Dataset Information

Assembly of human C-terminal binding protein (CtBP) into tetramers.

ABSTRACT: C-terminal binding protein 1 (CtBP1) and CtBP2 are transcriptional coregulators that repress numerous cellular processes, such as apoptosis, by binding transcription factors and recruiting chromatin-remodeling enzymes to gene promoters. The NAD(H)-linked oligomerization of human CtBP is coupled to its co-transcriptional activity, which is implicated in cancer progression. However, the biologically relevant level of CtBP assembly has not been firmly established; nor has the stereochemical arrangement of the subunits above that of a dimer. Here, multi-angle light scattering (MALS) data established the NAD+- and NADH-dependent assembly of CtBP1 and CtBP2 into tetramers. An examination of subunit interactions within CtBP1 and CtBP2 crystal lattices revealed that both share a very similar tetrameric arrangement resulting from assembly of two dimeric pairs, with specific interactions probably being sensitive to NAD(H) binding. Creating a series of mutants of both CtBP1 and CtBP2, we tested the hypothesis that the crystallographically observed interdimer pairing stabilizes the solution tetramer. MALS data confirmed that these mutants disrupt both CtBP1 and CtBP2 tetramers, with the dimer generally remaining intact, providing the first stereochemical models for tetrameric assemblies of CtBP1 and CtBP2. The crystal structure of a subtle destabilizing mutant suggested that small structural perturbations of the hinge region linking the substrate- and NAD-binding domains are sufficient to weaken the CtBP1 tetramer. These results strongly suggest that the tetramer is important in CtBP function, and the series of CtBP mutants reported here can be used to investigate the physiological role of the tetramer.

SUBMITTER: Bellesis AG

PROVIDER: S-EPMC5995525 | biostudies-literature | 2018 Jun

REPOSITORIES: biostudies-literature

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Assembly of human C-terminal binding protein (CtBP) into tetramers.

Bellesis Andrew G AG Jecrois Anne M AM Hayes Janelle A JA Schiffer Celia A CA Royer William E WE

The Journal of biological chemistry 20180426 23

C-terminal binding protein 1 (CtBP1) and CtBP2 are transcriptional coregulators that repress numerous cellular processes, such as apoptosis, by binding transcription factors and recruiting chromatin-remodeling enzymes to gene promoters. The NAD(H)-linked oligomerization of human CtBP is coupled to its co-transcriptional activity, which is implicated in cancer progression. However, the biologically relevant level of CtBP assembly has not been firmly established; nor has the stereochemical arrange ...[more]

PMID: 29700119

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Project description:Pancreatic ductal adenocarcinoma (PDAC) remains among the most lethal of human cancers underscoring the need to identify new therapeutic vulnerabilities. Previously, we reported high expression of transcriptional co-regulators C-terminal binding proteins (CtBP) 1 and 2 in human PDAC, however their precise role in PDAC formation or progression remains unclear. Here, we have studied PDAC tumor dependency on CtBPs for growth and metastasis using an orthotopic syngeneic pancreatic tumor mouse model. CRISPR-based homozygous deletion of Ctbp2 dramatically decreased PDAC tumor growth, drastically reduced metastatic potential, and significantly prolonged survival. Interrogating differential gene expression of the orthotopic PDAC tumors from CtBP2 WT vs. CtBP2 KO cohorts, we identified significant downregulation of the EGFR-superfamily receptor ErbB3 in CtBP2 KO tumors, and further determined that CtBP regulates expression of both the ErbB2 and 3 EGFR superfamily genes in PDAC cells. We therefore hypothesized that CtBP regulation of physiologic ErbB2/3 signaling contributes, in part, to PDAC growth and metastasis. Indeed, we observed that CtBP2 KO cells exhibited severely attenuated activation of phospho-Akt after neuregulin stimulation of ErbB2/3, and we demonstrate that human PDAC cells also show CtBP dependence of ErbB2/3 expression. Our results suggest that a subset of PDAC tumors is dependent on physiologic ErbB2/3 signaling and could be targeted by pharmacologic inhibitors of ErbB2 and/or ErbB3. Providing proof of concept, the ErbB2-targeted multikinase inhibitor lapatinib, but not the ErbB1/EGFR targeted agent erlotinib, effectively killed ErbB3 expressing PDAC cells, while CtBP2 KO cells where ErbB3 expression was extinguished, were resistant to lapatinib. Taken together, our data suggests that ErBb2/3 targeted therapeutics can effectively target a critical PDAC dependency on physiologic ErbB2/3 signaling which is the result of CtBP’s oncogenic transcriptional program that drives PDAC tumor progression.

Dataset Information

Assembly of human C-terminal binding protein (CtBP) into tetramers.

Publications

Assembly of human C-terminal binding protein (CtBP) into tetramers.

Similar Datasets

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