Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 123
Filtrar
1.
Cell ; 187(17): 4770-4789.e23, 2024 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-38981482

RESUMO

Cellular senescence is an irreversible state of cell-cycle arrest induced by various stresses, including aberrant oncogene activation, telomere shortening, and DNA damage. Through a genome-wide screen, we discovered a conserved small nucleolar RNA (snoRNA), SNORA13, that is required for multiple forms of senescence in human cells and mice. Although SNORA13 guides the pseudouridylation of a conserved nucleotide in the ribosomal decoding center, loss of this snoRNA minimally impacts translation. Instead, we found that SNORA13 negatively regulates ribosome biogenesis. Senescence-inducing stress perturbs ribosome biogenesis, resulting in the accumulation of free ribosomal proteins (RPs) that trigger p53 activation. SNORA13 interacts directly with RPL23, decreasing its incorporation into maturing 60S subunits and, consequently, increasing the pool of free RPs, thereby promoting p53-mediated senescence. Thus, SNORA13 regulates ribosome biogenesis and the p53 pathway through a non-canonical mechanism distinct from its role in guiding RNA modification. These findings expand our understanding of snoRNA functions and their roles in cellular signaling.


Assuntos
Senescência Celular , RNA Nucleolar Pequeno , Proteínas Ribossômicas , Ribossomos , Proteína Supressora de Tumor p53 , Humanos , RNA Nucleolar Pequeno/metabolismo , RNA Nucleolar Pequeno/genética , Senescência Celular/genética , Proteína Supressora de Tumor p53/metabolismo , Proteína Supressora de Tumor p53/genética , Ribossomos/metabolismo , Animais , Camundongos , Proteínas Ribossômicas/metabolismo , Proteínas Ribossômicas/genética
2.
Annu Rev Biochem ; 88: 281-306, 2019 06 20.
Artigo em Inglês | MEDLINE | ID: mdl-30566372

RESUMO

Ribosomes, which synthesize the proteins of a cell, comprise ribosomal RNA and ribosomal proteins, which coassemble hierarchically during a process termed ribosome biogenesis. Historically, biochemical and molecular biology approaches have revealed how preribosomal particles form and mature in consecutive steps, starting in the nucleolus and terminating after nuclear export into the cytoplasm. However, only recently, due to the revolution in cryo-electron microscopy, could pseudoatomic structures of different preribosomal particles be obtained. Together with in vitro maturation assays, these findings shed light on how nascent ribosomes progress stepwise along a dynamic biogenesis pathway. Preribosomes assemble gradually, chaperoned by a myriad of assembly factors and small nucleolar RNAs, before they reach maturity and enter translation. This information will lead to a better understanding of how ribosome synthesis is linked to other cellular pathways in humans and how it can cause diseases, including cancer, if disturbed.


Assuntos
Eucariotos/metabolismo , RNA Ribossômico/metabolismo , Proteínas Ribossômicas/metabolismo , Ribossomos/metabolismo , Nucléolo Celular/metabolismo , Microscopia Crioeletrônica , Humanos , Biogênese de Organelas , Multimerização Proteica
3.
Mol Cell ; 84(8): 1527-1540.e7, 2024 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-38521064

RESUMO

Nucleolar stress (NS) has been associated with age-related diseases such as cancer or neurodegeneration. To investigate how NS triggers toxicity, we used (PR)n arginine-rich peptides present in some neurodegenerative diseases as inducers of this perturbation. We here reveal that whereas (PR)n expression leads to a decrease in translation, this occurs concomitant with an accumulation of free ribosomal (r) proteins. Conversely, (PR)n-resistant cells have lower rates of r-protein synthesis, and targeting ribosome biogenesis by mTOR inhibition or MYC depletion alleviates (PR)n toxicity in vitro. In mice, systemic expression of (PR)97 drives widespread NS and accelerated aging, which is alleviated by rapamycin. Notably, the generalized accumulation of orphan r-proteins is a common outcome of chemical or genetic perturbations that induce NS. Together, our study presents a general model to explain how NS induces cellular toxicity and provides in vivo evidence supporting a role for NS as a driver of aging in mammals.


