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Sin3 corepressor function in Myc-induced transcription and transformation
1Department of Biology, Massachusetts Institute of Technology, Cambridge 02139, USA.
Summary
Basic helix-loop-helix-leucine zipper (b-HLH-LZ) proteins bind DNA similarly but act differently. Targeting the mSin3 corepressor to specific DNA sites can suppress Myc-driven cell growth and transformation.
Area of Science:
- Molecular Biology
- Gene Regulation
- Oncology
Background:
- Basic helix-loop-helix-leucine zipper (b-HLH-LZ) proteins, including Myc family members, bind the DNA sequence CACGTG.
- While Myc activates transcription and transformation, related proteins like Mad and Mxi1 suppress these processes by interacting with the mSin3 corepressor.
Purpose of the Study:
- To investigate if the DNA binding specificity of b-HLH-LZ proteins is shared.
- To determine if targeting the mSin3 corepressor to specific DNA sites can oppose Myc activity.
Main Methods:
- Transferring a mSin3-interacting region from Mad or Mxi1 to the b-HLH-LZ domain of TFEB.
- Assessing the effect of engineered TFEB on Myc-induced transcription and transformation.
Main Results:
- The b-HLH-LZ domain of TFEB alone did not suppress Myc activity.
- Transferring the mSin3-interacting region to TFEB conferred profound suppression of Myc-induced transcription and transformation.
- These findings indicate shared DNA binding specificities among b-HLH-LZ proteins relevant to Myc-induced transformation.
Conclusions:
- The DNA binding specificities of Myc family and non-Myc family b-HLH-LZ proteins are shared in the context of Myc-induced transformation.
- Recruiting the mSin3 corepressor to CACGTG sites via a non-Myc b-HLH-LZ domain is sufficient to counteract Myc's role in cell growth regulation.