Interaction and Cooperation of the CCAAT-box Enhancer-binding Protein β (C/EBPβ) with the Homeodomain-interacting Protein Kinase 2 (Hipk2)

Steinmann, Simone; Coulibaly, Anna; Ohnheiser, Johanna; Jakobs, Anke; Klempnauer, Karl‐Heinz

doi:10.1074/jbc.m113.487769

Cited by 16 publications

(15 citation statements)

References 51 publications

(81 reference statements)

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“…For example, the acetylation of a specific lysine residue in the N-terminal part of C/EBP␤ by p300, Lys-39, is known to exert a major effect on the activity of C/EBP␤ (45). Moreover, the N-terminal domain of C/EBP␤ has been implicated in the binding of other proteins, including the SWI/SNF chromatin remodeling complex (39), the Mediator complex (15), and protein kinase Hipk2 (10). It is therefore possible that the inhibitory mechanism of helenalin acetate is even more complex and also involves inhibition of further protein-protein interactions or post-translational modifications of the N-terminal domain of LAP*.…”

Section: Discussionmentioning

confidence: 99%

“…Human recombinant TNF␣ was obtained from Biomol. The expression of the endogenous MRP126 and ribosomal protein S17 mRNAs was analyzed as described before (10).…”

Section: Methodsmentioning

confidence: 99%

“…In Vitro GST Pulldown-Purification of GST fusion proteins and in vitro GST pulldown experiments were performed as described before (10).…”

Section: Methodsmentioning

confidence: 99%

“…As a read-out of C/EBP␤ activity, we analyzed the expression of the endogenous C/EBP-inducible MRP126 gene by Northern blotting, using S17 mRNA as a loading control. The MRP126 gene is not expressed in fibroblasts; however, its expression is induced when the cells are transfected with an expression vector for C/EBP␤ (10,26). Analysis of the increase of MRP126 mRNA levels caused by C/EBP␤ expression is therefore a convenient method to assess the activity of C/EBP␤.…”

Section: The Presence Of Reactive Groups Is Not Sufficient To Explainmentioning

confidence: 99%

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Helenalin Acetate, a Natural Sesquiterpene Lactone with Anti-inflammatory and Anti-cancer Activity, Disrupts the Cooperation of CCAAT Box/Enhancer-binding Protein β (C/EBPβ) and Co-activator p300

Jakobs

Steinmann

Henrich

et al. 2016

Journal of Biological Chemistry

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Edited by Joel GottesfeldRecent work has demonstrated pro-oncogenic functions of the transcription factor CCAAT box/enhancer-binding protein ␤ (C/EBP␤) in various tumors, implicating C/EBP␤ as an interesting target for the development of small-molecule inhibitors. We have previously discovered that the sesquiterpene lactone helenalin acetate, a natural compound known to inhibit NF-B, is a potent C/EBP␤ inhibitor. We have now examined the inhibitory mechanism of helenalin acetate in more detail. We demonstrate that helenalin acetate is a significantly more potent inhibitor of C/EBP␤ than of NF-B. Our work shows that helenalin acetate inhibits C/EBP␤ by binding to the N-terminal part of C/EBP␤, thereby disrupting the cooperation of C/EBP␤ with the co-activator p300. C/EBP␤ is expressed in several isoforms from alternative translational start codons. We have previously demonstrated that helenalin acetate selectively inhibits only the full-length (liver-enriched activating protein* (LAP*)) isoform but not the slightly shorter (LAP) isoform. Consistent with this, helenalin acetate binds to the LAP* but not to the LAP isoform, explaining why its inhibitory activity is selective for LAP*. Although helenalin acetate contains reactive groups that are able to interact covalently with cysteine residues, as exemplified by its effect on NF-B, the inhibition of C/EBP␤ by helenalin acetate is not due to irreversible reaction with cysteine residues of C/EBP␤. In summary, helenalin acetate is the first highly active small-molecule C/EBP␤ inhibitor that inhibits C/EBP␤ by a direct binding mechanism. Its selectivity for the LAP* isoform also makes helenalin acetate an interesting tool to dissect the functions of the LAP* and LAP isoforms.

