HDMX and its homologue HDM2 are two essential proteins for the cell; after genotoxic stress, both are phosphorylated near to their RING domain, specifically at serine 403 and 395, respectively. Once phosphorylated, both can bind the p53 mRNA and enhance its translation; however, both recognize p53 protein and provoke its degradation under normal conditions. HDM2 has been well-recognized as an E3 ubiquitin ligase, whereas it has been reported that even with the high similarity between the RING domains of the two homologs, HDMX does not have the E3 ligase activity. Despite this, HDMX is needed for the proper p53 poly-ubiquitination. Phosphorylation at serine 395 changes the conformation of HDM2, helping to explain the switch in its activity, but no information on HDMX has been published. Here, we study the conformation of HDMX and its phospho-mimetic mutant S403D, investigate its E3 ligase activity and dissect its binding with p53. We show that phospho-mutation does not change the conformation of the protein, but HDMX is indeed an E3 ubiquitin ligase in vitro; however, in vivo, no activity was found. We speculated that HDMX is regulated by induced fit, being able to switch activity accordingly to the specific partner as p53 protein, p53 mRNA or HDM2. Our results aim to contribute to the elucidation of the contribution of the HDMX to p53 regulation.

• Klíčová slova
• HDM2, HDMX, Induced fit, MDM2, MDMX, cancer, p53, ubiquitination,
• MeSH
• jaderné proteiny genetika   MeSH
• messenger RNA metabolismus   MeSH
• nádorový supresorový protein p53 * genetika   metabolismus   MeSH
• proteiny buněčného cyklu metabolismus   MeSH
• protoonkogenní proteiny c-mdm2 * genetika   metabolismus   MeSH
• protoonkogenní proteiny genetika   MeSH
• serin metabolismus   MeSH
• ubikvitin genetika   MeSH
• ubikvitinace MeSH
• ubikvitinligasy genetika   metabolismus   MeSH
• vazba proteinů MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• jaderné proteiny MeSH
• messenger RNA MeSH
• nádorový supresorový protein p53 * MeSH
• proteiny buněčného cyklu MeSH
• protoonkogenní proteiny c-mdm2 * MeSH
• protoonkogenní proteiny MeSH
• serin MeSH
• ubikvitin MeSH
• ubikvitinligasy MeSH

Since the discovery of the first MDM2 inhibitors, we have gained deeper insights into the cellular roles of MDM2 and p53. In this review, we focus on MDM2 inhibitors that bind to the p53-binding domain of MDM2 and aim to disrupt the binding of MDM2 to p53. We describe the basic mechanism of action of these MDM2 inhibitors, such as nutlin-3a, summarise the determinants of sensitivity to MDM2 inhibition from p53-dependent and p53-independent points of view and discuss the problems with innate and acquired resistance to MDM2 inhibition. Despite progress in MDM2 inhibitor design and ongoing clinical trials, their broad use in cancer treatment is not fulfilling expectations in heterogenous human cancers. We assess the MDM2 inhibitor types in clinical trials and provide an overview of possible sources of resistance to MDM2 inhibition, underlining the need for patient stratification based on these aspects to gain better clinical responses, including the use of combination therapies for personalised medicine.

• Klíčová slova
• Combination therapy, MDM2, MDM2 inhibitor, Nutlin-3a, Personalised medicine, Resistance, p53,
• MeSH
• antitumorózní látky farmakologie   MeSH
• bakteriální léková rezistence účinky léků   fyziologie   MeSH
• cílená molekulární terapie metody   MeSH
• klinické zkoušky jako téma MeSH
• lidé MeSH
• nádorový supresorový protein p53 antagonisté a inhibitory   genetika   metabolismus   MeSH
• nádory farmakoterapie   MeSH
• protoonkogenní proteiny c-mdm2 antagonisté a inhibitory   genetika   metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• antitumorózní látky MeSH
• MDM2 protein, human MeSH Prohlížeč
• nádorový supresorový protein p53 MeSH
• protoonkogenní proteiny c-mdm2 MeSH
• TP53 protein, human MeSH Prohlížeč

