Physiological and coordinate downregulation of the NPC1 and NPC2 genes are associated with the sequestration of LDL-derived cholesterol within endocytic compartments.
J Cell Biochem
; 108(5): 1102-16, 2009 Dec 01.
Article
em En
| MEDLINE
| ID: mdl-19746448
ABSTRACT
The Niemann-Pick C1 and C2 (NPC1 and NPC2) proteins have a central role in regulating the transport of lipoprotein-derived cholesterol from endocytic compartments to the endoplasmic reticulum for esterification by acyl-CoAcholesterol acyltransferase (ACAT) and feedback inhibition of the sterol regulatory element-binding protein (SREBP) pathway. Since the NPC1 gene/protein has recently been shown to be downregulated by feedback inhibition of the SREBP pathway, the present study was performed to determine whether physiological downregulation of the NPC1 gene/protein alters the transport and metabolism of low-density lipoprotein (LDL)-derived cholesterol in human fibroblasts. To perform this study, three different culture conditions were used that included fibroblasts grown in lipoprotein-deficient serum (LPDS), LPDS supplemented with LDL, and LPDS supplemented with LDL, followed by equilibration in the absence of LDL to allow the transport of LDL-derived cholesterol from endocytic compartments and equilibration of cellular sterol pools. The results from this study indicated that in addition to the NPC1 gene/protein, the NPC2 gene/protein was also downregulated by LDL-derived cholesterol-dependent feedback inhibition and that downregulation of both the NPC1 and NPC2 genes/proteins was associated with the sequestration of LDL-derived cholesterol within endocytic compartments, including late endosomes/lysosomes after equilibration. Therefore, it is proposed that physiological and coordinate downregulation of the NPC1 and NPC2 genes/proteins promotes the sequestration of LDL-derived cholesterol within endocytic compartments and serves a role in maintaining intracellular cholesterol homeostasis.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Glicoproteínas de Membrana
/
Glicoproteínas
/
Proteínas de Transporte
/
Fibroblastos
/
LDL-Colesterol
Tipo de estudo:
Risk_factors_studies
Limite:
Humans
Idioma:
En
Ano de publicação:
2009
Tipo de documento:
Article