scholarly journals Structural basis of reactivation of oncogenic p53 mutants by a small molecule: methylene quinuclidinone (MQ)

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Oksana Degtjarik ◽  
Dmitrij Golovenko ◽  
Yael Diskin-Posner ◽  
Lars Abrahmsén ◽  
Haim Rozenberg ◽  
...  
Keyword(s):  
Genotoxic Stress ◽  
Biologically Active ◽  
Structural Basis ◽  
Cysteine Residues ◽  
Mutant P53 ◽  
Tumor Suppressor P53 ◽  
Gene Encoding ◽  
Core Domain ◽  
Expression Of Genes ◽  
P53 Reactivation

AbstractIn response to genotoxic stress, the tumor suppressor p53 acts as a transcription factor by regulating the expression of genes critical for cancer prevention. Mutations in the gene encoding p53 are associated with cancer development. PRIMA-1 and eprenetapopt (APR-246/PRIMA-1MET) are small molecules that are converted into the biologically active compound, methylene quinuclidinone (MQ), shown to reactivate mutant p53 by binding covalently to cysteine residues. Here, we investigate the structural basis of mutant p53 reactivation by MQ based on a series of high-resolution crystal structures of cancer-related and wild-type p53 core domains bound to MQ in their free state and in complexes with their DNA response elements. Our data demonstrate that MQ binds to several cysteine residues located at the surface of the core domain. The structures reveal a large diversity in MQ interaction modes that stabilize p53 and its complexes with DNA, leading to a common global effect that is pertinent to the restoration of non-functional p53 proteins.

scholarly journals A p53-Phosphoinositide Signalosome Regulates Nuclear Akt Activation

2021 ◽  
Author(s):  
Mo Chen ◽  
Suyong Choi ◽  
Tianmu Wen ◽  
Changliang Chen ◽  
Narendra Thapa ◽  
...  
Keyword(s):  
Genotoxic Stress ◽  
Akt Pathway ◽  
Mutant P53 ◽  
Tumor Suppressor P53 ◽  
Wild Type ◽  
Akt Activation ◽  
Pi3k Inhibitors ◽  
Phosphoinositide 3 Kinase ◽  
Induced Apoptosis ◽  
Dependent Mechanism

The tumor suppressor p53 and the phosphoinositide 3-kinase (PI3K)-Akt pathway have fundamental roles in regulating cell growth, apoptosis and are frequently mutated in cancer. Here, we show that genotoxic stress induces nuclear Akt activation by a p53-dependent mechanism that is independent from the canonical membrane-localized PI3K-Akt pathway. Upon genotoxic stress a nuclear p53-PI3,4,5P3 complex is generated in regions devoid of membranes by a nuclear PI3K, and this complex recruits all the kinases required to activate Akt and phosphorylate FOXOs, inhibiting DNA damage-induced apoptosis. Wild-type p53 activates nuclear Akt in an on/off fashion upon stress, whereas mutant p53 stimulates high basal Akt activity, indicating a fundamental difference. The nuclear p53-phosphoinositide signalosome is distinct from the canonical membrane-localized pathway and insensitive to PI3K inhibitors currently in the clinic, underscoring its therapeutic relevance.

scholarly journals p53 as a hub in cellular redox regulation and therapeutic target in cancer

2019 ◽  
Vol 11 (4) ◽  
pp. 330-341 ◽  
Author(s):  
Sofi E Eriksson ◽  
Sophia Ceder ◽  
Vladimir J N Bykov ◽  
Klas G Wiman
Keyword(s):  
Transcription Factor ◽  
Dna Binding ◽  
Redox Homeostasis ◽  
Single Amino Acid ◽  
Cysteine Residues ◽  
Mutant P53 ◽  
Efficient Treatment ◽  
Cellular Redox ◽  
Core Domain ◽  
Cellular Environment

