title: Expression of human scavenger receptor B1 on and in human platelets.
abstract: OBJECTIVE
  The abundance of HDL particles correlates inversely with the incidence of coronary heart disease. The human scavenger receptor B1 (hSR-B1/CLA-1) is a receptor for HDL. Expression of hSR-B1/CLA-1 mRNA and protein in human platelets was determined using reverse transcriptase-polymerase chain reaction and Western blot, respectively. Presence of the protein on the surface of platelets was shown using flow cytometry.
  
  
  RESULTS
  Immunochemical staining for hSR-B1/CLA-1 showed that it was expressed in megakaryocytes, the platelet precursors of human bone marrow. These findings prompted us to ask whether hSR-B1/CLA-1 was differentially expressed on platelets obtained from patients with atherosclerotic disease compared with those in control subjects. Our findings showed that abundance of hSR-B1/CLA-1 was significantly reduced on the surface of platelets from patients with atherosclerotic disease. The reduced levels of hSR-B1/CLA-1 were associated with increased cholesterol ester content in platelets from patients with atherosclerotic disease compared with control subjects. A negative correlation existed between hSR-B1/CLA-1 expression and platelet aggregation. In summary, our studies show that the HDL receptor hSR-B1/CLA-1 is expressed in platelets and their precursor, the megakaryocyte. The levels of hSR-B1/CLA-1 expression correlate inversely with cholesterol ester content and platelet aggregation.
  
  
  CONCLUSIONS
  These findings suggest that determining the level of hSR-B1/CLA-1 expression on the platelets may be a useful clinical marker for atherosclerotic diseases.
authors.affiliation: First Department of Internal Medicine, Central Laboratory, Kagawa Medical University, 1750-1, Miki-cho, Kita-gun, Kagawa, 761-0793, Japan.
authors.forename: Hitomi
authors.initials: H
authors.lastname: Imachi
authors.forename: Koji
authors.initials: K
authors.lastname: Murao
authors.forename: Wenming
authors.initials: W
authors.lastname: Cao
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tada
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Taminato
authors.forename: Norman C W
authors.initials: NC
authors.lastname: Wong
authors.forename: Jiro
authors.initials: J
authors.lastname: Takahara
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Ishida
mesh_terms: D000328:Adult; D000368:Aged; D001161:Arteriosclerosis / Q000097:blood*; D015415:Biomarkers; D001792:Blood Platelets / Q000737:chemistry*; D018955:CD36 Antigens / Q000097:blood* / Q000235:genetics; D002462:Cell Membrane / Q000737:chemistry; D002478:Cells, Cultured; D002784:Cholesterol / Q000378:metabolism; D002788:Cholesterol Esters / Q000097:blood; D005260:Female; D006801:Humans; D008297:Male; D008533:Megakaryocytes / Q000737:chemistry; D008565:Membrane Proteins; D008875:Middle Aged; D010974:Platelet Aggregation; D012333:RNA, Messenger / Q000097:blood; D011971:Receptors, Immunologic; D018110:Receptors, Lipoprotein; D051116:Receptors, Scavenger; D051122:Scavenger Receptors, Class B; D014162:Transfection
chemical_list: D015415:Biomarkers; D018955:CD36 Antigens; D002788:Cholesterol Esters; D008565:Membrane Proteins; D012333:RNA, Messenger; D011971:Receptors, Immunologic; D018110:Receptors, Lipoprotein; D051116:Receptors, Scavenger; C454739:Scarb1 protein, mouse; D051122:Scavenger Receptors, Class B; D002784:Cholesterol