scholarly journals Scavenger receptor class B, type I (SR-BI) is the major route for the delivery of high density lipoprotein cholesterol to the steroidogenic pathway in cultured mouse adrenocortical cells

1997 ◽  
Vol 94 (25) ◽  
pp. 13600-13605 ◽  
Author(s):  
R. E. Temel ◽  
B. Trigatti ◽  
R. B. DeMattos ◽  
S. Azhar ◽  
M. Krieger ◽  
...  
Keyword(s):  
High Density Lipoprotein ◽  
High Density Lipoprotein Cholesterol ◽  
Scavenger Receptor ◽  
Density Lipoprotein ◽  
Lipoprotein Cholesterol ◽  
Type I ◽  
Adrenocortical Cells ◽  
Scavenger Receptor Class ◽  
Class B ◽  
Major Route

scholarly journals Scavenger Receptor Class B Type I in the Rat Ovary: Possible Role in High Density Lipoprotein Cholesterol Uptake and in the Recognition of Apoptotic Granulosa Cells*

Endocrinology ◽  
1999 ◽  
Vol 140 (6) ◽  
pp. 2494-2500 ◽  
Author(s):  
Per-Arne Svensson ◽  
Magnus S. C. Johnson ◽  
Charlotte Ling ◽  
Lena M. S. Carlsson ◽  
Håkan Billig ◽  
...  
Keyword(s):  
High Density Lipoprotein ◽  
Granulosa Cells ◽  
High Density Lipoprotein Cholesterol ◽  
Scavenger Receptor ◽  
Density Lipoprotein ◽  
High Density ◽  
Lipoprotein Cholesterol ◽  
Type I ◽  
Anionic Phospholipids ◽  
Thecal Cells

Abstract Scavenger receptor class B type I (SR-BI) mediates the selective uptake of high density lipoprotein cholesterol. SR-BI is expressed at high levels in the ovary, indicating that it plays a role in the delivery of cholesterol as substrate for steroid hormone production. However, SR-BI also binds anionic phospholipids with high affinity and could therefore be involved in the recognition of apoptotic cells. In this study we have characterized the expression of SR-BI in rat ovarian follicles undergoing atresia. Atretic follicles with cells undergoing apoptosis were identified by in situ DNA end labeling, and SR-BI expression was determined by in situ hybridization and immunohistochemistry. SR-BI was expressed in thecal cells at all stages of follicular development, including atretic follicles, and in corpus luteum. Isolated apoptotic granulosa cells (but not viable granulosa cells) bound annexin V, indicating that they display anionic phospholipids on the cell surface. Transfection of COS-7 cells with an expression vector carrying the rat SR-BI complementary DNA resulted in increased binding to apoptotic granulosa cells (46 ± 2% of the SR-BI-expressing cells bound at least one granulosa cell compared with 24 ± 3% for the mock-transfected cells; P < 0.0001), whereas the binding to viable granulosa cells was unchanged. Apoptotic granulosa cells also bound to isolated thecal shells. We conclude that thecal cells of both nonatretic and atretic follicles express SR-BI. The location of SR-BI expression in the ovary supports a role of this receptor in the uptake of high density lipoprotein cholesterol. In addition, our data suggest that SR-BI mediates the recognition of apoptotic granulosa cells by the surrounding thecal cells and that it therefore may play a role in the remodeling of atretic follicles to secondary interstitial cells.

scholarly journals Binding of High Density Lipoprotein (HDL) and Discoidal Reconstituted HDL to the HDL Receptor Scavenger Receptor Class B Type I

2000 ◽  
Vol 275 (28) ◽  
pp. 21262-21271 ◽  
Author(s):  
Kalliopi N. Liadaki ◽  
Tong Liu ◽  
Shangzhe Xu ◽  
Brian Y. Ishida ◽  
Philippe N. Duchateaux ◽  
...  
Keyword(s):  
High Density Lipoprotein ◽  
Scavenger Receptor ◽  
Density Lipoprotein ◽  
High Density ◽  
Type I ◽  
Scavenger Receptor Class ◽  
Class B

scholarly journals p21-activated Kinase-1 (PAK1) Inhibition of the Human Scavenger Receptor Class B, Type I Promoter in Macrophages Is Independent of PAK1 Kinase Activity, but Requires the GTPase-binding Domain

2001 ◽  
Vol 276 (50) ◽  
pp. 46807-46814 ◽  
Author(s):  
Thomas G. Hullinger ◽  
Robert L. Panek ◽  
Xiangyang Xu ◽  
Sotirios K. Karathanasis
Keyword(s):  
High Density Lipoprotein ◽  
Promoter Activity ◽  
Kinase Activity ◽  
Scavenger Receptor ◽  
Density Lipoprotein ◽  
Type I ◽  
Down Regulation ◽  
Scavenger Receptor Class ◽  
Class B

Scavenger receptor class B, type I (SR-BI), is a high density lipoprotein receptor that mediates the flux of cholesterol between high density lipoprotein and cells. Recent evidence suggests that SR-BI plays a role in atherosclerosis and that inflammatory mediators down-regulate SR-BI in the macrophage. The purpose of this study was to evaluate the ability of lipopolysaccharide (LPS) to down-regulate the activity of the human SR-BI promoter in the macrophage and to delineate the mechanisms involved. Experiments with cultured cells andin vivoderived macrophages showed that LPS has a powerful suppressive effect on SR-BI expression bothin vitroandin vivo. Transient transfection studies demonstrated that LPS represses SR-BI promoter activity in the macrophage cell line RAW 264.7. Cotransfection with either a constitutively active p21-activated protein kinase-1 (PAK1) construct (T423E) or a kinase-deficient PAK1 construct (K299R) resulted in repression of the SR-BI promoter, similar to LPS. These results demonstrate that PAK1-mediated down-regulation of the SR-BI promoter is independent of PAK1 kinase activity and suggest that PAK1 mediates the LPS-induced decrease in promoter activity. Cotransfection with constitutively active Cdc42 or Rac expression constructs also resulted in down-regulation of the promoter; whereas the dominant-negative Cdc42 and Rac constructs elevated basal promoter activity and blunted the LPS response. Cotransfection of PAK1 constructs containing mutations in both the kinase domain and the Cdc42/Rac-binding domain attenuated the PAK1-mediated down-regulation of the promoter, suggesting that Rac and Cdc42 are required for PAK1-mediated decreases in SR-BI promoter activity. 5′-Deletion analysis and gel shift data suggest that LPS inhibits binding of a novel transcription factor to a myeloid zing finger protein-1-like element (−476 to −456) in the human SR-BI promoter. These results demonstrate that the PAK1 pathway down-regulates the SR-BI promoter and suggest that activation of this pathway may play an important role in cholesterol trafficking in the vessel wall.

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