KAP1 is an antiparallel dimer with a functional asymmetry

Fonti, Giulia; Marcaida, M.J.; Bryan, Louise; Träger, Sylvain; Kalantzi, Alexandra Styliani; Helleboid, Pierre-Yves Jl; Demurtas, Davide; Tully, Mark D.; Grudinin, Sergei; Trono, Didier; Fierz, Beat; Peraro, Matteo Dal

doi:10.26508/lsa.201900349

Cited by 18 publications

(17 citation statements)

References 105 publications

(173 reference statements)

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“…Our observation of reduced binding of the KRAB domain by TRIM28-K304Q, which was not the case for either mutant K266Q or K340Q, suggests that the speci c acetylation of K304 may impact the interaction between the KRAB domain and the TRIM28 homodimer (dimerization is mediated by the RBCCs). Molecular modeling failed to pinpoint the interaction at atomic resolution based on published structural studies (6,7,53,54) and our unpublished observations. As such, further structural studies are needed.…”

Section: Discussionmentioning

confidence: 95%

Mutation of TRIM28-Lys304 to Gln Attenuates its Interaction with KRAB-ZNFs and Promotes Differentiation of Erythroleukemic K562 Cells

Chang¹,

Lin²,

Kang³

et al. 2020

Preprint

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BackgroundTRIM28/KAP1/TIF1β is a key epigenetic modifier. Genetic ablation of trim28 is embryonic lethal although RNAi-mediated knockdown in somatic cells yields viable cells. Reduction in TRIM28 abundance at the cellular or organismal level results in polyphenism. Posttranslational modifications such as phosphorylation and sumoylation have been shown to regulate TRIM28 activity. Moreover, the methylation of DNA, RNA and histones and acetylation of histones are key epigenetic modifications that regulate gene expression. A number of lysine residues of TRIM28 are subject to acetylation, but how acetylation of TRIM28 affects its functions remains poorly understood. ResultsHere we report that, compared with wild-type TRIM28, the acetylation-mimic mutant TRIM28-K304Q has an altered interaction with Krüppel-associated box zinc-finger proteins (KRAB-ZNFs), with consequent effects on the phenotype of the erythroleukemic cell line K562. TRIM28-K304Q was comparable with its wild-type counterpart with respect to intracellular level, homodimerization, phosphorylation at S473 and S824, and interactions with heterochromatin-binding protein HP1. The expression of embryonic-related and fetal globin genes was activated in TRIM28-K304Q mutant cells. Transcriptome analysis revealed that TRIM28-K304Q and TRIM28 knockout K562 cells had similar global gene expression profiles, yet the profiles differed considerably from that of wild-type K562 cells. The gene expression ensemble of mutant K562 cells indicated a general induction of differentiation-promoting genes and attenuation of proliferation-promoting genes. ConclusionsThese results suggest that acetylation/deacetylation of K304 in TRIM28 or TRIM28-K304Q constitutes a switch for regulating its interaction with KRAB-ZNFs and alters the gene regulation of this key epigenetic modifier as demonstrated by the acetylation mimic TRIM28-K304Q.

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Section: Discussionmentioning

confidence: 95%

Mutation of TRIM28-Lys304 to Gln Attenuates its Interaction with KRAB-ZNFs and Promotes Differentiation of Erythroleukemic K562 Cells

Chang¹,

Lin²,

Kang³

et al. 2020

Preprint

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“…Only when we mutated a surface residue of the B1 box (Figure 1D ), arginine 184 to aspartate (R184D), the dominant population at mass of 97.5 kDa matches well with a stoichiometry of 2:1 (Figure 1C and F ). It is still debatable in the literature whether TRIM28 (full length or RBCC) forms high-order oligomers ( 14 , 19 , 20 , 49 ), which might depend on the protein concentration range tested under varied laboratory conditions (see the ‘Discussion’ section in the Supplementary Data). In addition, introducing the chato mutation ( 50 , 51 ) in the context of ZFP568 1K and 2K fragments significantly reduced interactions with Trim28 in the pull-down assay ( Supplementary Figure S2 ).…”

