Lipoprotein-stimulated surfactant secretion in alveolar type II cells: mediation by heterotrimeric G proteins.
Am J Physiol
; 273(3 Pt 1): L634-9, 1997 Sep.
Article
en En
| MEDLINE
| ID: mdl-9316499
ABSTRACT
Low- and high-density lipoproteins (LDL and HDL, respectively) stimulate alveolar type II cells to secrete surfactant. Increases in phosphoinositide hydrolysis, cytosolic Ca2+, and membrane-associated protein kinase C activity precede LDL- and HDL-stimulated secretion. We report three lines of evidence supporting the hypothesis that Gi mediates LDL- and HDL-stimulated surfactant secretion and signal transduction in type II cells. First, pertussis toxin (PTX) inhibited secretion stimulated by the apolipoprotein ligands for either the LDL receptor or the HDL binding protein. Second, PTX inhibited protein kinase C activity in cell membranes stimulated by LDL or HDL. Third, treatment of cell membranes with LDL or HDL inhibited PTX-catalyzed labeling of substrates corresponding in molecular mass to Gi alpha. These observations suggest that receptor-mediated activation of Gi is required for LDL- and HDL-stimulated secretion and that LDL and HDL activate Gi. These studies in type II cells are the first to support the hypothesis that Gi mediates the effects of LDL or HDL on important phenotype-specific functions of differentiated cells.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Alveolos Pulmonares
/
Surfactantes Pulmonares
/
Receptores de LDL
/
Proteínas Portadoras
/
Proteínas de Unión al ARN
/
Receptores de Lipoproteína
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Proteínas de Unión al GTP
/
Lipoproteínas HDL
/
Lipoproteínas LDL
Límite:
Animals
Idioma:
En
Revista:
Am J Physiol
Año:
1997
Tipo del documento:
Article
País de afiliación:
Estados Unidos