Abstract The TP53 tumor suppressor gene encodes a DNA-binding transcription factor that regulates multiple cellular processes including cell growth and cell death. The ability of p53 to bind to DNA and activate transcription is tightly regulated by post-translational modifications and is dependent on a reducing cellular environment. Some p53 transcriptional target genes are involved in regulation of the cellular redox homeostasis, e.g. TIGAR and GLS2. A large fraction of human tumors carry TP53 mutations, most commonly missense mutations that lead to single amino acid substitutions in the core domain. Mutant p53 proteins can acquire so called gain-of-function activities and influence the cellular redox balance in various ways, for instance by binding of the Nrf2 transcription factor, a major regulator of cellular redox state. The DNA-binding core domain of p53 has 10 cysteine residues, three of which participate in holding a zinc atom that is critical for p53 structure and function. Several novel compounds that refold and reactivate missense mutant p53 bind to specific p53 cysteine residues. These compounds can also react with other thiols and target components of the cellular redox system, such as glutathione. Dual targeting of mutant p53 and redox homeostasis may allow more efficient treatment of cancer.

scholarly journals PKR is not a universal target of tumor suppressor p53 in response to genotoxic stress

Cell Cycle ◽  
2009 ◽  
Vol 8 (21) ◽  
pp. 3606-3607 ◽  
Author(s):  
Mashrur Rahman ◽  
Christopher Lem ◽  
Hala Muaddi ◽  
Antonis Koromilas
Keyword(s):  
Tumor Suppressor ◽  
Genotoxic Stress ◽  
Tumor Suppressor P53

The tumor suppressor p53 regulates its own transcription

1993 ◽  
Vol 13 (6) ◽  
pp. 3415-3423
Author(s):  
A Deffie ◽  
H Wu ◽  
V Reinke ◽  
G Lozano
Keyword(s):  
Consensus Sequence ◽  
Point Mutations ◽  
Direct Interaction ◽  
Mutant P53 ◽  
Tumor Suppressor P53 ◽  
Mobility Shift ◽  
Shift Analysis ◽  
Promoter Deletion Analysis ◽  
Protein Dna Interactions ◽  
Responsive Element

The ability of p53 to suppress transformation correlates with its ability to activate transcription. To identify targets of p53 transactivation, we examined the p53 promoter itself. Northern (RNA) analysis and transient transfection experiments showed that p53 transcriptionally regulated itself. A functionally inactive mutant p53 could not regulate the p53 promoter. Deletion analysis of the p53 promoter delineated sequences between +22 and +67 as being critical for regulation. Electrophoretic mobility shift analysis and methylation interference pinpointed the p53 DNA responsive element. When oligomerized in front of a heterologous minimal promoter, this element was regulated by wild-type p53 and not by mutant p53. Point mutations in the DNA element that eliminated protein-DNA interactions also resulted in a nonresponsive p53 promoter. The DNA element in the p53 promoter responsive to p53 regulation is similar to the p53 consensus sequence. However, we have been unable to detect a direct interaction of p53 with its promoter.

Eukaryotic protein uS19: a component of the decoding site of ribosomes and a player in human diseases

2021 ◽  
Vol 478 (5) ◽  
pp. 997-1008
Author(s):  
Dmitri Graifer ◽  
Galina Karpova
Keyword(s):  
Ribosome Biogenesis ◽  
Lymphocytic Leukemia ◽  
Human Diseases ◽  
Tumor Suppressor P53 ◽  
Translational Fidelity ◽  
Gene Encoding ◽  
Ribosomal Subunits ◽  
Translational Machinery ◽  
Diamond Blackfan Anemia ◽  
Ribosomal Function

Proteins belonging to the universal ribosomal protein (rp) uS19 family are constituents of small ribosomal subunits, and their conserved globular parts are involved in the formation of the head of these subunits. The eukaryotic rp uS19 (previously known as S15) comprises a C-terminal extension that has no homology in the bacterial counterparts. This extension is directly implicated in the formation of the ribosomal decoding site and thereby affects translational fidelity in a manner that has no analogy in bacterial ribosomes. Another eukaryote-specific feature of rp uS19 is its essential participance in the 40S subunit maturation due to the interactions with the subunit assembly factors required for the nuclear exit of pre-40S particles. Beyond properties related to the translation machinery, eukaryotic rp uS19 has an extra-ribosomal function concerned with its direct involvement in the regulation of the activity of an important tumor suppressor p53 in the Mdm2/Mdmx-p53 pathway. Mutations in the RPS15 gene encoding rp uS19 are linked to diseases (Diamond Blackfan anemia, chronic lymphocytic leukemia and Parkinson's disease) caused either by defects in the ribosome biogenesis or disturbances in the functioning of ribosomes containing mutant rp uS19, likely due to the changed translational fidelity. Here, we review currently available data on the involvement of rp uS19 in the operation of the translational machinery and in the maturation of 40S subunits, on its extra-ribosomal function, and on relationships between mutations in the RPS15 gene and certain human diseases.