The p53 and Mouse double minute 2 (MDM2) proteins are hubs in extensive networks of interactions with multiple partners and functions. Intrinsically disordered regions help to adopt function-specific structural conformations in response to ligand binding and post-translational modifications. Different techniques have been used to dissect interactions of the p53-MDM2 pathway, in vitro, in vivo, and in situ each having its own advantages and disadvantages. This review uses the p53-MDM2 to show how different techniques can be employed, illustrating how a combination of in vitro and in vivo techniques is highly recommended to study the spatio-temporal location and dynamics of interactions, and to address their regulation mechanisms and functions. By using well-established techniques in combination with more recent advances, it is possible to rapidly decipher complex mechanisms, such as the p53 regulatory pathway, and to demonstrate how protein and nucleotide ligands in combination with post-translational modifications, result in inter-allosteric and intra-allosteric interactions that govern the activity of the protein complexes and their specific roles in oncogenesis. This promotes elegant therapeutic strategies that exploit protein dynamics to target specific interactions.

• Klíčová slova
• ATM *, DNA damage response *, MDM2 *, MDMX *, p53 *, p53 mRNA *, post-translational modification *, protein-RNA interactions *, protein-protein interactions *,
• MeSH
• fosforylace genetika   MeSH
• jaderné proteiny MeSH
• lidé MeSH
• myši MeSH
• nádorový supresorový protein p53 genetika   MeSH
• poškození DNA genetika   MeSH
• posttranslační úpravy proteinů genetika   MeSH
• proteiny buněčného cyklu genetika   MeSH
• protoonkogenní proteiny c-mdm2 genetika   MeSH
• vazba proteinů genetika   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• jaderné proteiny MeSH
• MDM2 protein, human MeSH Prohlížeč
• nádorový supresorový protein p53 MeSH
• proteiny buněčného cyklu MeSH
• protoonkogenní proteiny c-mdm2 MeSH

Cell growth requires a high level of protein synthesis and oncogenic pathways stimulate cell proliferation and ribosome biogenesis. Less is known about how cells respond to dysfunctional mRNA translation and how this feeds back into growth regulatory pathways. The Epstein-Barr virus (EBV)-encoded EBNA1 causes mRNA translation stress in cis that activates PI3Kδ. This leads to the stabilization of MDM2, induces MDM2's binding to the E2F1 mRNA and promotes E2F1 translation. The MDM2 serine 166 regulates the interaction with the E2F1 mRNA and deletion of MDM2 C-terminal RING domain results in a constitutive E2F1 mRNA binding. Phosphorylation on serine 395 following DNA damage instead regulates p53 mRNA binding to its RING domain and prevents the E2F1 mRNA interaction. The p14Arf tumour suppressor binds MDM2 and in addition to preventing degradation of the p53 protein it also prevents the E2F1 mRNA interaction. The data illustrate how two MDM2 domains selectively bind specific mRNAs in response to cellular conditions to promote, or suppress, cell growth and how p14Arf coordinates MDM2's activity towards p53 and E2F1. The data also show how EBV via EBNA1-induced mRNA translation stress targets the E2F1 and the MDM2 - p53 pathway.

• MeSH
• buněčný cyklus genetika   MeSH
• fosforylace genetika   MeSH
• karcinogeneze genetika   MeSH
• lidé MeSH
• messenger RNA genetika   MeSH
• nádorový supresorový protein p14ARF genetika   MeSH
• nádorový supresorový protein p53 genetika   MeSH
• nádory genetika   virologie   MeSH
• onkogeny genetika   MeSH
• poškození DNA genetika   MeSH
• proliferace buněk genetika   MeSH
• proteinové domény genetika   MeSH
• protoonkogenní proteiny c-mdm2 genetika   MeSH
• RRM proteiny genetika   MeSH
• transkripční faktor E2F1 genetika   MeSH
• tumor supresorové geny MeSH
• virus Epsteinův-Barrové genetika   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• E2F1 protein, human MeSH Prohlížeč
• MDM2 protein, human MeSH Prohlížeč
• messenger RNA MeSH
• nádorový supresorový protein p14ARF MeSH
• nádorový supresorový protein p53 MeSH
• protoonkogenní proteiny c-mdm2 MeSH
• RRM proteiny MeSH
• TP53 protein, human MeSH Prohlížeč
• transkripční faktor E2F1 MeSH