Assuntos
Neoplasias , Ribossomos , Camundongos , Animais , Ribossomos/metabolismo , Envelhecimento/genética , Peptídeos/metabolismo , Sirolimo/farmacologia , Neoplasias/metabolismo , Nucléolo Celular/genética , Mamíferos
4.
Trends Biochem Sci ; 48(3): 274-287, 2023 03.
Artigo em Inglês | MEDLINE | ID: mdl-36229381

RESUMO

The nucleolus is the site of ribosome biogenesis, one of the most resource-intensive processes in eukaryotic cells. Accordingly, nucleolar morphology and activity are highly responsive to growth signaling and nucleolar insults which are collectively included in the actively evolving concept of nucleolar stress. Importantly, nucleolar alterations are a prominent feature of multiple human pathologies, including cancer and neurodegeneration, as well as being associated with aging. The past decades have seen numerous attempts to isolate compounds targeting different facets of nucleolar activity. We provide an overview of therapeutic opportunities for targeting nucleoli in different pathologies and currently available therapies.


Assuntos
Neoplasias , Ribossomos , Humanos , Nucléolo Celular/patologia , Neoplasias/tratamento farmacológico , Neoplasias/patologia , Envelhecimento
5.
Semin Cell Dev Biol ; 136: 64-74, 2023 02 28.
Artigo em Inglês | MEDLINE | ID: mdl-35410715

RESUMO

The nucleolus is a large nuclear membraneless organelle responsible for ribosome biogenesis. Ribosomes are cytoplasmic macromolecular complexes comprising RNA and proteins that link amino acids together to form new proteins. The biogenesis of ribosomes is an intricate multistep process that involves the transcription of ribosomal DNA (rDNA), the processing of ribosomal RNA (rRNA), and the assembly of rRNA with ribosomal proteins to form active ribosomes. Nearly all steps necessary for ribosome production and maturation occur in the nucleolus. Nucleolar shape, size, and number are directly linked to ribosome biogenesis. Errors in the steps of ribosomal biogenesis are sensed by the nucleolus causing global alterations in nucleolar function and morphology. This phenomenon, known as nucleolar stress, can lead to molecular changes such as stabilization of p53, which in turn activates cell cycle arrest or apoptosis. In this review, we discuss recent work on the association of nucleolar stress with degenerative diseases and developmental defects. In addition, we highlight the importance of de novo nucleotide biosynthesis for the enhanced nucleolar activity of cancer cells and discuss targeting nucleotide biosynthesis as a strategy to activate nucleolar stress to specifically target cancer cells.


Assuntos
Nucléolo Celular , Neoplasias , Humanos , Ribossomos/metabolismo , Proteínas Ribossômicas/genética , Proteínas Ribossômicas/metabolismo , RNA Ribossômico/genética , RNA Ribossômico/metabolismo , Neoplasias/metabolismo , Nucleotídeos
6.
J Biol Chem ; : 107858, 2024 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-39374783

RESUMO

The mechanisms of action for the platinum compounds cisplatin and oxaliplatin have yet to be fully elucidated, despite the worldwide use of these drugs. Recent studies suggest that the two compounds may be working through different mechanisms, with cisplatin inducing cell death via the DNA damage response (DDR) and oxaliplatin utilizing a nucleolar stress-based cell death pathway. While cisplatin-induced DDR has been subject to much research, the mechanisms for oxaliplatin's influence on the nucleolus are not well understood. Prior work has outlined structural parameters for Pt(II) derivatives capable of nucleolar stress induction. In this work, we gain insight into the nucleolar stress response induced by these Pt(II) derivatives by investigating potential correlations between this unique pathway and DDR. Key findings from this study indicate that Pt(II)-induced nucleolar stress occurs when DDR is inhibited and works independently of the ATM/ATR-dependent DDR pathway. We also determine that Pt(II)-induced stress may be linked to the G1 cell cycle phase, as cisplatin can induce nucleolar stress when cell cycle inhibition occurs at the G1/S checkpoint. Finally, we compare Pt(II)-induced nucleolar stress with other small-molecule nucleolar stress-inducing compounds Actinomycin D, BMH-21, and CX-5461, and find that only Pt(II) compounds cause irreversible nucleolar stress. Taken together, these findings contribute to a better understanding of Pt(II)-induced nucleolar stress, its deviation from ATM/ATR-dependent DDR, and the possible influence of cell cycle on the ability of Pt(II) compounds to cause nucleolar stress.