scholarly journals Mutant p53 Sequestration of the MDM2 Acidic Domain Inhibits E3 Ligase Activity

2018 ◽  
Vol 39 (4) ◽  
Author(s):  
Leixiang Yang ◽  
Tanjing Song ◽  
Qian Cheng ◽  
Lihong Chen ◽  
Jiandong Chen
Keyword(s):  
Tumor Cells ◽  
Recent Work ◽  
Intramolecular Interaction ◽  
E3 Ligase ◽  
Mutant P53 ◽  
Wild Type ◽  
Gain Of Function ◽  
Core Domain ◽  
Acidic Domain ◽  
Wild Type P53

ABSTRACT Missense p53 mutants often accumulate in tumors and drive progression through gain of function. MDM2 efficiently degrades wild-type p53 but fails to degrade mutant p53 in tumor cells. Previous studies revealed that mutant p53 inhibits MDM2 autoubiquitination, suggesting that the interaction inhibits MDM2 E3 activity. Recent work showed that MDM2 E3 activity is stimulated by intramolecular interaction between the RING and acidic domains. Here, we show that in the mutant p53-MDM2 complex, the mutant p53 core domain binds to the MDM2 acidic domain with significantly higher avidity than wild-type p53. The mutant p53-MDM2 complex is deficient in catalyzing ubiquitin release from the activated E2 conjugating enzyme. An MDM2 construct with extra copies of the acidic domain is resistant to inhibition by mutant p53 and efficiently promotes mutant p53 ubiquitination and degradation. The results suggest that mutant p53 interferes with the intramolecular autoactivation mechanism of MDM2, contributing to reduced ubiquitination and increased accumulation in tumor cells.

scholarly journals Cryo-EM Structures of Prestin and the Molecular Basis of Outer Hair Cell Electromotility

2021 ◽  
Author(s):  
Navid Bavi ◽  
Michael D Clark ◽  
Gustavo F Contreras ◽  
Rong Shen ◽  
Bharat Reddy ◽  
...  
Keyword(s):  
Outer Hair Cell ◽  
Binding Pocket ◽  
Structural Features ◽  
Outer Hair Cells ◽  
Anion Binding ◽  
Structural Basis ◽  
Inhibition Mechanism ◽  
Core Domain ◽  
The Core ◽  
Voltage Dependent

The voltage-dependent motor protein, Prestin (SLC26A5) is responsible for the electromotive behavior of outer hair cells (OHCs). Here, we determined the structure of dolphin Prestin in complex with Cl- and the inhibitor Salicylate using single particle cryo-electron microscopy. These structures establish the specific structural features of mammalian Prestin and reveal small but significant differences with the transporter members of the SLC26 family of membrane proteins. Comparison with SLC26A9 point to conformational differences in the special relationship between the core and gate domains. Importantly, we highlight substantial alterations to the hydrophobic footprint of Prestin as it relates to the membrane, which point to a potential influence of Prestin on its surrounding lipid. The structure of Prestin bound to the inhibitor Salicylate confirms the nature of the anion binding pocket, formed by TM3 and TM10 in the Core domain and a set of anion coordinating residues which include Q97, F101, F137, S398 and R399. The presence of a well-defined density for Salycilate points to an inhibition mechanism based on competition for the anion-binding pocket of Prestin. These observations illuminate the structural basis of Prestin electromotility, a key component in the mammalian cochlear amplifier.