Section: Resultsmentioning

confidence: 99%

KRAB domain of ZFP568 disrupts TRIM28-mediated abnormal interactions in cancer cells

et al. 2020

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Interactions of KRAB (Krüppel-associated box)-associated protein KAP1 [also known as TRIM28 (tripartite motif containing protein 28)] with DNA-binding KRAB zinc finger (KRAB-ZF) proteins silence many transposable elements during embryogenesis. However, in some cancers, TRIM28 is upregulated and interacts with different partners, many of which are transcription regulators such as EZH2 in MCF7 cells, to form abnormal repressive or activating complexes that lead to misregulation of genes. We ask whether a KRAB domain—the TRIM28 interaction domain present in native binding partners of TRIM28 that mediate repression of transposable elements—could be used as a tool molecule to disrupt aberrant TRIM28 complexes. Expression of KRAB domain containing fragments from a KRAB-ZF protein (ZFP568) in MCF7 cells, without the DNA-binding zinc fingers, inhibited TRIM28–EZH2 interactions and caused degradation of both TRIM28 and EZH2 proteins as well as other components of the EZH2-associated polycomb repressor 2 complex. In consequence, the product of EZH2 enzymatic activity, trimethylation of histone H3 lysine 27 level, was significantly reduced. The expression of a synthetic KRAB domain significantly inhibits the growth of breast cancer cells (MCF7) but has no effect on normal (immortalized) human mammary epithelial cells (MCF10a). Further, we found that TRIM28 is a positive regulator of TRIM24 protein levels, as observed previously in prostate cancer cells, and expression of the KRAB domain also lowered TRIM24 protein. Importantly, reduction of TRIM24 levels, by treatment with either the KRAB domain or a small-molecule degrader targeted to TRIM24, is accompanied by an elevated level of tumor suppressor p53. Taken together, this study reveals a novel mechanism for a TRIM28-associated protein stability network and establishes TRIM28 as a potential therapeutic target in cancers where TRIM28 is elevated. Finally, we discuss a potential mechanism of KRAB-ZF gene expression controlled by a regulatory feedback loop of TRIM28–KRAB.

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“…This domain is crucial towards homodimerization of TRIMs and as such regulates its biological activity [75] . Additionally, the coiled‐coil domain has been described as a platform for macromolecular interactions, driving the recruitment of cellular partners modulated by specific environmental conditions [91,92] …”

Section: Tripartite Motif Proteins: Structural Determinantsmentioning

confidence: 99%

Targeting TRIM Proteins: A Quest towards Drugging an Emerging Protein Class

et al. 2021

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The ubiquitylation machinery regulates several fundamental biological processes from protein homeostasis to a wide variety of cellular signaling pathways. As a consequence, its dysregulation is linked to diseases including cancer, neurodegeneration, and autoimmunity. With this review, we aim to highlight the therapeutic potential of targeting E3 ligases, with a special focus on an emerging class of RING ligases, named tri‐partite motif (TRIM) proteins, whose role as targets for drug development is currently gaining pharmaceutical attention. TRIM proteins exert their catalytic activity as scaffolds involved in many protein–protein interactions, whose multidomains and adapter‐like nature make their druggability very challenging. Herein, we give an overview of the current understanding of this class of single polypeptide RING E3 ligases and discuss potential targeting options.

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KAP1 is an antiparallel dimer with a functional asymmetry

Cited by 18 publications

References 105 publications

Mutation of TRIM28-Lys304 to Gln Attenuates its Interaction with KRAB-ZNFs and Promotes Differentiation of Erythroleukemic K562 Cells

Mutation of TRIM28-Lys304 to Gln Attenuates its Interaction with KRAB-ZNFs and Promotes Differentiation of Erythroleukemic K562 Cells

KRAB domain of ZFP568 disrupts TRIM28-mediated abnormal interactions in cancer cells

Targeting TRIM Proteins: A Quest towards Drugging an Emerging Protein Class

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