H. Scholz et al., A FAR UPSTREAM CIS-ELEMENT IS REQUIRED FOR WILMS TUMOR-1 (WT1) GENE-EXPRESSION IN RENAL-CELL CULTURE, The Journal of biological chemistry, 272(52), 1997, pp. 32836-32846
To identify novel cis-regulatory elements responsible for the tissue-r
estricted expression pattern of the Wihms' tumor-1 (WT1) gene, we mapp
ed a total of 11 DNase I-hypersensitive sites in the 5'-flanking regio
n and first intron of the human gene, six of which were specific for W
T1 expressing cell lines. A 1.4-kilobase (kb) fragment from the mouse
wt1 5'-flanking region contained cross-hybridizing sequence with signi
ficant homology to a region of DNase I hypersensitivity in the human W
T1 gene which bound to nuclear matrix in human fetal kidney 293 cells.
None of the DNase I-hypersensitive sites/matrix attachment regions, e
ither alone or in combination, were sufficient for tissue-specific WT1
expression in transient and stably transfected cell lines. However, s
table transfection of an approximately 620-kb yeast artificial chromos
ome (YAC) that carried the entire mouse wt1 locus into 293 cells resul
ted in wt1 (trans)gene expression at a level of approximately 30% of t
he endogenous human gene. Deletion of the 1.4-kb cross-hybridizing mou
se fragment, located approximately 15 kb upstream of the transcription
start site, caused complete loss of wt1 gene expression in the YAC-tr
ansfected 293 cells. In summary, we have identified a far upstream ele
ment that contains a region of DNase I hypersensitivity and that binds
to nuclear matrix. This element includes phylogenetically conserved s
equence and is required, although not sufficient, for mouse wt1 gene e
xpression in human fetal kidney cells in culture.