scholarly journals APE1/Ref-1 Interacts with NPM1 within Nucleoli and Plays a Role in the rRNA Quality Control Process

2009 ◽  
Vol 29 (7) ◽  
pp. 1834-1854 ◽  
Author(s):  
Carlo Vascotto ◽  
Damiano Fantini ◽  
Milena Romanello ◽  
Laura Cesaratto ◽  
Marta Deganuto ◽  
...  
Keyword(s):  
Quality Control ◽  
Cell Growth ◽  
Ribosome Biogenesis ◽  
Molecular Mechanisms ◽  
Rna Binding ◽  
Rrna Synthesis ◽  
Control Mechanisms ◽  
Endonuclease Activity ◽  
Proteomic Approach ◽  
Quality Control Process

ABSTRACT APE1/Ref-1 (hereafter, APE1), a DNA repair enzyme and a transcriptional coactivator, is a vital protein in mammals. Its role in controlling cell growth and the molecular mechanisms that fine-tune its different cellular functions are still not known. By an unbiased proteomic approach, we have identified and characterized several novel APE1 partners which, unexpectedly, include a number of proteins involved in ribosome biogenesis and RNA processing. In particular, a novel interaction between nucleophosmin (NPM1) and APE1 was characterized. We observed that the 33 N-terminal residues of APE1 are required for stable interaction with the NPM1 oligomerization domain. As a consequence of the interaction with NPM1 and RNA, APE1 is localized within the nucleolus and this localization depends on cell cycle and active rRNA transcription. NPM1 stimulates APE1 endonuclease activity on abasic double-stranded DNA (dsDNA) but decreases APE1 endonuclease activity on abasic single-stranded RNA (ssRNA) by masking the N-terminal region of APE1 required for stable RNA binding. In APE1-knocked-down cells, pre-rRNA synthesis and rRNA processing were not affected but inability to remove 8-hydroxyguanine-containing rRNA upon oxidative stress, impaired translation, lower intracellular protein content, and decreased cell growth rate were found. Our data demonstrate that APE1 affects cell growth by directly acting on RNA quality control mechanisms, thus affecting gene expression through posttranscriptional mechanisms.

scholarly journals Polyamines as Quality Control Metabolites Operating at the Post-Transcriptional Level

Plants ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 109 ◽  
Author(s):  
Laetitia Poidevin ◽  
Dilek Unal ◽  
Borja Belda-Palazón ◽  
Alejandro Ferrando
Keyword(s):  
Quality Control ◽  
Molecular Mechanisms ◽  
Transcriptional Level ◽  
Control Mechanisms ◽  
Physiological Functions ◽  
Nonsense Mediated Decay ◽  
Stop Codons ◽  
Ribosome Stalling ◽  
Molecular Functions

Plant polyamines (PAs) have been assigned a large number of physiological functions with unknown molecular mechanisms in many cases. Among the most abundant and studied polyamines, two of them, namely spermidine (Spd) and thermospermine (Tspm), share some molecular functions related to quality control pathways for tightly regulated mRNAs at the level of translation. In this review, we focus on the roles of Tspm and Spd to facilitate the translation of mRNAs containing upstream ORFs (uORFs), premature stop codons, and ribosome stalling sequences that may block translation, thus preventing their degradation by quality control mechanisms such as the nonsense-mediated decay pathway and possible interactions with other mRNA quality surveillance pathways.

scholarly journals Direct Regulation of rRNA Transcription by Fibroblast Growth Factor 2

2005 ◽  
Vol 25 (21) ◽  
pp. 9419-9426 ◽  
Author(s):  
Zhi Sheng ◽  
Yanping Liang ◽  
Chih-Yin Lin ◽  
Lucio Comai ◽  
William J. Chirico
Keyword(s):  
Growth Factor ◽  
Cell Growth ◽  
Fibroblast Growth Factor ◽  
Ribosome Biogenesis ◽  
Secretory Pathway ◽  
Rrna Genes ◽  
Fibroblast Growth Factor 2 ◽  
Rrna Synthesis ◽  
Fibroblast Growth ◽  
Rrna Transcription

ABSTRACT Fibroblast growth factor 2 (FGF-2), which is highly expressed in developing tissues and malignant cells, regulates cell growth, differentiation, and migration. Five isoforms (18 to ∼34 kDa) of FGF-2 are derived from alternative initiation codons of a single mRNA. The 18-kDa FGF-2 isoform is released from cells by a nonclassical secretory pathway and regulates gene expression by binding to cell surface receptors. This isoform also localizes to the nucleolus, raising the possibility that it may directly regulate ribosome biogenesis, a rate-limiting process in cell growth. Although several growth factors have been shown to accumulate in the nucleolus, their function and mechanism of action remain unclear. Here we show that 18-kDa FGF-2 interacts with upstream binding factor (UBF), an architectural transcription factor essential for rRNA transcription. The maximal activation of rRNA transcription in vitro by 18-kDa FGF-2 requires UBF. The 18-kDa FGF-2 localizes to rRNA genes and is necessary for the full activation of pre-rRNA synthesis in vivo. Our results demonstrate that 18-kDa FGF-2 directly regulates rRNA transcription.