7.
Plant J ; 114(1): 96-109, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-36705084

RESUMO

Ribosome biogenesis is a process of making ribosomes that is tightly linked with plant growth and development. Here, through a suppressor screen for the smo2 mutant, we found that lack of a ribosomal stress response mediator, ANAC082 partially restored growth defects of the smo2 mutant, indicating SMO2 is required for the repression of nucleolar stress. Consistently, the smo2 knock-out mutant exhibited typical phenotypes characteristic of ribosome biogenesis mutants, such as pointed leaves, aberrant leaf venation, disrupted nucleolar structure, abnormal distribution of rRNA precursors, and enhanced tolerance to aminoglycoside antibiotics that target ribosomes. SMO2 interacted with ROOT INITIATION DEFECTIVE 2 (RID2), a methyltransferase-like protein required for pre-rRNA processing. SMO2 enhanced RID2 solubility in Escherichia coli and the loss of function of SMO2 in plant cells reduced RID2 abundance, which may result in abnormal accumulation of FIBRILLARIN 1 (FIB1) and NOP56, two key nucleolar proteins, in high-molecular-weight protein complex. Taken together, our results characterized a novel plant ribosome biogenesis factor, SMO2 that maintains the abundance of RID2, thereby sustaining ribosome biogenesis during plant organ growth.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Nucléolo Celular/genética , Plantas/metabolismo , Ribossomos/metabolismo , RNA Ribossômico/genética , RNA Ribossômico/metabolismo
8.
Gastroenterology ; 165(3): 629-646, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-37247644

RESUMO

BACKGROUND & AIMS: Hyperactivation of ribosome biogenesis leads to hepatocyte transformation and plays pivotal roles in hepatocellular carcinoma (HCC) development. We aimed to identify critical ribosome biogenesis proteins that are overexpressed and crucial in HCC progression. METHODS: HEAT repeat containing 1 (HEATR1) expression and clinical correlations were analyzed using The Cancer Genome Atlas and Gene Expression Omnibus databases and further evaluated by immunohistochemical analysis of an HCC tissue microarray. Gene expression was knocked down by small interfering RNA. HEATR1-knockdown cells were subjected to viability, cell cycle, and apoptosis assays and used to establish subcutaneous and orthotopic tumor models. Chromatin immunoprecipitation and quantitative polymerase chain reaction were performed to detect the association of candidate proteins with specific DNA sequences. Endogenous coimmunoprecipitation combined with mass spectrometry was used to identify protein interactions. We performed immunoblot and immunofluorescence assays to detect and localize proteins in cells. The nucleolus ultrastructure was detected by transmission electron microscopy. Click-iT (Thermo Fisher Scientific) RNA imaging and puromycin incorporation assays were used to measure nascent ribosomal RNA and protein synthesis, respectively. Proteasome activity, 20S proteasome foci formation, and protein stability were evaluated in HEATR1-knockdown HCC cells. RESULTS: HEATR1 was the most up-regulated gene in a set of ribosome biogenesis mediators in HCC samples. High expression of HEATR1 was associated with poor survival and malignant clinicopathologic features in patients with HCC and contributed to HCC growth in vitro and in vivo. HEATR1 expression was regulated by the transcription factor specificity protein 1, which can be activated by insulin-like growth factor 1-mammalian target of rapamycin complex 1 signaling in HCC cells. HEATR1 localized predominantly in the nucleolus, bound to ribosomal DNA, and was associated with RNA polymerase I transcription/processing factors. Knockdown of HEATR1 disrupted ribosomal RNA biogenesis and impaired nascent protein synthesis, leading to reduced cytoplasmic proteasome activity and inhibitory-κB/nuclear factor-κB signaling. Moreover, HEATR1 knockdown induced nucleolar stress with increased nuclear proteasome activity and inactivation of the nucleophosmin 1-MYC axis. CONCLUSIONS: Our study revealed that HEATR1 is up-regulated by insulin-like growth factor 1-mammalian target of rapamycin complex 1-specificity protein 1 signaling in HCC and functions as a crucial regulator of ribosome biogenesis and proteome homeostasis to promote HCC development.


