BACKGROUND: Synonymous mutations (SMs) change the mRNA nucleotide sequences without altering the corresponding amino acid sequence and are usually overlooked due to their perceived lack of influence on protein function. However, emerging reports suggest that SMs play a significant role in disease development and progression. METHODS: Whole exome sequencing, RNA-sequencing, and droplet digital PCR were performed to identify the SMs from the malignant glioma patients. MutaRNA was used to predict the effect of SMs on RNA structure in silico. SHAPE-MaP was performed to probe and assess the effect of SMs on RNA structure in-cellulo. RESULTS: Here, we report that a Cancer-Associated SM in TP53 codon valine 203 (CASM203) results in the induction of the alternative translation initiated p53 protein isoform, p47. In-cell high-throughput RNA structural mapping showed that CASM203 mimics the Protein Kinase RNA-Like ER Kinase (PERK)-mediated p53 mRNA secondary structure that induces p47 expression of during the unfolded protein response (UPR). CONCLUSIONS: Overall, the single gain-of-function SM mimics the UPR-mediated p53 stress response, by generating RNA secondary structures akin to the PERK-mediated p53 mRNA structural switch. This illustrates the link between RNA structures and cellular biology and underscores the importance of SMs in cancer biology and their potential to further refine genetic diagnostics.

• Publikační typ
• časopisecké články MeSH

The p53 family of proteins evolved from a common ancestor into three separate genes encoding proteins that act as transcription factors with distinct cellular roles. Isoforms of each member that lack specific regions or domains are suggested to result from alternative transcription start sites, alternative splicing or alternative translation initiation, and have the potential to exponentially increase the functional repertoire of each gene. However, evidence supporting the presence of individual protein variants at functional levels is often limited and is inferred by mRNA detection using highly sensitive amplification techniques. We provide a critical appraisal of the current evidence for the origins, expression, functions and regulation of p53-family isoforms. We conclude that despite the wealth of publications, several putative isoforms remain poorly established. Future research with improved technical approaches and the generation of isoform-specific protein detection reagents is required to establish the physiological relevance of p53-family isoforms in health and disease. In addition, our analyses suggest that p53-family variants evolved partly through convergent rather than divergent evolution from the ancestral gene.

• MeSH
• alternativní sestřih * MeSH
• lidé MeSH
• messenger RNA metabolismus   genetika   MeSH
• molekulární evoluce MeSH
• nádorový supresorový protein p53 * metabolismus   genetika   MeSH
• počátek transkripce MeSH
• protein - isoformy * genetika   metabolismus   MeSH
• regulace genové exprese MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• messenger RNA MeSH
• nádorový supresorový protein p53 * MeSH
• protein - isoformy * MeSH

Cellular stress conditions activate p53-dependent pathways to counteract the inflicted damage. To achieve the required functional diversity, p53 is subjected to numerous post-translational modifications and the expression of isoforms. Little is yet known how p53 has evolved to respond to different stress pathways. The p53 isoform p53/47 (p47 or ΔNp53) is linked to aging and neural degeneration and is expressed in human cells via an alternative cap-independent translation initiation from the 2nd in-frame AUG at codon 40 (+118) during endoplasmic reticulum (ER) stress. Despite an AUG codon in the same location, the mouse p53 mRNA does not express the corresponding isoform in either human or mouse-derived cells. High-throughput in-cell RNA structure probing shows that p47 expression is attributed to PERK kinase-dependent structural alterations in the human p53 mRNA, independently of eIF2α. These structural changes do not take place in murine p53 mRNA. Surprisingly, PERK response elements required for the p47 expression are located downstream of the 2nd AUG. The data show that the human p53 mRNA has evolved to respond to PERK-mediated regulation of mRNA structures in order to control p47 expression. The findings highlight how p53 mRNA co-evolved with the function of the encoded protein to specify p53-activities under different cellular conditions.

• MeSH
• kinasa eIF-2 genetika   metabolismus   MeSH
• lidé MeSH
• messenger RNA genetika   metabolismus   MeSH
• myši MeSH
• nádorový supresorový protein p53 * genetika   metabolismus   MeSH
• posttranslační úpravy proteinů MeSH
• protein - isoformy metabolismus   MeSH
• stres endoplazmatického retikula * genetika   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• kinasa eIF-2 MeSH
• messenger RNA MeSH
• nádorový supresorový protein p53 * MeSH
• protein - isoformy MeSH

The tumor suppressor protein p53 orchestrates cellular responses to a vast number of stresses, with DNA damage and oncogenic activation being some of the best described. The capacity of p53 to control cellular events such as cell cycle progression, DNA repair, and apoptosis, to mention some, has been mostly linked to its role as a transcription factor. However, how p53 integrates different signaling cascades to promote a particular pathway remains an open question. One way to broaden its capacity to respond to different stimuli is by the expression of isoforms that can modulate the activities of the full-length protein. One of these isoforms is p47 (p53/47, Δ40p53, p53ΔN40), an alternative translation initiation variant whose expression is specifically induced by the PERK kinase during the Unfolded Protein Response (UPR) following Endoplasmic Reticulum stress. Despite the increasing knowledge on the p53 pathway, its activity when the translation machinery is globally suppressed during the UPR remains poorly understood. Here, we focus on the expression of p47 and we propose that the alternative initiation of p53 mRNA translation offers a unique condition-dependent mechanism to differentiate p53 activity to control cell homeostasis during the UPR. We also discuss how the manipulation of these processes may influence cancer cell physiology in light of therapeutic approaches.

