title: Human retinal pigment epithelial cells express scavenger receptors BI and BII.
abstract: The retinal pigment epithelial (RPE) cells that underlie the retina ingest and metabolize thousands of lipid-rich photoreceptor outer segments (POS) every day. The scavenger receptor (SR) CD36 and integrin alphavbeta5 have been shown to participate in POS binding and internalization by RPE cells. The objective of the current study was to determine whether RPE cells express SRs other than CD36. Primary cultures of human RPE cells express both mRNA and protein for SR-BI and SR- BII. SR-BI and SR-BII mRNAs were detected by reverse transcription-polymerase chain reaction. SR-BI protein was detected by immune precipitation of [(35)S]methionine-labeled crude cellular extracts. SR-BII was detected by Western blotting of immune precipitated crude cellular extracts. SR-BI and SR-BII proteins were also detected by immunofluorescence staining of RPE cells in culture. The results suggest that these SRs may play a role in POS lipid binding and uptake by RPE cells in the eye.
authors.affiliation: Department of Ophthalmology, University of California at San Francisco, San Francisco, California 94143, USA.
authors.forename: Keith G
authors.initials: KG
authors.lastname: Duncan
authors.forename: Kathy R
authors.initials: KR
authors.lastname: Bailey
authors.forename: John P
authors.initials: JP
authors.lastname: Kane
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Schwartz
mesh_terms: D015153:Blotting, Western; D018955:CD36 Antigens / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics; D002457:Cell Extracts / Q000737:chemistry; D002478:Cells, Cultured; D005455:Fluorescent Antibody Technique; D006801:Humans; D051907:Lysosomal Membrane Proteins; D008565:Membrane Proteins; D010857:Pigment Epithelium of Eye / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D011233:Precipitin Tests; D020033:Protein Isoforms / Q000032:analysis / Q000096:biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D018110:Receptors, Lipoprotein / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics; D051116:Receptors, Scavenger; D051122:Scavenger Receptors, Class B; D012795:Sialoglycoproteins
chemical_list: D018955:CD36 Antigens; D002457:Cell Extracts; D051907:Lysosomal Membrane Proteins; D008565:Membrane Proteins; D020033:Protein Isoforms; D012333:RNA, Messenger; D018110:Receptors, Lipoprotein; D051116:Receptors, Scavenger; C074299:SCARB2 protein, human; C454739:Scarb1 protein, mouse; D051122:Scavenger Receptors, Class B; D012795:Sialoglycoproteins