The Wilms' tumor gene product WT1 activates or suppresses transcription through separate functional domains

Area of Science:

• Molecular Biology
• Gene Regulation
• Cancer Biology

Background:

• The Wilms tumor 1 (WT1) gene product was previously identified as a potential tumor suppressor.
• WT1 was shown to interact with the platelet-derived growth factor A-chain (PDGF-A) gene promoter, inhibiting its activity.

Purpose of the Study:

• To investigate the dual role of WT1 as a transcriptional regulator.
• To identify the specific domains of WT1 responsible for transcriptional activation and suppression.

Main Methods:

• Chimeric reporter plasmids were used to assess WT1's effect on gene transcription.
• Site-directed mutagenesis and gene truncation were employed to map functional domains within the WT1 protein.

Main Results:

• WT1 functions as a transcriptional activator in addition to its suppressor role.
• Transcriptional repression by WT1 requires binding to both 5' and 3' DNA sites, while binding to either site alone results in activation.
• Amino acid residues 84-179 are critical for suppression, while residues 180-294 mediate activation.

Conclusions:

• WT1 possesses distinct regulatory domains enabling both transcriptional activation and suppression.
• The function of WT1 as an activator or suppressor may depend on its binding context and specific gene targets.