• Klíčová slova
• ER stress, UPR, mRNA translation, p47, p53,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

A large number of signalling pathways converge on p53 to induce different cellular stress responses that aim to promote cell cycle arrest and repair or, if the damage is too severe, to induce irreversible senescence or apoptosis. The differentiation of p53 activity towards specific cellular outcomes is tightly regulated via a hierarchical order of post-translational modifications and regulated protein-protein interactions. The mechanisms governing these processes provide a model for how cells optimize the genetic information for maximal diversity. The p53 mRNA also plays a role in this process and this review aims to illustrate how protein and RNA interactions throughout the p53 mRNA in response to different signalling pathways control RNA stability, translation efficiency or alternative initiation of translation. We also describe how a p53 mRNA platform shows riboswitch-like features and controls the rate of p53 synthesis, protein stability and modifications of the nascent p53 protein. A single cancer-derived synonymous mutation disrupts the folding of this platform and prevents p53 activation following DNA damage. The role of the p53 mRNA as a target for signalling pathways illustrates how mRNA sequences have co-evolved with the function of the encoded protein and sheds new light on the information hidden within mRNAs.

• MeSH
• 3' nepřekládaná oblast genetika   MeSH
• 5' nepřekládaná oblast genetika   MeSH
• fyziologický stres genetika   MeSH
• lidé MeSH
• ligandy MeSH
• messenger RNA genetika   MeSH
• nádorový supresorový protein p53 genetika   MeSH
• protoonkogenní proteiny c-mdm2 metabolismus   MeSH
• riboswitch genetika   MeSH
• vazba proteinů MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• 3' nepřekládaná oblast MeSH
• 5' nepřekládaná oblast MeSH
• ligandy MeSH
• messenger RNA MeSH
• nádorový supresorový protein p53 MeSH
• protoonkogenní proteiny c-mdm2 MeSH
• riboswitch MeSH

Physiological and pathological conditions that affect the folding capacity of the endoplasmic reticulum (ER) provoke ER stress and trigger the unfolded protein response (UPR). The UPR aims to either restore the balance between newly synthesized and misfolded proteins or if the damage is severe, to trigger cell death. However, the molecular events underlying the switch between repair and cell death are not well understood. The ER-resident chaperone BiP governs the UPR by sensing misfolded proteins and thereby releasing and activating the three mediators of the UPR: PERK, IRE1 and ATF6. PERK promotes G2 cell cycle arrest and cellular repair by inducing the alternative translated p53 isoform p53ΔN40 (p53/47), which activates 14-3-3σ via suppression of p21CDKN1A. Here we show that prolonged ER stress promotes apoptosis via a p53-dependent inhibition of BiP expression. This leads to the release of the pro-apoptotic BH3-only BIK from BiP and activation of apoptosis. Suppression of bip mRNA translation is mediated via the specific binding of p53 to the first 346-nt of the bip mRNA and via a p53 trans-suppression domain located within the first seven N-terminal amino acids of p53ΔN40. This work shows how p53 targets BiP to promote apoptosis during severe ER stress and further illustrates how regulation of mRNA translation has a key role in p53-mediated regulation of gene expression during the UPR.

• MeSH
• adaptorové proteiny signální transdukční metabolismus   MeSH
• apoptóza fyziologie   MeSH
• chaperon endoplazmatického retikula BiP MeSH
• endoplazmatické retikulum metabolismus   MeSH
• endoribonukleasy metabolismus   MeSH
• lidé MeSH
• mitochondriální proteiny metabolismus   MeSH
• nádorové buněčné linie MeSH
• nádorový supresorový protein p53 genetika   metabolismus   MeSH
• protein-serin-threoninkinasy metabolismus   MeSH
• proteiny regulující apoptózu metabolismus   MeSH
• proteiny teplotního šoku metabolismus   MeSH
• signální dráha UPR fyziologie   MeSH
• stres endoplazmatického retikula fyziologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• adaptorové proteiny signální transdukční MeSH
• Bik protein, mouse MeSH Prohlížeč
• chaperon endoplazmatického retikula BiP MeSH
• endoribonukleasy MeSH
• mitochondriální proteiny MeSH
• nádorový supresorový protein p53 MeSH
• protein-serin-threoninkinasy MeSH
• proteiny regulující apoptózu MeSH
• proteiny teplotního šoku MeSH
• TP53 protein, human MeSH Prohlížeč