Assuntos
Carcinoma Hepatocelular , Neoplasias Hepáticas , Humanos , Carcinoma Hepatocelular/patologia , Linhagem Celular Tumoral , Proliferação de Células/genética , Regulação Neoplásica da Expressão Gênica , Homeostase , Temperatura Alta , Fator de Crescimento Insulin-Like I/genética , Neoplasias Hepáticas/patologia , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Complexo de Endopeptidases do Proteassoma/genética , Proteoma/metabolismo , Ribossomos/metabolismo , Ribossomos/patologia , RNA Ribossômico/genética , RNA Ribossômico/metabolismo
9.
J Transl Med ; 22(1): 204, 2024 02 26.
Artigo em Inglês | MEDLINE | ID: mdl-38409136

RESUMO

BACKGROUND: Prior evidence demonstrated that Regulator of G protein Signaling 6 (RGS6) translocates to the nucleolus in response to cytotoxic stress though the functional significance of this phenomenon remains unknown. METHODS: Utilizing in vivo gene manipulations in mice, primary murine cardiac cells, human cell lines and human patient samples we dissect the participation of a RGS6-nucleolin complex in chemotherapy-dependent cardiotoxicity. RESULTS: Here we demonstrate that RGS6 binds to a key nucleolar protein, Nucleolin, and controls its expression and activity in cardiomyocytes. In the human myocyte AC-16 cell line, induced pluripotent stem cell derived cardiomyocytes, primary murine cardiomyocytes, and the intact murine myocardium tuning RGS6 levels via overexpression or knockdown resulted in diametrically opposed impacts on Nucleolin mRNA, protein, and phosphorylation.RGS6 depletion provided marked protection against nucleolar stress-mediated cell death in vitro, and, conversely, RGS6 overexpression suppressed ribosomal RNA production, a key output of the nucleolus, and triggered death of myocytes. Importantly, overexpression of either Nucleolin or Nucleolin effector miRNA-21 counteracted the pro-apoptotic effects of RGS6. In both human and murine heart tissue, exposure to the genotoxic stressor doxorubicin was associated with an increase in the ratio of RGS6/Nucleolin. Preventing RGS6 induction via introduction of RGS6-directed shRNA via intracardiac injection proved cardioprotective in mice and was accompanied by restored Nucleolin/miRNA-21 expression, decreased nucleolar stress, and decreased expression of pro-apoptotic, hypertrophy, and oxidative stress markers in heart. CONCLUSION: Together, these data implicate RGS6 as a driver of nucleolar stress-dependent cell death in cardiomyocytes via its ability to modulate Nucleolin. This work represents the first demonstration of a functional role for an RGS protein in the nucleolus and identifies the RGS6/Nucleolin interaction as a possible new therapeutic target in the prevention of cardiotoxicity.


Assuntos
MicroRNAs , Proteínas RGS , Animais , Humanos , Camundongos , Cardiotoxicidade , MicroRNAs/genética , Miócitos Cardíacos , Nucleolina , Proteínas RGS/genética , Transdução de Sinais/fisiologia
10.
J Plant Res ; 2024 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-39235732

RESUMO

Nucleotides are the building blocks of living organisms and their biosynthesis must be tightly regulated. Inosine monophosphate dehydrogenase (IMPDH) is a rate-limiting enzyme in GTP synthesis that is essential for biological activities, such as RNA synthesis. In animals, the suppression of IMPDH function causes ribosomal stress (also known as nucleolar stress), a disorder in ribosome biogenesis that results in cell proliferation defects and apoptosis. Despite its importance, plant IMPDH has not been analyzed in detail. Therefore, we analyzed the phenotypes of mutants of the two IMPDH genes in Arabidopsis thaliana and investigated their relationship with ribosomal stress. Double mutants of IMPDH1 and IMPDH2 were lethal, and only the impdh2 mutants showed growth defects and transient chlorophyll deficiency. These results suggested that IMPDH1 and IMPDH2 are redundant and essential, whereas IMPDH2 has a crucial role. In addition, the impdh2 mutants showed a reduction in nucleolus size and resistance to several translation inhibitors, which is a known response to ribosomal stress. Furthermore, the IMPDH1/impdh1 impdh2 mutants showed more severe growth defects and phenotypes such as reduced plastid rRNA levels and abnormal processing patterns than the impdh2 mutants. Finally, multiple mutations of impdh with as2, which has abnormal leaf polarity, caused the development of needle-like leaves because of the enhancement of the as2 phenotype, which is a typical effect observed in mutants of genes involved in ribosome biogenesis. These results indicated that IMPDH is closely related to ribosome biogenesis, and that mutations in the genes lead to not only known responses to ribosomal stress, but also plant-specific responses.

