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Senescence plays a key role in various physiological and pathological processes. We reported that injury-induced transient senescence correlates with heart regeneration, yet the multi-omics profile and molecular underpinnings of regenerative senescence remain obscure. Using proteomics and single-cell RNA sequencing, here we report the regenerative senescence multi-omic signature in the adult mouse heart and establish its role in neonatal heart regeneration and agrin-mediated cardiac repair in adult mice. We identified early growth response protein 1 (Egr1) as a regulator of regenerative senescence in both models. In the neonatal heart, Egr1 facilitates angiogenesis and cardiomyocyte proliferation. In adult hearts, agrin-induced senescence and repair require Egr1, activated by the integrin-FAK-ERK-Akt1 axis in cardiac fibroblasts. We also identified cathepsins as injury-induced senescence-associated secretory phenotype components that promote extracellular matrix degradation and potentially assist in reducing fibrosis. Altogether, we uncovered the molecular signature and functional benefits of regenerative senescence during heart regeneration, with Egr1 orchestrating the process.
Assuntos
Proliferação de Células , Senescência Celular , Proteína 1 de Resposta de Crescimento Precoce , Miócitos Cardíacos , Regeneração , Animais , Proteína 1 de Resposta de Crescimento Precoce/metabolismo , Proteína 1 de Resposta de Crescimento Precoce/genética , Regeneração/fisiologia , Senescência Celular/fisiologia , Miócitos Cardíacos/metabolismo , Camundongos Endogâmicos C57BL , Neovascularização Fisiológica/fisiologia , Transdução de Sinais , Fibroblastos/metabolismo , Camundongos , Proteínas Proto-Oncogênicas c-akt/metabolismo , Células Cultivadas , Animais Recém-Nascidos , Modelos Animais de Doenças , Fenótipo Secretor Associado à Senescência , Proteômica , Análise de Célula Única , Masculino , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Camundongos Knockout , Quinase 1 de Adesão FocalRESUMO
The p53 tumor suppressor, encoded by the TP53 gene, serves as a major barrier against malignant transformation. Patients with Li-Fraumeni syndrome (LFS) inherit a mutated TP53 allele from one parent and a wild-type TP53 allele from the other. Subsequently, the wild-type allele is lost and only the mutant TP53 allele remains. This process, which is termed loss of heterozygosity (LOH), results in only mutant p53 protein expression. We used primary dermal fibroblasts from LFS patients carrying the hotspot p53 gain-of-function pathogenic variant, R248Q to study the LOH process and characterize alterations in various pathways before and after LOH. We previously described the derivation of mutant p53 reactivating peptides, designated pCAPs (p53 Conformation Activating Peptides). In this study, we tested the effect of lead peptide pCAP-250 on LOH and on its associated cellular changes. We report that treatment of LFS fibroblasts with pCAP-250 prevents the accumulation of mutant p53 protein, inhibits LOH, and alleviates its cellular consequences. Furthermore, prolonged treatment with pCAP-250 significantly reduces DNA damage and restores long-term genomic stability. pCAPs may thus be contemplated as a potential preventive treatment to prevent or delay early onset cancer in carriers of mutant p53.
Assuntos
Fibroblastos , Síndrome de Li-Fraumeni , Perda de Heterozigosidade , Proteína Supressora de Tumor p53 , Síndrome de Li-Fraumeni/genética , Síndrome de Li-Fraumeni/patologia , Humanos , Proteína Supressora de Tumor p53/metabolismo , Proteína Supressora de Tumor p53/genética , Fibroblastos/metabolismo , Fibroblastos/efeitos dos fármacos , Fibroblastos/patologia , Dano ao DNA , MutaçãoRESUMO
Tumor suppressor p53 (TP53) is frequently mutated in cancer, often resulting not only in loss of its tumor-suppressive function but also acquisition of dominant-negative and even oncogenic gain-of-function traits. While wild-type p53 levels are tightly regulated, mutants are typically stabilized in tumors, which is crucial for their oncogenic properties. Here, we systematically profiled the factors that regulate protein stability of wild-type and mutant p53 using marker-based genome-wide CRISPR screens. Most regulators of wild-type p53 also regulate p53 mutants, except for p53 R337H regulators, which are largely private to this mutant. Mechanistically, FBXO42 emerged as a positive regulator for a subset of p53 mutants, working with CCDC6 to control USP28-mediated mutant p53 stabilization. Additionally, C16orf72/HAPSTR1 negatively regulates both wild-type p53 and all tested mutants. C16orf72/HAPSTR1 is commonly amplified in breast cancer, and its overexpression reduces p53 levels in mouse mammary epithelium leading to accelerated breast cancer. This study offers a network perspective on p53 stability regulation, potentially guiding strategies to reinforce wild-type p53 or target mutant p53 in cancer.
