Related Experiment Videos
Inhibition of Tcf3 binding by I-mfa domain proteins
L Snider1, H Thirlwell, J R Miller
1Fred Hutchinson Cancer Research Center, University of Washington Medical Center, Seattle, Washington 98109.
Abstract:
We have determined that I-mfa, an inhibitor of several basic helix-loop-helix (bHLH) proteins, and XIC, a Xenopus ortholog of human I-mf domain-containing protein that shares a highly conserved cysteine-rich C-terminal domain with I-mfa, inhibit the activity and DNA binding of the HMG box transcription factor XTcf3. Ectopic expression of I-mfa or XIC in early Xenopus embryos inhibited dorsal axis specification, the expression of the Tcf3/beta-catenin-regulated genes siamois and Xnr3, and the ability of beta-catenin to activate reporter constructs driven by Lef/Tcf binding sites. I-mfa domain proteins can regulate both the Wnt signaling pathway and a subset of bHLH proteins, possibly coordinating the activities of these two critical developmental pathways.
Insights
I-mfa and XIC inhibit the HMG box transcription factor XTcf3, impacting dorsal axis specification and gene expression in Xenopus embryos. These proteins may coordinate Wnt signaling and basic helix-loop-helix (bHLH) protein activities.
Area of Science:
- Developmental Biology
- Molecular Biology
- Genetics
Background:
- Basic helix-loop-helix (bHLH) proteins and HMG box transcription factors are crucial for embryonic development.
- The Wnt signaling pathway plays a vital role in early embryonic patterning.
- XTcf3 is an HMG box transcription factor involved in embryonic development.
Purpose of the Study:
- To investigate the inhibitory effects of I-mfa and XIC on XTcf3 activity and DNA binding.
- To determine the role of I-mfa and XIC in Xenopus embryonic development and Wnt signaling.
Main Methods:
- Inhibition assays to assess XTcf3 activity and DNA binding.
- Ectopic expression of I-mfa and XIC in early Xenopus embryos.
- Analysis of dorsal axis specification and gene expression (siamois, Xnr3).
- Reporter gene assays to evaluate beta-catenin activity.
Main Results:
- I-mfa and XIC were found to inhibit the activity and DNA binding of XTcf3.
- Ectopic expression of I-mfa or XIC disrupted dorsal axis formation in Xenopus embryos.
- The expression of Tcf3/beta-catenin-regulated genes (siamois, Xnr3) was inhibited.
- Beta-catenin's ability to activate Lef/Tcf-driven reporter constructs was reduced.
Conclusions:
- I-mfa and XIC proteins can inhibit the HMG box transcription factor XTcf3.
- These proteins play a role in regulating dorsal axis specification and gene expression in Xenopus.
- I-mfa domain proteins may coordinate the Wnt signaling pathway and bHLH protein activities during development.