11.
Int J Mol Sci ; 25(10)2024 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-38791244

RESUMO

Cervical artery dissection (CeAD) is the primary cause of ischemic stroke in young adults. Monogenic heritable connective tissue diseases account for fewer than 5% of cases of CeAD. The remaining sporadic cases have known risk factors. The clinical, radiological, and histological characteristics of systemic vasculopathy and undifferentiated connective tissue dysplasia are present in up to 70% of individuals with sporadic CeAD. Genome-wide association studies identified CeAD-associated genetic variants in the non-coding genomic regions that may impact the gene transcription and RNA processing. However, global gene expression profile analysis has not yet been carried out for CeAD patients. We conducted bulk RNA sequencing and differential gene expression analysis to investigate the expression profile of protein-coding genes in the peripheral blood of 19 CeAD patients and 18 healthy volunteers. This was followed by functional annotation, heatmap clustering, reports on gene-disease associations and protein-protein interactions, as well as gene set enrichment analysis. We found potential correlations between CeAD and the dysregulation of genes linked to nucleolar stress, senescence-associated secretory phenotype, mitochondrial malfunction, and epithelial-mesenchymal plasticity.


Assuntos
Perfilação da Expressão Gênica , Humanos , Masculino , Feminino , Perfilação da Expressão Gênica/métodos , Adulto , Pessoa de Meia-Idade , Estudo de Associação Genômica Ampla , Transcriptoma/genética , Dissecação da Artéria Vertebral/genética , Estudos de Casos e Controles
12.
Bull Exp Biol Med ; 176(4): 519-522, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38492107

RESUMO

Structural changes in rat hepatocyte nucleoli were studied during deep hypothermia simulated by immersion in water at 5°C for 40 min (ambient air temperature 7°C). In comparison with the control, phenomena of nucleolar stress occurred in rats during hypothermia: the number of fibrillar centers (FC) per nucleus (by 1.7 times) and per nucleolus (by 1.6 times), nucleolonemal nucleoli per nucleus (by 2.8 times), and the relative content of nucleolonemal nucleoli per nucleus (by 2.6 times) significantly decreased (p=0.0000001); the number of FC per nucleolonemal nucleolus also decreased by 1.4 times (p=0.01). In the hepatocyte nuclei, we observed an increase in the relative content of transitional type nucleoli per nucleus (by 1.3 times; p=0.01), the number of FC per transitional type nucleolus (by 1.4 times; p=0.003), the content of free FC per nucleus (by 3 times; p=0.00004), and the percentage of free FC per nucleus (by 3.5 times; p=0.00004). These changes can be considered as compensatory and adaptive reactions, and transitional type nucleoli can be attributed to the "reserve" nucleolar pool.


Assuntos
Hipotermia , Ratos , Animais , Nucléolo Celular , Hepatócitos , Região Organizadora do Nucléolo/genética
13.
J Biol Chem ; 298(2): 101524, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-34953860

RESUMO

RNA-binding protein RBM28 (RBM28), as a nucleolar component of spliceosomal small nuclear ribonucleoproteins, is involved in the nucleolar stress response. Whether and how RBM28 regulates tumor progression remains unclear. Here, we report that RBM28 is frequently overexpressed in various types of cancer and that its upregulation is associated with a poor prognosis. Functional and mechanistic assays revealed that RBM28 promotes the survival and growth of cancer cells by interacting with the DNA-binding domain of tumor suppressor p53 to inhibit p53 transcriptional activity. Upon treatment with chemotherapeutic drugs (e.g., adriamycin), RBM28 is translocated from the nucleolus to the nucleoplasm, which is likely mediated via phosphorylation of RBM28 at Ser122 by DNA checkpoint kinases 1 and 2 (Chk1/2), indicating that RBM28 may act as a nucleolar stress sensor in response to DNA damage stress. Our findings not only reveal RBM28 as a potential biomarker and therapeutic target for cancers but also provide mechanistic insights into how cancer cells convert stress signals into a cellular response linking the nucleolus to regulation of the tumor suppressor p53.