Assuntos
Mutação , Estabilidade Proteica , Proteína Supressora de Tumor p53 , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo , Animais , Humanos , Camundongos , Feminino , Sistemas CRISPR-Cas , Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Linhagem Celular Tumoral , Ubiquitina Tiolesterase/genética , Ubiquitina Tiolesterase/metabolismo , Regulação Neoplásica da Expressão Gênica , Repetições Palindrômicas Curtas Agrupadas e Regularmente EspaçadasRESUMO
Li-Fraumeni syndrome (LFS) is a hereditary cancer predisposition syndrome associated with germline TP53 pathogenic variants. Here, we perform whole-genome sequence (WGS) analysis of tumors from 22 patients with TP53 germline pathogenic variants. We observe somatic mutations affecting Wnt, PI3K/AKT signaling, epigenetic modifiers and homologous recombination genes as well as mutational signatures associated with prior chemotherapy. We identify near-ubiquitous early loss of heterozygosity of TP53, with gain of the mutant allele. This occurs earlier in these tumors compared to tumors with somatic TP53 mutations, suggesting the timing of this mark may distinguish germline from somatic TP53 mutations. Phylogenetic trees of tumor evolution, reconstructed from bulk and multi-region WGS, reveal that LFS tumors exhibit comparatively limited heterogeneity. Overall, our study delineates early copy number gains of mutant TP53 as a characteristic mutational process in LFS tumorigenesis, likely arising years prior to tumor diagnosis.
Assuntos
Síndrome de Li-Fraumeni , Síndromes Neoplásicas Hereditárias , Humanos , Proteína Supressora de Tumor p53/genética , Predisposição Genética para Doença , Variações do Número de Cópias de DNA/genética , Fosfatidilinositol 3-Quinases/genética , Filogenia , Síndrome de Li-Fraumeni/diagnóstico , Síndrome de Li-Fraumeni/genética , Mutação em Linhagem Germinativa/genética , MutaçãoRESUMO
While multiplexing samples using DNA barcoding revolutionized the pace of biomedical discovery, multiplexing of live imaging-based applications has been limited by the number of fluorescent proteins that can be deconvoluted using common microscopy equipment. To address this limitation, we develop visual barcodes that discriminate the clonal identity of single cells by different fluorescent proteins that are targeted to specific subcellular locations. We demonstrate that deconvolution of these barcodes is highly accurate and robust to many cellular perturbations. We then use visual barcodes to generate 'Signalome' cell-lines by mixing 12 clones of different live reporters into a single population, allowing simultaneous monitoring of the activity in 12 branches of signaling, at clonal resolution, over time. Using the 'Signalome' we identify two distinct clusters of signaling pathways that balance growth and proliferation, emphasizing the importance of growth homeostasis as a central organizing principle in cancer signaling. The ability to multiplex samples in live imaging applications, both in vitro and in vivo may allow better high-content characterization of complex biological systems.
