Scavenger receptor class B Type I (SR-BI) assembles into detergent-sensitive dimers and tetramers

Sahoo, Daisy; Darlington, Yolanda F.; Pop, Diana; Williams, David L.; Connelly, Margery A.

doi:10.1016/j.bbalip.2006.03.003

Cited by 44 publications

(61 citation statements)

References 48 publications

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“…44,[47][48][49][50] Interestingly, SR-BI has been shown to exist as dimeric complexes in a variety of cell types; also, there is recent biochemical evidence that SR-BI forms stable oligomeric structures. 51,52 By using fluorescence resonance energy transfer, it has been demonstrated in live cells that the C-terminal region of SR-BI containing both the CTTM and the C-terminal cytoplasmic tail supports its homooligomerization. 52 The molecular basis of SR-BI homooligmerization and its functional significance in HDL-SR-BI signaling remain unknown.…”

Section: Arterioscler Thromb Vasc Biol February 2010mentioning

confidence: 99%

Signaling by the High-Affinity HDL Receptor Scavenger Receptor B Type I

Saddar

Mineo

Shaul

2010

ATVB

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Abstract-Scavenger receptor B type I (SR-BI) plays an important role in mediating cholesterol exchange between cells, high-density lipoprotein (HDL) cholesterol, and other lipoproteins. SR-BI in hepatocytes is essential for reverse cholesterol transport and biliary secretion of HDL cholesterol; thus, it is atheroprotective. More recently, it has been discovered that the HDL-SR-BI tandem serves other functions that also likely contribute to HDL-related cardiovascular protection. A number of the latter mechanisms, particularly in endothelial cells, involve unique direct signal initiation by SR-BI that leads to the activation of diverse kinase cascades. SR-BI signaling occurs in response to plasma membrane cholesterol flux. It requires the C-terminal PDZ-interacting domain of the receptor, which mediates direct interaction with the adaptor molecule PDZK1; and the C-terminal transmembrane domain, which directly binds membrane cholesterol. In endothelium, direct SR-BI signaling in response to HDL results in enhanced production of the antiatherogenic molecule nitric oxide; in a nitric oxide-independent manner, it serves to maintain endothelial monolayer integrity. The role of SR-BI signaling in the numerous other cellular targets of HDL, including hepatocytes, macrophages, and platelets, and the basis by which SR-BI senses plasma membrane cholesterol movement to modify cell behavior are unknown.

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Section: Arterioscler Thromb Vasc Biol February 2010mentioning

confidence: 99%

Signaling by the High-Affinity HDL Receptor Scavenger Receptor B Type I

Saddar

Mineo

Shaul

2010

ATVB

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“…The mechanisms by which HDL and AcLDL trigger different lipid uptake pathways remain to be discovered. It is currently unclear whether SR-BI's oligomerization state (69,70) and/or localization in lipid rafts/caveolae (49) determine endocytic versus nonendocytic pathways, or are influenced by binding to distinct ligands. Nevertheless, our data suggest that mSR-BI endocytosis versus retention on the cell surface may be a step at which SR-BI's selective uptake activity can be regulated.…”

Section: Discussionmentioning

confidence: 99%

Regulation of SR-BI-mediated selective lipid uptake in Chinese hamster ovary-derived cells by protein kinase signaling pathways

Zhang

Ahmed

McFarlane

et al. 2007

Journal of Lipid Research

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Scavenger receptor, class B, type I (SR-BI) mediates binding and internalization of a variety of lipoprotein and nonlipoprotein ligands, including HDL. Studies in genetically engineered mice revealed that SR-BI plays an important role in HDL reverse cholesterol transport and protection against atherosclerosis. Understanding how SR-BI's function is regulated may reveal new approaches to therapeutic intervention in atherosclerosis and heart disease. We utilized a model cell system to explore pathways involved in SR-BI-mediated lipid uptake from and signaling in response to distinct lipoprotein ligands: the physiological ligand, HDL, and a model ligand, acetyl LDL (AcLDL). In Chinese hamster ovary-derived cells, murine SR-BI (mSR-BI) mediates lipid uptake via distinct pathways that are dependent on the lipoprotein ligand. Furthermore, HDL and AcLDL activate distinct signaling pathways. Finally, mSR-BImediated selective lipid uptake versus endocytic uptake are differentially regulated by protein kinase signaling pathways. The protein kinase C (PKC) activator PMA and the phosphatidyl inositol 3-kinase inhibitor wortmannin increase the degree of mSR-BI-mediated selective lipid uptake, whereas a PKC inhibitor has the opposite effect. These data demonstrate that SR-BI's selective lipid uptake activity can be acutely regulated by intracellular signaling cascades, some of which can originate from HDL binding to murine SR-BI itself.