Assuntos
Proteínas de Ligação a RNA , Proteína Supressora de Tumor p53 , Linhagem Celular Tumoral , Nucléolo Celular/genética , Nucléolo Celular/metabolismo , Núcleo Celular/genética , Núcleo Celular/metabolismo , Humanos , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismo , Ribonucleoproteínas Nucleares Pequenas/metabolismo , Transcrição Gênica , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo
14.
Cancer Sci ; 114(5): 2078-2086, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-36762786

RESUMO

Ribosome biogenesis in the nucleolus is an important process that consumes 80% of a cell's intracellular energy supply. Disruption of this process results in nucleolar stress, triggering the activation of molecular systems that respond to this stress to maintain homeostasis. Although nucleolar stress was originally thought to be caused solely by abnormalities of ribosomal RNA (rRNA) and ribosomal proteins (RPs), an accumulating body of more current evidence suggests that many other factors, including the DNA damage response and oncogenic stress, are also involved in nucleolar stress response signaling. Cells reacting to nucleolar stress undergo cell cycle arrest or programmed death, mainly driven by activation of the tumor suppressor p53. This observation has nominated nucleolar stress as a promising target for cancer therapy. However, paradoxically, some RP mutations have also been implicated in cancer initiation and progression, necessitating caution. In this article, we summarize recent findings on the molecular mechanisms of nucleolar stress and the human ribosomal diseases and cancers that arise in its wake.


Assuntos
Neoplasias , Proteínas Ribossômicas , Humanos , Proteínas Ribossômicas/genética , Proteínas Ribossômicas/metabolismo , Ribossomos/genética , Ribossomos/metabolismo , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo , RNA Ribossômico/genética , RNA Ribossômico/metabolismo , Pontos de Checagem do Ciclo Celular/genética , Neoplasias/genética , Neoplasias/metabolismo
15.
Parasitol Res ; 122(9): 1961-1971, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37400534

RESUMO

Giardia duodenalis is a protozoan intestinal parasite that causes a significant number of infections worldwide each year, particularly in low-income and developing countries. Despite the availability of treatments for this parasitic infection, treatment failures are alarmingly common. As a result, new therapeutic strategies are urgently needed to effectively combat this disease. On the other hand, within the eukaryotic nucleus, the nucleolus stands out as the most prominent structure. It plays a crucial role in coordinating ribosome biogenesis and is involved in vital processes such as maintaining genome stability, regulating cell cycle progression, controlling cell senescence, and responding to stress. Given its significance, the nucleolus presents itself as a valuable target for selectively inducing cell death in undesirable cells, making it a potential avenue for anti-Giardia treatments. Despite its potential importance, the Giardia nucleolus remains poorly studied and often overlooked. In light of this, the objective of this study is to provide a detailed molecular description of the structure and function of the Giardia nucleolus, with a primary focus on its involvement in ribosomal biogenesis. Likewise, it discusses the targeting of the Giardia nucleolus as a therapeutic strategy, its feasibility, and the challenges involved.


Assuntos
Nucléolo Celular , Giardia , Ribossomos , Nucléolo Celular/genética , Nucléolo Celular/metabolismo , Giardia/citologia , Giardia/genética , RNA Ribossômico/genética , DNA Ribossômico/genética , DNA de Protozoário/genética , RNA de Protozoário/genética , Transcrição Gênica , Regulação da Expressão Gênica , Processamento Pós-Transcricional do RNA/genética , Ribossomos/genética , Ribossomos/metabolismo , Giardíase/tratamento farmacológico , Antiparasitários/uso terapêutico , Desenvolvimento de Medicamentos/tendências
16.
Int J Mol Sci ; 24(17)2023 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-37686003

RESUMO

The N-methyl-D-aspartate (NMDA) glutamate receptors function as plasma membrane ionic channels and take part in very tightly controlled cellular processes activating neurogenic and inflammatory pathways. In particular, the NR1 subunit (new terminology: GluN1) is required for many neuronal and non-neuronal cell functions, including plasticity, survival, and differentiation. Physiologic levels of glutamate agonists and NMDA receptor activation are required for normal neuronal functions such as neuronal development, learning, and memory. When glutamate receptor agonists are present in excess, binding to NMDA receptors produces neuronal/CNS/PNS long-term potentiation, conditions of acute pain, ongoing severe intractable pain, and potential excitotoxicity and pathology. The GluNR1 subunit (116 kD) is necessary as the anchor component directing ion channel heterodimer formation, cellular trafficking, and the nuclear localization that directs functionally specific heterodimer formation, cellular trafficking, and nuclear functions. Emerging studies report the relevance of GluN1 subunit composition and specifically that nuclear GluN1 has major physiologic potential in tissue and/or subnuclear functioning assignments. The shift of the GluN1 subunit from a surface cell membrane to nuclear localization assigns the GluN1 promoter immediate early gene behavior with access to nuclear and potentially nucleolar functions. The present narrative review addresses the nuclear translocation of GluN1, focusing particularly on examples of the role of GluN1 in nociceptive processes.