Assuntos
DNA , Microscopia , Células Clonais , Código de Barras de DNA Taxonômico/métodosRESUMO
Pre-leukemic clones carrying DNMT3A mutations have a selective advantage and an inherent chemoresistance, however the basis for this phenotype has not been fully elucidated. Mutations affecting the gene TP53 occur in pre-leukemic hematopoietic stem/progenitor cells (preL-HSPC) and lead to chemoresistance. Many of these mutations cause a conformational change and some of them were shown to enhance self-renewal capacity of preL-HSPC. Intriguingly, a misfolded P53 was described in AML blasts that do not harbor mutations in TP53, emphasizing the dynamic equilibrium between wild-type (WT) and "pseudo-mutant" conformations of P53. By combining single cell analyses and P53 conformation-specific monoclonal antibodies we studied preL-HSPC from primary human DNMT3A-mutated AML samples. We found that while leukemic blasts express mainly the WT conformation, in preL-HSPC the pseudo-mutant conformation is the dominant. HSPC from non-leukemic samples expressed both conformations to a similar extent. In a mouse model we found a small subset of HSPC with a dominant pseudo-mutant P53. This subpopulation was significantly larger among DNMT3AR882H-mutated HSPC, suggesting that while a pre-leukemic mutation can predispose for P53 misfolding, additional factors are involved as well. Treatment with a short peptide that can shift the dynamic equilibrium favoring the WT conformation of P53, specifically eliminated preL-HSPC that had dysfunctional canonical P53 pathway activity as reflected by single cell RNA sequencing. Our observations shed light upon a possible targetable P53 dysfunction in human preL-HSPC carrying DNMT3A mutations. This opens new avenues for leukemia prevention.
Assuntos
Leucemia Mieloide Aguda , Proteína Supressora de Tumor p53 , Animais , Humanos , Camundongos , Células Clonais , Leucemia Mieloide Aguda/genética , Mutação , Fenótipo , Proteína Supressora de Tumor p53/genética , Proteínas Mutantes , Dobramento de ProteínaRESUMO
Isolating human MEK/ERK signaling-independent pluripotent stem cells (PSCs) with naive pluripotency characteristics while maintaining differentiation competence and (epi)genetic integrity remains challenging. Here, we engineer reporter systems that allow the screening for defined conditions that induce molecular and functional features of human naive pluripotency. Synergistic inhibition of WNT/ß-CATENIN, protein kinase C (PKC), and SRC signaling consolidates the induction of teratoma-competent naive human PSCs, with the capacity to differentiate into trophoblast stem cells (TSCs) and extraembryonic naive endodermal (nEND) cells in vitro. Divergent signaling and transcriptional requirements for boosting naive pluripotency were found between mouse and human. P53 depletion in naive hPSCs increased their contribution to mouse-human cross-species chimeric embryos upon priming and differentiation. Finally, MEK/ERK inhibition can be substituted with the inhibition of NOTCH/RBPj, which induces alternative naive-like hPSCs with a diminished risk for deleterious global DNA hypomethylation. Our findings set a framework for defining the signaling foundations of human naive pluripotency.
Assuntos
Células-Tronco Pluripotentes , Animais , Diferenciação Celular , Embrião de Mamíferos , Humanos , Camundongos , Transdução de Sinais , TrofoblastosRESUMO
The p53 protein is mutated in about 50% of human cancers. Aside from losing its tumor-suppressive activities, mutant p53 may acquire pro-oncogenic activity, which is facilitated by two underlying mechanisms. The first mechanism is the inhibition of co-expressed wild-type p53 (WTp53) activity, dubbed the dominant-negative effect (DNE). The second mechanism is a neomorphic pro-oncogenic activity that does not involve the inhibition of WTp53, termed gain-of-function (GOF). Throughout the years, both mechanisms were demonstrated in a plethora of in vitro and in vivo models. However, whether both account for protumorigenic activities of mutant p53 and in which contexts is still a matter of ongoing debate. Here, we discuss evidence for both DNE and GOF in a variety of models. These models suggest that both GOF and DNE can be relevant, but are highly dependent on the specific mutation type, genetic and cellular context and even the phenotype that is being assessed. In addition, we discuss how mutant and WTp53 might not exist as two separate entities, but rather as a continuum that may involve a balance between the two forms in the same cells, which could be tilted by various factors and drugs. Further elucidation of the factors that dictate the balance between the WT and mutant p53 states, as well as the factors that govern the impact of DNE and GOF in different cancer types, may lead to the development of more effective treatment regimens for cancer patients.