Fibrillar Aggregates of the Tumor Suppressor p53 Core Domain†

Biochemistry ◽  
2003 ◽  
Vol 42 (30) ◽  
pp. 9022-9027 ◽  
Author(s):  
Daniella Ishimaru ◽  
Leonardo R. Andrade ◽  
Luciano S. P. Teixeira ◽  
Pablo A. Quesado ◽  
Larissa M. Maiolino ◽  
...  
Keyword(s):  
Tumor Suppressor ◽  
Tumor Suppressor P53 ◽  
Core Domain

scholarly journals Cytoplasmic p53 polypeptide is associated with ribosomes.

1997 ◽  
Vol 17 (6) ◽  
pp. 3146-3154 ◽  
Author(s):  
B M Fontoura ◽  
C A Atienza ◽  
E A Sorokina ◽  
T Morimoto ◽  
R B Carroll
Keyword(s):  
Sodium Dodecyl ◽  
Proteinase K ◽  
Mutant P53 ◽  
Tumor Suppressor P53 ◽  
Wild Type ◽  
Mcf7 Cells ◽  
Gapdh Mrna ◽  
5.8S Rrna ◽  
Proteinase K Treatment ◽  
Covalently Linked

Our previous finding that the tumor suppressor p53 is covalently linked to 5.8S rRNA suggested functional association of p53 polypeptide with ribosomes. p53 polypeptide is expressed at low basal levels in the cytoplasm of normal growing cells in the G1 phase of the cell cycle. We report here that cytoplasmic wild-type p53 polypeptide from both rat embryo fibroblasts and MCF7 cells and the A135V transforming mutant p53 polypeptide were found associated with ribosomes to various extents. Treatment of cytoplasmic extracts with RNase or puromycin in the presence of high salt, both of which are known to disrupt ribosomal function, dissociated p53 polypeptide from the ribosomes. In immunoprecipitates of p53 polypeptide-associated ribosomes, 5.8S rRNA was detectable only after proteinase K treatment, indicating all of the 5.8S rRNA in p53-associated ribosomes is covalently linked to protein. While 5.8S rRNA linked to protein was found in the immunoprecipitates of either wild-type or A135V mutant p53 polypeptide associated with ribosomes, little 5.8S rRNA was found in the immunoprecipitates of the slowly sedimenting p53 polypeptide, which was not associated with ribosomes. In contrast, 5.8S rRNA was liberated from bulk ribosomes by 1% sodium dodecyl sulfate, without digestion with proteinase K, indicating that these ribosomes contain 5.8S rRNA, which is not linked to protein. Immunoprecipitation of p53 polypeptide coprecipitated a small fraction of ribosomes. p53 mRNA immunoprecipitated with cytoplasmic p53 polypeptide, while GAPDH mRNA did not. These results show that cytoplasmic p53 polypeptide is associated with a subset of ribosomes, having covalently modified 5.8S rRNA.

scholarly journals Synergistic and additive effect of retinoic acid in circumventing resistance to p53 restoration

2018 ◽  
Vol 115 (9) ◽  
pp. 2198-2203 ◽  
Author(s):  
Connie A. Larsson ◽  
Sydney M. Moyer ◽  
Bin Liu ◽  
Keith A. Michel ◽  
Vinod Pant ◽  
...  
Keyword(s):  
Gene Expression ◽  
Retinoic Acid ◽  
Gene Expression Profiling ◽  
Expression Profiling ◽  
Therapeutic Response ◽  
Retinoic Acid Receptor ◽  
Mutant P53 ◽  
Missense Mutations ◽  
Synthetic Retinoid ◽  
P53 Reactivation

TP53 mutations occur in ∼50% of all human tumors, with increased frequency in aggressive cancers that are notoriously difficult to treat. Additionally, p53 missense mutations are remarkably predictive of refractoriness to chemo/radiotherapy in various malignancies. These observations have led to the development of mutant p53-targeting agents that restore p53 function. An important unknown is which p53-mutant tumors will respond to p53 reactivation-based therapies. Here, we found a heterogeneous impact on therapeutic response to p53 restoration, suggesting that it will unlikely be effective as a monotherapy. Through gene expression profiling of p53R172H-mutant lymphomas, we identified retinoic acid receptor gamma (RARγ) as an actionable target and demonstrated that pharmacological activation of RARγ with a synthetic retinoid sensitizes resistant p53-mutant lymphomas to p53 restoration, while additively improving outcome and survival in inherently sensitive tumors.

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