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Updated: Jun 11, 2026
Mapping the Structure-Function Relationships of Disordered Oncogenic Transcription Factors Using Transcriptomic Analysis
Published on: June 27, 2020
Identification of a structural motif in the tumor-suppressive protein GRIM-19 required for its antitumor activity
Shreeram C Nallar1, Sudhakar Kalakonda, Peng Sun
1Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
Abstract:
We have previously isolated GRIM-19, a novel growth suppressor, using a genetic method. GRIM-19 ablates cell growth by inhibiting the transcription factor signal transducer and activator of transcription 3 (STAT3). Up-regulation of STAT3 and growth promotion were observed in a number of human tumors. Although the tumor-suppressive actions of GRIM-19 are known, the structural elements required for its antitumor actions are not understood. Mutational and protein sequence analyses identified a motif in the N terminus of GRIM-19 that exhibited similarity to certain RNA viral proteins. We show that disruption of specific amino acids within this motif cripples the antitumor actions of GRIM-19. These mutants fail to interact with STAT3 efficiently and consequently do not inhibit growth-promoting gene expression. More importantly, we show that a clinically observed mutation in the N terminus of GRIM-19 also weakened its interaction with STAT3 and antitumor action. Together, these studies identify a major role for the N terminus of GRIM-19 in mediating its tumor-suppressive actions.
Insights
GRIM-19 inhibits tumor growth by blocking signal transducer and activator of transcription 3 (STAT3). Specific N-terminal amino acids are crucial for GRIM-19's interaction with STAT3 and its tumor-suppressive function.
Area of Science:
- Molecular Biology
- Cancer Research
- Genetics
Background:
- GRIM-19 is a novel growth suppressor identified through genetic screening.
- GRIM-19 inhibits cell growth by targeting the signal transducer and activator of transcription 3 (STAT3).
- STAT3 is frequently upregulated in human tumors, promoting cancer growth.
Purpose of the Study:
- To identify the structural elements within GRIM-19 essential for its tumor-suppressive activity.
- To investigate the mechanism by which GRIM-19 interacts with STAT3.
Main Methods:
- Mutational analysis of the GRIM-19 protein sequence.
- Protein-protein interaction studies between GRIM-19 and STAT3.
- Assessment of gene expression related to growth promotion.
Main Results:
- A specific motif in the N terminus of GRIM-19, similar to RNA viral proteins, is critical for its antitumor function.
- Disruption of this motif impairs GRIM-19's interaction with STAT3.
- Mutations in this motif lead to reduced inhibition of growth-promoting genes.
- A clinically observed mutation in the N terminus also weakened STAT3 interaction and antitumor effects.
Conclusions:
- The N terminus of GRIM-19 plays a critical role in mediating its tumor-suppressive actions.
- Effective interaction with STAT3 is essential for GRIM-19's ability to inhibit tumor growth.
- Understanding these structural requirements could inform cancer therapy development.
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