during histamine-induced Ca²âº mobilization in the absence of extracellular Ca²âº as well as during receptor-operated Ca²âº entry (ROCE). The SK1-induced increase in [Ca²âº]cav during ROCE was reverted by S1P receptor antagonists. In accordance, pharmacologic inhibition of SK1 reduced the [Ca²âº]cav during ROCE. S1P treatment stimulated the [Ca²âº]cav upon ROCE. The Ca²âº responses at the plasma membrane in general were not affected by SK1 expression. In summary, our results show that SK1/S1P-signaling regulates Ca²âº signals at the caveolae. This article is part of a Special Issue entitled 13th European Symposium on Calcium.
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Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteínas Recombinantes de Fusão
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Fosfotransferases (Aceptor do Grupo Álcool)
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Equorina
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Sinalização do Cálcio
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Cavéolas
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Caveolina 1
Limite:
Humans
Idioma:
En
Revista:
Biochim Biophys Acta
Ano de publicação:
2015
Tipo de documento:
Article
País de afiliação:
Finlândia