Assuntos
Carcinogênese/patologia , Mutação com Ganho de Função , Genes Dominantes , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo , Animais , Carcinogênese/genética , Carcinogênese/metabolismo , HumanosRESUMO
The p53 protein is mutated in about 50% of human cancers. Aside from losing the tumor-suppressive functions of the wild-type form, mutant p53 proteins often acquire inherent, novel oncogenic functions, a phenomenon termed mutant p53 gain-of-function (GOF). A growing body of evidence suggests that these pro-oncogenic functions of mutant p53 proteins are mediated by affecting the transcription of various genes, as well as by protein-protein interactions with transcription factors and other effectors. In the current review, we discuss the various GOF effects of mutant p53, and how it may serve as a central node in a network of genes and proteins, which, altogether, promote the tumorigenic process. Finally, we discuss mechanisms by which "Mother Nature" tries to abrogate the pro-oncogenic functions of mutant p53. Thus, we suggest that targeting mutant p53, via its reactivation to the wild-type form, may serve as a promising therapeutic strategy for many cancers that harbor mutant p53. Not only will this strategy abrogate mutant p53 GOF, but it will also restore WT p53 tumor-suppressive functions.
Assuntos
Mutação com Ganho de Função , Neoplasias/genética , Proteína Supressora de Tumor p53/genética , Animais , Carcinogênese , Humanos , Neoplasias/metabolismo , OncogenesRESUMO
A plethora of studies suggest that the non-transformed cellular and non-cellular components of the tumor, collectively known as the tumor microenvironment, have a significant impact on the tumorigenic process. It was suggested that the microenvironment, which initially restricts tumor development, is recruited by the tumor and maintains a crosstalk that further promotes cancer progression. Indeed, many of the molecules that participate in the tumor-stroma crosstalk have been characterized. However, the crucial factors that are responsible for the initiation of this crosstalk or the 'recruitment' process remain poorly understood. We propose that oncogenes themselves may influence the 'recruitment' of the stromal cells, while focusing on mutant p53. Apart from losing its tumor-suppressing properties, mutant p53 gains novel oncogenic functions, a phenomenon dubbed mutant p53 gain of function (GOF). Here, we discuss possible ways in which mutant p53 may modulate the microenvironment in order to promote tumorigenesis. We thus propose that mutant p53 may serve as a key player in the modulation of the tumor-stroma crosstalk in a way that benefits the tumor. Further elucidation of these 'recruitment' processes, dictated by mutant p53, may be utilized for tailoring personalized therapeutic approaches for patients with tumors that harbor p53 mutation.
Assuntos
Carcinogênese , Mutação com Ganho de Função , Regulação Neoplásica da Expressão Gênica , Microambiente Tumoral/genética , Proteína Supressora de Tumor p53 , Animais , Carcinogênese/genética , Carcinogênese/metabolismo , Carcinogênese/patologia , Humanos , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismoRESUMO
The liver is the main metabolic organ in the body, serving as a significant hormonal secretory gland and functioning to maintain hormone balance and homeostasis. Steroid hormones regulate various biological pathways, mainly in the reproductive system and in many metabolic processes. The liver, as well as steroid hormones, contribute significantly, through functional intertwine, to homeostasis maintenance, and proper responses during stress. Malfunction of either has a significant impact on the other and may lead to severe liver diseases as well as to several endocrine syndromes. Thus, the regulation on liver functions as on steroid hormones levels and activities is well-controlled. p53, the well-known tumor suppressor gene, was recently found to regulate metabolism and general homeostasis processes, particularly within the liver. Moreover, p53 was shown to be involved in steroid hormones regulation. In this review, we discuss the bi-directional regulation of the liver and the steroid hormones pointing to p53 as a novel regulator in this axis. A comprehensive understanding of the molecular mechanisms of this axis may help to prevent and treat related disease, especially with the increasing exposure of the population to environmental steroid hormones and steroid hormone-based medication.
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[This corrects the article DOI: 10.18632/oncotarget.10516.].