MDMX and MDM2 are two nonredundant essential regulators of p53 tumor suppressor activity. MDM2 controls p53 expression levels, whereas MDMX is predominantly a negative regulator of p53 trans-activity. The feedback loops between MDM2 and p53 are well studied and involve both negative and positive regulation on transcriptional, translational and post-translational levels but little is known on the regulatory pathways between p53 and MDMX. Here we show that overexpression of p53 suppresses mdmx mRNA translation in vitro and in cell-based assays. The core domain of p53 binds the 5' untranslated region (UTR) of the mdmx mRNA in a zinc-dependent manner that together with a trans-suppression domain located in p53 N-terminus controls MDMX synthesis. This interaction can be visualized in the nuclear and cytoplasmic compartment. Fusion of the mdmx 5'UTR to the ovalbumin open reading frame leads to suppression of ovalbumin synthesis. Interestingly, the transcription inactive p53 mutant R273H has a different RNA-binding profile compared with the wild-type p53 and differentiates the synthesis of MDMX isoforms. This study describes p53 as a trans-suppressor of the mdmx mRNA and adds a further level to the intricate feedback system that exist between p53 and its key regulatory factors and emphasizes the important role of mRNA translation control in regulating protein expression in the p53 pathway.

• MeSH
• jaderné proteiny metabolismus   MeSH
• lidé MeSH
• messenger RNA genetika   MeSH
• myši MeSH
• nádorový supresorový protein p53 metabolismus   MeSH
• protoonkogenní proteiny c-mdm2 genetika   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• jaderné proteiny MeSH
• messenger RNA MeSH
• nádorový supresorový protein p53 MeSH
• protoonkogenní proteiny c-mdm2 MeSH

Recent years have seen a great expansion in our understandings of how silent mutations can drive a disease and that mRNAs are not only mere messengers between the genome and the encoded proteins but also encompass regulatory activities. This review focuses on how silent mutations within open reading frames can affect the functional properties of the encoded protein. We describe how mRNAs exert control of cell biological processes governed by the encoded proteins via translation kinetics, protein folding, mRNA stability, spatio-temporal protein expression and by direct interactions with cellular factors. These examples illustrate how additional levels of information lie within the coding sequences and that the degenerative genetic code is not redundant and have co-evolved with the encoded proteins. Hence, so called synonymous mutations are not always silent but 'whisper'.

• MeSH
• genetický kód genetika   MeSH
• kodon genetika   MeSH
• lidé MeSH
• messenger RNA chemie   genetika   MeSH
• modely genetické MeSH
• mutace * MeSH
• otevřené čtecí rámce genetika   MeSH
• proteiny chemie   genetika   metabolismus   MeSH
• proteosyntéza genetika   MeSH
• sbalování proteinů MeSH
• sbalování RNA MeSH
• stabilita RNA genetika   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• kodon MeSH
• messenger RNA MeSH
• proteiny MeSH

p53 is activated by different stress and damage pathways and regulates cell biological responses including cell cycle arrest, repair pathways, apoptosis and senescence. Following DNA damage, the levels of p53 increase and via binding to target gene promoters, p53 induces expression of multiple genes including p21(CDKN1A) and mdm2. The effects of p53 on gene expression during the DNA damage response are well mimicked by overexpressing p53 under normal conditions. However, stress to the Endoplasmic Reticulum (ER) and the consequent Unfolded Protein Response (UPR) leads to the induction of the p53/47 isoform that lacks the first 40 aa of p53 and to an active suppression of p21(CDKN1A) transcription and mRNA translation. We now show that during ER stress p53 also suppresses MDM2 protein levels via a similar mechanism. These observations not only raise questions about the physiological role of MDM2 during ER stress but it also reveals a new facet of p53 as a repressor toward 2 of its major target genes during the UPR. As suppression of p21(CDKN1A) and MDM2 protein synthesis is mediated via their coding sequences, it raises the possibility that p53 controls mRNA translation via a common mechanism that might play an important role in how p53 regulates gene expression during the UPR, as compared to the transcription-dependent gene regulation taking place during the DNA damage response.

• Klíčová slova
• ER stress, MDM2, mRNA translation, p53, p53/47,
• MeSH
• chaperon endoplazmatického retikula BiP MeSH
• down regulace MeSH
• genový knockdown MeSH
• HCT116 buňky MeSH
• inhibitor p21 cyklin-dependentní kinasy biosyntéza   genetika   MeSH
• lidé MeSH
• messenger RNA genetika   metabolismus   MeSH
• nádorový supresorový protein p53 genetika   metabolismus   MeSH
• nádory genetika   metabolismus   patologie   MeSH
• proteiny teplotního šoku metabolismus   MeSH
• protoonkogenní proteiny c-mdm2 biosyntéza   genetika   MeSH
• regulace genové exprese u nádorů * MeSH
• signální dráha UPR MeSH
• signální transdukce MeSH
• stres endoplazmatického retikula * MeSH
• transfekce MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• CDKN1A protein, human MeSH Prohlížeč
• chaperon endoplazmatického retikula BiP MeSH
• inhibitor p21 cyklin-dependentní kinasy MeSH
• MDM2 protein, human MeSH Prohlížeč
• messenger RNA MeSH
• nádorový supresorový protein p53 MeSH
• proteiny teplotního šoku MeSH
• protoonkogenní proteiny c-mdm2 MeSH
• TP53 protein, human MeSH Prohlížeč