Assuntos
N-Metilaspartato , Nociceptividade , Humanos , Núcleo Celular , Agonistas de Aminoácidos Excitatórios , Dor , Receptores de N-Metil-D-Aspartato/genética
17.
J Biol Chem ; 296: 100633, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33819479

RESUMO

Recent reports provide evidence that the platinum chemotherapeutic oxaliplatin causes cell death via ribosome biogenesis stress, while cisplatin causes cell death via the DNA damage response (DDR). Underlying differences in mechanisms that might initiate disparate routes to cell death by these two broadly used platinum compounds have not yet been carefully explored. Additionally, prior studies had demonstrated that cisplatin can also inhibit ribosome biogenesis. Therefore, we sought to directly compare the initial influences of oxaliplatin and cisplatin on nucleolar processes and on the DDR. Using pulse-chase experiments, we found that at equivalent doses, oxaliplatin but not cisplatin significantly inhibited ribosomal RNA (rRNA) synthesis by Pol I, but neither compound affected rRNA processing. Inhibition of rRNA synthesis occurred as early as 90 min after oxaliplatin treatment in A549 cells, concurrent with the initial redistribution of the nucleolar protein nucleophosmin (NPM1). We observed that the nucleolar protein fibrillarin began to redistribute by 6 h after oxaliplatin treatment and formed canonical nucleolar caps by 24 h. In cisplatin-treated cells, DNA damage, as measured by γH2AX immunofluorescence, was more extensive, whereas nucleolar organization was unaffected. Taken together, our results demonstrate that oxaliplatin causes early nucleolar disruption via inhibition of rRNA synthesis accompanied by NPM1 relocalization and subsequently causes extensive nucleolar reorganization, while cisplatin causes early DNA damage without significant nucleolar disruption. These data support a model in which, at clinically relevant doses, cisplatin kills cells via the canonical DDR, and oxaliplatin kills cells via ribosome biogenesis stress, specifically via rapid inhibition of rRNA synthesis.


Assuntos
Adenocarcinoma de Pulmão/patologia , Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Morte Celular , Nucléolo Celular/patologia , Neoplasias Pulmonares/patologia , Proteínas Nucleares/metabolismo , Células A549 , Adenocarcinoma de Pulmão/tratamento farmacológico , Adenocarcinoma de Pulmão/metabolismo , Nucléolo Celular/efeitos dos fármacos , Nucléolo Celular/metabolismo , Cisplatino/administração & dosagem , Dano ao DNA , Humanos , Neoplasias Pulmonares/tratamento farmacológico , Neoplasias Pulmonares/metabolismo , Proteínas Nucleares/genética , Nucleofosmina , Oxaliplatina/administração & dosagem , Ribossomos/efeitos dos fármacos , Ribossomos/metabolismo
18.
Biochem Biophys Res Commun ; 637: 203-209, 2022 12 31.
Artigo em Inglês | MEDLINE | ID: mdl-36403484