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Normal tissues are organized in a hierarchical model, whereas at the apex of these hierarchies reside stem cells (SCs) capable of self-renewal and of producing differentiated cellular progenies, leading to normal development and homeostasis. Alike, tumors are organized in a hierarchical manner, with cancer SCs residing at the apex, contributing to the development and nourishment of tumors. p53, the well-known 'guardian of the genome', possesses various roles in embryonic development as well as in adult SC life and serves as the 'guardian of tissue hierarchy'. Moreover, p53 serves as a barrier for dedifferentiation and reprogramming by constraining the cells to a somatic state and preventing their conversion to SCs. On the contrary, the mutant forms of p53 that lost their tumor suppressor activity and gain oncogenic functions serve as 'inducers of tissue anarchy' and promote cancer development. In this review, we discuss these two sides of the p53 token that sentence a tissue either to an ordered hierarchy and life or to anarchy and death. A better understanding of these processes may open new horizons for the development of new cancer therapies.
Assuntos
Células-Tronco Adultas/metabolismo , Desdiferenciação Celular/genética , Reprogramação Celular/genética , Homeostase , Mutação , Neoplasias , Proteína Supressora de Tumor p53 , Células-Tronco Adultas/patologia , Animais , Humanos , Neoplasias/genética , Neoplasias/metabolismo , Neoplasias/patologia , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismoRESUMO
The human immunodeficiency virus enters its host cells by membrane fusion, initiated by the gp41 subunit of its envelope protein. gp41 has also been shown to bind T-cell receptor (TCR) complex components, interfering with TCR signaling leading to reduced T-cell activation. This immunoinhibitory activity is suggested to occur during the membrane fusion process and is attributed to various membranotropic regions of the gp41 ectodomain and to the transmembrane domain. Although extensively studied, the cytosolic region of gp41, termed the cytoplasmic tail (CT), has not been examined in the context of immune suppression. Here we investigated whether the CT inhibits T-cell activation in different T-cell models by utilizing gp41-derived peptides and expressed full gp41 proteins. We found that a conserved region of the CT, termed lentiviral lytic peptide 2 (LLP2), specifically inhibits the activation of mouse, Jurkat, and human primary T-cells. This inhibition resulted in reduced T-cell proliferation, gene expression, cytokine secretion, and cell surface expression of CD69. Differential activation of the TCR signaling cascade revealed that CT-based immune suppression occurs downstream of the TCR complex. Moreover, LLP2 peptide treatment of Jurkat and primary human T-cells impaired Akt but not NFκB and ERK1/2 activation, suggesting that immune suppression occurs through the Akt pathway. These findings identify a novel gp41 T-cell suppressive element with a unique inhibitory mechanism that can take place post-membrane fusion.
Assuntos
Proteína gp41 do Envelope de HIV/imunologia , HIV-1/imunologia , Ativação Linfocitária/imunologia , Linfócitos T/imunologia , Motivos de Aminoácidos , Animais , Proliferação de Células , Citocinas/genética , Citocinas/metabolismo , Expressão Gênica , Proteína gp41 do Envelope de HIV/química , Humanos , Células Jurkat , Camundongos , Camundongos Endogâmicos C57BL , Fosforilação , Domínios Proteicos , Proteínas Proto-Oncogênicas c-akt/química , Proteínas Proto-Oncogênicas c-akt/metabolismo , Células RAW 264.7 , Transdução de Sinais , Linfócitos T/metabolismo , Linfócitos T/virologia , Serina-Treonina Quinases TOR/química , Serina-Treonina Quinases TOR/metabolismoRESUMO
It is well accepted that malignant transformation is associated with unique metabolism. Malignant transformation involves a variety of cellular pathways that are associated with initiation and progression of the malignant process that remain to be deciphered still. Here we used a mouse model of mutant p53 that presents a stepwise progressive transformation of adult Mesenchymal Stem Cells (MSCs). While the established parental p53Mut-MSCs induce tumors, the parental p53WT-MSCs that were established in parallel, did not. Furthermore, tumor lines derived from the parental p53Mut-MSCs (p53Mut-MSC-TLs), exhibited yet a more aggressive transformed phenotype, suggesting exacerbation in tumorigenesis. Metabolic tracing of these various cell types, indicated that while malignant transformation is echoed by a direct augmentation in glycolysis, the more aggressive p53Mut-MSC-TLs demonstrate increased mitochondrial oxidation that correlates with morphological changes in mitochondria mass and function. Finally, we show that these changes are p53Mut-dependent. Computational transcriptional analysis identified a mitochondrial gene signature specifically downregulated upon knock/out of p53Mut in MSC-TLs. Our results suggest that stem cells exhibiting different state of malignancy are also associated with a different quantitative and qualitative metabolic profile in a p53Mut-dependent manner. This may provide important insights for cancer prognosis and the use of specific metabolic inhibitors in a personalized designed cancer therapy.
