M. Little et al., DNA-BINDING CAPACITY OF THE WT1 PROTEIN IS ABOLISHED BY DENYS-DRASH SYNDROME WT1 POINT MUTATIONS, Human molecular genetics, 4(3), 1995, pp. 351-358
Constitutional point mutations in the zinc finger (ZF) region of the W
ilms' tumour suppressor gene 1 (WT1) lead to Denys-Drash syndrome (DDS
). Patients with this-syndrome display renal failure, Wilms' tumour (W
T) acid pseudohermaphroditism. DDS WT1 mutations fall into three major
categories: (a) missense mutations altering amino acids which directl
y interact with the DNA target; (b) substitution of amino acids involv
ed in zinc complexing; and (c) nonsense mutations leading to the remov
al of at least two zinc fingers. We have expressed the WT1 zinc finger
s as glutathione-S-transferase fusion proteins, with the lysine-threon
ine-serine (KTS) alternate splice between ZF3 and ZF4 either present o
r absent. WT1 fusion constructs with all three classes of DDS mutation
were also created. Wild-type and mutant fusion proteins were assayed
for their DNA-binding affinity using four previously identified WT1 DN
A targets: an EGR1 consensus site; murine insulin-like growth factor 2
promoter 2 (IGF2P2); a (TCC)n motif from the PDGFA-chain promoter; an
d +P5, a genomic fragment isolated by its affinity for WT1 + KTS. WT1
- KTS bound all four targets, but WT1 + KTS only bound +P5. All three
classes of DDS mutation investigated, with or without KTS, abolished b
inding to all four targets. This provides evidence that DDS mutations
act either as dominant-negative antimorphs, or elicit their effect thr
ough disturbed isoform dosage balance.