RESUMO

Ribosome biogenesis proceeds with the successive cleavage and trimming of the large 47S rRNA precursor, where the RNA exosome plays major roles in concert with the Ski2-like RNA helicase, MTR4. The recent finding of a consensus amino acid sequence, the arch-interacting motif (AIM), for binding to the arch domain in MTR4 suggests that recruitment of the RNA processing machinery to the maturing pre-rRNA at appropriate places and timings is mediated by several adaptor proteins possessing the AIM sequence. In yeast Saccharomyces cerevisiae, Nop53 plays such a role in the maturation of the 3'-end of 5.8S rRNA. Here, we investigated the functions of PICT1 (also known as GLTSCR2 or NOP53), a mammalian ortholog of Nop53, during ribosome biogenesis in human cells. PICT1 interacted with MTR4 and exosome in an AIM-dependent manner. Overexpression of PICT1 mutants defecting AIM sequence and siRNA-mediated depletion of PICT1 showed that PICT1 is involved in two distinct pre-rRNA processing steps during the generation of 60S ribosomes; first step is the early cleavage of 32S intermediate RNA, while the second step is the late maturation of 12S precursor into 5.8S rRNA. The recruitment of MTR4 and RNA exosome via the AIM sequence was required only during the late processing step. Although, the depletion of MTR4 and PICT1 induced stabilization of the tumor suppressor p53 protein in cancer cell lines, the depletion of the exosome catalytic subunits, RRP6 and DIS3, did not exert such an effect. These results suggest that recruitment of the RNA processing machinery to the 3'-end of pre-5.8S rRNA may be involved in the induction of the nucleolar stress response, but the pre-rRNA processing capabilities themselves were not involved in this process.


Assuntos
RNA Helicases , Precursores de RNA , Proteínas Supressoras de Tumor , Humanos , Complexo Multienzimático de Ribonucleases do Exossomo/genética , Proteínas Nucleares , Oligonucleotídeos , Precursores de RNA/genética , Processamento Pós-Transcricional do RNA , RNA Ribossômico 5,8S , RNA Interferente Pequeno , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genética , RNA Helicases/genética , Proteínas Supressoras de Tumor/genética
19.
J Neurosci Res ; 100(4): 1084-1104, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35170061

RESUMO

Tau protein abnormalities are associated with various neurodegenerative disorders, including Alzheimer's disease (AD) and traumatic brain injury (TBI). In tau-overexpressing SHSY5Y cells and iPSC-derived neuron models of frontotemporal dementia (FTD), axonal tau translocates into the nuclear compartment, resulting in neuronal dysfunction. Despite extensive research, the mechanisms by which tau translocation results in neurodegeneration remain elusive thus far. We studied the nuclear displacement of different P-tau species [Cis phosphorylated Thr231-tau (cis P-tau), phosphorylated Ser202/Thr205-tau (AT8 P-tau), and phosphorylated Thr212/Ser214-tau (AT100 P-tau)] at various time points using starvation in primary cortical neurons and single severe TBI (ssTBI) in male mouse cerebral cortices as tauopathy models. While all P-tau species translocated into the somatodendritic compartment in response to stress, cis P-tau did so more rapidly than the other species. Notably, nuclear localization of P-tau was associated with p53 apoptotic stabilization and nucleolar stress, both of which resulted in neurodegeneration. In summary, our findings indicate that P-tau nuclear translocation results in p53-dependent apoptosis and nucleolar dispersion, which is consistent with neurodegeneration.


Assuntos
Doença de Alzheimer , Tauopatias , Doença de Alzheimer/metabolismo , Animais , Masculino , Camundongos , Transporte Proteico , Proteína Supressora de Tumor p53/metabolismo , Proteínas tau/metabolismo
20.
Chembiochem ; 23(14): e202200130, 2022 07 19.
Artigo em Inglês | MEDLINE | ID: mdl-35475312

RESUMO

Oxaliplatin, a platinum compound in broad clinical use, can induce cell death through a nucleolar stress pathway rather than the canonical DNA damage response studied for other Pt(II) compounds. Previous work has found that the oxaliplatin 1,2-diaminocyclohexane (DACH) ring but not the oxalate leaving group is important to the ability to induce nucleolar stress. Here we study the influence of DACH ring substituents at the 4-position on the ability of DACH-Pt(II) compounds to cause nucleolar stress. We determine that DACH-Pt(II) compounds with 4-position methyl, ethyl, or propyl substituents induce nucleolar stress, but DACH-Pt(II) compounds with 4-isopropyl substituents do not induce nucleolar stress. This effect is independent of whether the substituent is in the axial or equatorial position relative to the trans diamines of the ligand. These results suggest that spatially sensitive interactions could be involved in the ability of platinum compounds to cause nucleolar stress.


Assuntos
Antineoplásicos , Compostos Organoplatínicos , Antineoplásicos/farmacologia , Ligantes , Compostos Organoplatínicos/metabolismo , Compostos Organoplatínicos/farmacologia , Oxaliplatina/farmacologia
SELEÇÃO DE REFERÊNCIAS
Detalhe da pesquisa