ORP-3, a human oxysterol-binding protein gene differentially expressed in hematopoietic cells.
Using differential display polymerase chain reaction, a gene was identified in CD34(+)-enriched populations that had with low or absent expression in CD34(-) populations. The full coding sequence of this transcript was obtained, and the predicted protein has a high degree of homology to oxysterol-binding protein. This gene has been designated OSBP-related protein 3 (ORP-3). Expression of ORP-3 was found to be 3- to 4-fold higher in CD34(+) cells than in CD34(-) cells. Additionally, expression of this gene was 2-fold higher in the more primitive subfraction of hematopoietic cells defined by the CD34(+)38(-) phenotype and was down-regulated with the proliferation and differentiation of CD34(+) cells. The ORP-3 predicted protein contains an oxysterol-binding domain. Well-characterized proteins expressing this domain bind oxysterols in a dose-dependent fashion. Biologic activities of oxysterols include inhibition of cholesterol biosynthesis and cell proliferation in a variety of cell types, among them hematopoietic cells. Characterization and differential expression of ORP-3 implicates a possible role in the mediation of oxysterol effects on hematopoiesis.
Gregorio-King
C C
CC
Stem Cell Laboratory, Douglas Hocking Research Institute, Barwon Health, The Geelong Hospital, Geelong Victoria, Australia. ccgk@deakin.edu.au
Collier
G R
GR
McMillan
J S
JS
Waugh
C M
CM
McLeod
J L
JL
Collier
F M
FM
Kirkland
M A
MA
D018952:Antigens, CD34; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics*; D050556:Fatty Acid-Binding Proteins; D005312:Fetal Blood / Q000166:cytology; D005786:Gene Expression Regulation; D006412:Hematopoietic Stem Cells / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction / Q000379:methods; D012333:RNA, Messenger / Q000302:isolation & purification; D011987:Receptors, Steroid / Q000235:genetics*; D017423:Sequence Analysis, RNA; D012689:Sequence Homology, Nucleic Acid; D000098825:Oxysterol Binding Proteins
D018952:Antigens, CD34; D002352:Carrier Proteins; D050556:Fatty Acid-Binding Proteins; C471934:OSBPL3 protein, human; D012333:RNA, Messenger; D011987:Receptors, Steroid; D000098825:Oxysterol Binding Proteins