Allosteric changes imposed by post-translational modifications regulate and differentiate the functions of proteins with intrinsic disorder regions. HDM2 is a hub protein with a large interactome and with different cellular functions. It is best known for its regulation of the p53 tumour suppressor. Under normal cellular conditions, HDM2 ubiquitinates and degrades p53 by the 26S proteasome but after DNA damage, HDM2 switches from a negative to a positive regulator of p53 by binding to p53 mRNA to promote translation of the p53 mRNA. This change in activity is governed by the ataxia telangiectasia mutated kinase via phosphorylation on serine 395 and is mimicked by the S395D phosphomimetic mutant. Here we have used different approaches to show that this event is accompanied by a specific change in the HDM2 structure that affects the HDM2 interactome, such as the N-termini HDM2-p53 protein-protein interaction. These data will give a better understanding of how HDM2 switches from a negative to a positive regulator of p53 and gain new insights into the control of the HDM2 structure and its interactome under different cellular conditions and help identify interphases as potential targets for new drug developments.

• Klíčová slova
• ATM, DNA damage, MDM2, p53, phosphomimetic mutation,
• MeSH
• alosterická regulace MeSH
• aminokyselinové motivy MeSH
• ATM protein genetika   metabolismus   MeSH
• fosforylace MeSH
• lidé MeSH
• missense mutace * MeSH
• nádorový supresorový protein p53 genetika   metabolismus   MeSH
• protoonkogenní proteiny c-mdm2 chemie   genetika   metabolismus   MeSH
• vazba proteinů MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• ATM protein MeSH
• MDM2 protein, human MeSH Prohlížeč
• nádorový supresorový protein p53 MeSH
• protoonkogenní proteiny c-mdm2 MeSH
• TP53 protein, human MeSH Prohlížeč

The Wnt, TGF-β, and Notch signaling pathways are essential for the regulation of cellular polarity, differentiation, proliferation, and migration. Differential activation and mutual crosstalk of these pathways during animal development are crucial instructive forces in the initiation of the body axis and the development of organs and tissues. Due to the ability to initiate cell proliferation, these pathways are vulnerable to somatic mutations selectively producing cells, which ultimately slip through cellular and organismal checkpoints and develop into cancer. The architecture of the Wnt, TGF-β, and Notch signaling pathways is simple. The transmembrane receptor, activated by the extracellular stimulus, induces nuclear translocation of the transcription factor, which subsequently changes the expression of target genes. Nevertheless, these pathways are regulated by a myriad of factors involved in various feedback mechanisms or crosstalk. The most prominent group of regulators is the ubiquitin-proteasome system (UPS). To open the door to UPS-based therapeutic manipulations, a thorough understanding of these regulations at a molecular level and rigorous confirmation in vivo are required. In this quest, mouse models are exceptional and, thanks to the progress in genetic engineering, also an accessible tool. Here, we reviewed the current understanding of how the UPS regulates the Wnt, TGF-β, and Notch pathways and we summarized the knowledge gained from related mouse models.

• Klíčová slova
• cancer, gene inactivation, mouse model, ubiquitin–proteasome system,
• MeSH
• beta-katenin metabolismus   MeSH
• buněčná diferenciace fyziologie   MeSH
• homeostáza genetika   MeSH
• ligasy metabolismus   MeSH
• myši embryologie   genetika   MeSH
• proliferace buněk fyziologie   MeSH
• proteiny Wnt metabolismus   MeSH
• receptory Notch metabolismus   MeSH
• signální dráha Wnt fyziologie   MeSH
• transformující růstový faktor beta metabolismus   MeSH
• transkripční faktory metabolismus   MeSH
• ubikvitin metabolismus   MeSH
• ubikvitinligasy metabolismus   fyziologie   MeSH
• vývojová regulace genové exprese genetika   MeSH
• zvířata MeSH
• Check Tag
• myši embryologie   genetika   MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• beta-katenin MeSH
• ligasy MeSH
• proteiny Wnt MeSH
• receptory Notch MeSH
• transformující růstový faktor beta MeSH
• transkripční faktory MeSH
• ubikvitin MeSH
• ubikvitinligasy MeSH

