CK2 phosphorylation of the PRH/Hex homeodomain functions as a reversible switch for DNA binding

Soufi, Abdenour; Noy, Peter J.; Buckle, Malcolm; Sawasdichai, Anyaporn; Gaston, Kevin; Jayaraman, Padma-Sheela

doi:10.1093/nar/gkp197

Cited by 34 publications

(63 citation statements)

References 47 publications

(90 reference statements)

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“…There are several possible explanations for this difference. The expression vectors generate very high levels of CK2, which might be required for E1 phosphorylation (64). Alternatively, the viral genome may be able to autoregulate expression of E1 to compensate for E1 inactivated by phosphorylation, a possibility that does not exist when E1 is expressed from an expression vector.…”

Section: Discussionmentioning

confidence: 99%

CK2 Phosphorylation Inactivates DNA Binding by the Papillomavirus E1 and E2 Proteins

Schuck

Ruse

Stenlund

2013

J Virol

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Papillomaviruses have complex life cycles that are understood only superficially. Although it is well established that the viral E1 and E2 proteins play key roles in controlling viral transcription and DNA replication, how these factors are regulated is not well understood. Here, we demonstrate that phosphorylation by the protein kinase CK2 controls the biochemical activities of the bovine papillomavirus E1 and E2 proteins by modifying their DNA binding activity. Phosphorylation at multiple sites in the Nterminal domain in E1 results in the loss of sequence-specific DNA binding activity, a feature that is also conserved in human papillomavirus (HPV) E1 proteins. The bovine papillomavirus (BPV) E2 protein, when phosphorylated by CK2 on two specific sites in the hinge, also loses its site-specific DNA binding activity. Mutation of these sites in E2 results in greatly increased levels of latent viral DNA replication, indicating that CK2 phosphorylation of E2 is a negative regulator of viral DNA replication during latent viral replication. In contrast, mutation of the N-terminal phosphorylation sites in E1 has no effect on latent viral DNA replication. We propose that the phosphorylation of the N terminus of E1 plays a role only in vegetative viral DNA replication, and consistent with such a role, caspase 3 cleavage of E1, which has been shown to be necessary for vegetative viral DNA replication, restores the DNA binding activity to phosphorylated E1.T he study of papillomaviruses has resulted in a fair understanding of the overall strategy that these viruses employ to infect their hosts and to generate new virus particles. Papillomaviruses infect the basal layers of the epithelium, where the early viral genes are expressed and the viral DNA is replicated at a low level (1). As the infected cells migrate toward the skin surface and differentiate into keratinocytes, the viral DNA is replicated at high levels, viral capsid proteins are produced, and new virus particles are assembled (1). In contrast to other well-studied viruses, reproduction of the viral life cycle in vitro is difficult but can be achieved with low efficiency (2-4). Consequently, although the general functions of the virus-encoded polypeptides are known, many subtleties, including the consequences of modifications of the viral polypeptides, ranging from alternative splicing to posttranslational modifications, have been difficult to analyze and are poorly understood.The viral E1 and E2 proteins have been studied biochemically, genetically, and structurally and are among the best-studied polypeptides encoded by the papillomaviruses (5, 6). The E1 protein is a site-specific DNA binding protein that binds to the viral origin of DNA replication (ori) and opens the DNA duplex in preparation for initiation of DNA replication and also serves as the replicative DNA helicase (7-15). The E2 protein is a DNA binding transcription factor that can regulate viral transcription by binding to specific sites in the viral genome (16-21). The E2 protein is also required...

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Section: Discussionmentioning

confidence: 99%

CK2 Phosphorylation Inactivates DNA Binding by the Papillomavirus E1 and E2 Proteins

Schuck

Ruse

Stenlund

2013

J Virol

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“…The anti-Myc mouse monoclonal antibody Myc9B11 was obtained from Cell Signaling Technology and the lamin A/C rabbit polyclonal antibody H-110 from Santa Cruz. Anti-PRH mouse polyclonal antibodies were produced in-house and have been described previously (63).…”

Section: Methodsmentioning

confidence: 99%

PRH/Hhex Controls Cell Survival through Coordinate Transcriptional Regulation of Vascular Endothelial Growth Factor Signaling

Noy

Williams

Sawasdichai

et al. 2010

Molecular and Cellular Biology

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The proline-rich homeodomain protein (PRH) plays multiple roles in the control of gene expression during embryonic development and in the adult. Vascular endothelial growth factor (VEGF) is a mitogen that stimulates cell proliferation and survival via cell surface receptors including VEGFR-1 and VEGFR-2. VEGF signaling is of critical importance in angiogenesis and hematopoiesis and is elevated in many tumors. Here we show that PRH binds directly to the promoter regions of the Vegf, Vegfr-1, and Vegfr-2 genes and that in each case PRH represses transcription. We demonstrate that overexpression or knockdown of PRH directly impinges on the survival of both leukemic and tumor cells and that the modulation of VEGF and VEGF receptor signaling by PRH mediates these effects. Our findings demonstrate that PRH is a key regulator of the VEGF signaling pathway and describe a mechanism whereby PRH plays an important role in tumorigenesis and leukemogenesis.

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“…In the only previous yeast two-hybrid screening using Hhex as bait, two interactors were isolated; that is, the HC8 subunit of the proteasome (46) and the CK2␤ (47). In our study we have used an embryo-derived library instead of a chronic myelogenous leukemia cell line (K562)-derived cDNA library, which lacks any developmental context.…”

Section: Discussionmentioning

confidence: 99%

Interaction between Hhex and SOX13 Modulates Wnt/TCF Activity

Marfil

Moya

Pierreux

et al. 2010

Journal of Biological Chemistry

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Fine-tuning of the Wnt/TCF pathway is crucial for multiple embryological processes, including liver development. Here we describe how the interaction between Hhex (hematopoietically expressed homeobox) and SOX13 (SRY-related high mobility group box transcription factor 13), modulates Wnt/TCF pathway activity. Hhex is a homeodomain factor expressed in multiple endoderm-derived tissues, like the liver, where it is essential for proper development. The pleiotropic expression of Hhex during embryonic development and its dual role as a transcriptional repressor and activator suggest the presence of different tissue-specific partners capable of modulating its activity and function. While searching for developmentally regulated Hhex partners, we set up a yeast two-hybrid screening using an E9.5-10.5 mouse embryo library and the N-terminal domain of Hhex as bait. Among the putative protein interactors, we selected SOX13 for further characterization. We found that SOX13 interacts directly with full-length Hhex, and we delineated the interaction domains within the two proteins. SOX13 is known to repress Wnt/TCF signaling by interacting with TCF1. We show that Hhex is able to block the SOX13-dependent repression of Wnt/TCF activity by displacing SOX13 from the SOX13⅐TCF1 complex. Moreover, Hhex de-repressed the Wnt/TCF pathway in the ventral foregut endoderm of cultured mouse embryos electroporated with a SOX13-expressing plasmid. We conclude that the interaction between Hhex and SOX13 may contribute to control Wnt/TCF signaling in the early embryo.

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CK2 phosphorylation of the PRH/Hex homeodomain functions as a reversible switch for DNA binding

Cited by 34 publications

References 47 publications

CK2 Phosphorylation Inactivates DNA Binding by the Papillomavirus E1 and E2 Proteins

CK2 Phosphorylation Inactivates DNA Binding by the Papillomavirus E1 and E2 Proteins

PRH/Hhex Controls Cell Survival through Coordinate Transcriptional Regulation of Vascular Endothelial Growth Factor Signaling

Interaction between Hhex and SOX13 Modulates Wnt/TCF Activity

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