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“…Since human SR-BI forms oligomers on the cell surface (48,49), we wanted to investigate whether the impaired-sE2-binding phenotype of the E210A mutant could be due to a defect in receptor oligomerization. Therefore, we generated C terminus tagged versions of wild-type and mutant receptors, adding two different tag sequences: V5 or c-Myc.…”

Section: Sr-bi Is Involved In An Early Step Of Hcv Infectionmentioning

confidence: 99%

Role of Scavenger Receptor Class B Type I in Hepatitis C Virus Entry: Kinetics and Molecular Determinants

Catanese

Ansuini²,

Graziani³

et al. 2010

J Virol

147

140

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Scavenger receptor class B type I (SR-BI) is an essential receptor for hepatitis C virus (HCV) and a cellHepatitis C virus (HCV) is a global blood-borne pathogen, with 3% of the world's population chronically infected. Most infections are asymptomatic, yet 60 to 80% become persistent and lead to severe fibrosis and cirrhosis, hepatic failure, or hepatocellular carcinoma (3). Currently available therapies are limited to the administration of pegylated alpha interferon in combination with ribavirin, which are expensive and often unsuccessful, with significant side effects (23, 36). Thus, the development of novel therapeutic approaches against HCV remains a high priority (18,40,60). Targeting the early steps of HCV infection may represent one such option, and much effort is being devoted to uncovering the mechanism of viral attachment and entry.The current view is that HCV entry into target cells occurs after attachment to specific cellular receptors via its surface glycoproteins E1 and E2 (27). The molecules to which HCV initially binds might constitute a diverse collection of cellular proteins, carbohydrates, and lipids that concentrate viruses on the cell surface and determine to a large extent which cell types, tissues, and organisms HCV can infect.CD81, claudin 1 (CLDN1), occludin (OCLN), and scavenger receptor class B type I (SR-BI) were previously shown to play essential roles in HCV cell entry (15,22,26,35,42,43,50,63,64).Recent reports suggest that CD81 engagement triggers intracellular signaling responses, ultimately leading to actin remodeling and the relocalization of CD81 to tight junctions (TJ) (11). Thus, CD81 may function as a bridge between the initial interaction of the virus with receptors on the basolateral surface of the hepatocyte and the TJ where two of the HCV entry molecules, CLDN1 and OCLN, are located. CD81 acts as a postbinding factor, and the TJ proteins CLDN1 and OCLN seem to be involved in late steps of HCV entry, such as HCV glycoprotein-dependent cell fusion (9,11,22). The discovery of TJ proteins as entry factors has added complexity to the model of HCV entry, suggesting parallels with other viruses like coxsackievirus B infection, where an initial interaction of the viral particle with the primary receptor decay-accelerating factor induces the lateral movement of the virus from the luminal surface to TJ, where coxsackievirus B binds coxsackievirusadenovirus receptor and internalization takes place (17).Much less is known about the specific role of SR-BI in virus * Corresponding author. Mailing address: Okairòs, via dei Castelli Romani 22,

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Scavenger receptor class B Type I (SR-BI) assembles into detergent-sensitive dimers and tetramers

Cited by 44 publications

References 48 publications

Signaling by the High-Affinity HDL Receptor Scavenger Receptor B Type I

Signaling by the High-Affinity HDL Receptor Scavenger Receptor B Type I

Regulation of SR-BI-mediated selective lipid uptake in Chinese hamster ovary-derived cells by protein kinase signaling pathways

Role of Scavenger Receptor Class B Type I in Hepatitis C Virus Entry: Kinetics and Molecular Determinants

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