Blood, 1 October 2001, Vol. 98, No. 7, pp. 2279-2281
BRIEF REPORT
ORP-3, a human oxysterol-binding protein gene
differentially expressed in hematopoietic cells
Claudia C. Gregorio-King,
Gregory R. Collier,
Janine S. McMillan,
Caryll M. Waugh,
Janet L. McLeod,
Fiona M. Collier, and
Mark A. Kirkland
From the Stem Cell Laboratory, Douglas Hocking Research
Institute, Barwon Health, The Geelong Hospital, and the Metabolic
Research Unit, Deakin University, Geelong Victoria, Australia.
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.