Structured RNA regulatory motifs exist from the prebiotic stages of the RNA world to the more complex eukaryotic systems. In cases where a functional RNA structure is within the coding sequence a selective pressure drives a parallel co-evolution of the RNA structure and the encoded peptide domain. The p53-MDM2 axis, describing the interactions between the p53 tumor suppressor and the MDM2 E3 ubiquitin ligase, serves as particularly useful model revealing how secondary RNA structures have co-evolved along with corresponding interacting protein motifs, thus having an impact on protein - RNA and protein - protein interactions; and how such structures developed signal-dependent regulation in mammalian systems. The p53(BOX-I) RNA sequence binds the C-terminus of MDM2 and controls p53 synthesis while the encoded peptide domain binds MDM2 and controls p53 degradation. The BOX-I peptide domain is also located within p53 transcription activation domain. The folding of the p53 mRNA structure has evolved from temperature-regulated in pre-vertebrates to an ATM kinase signal-dependent pathway in mammalian cells. The protein - protein interaction evolved in vertebrates and became regulated by the same signaling pathway. At the same time the protein - RNA and protein - protein interactions evolved, the p53 trans-activation domain progressed to become integrated into a range of cellular pathways. We discuss how a single synonymous mutation in the BOX-1, the p53(L22 L), observed in a chronic lymphocyte leukaemia patient, prevents the activation of p53 following DNA damage. The concepts analysed and discussed in this review may serve as a conceptual mechanistic paradigm of the co-evolution and function of molecules having roles in cellular regulation, or the aetiology of genetic diseases and how synonymous mutations can affect the encoded protein.

• Klíčová slova
• Ciona intestinalis, Intrinsically disordered proteins, Molecular basis of disease, Protein-RNA interactions, RNA world, Transcription factor, mRNA translation,
• MeSH
• genetická predispozice k nemoci MeSH
• interakční proteinové domény a motivy MeSH
• lidé MeSH
• messenger RNA genetika   MeSH
• nádorové supresorové proteiny genetika   metabolismus   MeSH
• nádorový supresorový protein p53 genetika   metabolismus   MeSH
• nádory genetika   metabolismus   patologie   MeSH
• proteiny vázající RNA metabolismus   MeSH
• regulace genové exprese u nádorů * MeSH
• stanovení celkové genové exprese MeSH
• transkriptom MeSH
• vazba proteinů MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• messenger RNA MeSH
• nádorové supresorové proteiny MeSH
• nádorový supresorový protein p53 MeSH
• proteiny vázající RNA MeSH

Tumor suppressor p53 is mutated in about 50% of cancers. Most malignant melanomas carry wild-type p53, but p53 activity is often inhibited due to overexpression of its negative regulators Mdm2 or MdmX. We performed high throughput screening of 2448 compounds on A375 cells carrying p53 activity luciferase reporter construct to reveal compounds that promote p53 activity in melanoma. Albendazole and fenbendazole, two approved and commonly used benzimidazole anthelmintics, stimulated p53 activity and were selected for further studies. The protein levels of p53 and p21 increased upon the treatment with albendazole and fenbendazole, indicating activation of the p53-p21 pathway, while the levels of Mdm2 and MdmX decreased in melanoma and breast cancer cells overexpressing these proteins. We also observed a reduction of cell viability and changes of cellular morphology corresponding to mitotic catastrophe, i.e., G2/M cell cycle arrest of large multinucleated cells with disrupted microtubules. In summary, we established a new tool for testing the impact of small molecule compounds on the activity of p53 and used it to identify the action of benzimidazoles in melanoma cells. The drugs promoted the stability and transcriptional activity of wild-type p53 via downregulation of its negative regulators Mdm2 and MdmX in cells overexpressing these proteins. The results indicate the potential for repurposing the benzimidazole anthelmintics for the treatment of cancers overexpressing p53 negative regulators.

• Klíčová slova
• Mdm2, MdmX, benzimidazoles, drug repurposing, melanoma, p53,
• MeSH
• albendazol farmakologie   MeSH
• benzimidazoly farmakologie   MeSH
• down regulace MeSH
• fenbendazol farmakologie   MeSH
• jaderné proteiny metabolismus   MeSH
• léky antitumorózní - screeningové testy MeSH
• lidé MeSH
• melanom farmakoterapie   metabolismus   MeSH
• MFC-7 buňky MeSH
• nádorové buněčné linie MeSH
• nádorový supresorový protein p53 metabolismus   MeSH
• přehodnocení terapeutických indikací léčivého přípravku MeSH
• proliferace buněk účinky léků   MeSH
• proteiny buněčného cyklu MeSH
• protoonkogenní proteiny c-mdm2 metabolismus   MeSH
• protoonkogenní proteiny metabolismus   MeSH
• regulace genové exprese u nádorů účinky léků   MeSH
• rychlé screeningové testy MeSH
• viabilita buněk účinky léků   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• albendazol MeSH
• benzimidazoly MeSH
• fenbendazol MeSH
• jaderné proteiny MeSH
• MDM2 protein, human MeSH Prohlížeč
• MDM4 protein, human MeSH Prohlížeč
• nádorový supresorový protein p53 MeSH
• proteiny buněčného cyklu MeSH
• protoonkogenní proteiny c-mdm2 MeSH
• protoonkogenní proteiny MeSH
• TP53 protein, human MeSH Prohlížeč

