Cryo-EM structure of CtBP2 confirms tetrameric architecture
Anne M Jecrois1, M Michael Dcona2, Xiaoyan Deng3
1Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
Abstract:
C-terminal binding proteins 1 and 2 (CtBP1 and CtBP2) are transcriptional regulators that activate or repress many genes involved in cellular development, apoptosis, and metastasis. NADH-dependent CtBP activation has been implicated in multiple types of cancer and poor patient prognosis. Central to understanding activation of CtBP in oncogenesis is uncovering how NADH triggers protein assembly, what level of assembly occurs, and if oncogenic activity depends upon such assembly. Here, we present the cryoelectron microscopic structures of two different constructs of CtBP2 corroborating that the native state of CtBP2 in the presence of NADH is tetrameric. The physiological relevance of the observed tetramer was demonstrated in cell culture, showing that CtBP tetramer-destabilizing mutants are defective for cell migration, transcriptional repression of E-cadherin, and activation of TIAM1. Together with our cryoelectron microscopy studies, these results highlight the tetramer as the functional oligomeric form of CtBP2.
Insights
NADH activates C-terminal binding proteins (CtBP1 and CtBP2), crucial for gene regulation in cancer. This study reveals CtBP2 forms a tetramer in the presence of NADH, which is essential for its oncogenic functions like cell migration.
Area of Science:
- Molecular Biology
- Structural Biology
- Cancer Research
Background:
- C-terminal binding proteins (CtBP1 and CtBP2) are transcriptional regulators involved in cellular development, apoptosis, and metastasis.
- NADH-dependent CtBP activation is linked to various cancers and poor patient prognosis.
Purpose of the Study:
- To elucidate the oligomeric state of CtBP2 upon NADH activation.
- To determine if this assembly is critical for CtBP2's oncogenic functions.
Main Methods:
- Cryoelectron microscopy was used to determine the structures of CtBP2 constructs.
- Cell culture experiments were performed using CtBP tetramer-destabilizing mutants.
Main Results:
- The cryoelectron microscopy structures revealed that CtBP2 forms a tetramer in the presence of NADH.
- Mutants destabilizing the CtBP2 tetramer showed defects in cell migration, E-cadherin repression, and TIAM1 activation.
Conclusions:
- The tetrameric form of CtBP2 is the functional oligomeric state.
- CtBP2 tetramer formation is crucial for its role in oncogenesis, including cell migration and gene regulation.
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