Assuntos
Células-Tronco Mesenquimais/metabolismo , Mitocôndrias/metabolismo , Neoplasias/genética , Proteína Supressora de Tumor p53/genética , Animais , Carcinogênese/genética , Proliferação de Células/genética , Transformação Celular Neoplásica/genética , Modelos Animais de Doenças , Glicólise/genética , Humanos , Células-Tronco Mesenquimais/patologia , Metaboloma/genética , Camundongos , Mitocôndrias/genética , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , Neoplasias/metabolismo , Neoplasias/patologia , Proteína Supressora de Tumor p53/metabolismoRESUMO
Mutations in the tumor suppressor p53 are the most frequent alterations in human cancer. These mutations include p53-inactivating mutations as well as oncogenic gain-of-function (GOF) mutations that endow p53 with capabilities to promote tumor progression. A primary challenge in cancer therapy is targeting stemness features and cancer stem cells (CSC) that account for tumor initiation, metastasis, and cancer relapse. Here we show that in vitro cultivation of tumors derived from mutant p53 murine bone marrow mesenchymal stem cells (MSC) gives rise to aggressive tumor lines (TL). These MSC-TLs exhibited CSC features as displayed by their augmented oncogenicity and high expression of CSC markers. Comparative analyses between MSC-TL with their parental mutant p53 MSC allowed for identification of the molecular events underlying their tumorigenic properties, including an embryonic stem cell (ESC) gene signature specifically expressed in MSC-TLs. Knockout of mutant p53 led to a reduction in tumor development and tumorigenic cell frequency, which was accompanied by reduced expression of CSC markers and the ESC MSC-TL signature. In human cancer, MSC-TL ESC signature-derived genes correlated with poor patient survival and were highly expressed in human tumors harboring p53 hotspot mutations. These data indicate that the ESC gene signature-derived genes may serve as new stemness-based prognostic biomarkers as well as novel cancer therapeutic targets.Significance: Mesenchymal cancer stem cell-like cell lines express a mutant p53-dependent embryonic stem cell gene signature, which can serve as a potential prognostic biomarker and therapeutic target in cancer. Cancer Res; 78(20); 5833-47. ©2018 AACR.
Assuntos
Carcinogênese/genética , Células-Tronco Embrionárias/citologia , Regulação Neoplásica da Expressão Gênica , Proteína Supressora de Tumor p53/genética , Animais , Biomarcadores Tumorais , Sistemas CRISPR-Cas , Linhagem Celular Tumoral , Proliferação de Células , Humanos , Células-Tronco Mesenquimais/citologia , Camundongos , Camundongos Endogâmicos C57BL , Mutação , Recidiva Local de Neoplasia/patologia , Células-Tronco Neoplásicas/patologia , PrognósticoRESUMO
The discovery of the tumor suppressor p53, through its interactions with proteins of tumor-promoting viruses, paved the way to the understanding of p53 roles in tumor virology. Over the years, accumulating data suggest that WTp53 is involved in the viral life cycle of non-tumor-promoting viruses as well. These include the influenza virus, smallpox and vaccinia viruses, the Zika virus, West Nile virus, Japanese encephalitis virus, Human Immunodeficiency Virus Type 1, Human herpes simplex virus-1, and more. Viruses have learned to manipulate WTp53 through different strategies to improve their replication and spreading in a stage-specific, bidirectional way. While some viruses require active WTp53 for efficient viral replication, others require reduction/inhibition of WTp53 activity. A better understanding of WTp53 functionality in viral life may offer new future clinical approaches, based on WTp53 manipulation, for viral infections.