The biosynthesis of ribosomes is a complex process that requires the coordinated action of many factors and a huge energy investment from the cell. Ribosomes are essential for protein production, and thus for cellular survival, growth and proliferation. Ribosome biogenesis is initiated in the nucleolus and includes: the synthesis and processing of ribosomal RNAs, assembly of ribosomal proteins, transport to the cytoplasm and association of ribosomal subunits. The disruption of ribosome biogenesis at various steps, with either increased or decreased expression of different ribosomal components, can promote cell cycle arrest, senescence or apoptosis. Additionally, interference with ribosomal biogenesis is often associated with cancer, aging and age-related degenerative diseases. Here, we review current knowledge on impaired ribosome biogenesis, discuss the main factors involved in stress responses under such circumstances and focus on examples with clinical relevance.

• Klíčová slova
• aging, cancer, p53, ribosome biogenesis, ribosomopathy,
• MeSH
• biogeneze organel MeSH
• lidé MeSH
• nádory metabolismus   MeSH
• ribozomální proteiny metabolismus   MeSH
• ribozomy metabolismus   MeSH
• stárnutí metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• ribozomální proteiny MeSH

Ribosome biogenesis is an energy consuming process which takes place mainly in the nucleolus. By producing ribosomes to fuel protein synthesis, it is tightly connected with cell growth and cell cycle control. Perturbation of ribosome biogenesis leads to the activation of p53 tumor suppressor protein promoting processes like cell cycle arrest, apoptosis or senescence. This ribosome biogenesis stress pathway activates p53 through sequestration of MDM2 by a subset of ribosomal proteins (RPs), thereby stabilizing p53. Here, we identify human HEATR1, as a nucleolar protein which positively regulates ribosomal RNA (rRNA) synthesis. Downregulation of HEATR1 resulted in cell cycle arrest in a manner dependent on p53. Moreover, depletion of HEATR1 also caused disruption of nucleolar structure and activated the ribosomal biogenesis stress pathway - RPL5 / RPL11 dependent stabilization and activation of p53. These findings reveal an important role for HEATR1 in ribosome biogenesis and further support the concept that perturbation of ribosome biosynthesis results in p53-dependent cell cycle checkpoint activation, with implications for human pathologies including cancer.

• Klíčová slova
• HEATR1, cancer, p53, ribosome biogenesis, ribosome biogenesis stress,
• MeSH
• biogeneze organel * MeSH
• fyziologický stres MeSH
• genetická transkripce * MeSH
• jaderné proteiny metabolismus   MeSH
• kontrolní body buněčného cyklu MeSH
• lidé MeSH
• nádorové buněčné linie MeSH
• nádorový supresorový protein p53 metabolismus   MeSH
• proliferace buněk MeSH
• proteiny vázající RNA metabolismus   MeSH
• protoonkogenní proteiny c-mdm2 metabolismus   MeSH
• ribozomální proteiny metabolismus   MeSH
• ribozomy metabolismus   MeSH
• RNA ribozomální biosyntéza   MeSH
• RNA-polymerasa I genetika   MeSH
• signální transdukce MeSH
• vedlejší histokompatibilní antigeny metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• HEATR1 protein, human MeSH Prohlížeč
• jaderné proteiny MeSH
• MDM2 protein, human MeSH Prohlížeč
• nádorový supresorový protein p53 MeSH
• proteiny vázající RNA MeSH
• protoonkogenní proteiny c-mdm2 MeSH
• ribozomální proteiny MeSH
• RNA ribozomální MeSH
• RNA-polymerasa I MeSH
• vedlejší histokompatibilní antigeny MeSH