Related Experiment Videos
The Wilms' tumor gene product WT1 activates or suppresses transcription through separate functional domains
1Department of Medicine, Washington University School of Medicine, St. Louis, Missouri.
Abstract:
We recently reported that the putative tumor suppressor gene product WT1 interacts with a 5'-flanking DNA sequence 5'-GCGGGGGCG-3' within the platelet-derived growth factor A-chain gene and abolishes its promoter activity, suggesting that WT1 functions as a transcriptional suppressor of the platelet-derived growth factor A-chain gene. We now show that WT1 functions also as a transcriptional activator. Using chimeric reporter plasmids, we demonstrated that WT1 requires both 5' and 3' binding sites relative to transcription start site for transcriptional repression; however, when WT1 binds to either the 5' or the 3' site alone, WT1 functions to activate transcription. We truncated the wt1 gene and established that amino acid residues 84-179 are required for transcriptional suppression, whereas amino acid residues 180-294 contain a domain that mediates transcriptional activation. These results establish that WT1 has regulatory domains that function either to activate or suppress transcription and suggest the possibility that WT1 functions as an activator and not as a suppressor of selected gene transcription.
Insights
The Wilms tumor 1 (WT1) protein can both suppress and activate gene transcription. Specific domains within WT1 mediate these opposing regulatory functions, impacting gene expression in cellular processes.
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.