Blood, Vol. 92 No. 8 (October 15), 1998:
pp. 2777-2790
Human Integrin 
3 Gene Expression: Evidence for a
Megakaryocytic Cell-Specific cis-Acting
Element
Ying Jin,
Calvin C. Wilhide,
Chi Dang,
Lu Li,
Su-Xia Li,
Manuel Villa-Garcia, and
Paul F. Bray
From the Division of Hematology, Department of Medicine, Johns
Hopkins University School of Medicine, Baltimore, MD; and Centro de
Desarrollo Biotechnologico, Monterrey, Mexico.
The human integrin 
3 participates in a wide range of
adhesive biologic functions and is expressed in a selected subset of tissues, but little is known about the cis-acting DNA elements or trans-acting factors responsible for this regulation. Using cell lines characterized for 3 expression, a number of
upstream regulatory regions in the 3 gene were
identified. (1) The three regions from 
1159 to 584, 290 to
146, and 126 to 115 demonstrated positive, negative, and
negative activity, respectively. (2) The region from 115 to +29 of
the 3 gene was sufficient for cell-specific activity.
Deletion of the sequence from 115 to 89 produced a 6- to 40-fold
reduction in reporter gene activity in 3-expressing megakaryocytic cell lines (K562, Dami, and HEL), but only a 1.7- and
2.7-fold reduction, respectively, in 3-expressing
endothelial and melanoma cell lines, and 1.3- and 2.8-fold reduction,
respectively, in non-3-expressing Chinese hamster ovary
and 293 cell lines. This sequence also bound nuclear proteins in a
cell-specific manner in electrophoretic mobility shift assays.
Mutational analysis indicated that the sequence GAGGGG (positions
113 to 108) is a megakaryocytic cell line-specific
cis-acting element. (3) The region from 89 to +29 promoted
lower activity in all cell lines. We also provide evidence that a
CCCACCC sequence at position 70 has transcriptional activity, most
likely through the Sp1 transcription factor. These data supply the
first detailed map of the transcriptional regulatory elements of the
5
region of the 3 gene, define positive regulatory sequences with potent megakaryocyte preferential activity, and indicate that the ubiquitous transcription factor, Sp1, may augment
3 gene expression.
© 1998 by The American Society of Hematology.