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Section: Discussionmentioning

confidence: 99%

“…Human recombinant TNF␣ was obtained from Biomol. The expression of the endogenous MRP126 and ribosomal protein S17 mRNAs was analyzed as described before (10).…”

Section: Methodsmentioning

confidence: 99%

“…In Vitro GST Pulldown-Purification of GST fusion proteins and in vitro GST pulldown experiments were performed as described before (10).…”

Section: Methodsmentioning

confidence: 99%

Section: The Presence Of Reactive Groups Is Not Sufficient To Explainmentioning

confidence: 99%

See 2 more Smart Citations

Helenalin Acetate, a Natural Sesquiterpene Lactone with Anti-inflammatory and Anti-cancer Activity, Disrupts the Cooperation of CCAAT Box/Enhancer-binding Protein β (C/EBPβ) and Co-activator p300

Jakobs

Steinmann

Henrich

et al. 2016

Journal of Biological Chemistry

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“…Furthermore, the white adipose tissue deposits of HIPK2 knock-out mice are smaller and the size of the adipocytes is reduced in these animals. The necessity of HIPK2 in this context is equally well demonstrated in 3T3 fibroblast culture, being an established in vivo model of adipocytic differentiation [15].…”

Section: Introductionmentioning

confidence: 91%

Complex regulation of CREB-binding protein by homeodomain-interacting protein kinase 2

Kovács

Steinmann

Halfon

et al. 2015

Cellular Signalling

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CREB-binding protein (CBP) and p300 are transcriptional coactivators involved in numerous biological processes that affect cell growth, transformation, differentiation, and development. In this study, we provide evidence of the involvement of homeodomain-interacting protein kinase 2 (HIPK2) in the regulation of CBP activity. We show that HIPK2 interacts with and phosphorylates several regions of CBP. We demonstrate that serines 2361, 2363, 2371, 2376, and 2381 are responsible for the HIPK2-induced mobility shift of CBP C-terminal activation domain. Moreover, we show that HIPK2 strongly potentiates the transcriptional activity of CBP.However, our data suggest that HIPK2 activates CBP mainly by counteracting the repressive action of cell cycle regulatory domain 1 (CRD1), located between amino acids 977 and 1076, independently of CBP phosphorylation. Our findings thus highlight a complex regulation of CBP activity by HIPK2, which might be relevant for the control of specific sets of target genes involved in cellular proliferation, differentiation and apoptosis.

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Programmed cell death 4 protein (Pdcd4) and homeodomain-interacting protein kinase 2 (Hipk2) antagonistically control translation of Hipk2 mRNA

Ohnheiser

Ferlemann

Haas

et al. 2015

Biochimica et Biophysica Acta (BBA) - Molecular Cell Research

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The tumor suppressor protein programmed cell death 4 (Pdcd4) is a highly conserved RNA-binding protein that inhibits the translation of specific mRNAs. Here, we have identified the homeobox-interacting protein kinase-2 (Hipk2) mRNA as a novel translational target of Pdcd4. Unlike most other protein kinases Hipk2 is constitutively active after being synthesized by the ribosome and its expression and activity are thought to be mainly controlled by modulation of the half-life of the kinase. Our work provides the first evidence that Hipk2 expression is also controlled on the level of translation. We show that Hipk2 stimulates the translation of its own mRNA and that Pdcd4 suppresses the translation of Hipk2 mRNA by interfering with this auto-regulatory feedback mechanism. We also show that the translation of the related kinase Hipk1 is controlled by a similar feedback loop and that Hipk2 also stimulates the translation of Hipk1 mRNA. Taken together, our work describes a novel mechanism of translational suppression by Pdcd4 and shows for the first time that Hipk2 controls its own synthesis by an auto-regulatory feedback mechanism. Furthermore, the effect of Hipk2 on the translation of Hipk1 RNA suggests that Hipk2 and Pdcd4 can act in similar manner to control the translation of other mRNAs.

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Interaction and Cooperation of the CCAAT-box Enhancer-binding Protein β (C/EBPβ) with the Homeodomain-interacting Protein Kinase 2 (Hipk2)

Cited by 16 publications

References 51 publications

Helenalin Acetate, a Natural Sesquiterpene Lactone with Anti-inflammatory and Anti-cancer Activity, Disrupts the Cooperation of CCAAT Box/Enhancer-binding Protein β (C/EBPβ) and Co-activator p300

Helenalin Acetate, a Natural Sesquiterpene Lactone with Anti-inflammatory and Anti-cancer Activity, Disrupts the Cooperation of CCAAT Box/Enhancer-binding Protein β (C/EBPβ) and Co-activator p300

Complex regulation of CREB-binding protein by homeodomain-interacting protein kinase 2

Programmed cell death 4 protein (Pdcd4) and homeodomain-interacting protein kinase 2 (Hipk2) antagonistically control translation of Hipk2 mRNA

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