Abstract 259: Sam68 Regulates Endothelin-Converting Enzyme-1b Expression and Blood Pressure Homeostasis

Hypertension ◽  
2012 ◽  
Vol 60 (suppl_1) ◽  
Author(s):  
Junlan Zhou ◽  
Gangjian Qin
Keyword(s):  
Blood Pressure ◽  
Cell Cycle ◽  
Endothelial Cells ◽  
Molecular Mechanisms ◽  
Rna Binding ◽  
Umbilical Vein ◽  
Converting Enzyme ◽  
Proteomic Approach ◽  
Endothelin Converting Enzyme

We have previously reported that E2F2, a transcription factor known for its role in cell cycle, regulates the expression of endothelin-converting enzyme-1b (ECE-1b) in endothelial cells and contributes to the maintenance of vascular contractility and blood pressure (BP). However, the molecular mechanisms underlying this novel, cell-cycle independent function of E2F2 remain largely elusive. In this study, we profiled E2F2 interactome in the nucleus of human umbilical vein endothelial cells by utilizing a proteomic approach. We identified that Sam68, a classic RNA-binding protein and Src kinase substrate, acts as an E2F2-interacting protein; co-immunoprecipitation analyses confirmed that both endogenous and ectopically-expressed Sam68 interact with E2F2. Overexpression of Sam68 repressed whereas knockdown of Sam68 increased E2F2-induced ECE-1b promoter activity and mRNA expression. Chromatin immunoprecipitation assays further confirmed that E2F2 and Sam68 co-localize on ECE-1b promoter, indicating that ECE-1b is a direct transcriptional target of E2F2 and Sam68. In vivo, Sam68 knockout (KO) mice displayed a significantly lowered BP as compared to WT littermates (tail-cuff measurements of mean BP, KO vs. WT: 104 ± 6 vs. 123 ± 7 mmHg, n=25 males of age 4-6 months, P<0.05). Together, our studies have revealed a previously unknown function of Sam68 as a transcriptional co-repressor of E2F2 and a critical regulator of BP homeostasis.

scholarly journals The Exosome Associates Cotranscriptionally with the Nascent Pre-mRNP through Interactions with Heterogeneous Nuclear Ribonucleoproteins

2009 ◽  
Vol 20 (15) ◽  
pp. 3459-3470 ◽  
Author(s):  
Viktoria Hessle ◽  
Petra Björk ◽  
Marcus Sokolowski ◽  
Ernesto González de Valdivia ◽  
Rebecca Silverstein ◽  
...  
Keyword(s):  
Quality Control ◽  
Molecular Mechanisms ◽  
Mechanistic Model ◽  
Model Systems ◽  
Control Mechanisms ◽  
Hnrnp Proteins ◽  
Heterogeneous Nuclear Ribonucleoproteins ◽  
Transcription Sites ◽  
Mrna Binding

Eukaryotic cells have evolved quality control mechanisms to degrade aberrant mRNA molecules and prevent the synthesis of defective proteins that could be deleterious for the cell. The exosome, a protein complex with ribonuclease activity, is a key player in quality control. An early quality checkpoint takes place cotranscriptionally but little is known about the molecular mechanisms by which the exosome is recruited to the transcribed genes. Here we study the core exosome subunit Rrp4 in two insect model systems, Chironomus and Drosophila. We show that a significant fraction of Rrp4 is associated with the nascent pre-mRNPs and that a specific mRNA-binding protein, Hrp59/hnRNP M, interacts in vivo with multiple exosome subunits. Depletion of Hrp59 by RNA interference reduces the levels of Rrp4 at transcription sites, which suggests that Hrp59 is needed for the exosome to stably interact with nascent pre-mRNPs. Our results lead to a revised mechanistic model for cotranscriptional quality control in which the exosome is constantly recruited to newly synthesized RNAs through direct interactions with specific hnRNP proteins.

scholarly journals Molecular Mechanisms and Regulation of Mammalian Mitophagy

Cells ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 38
Author(s):  
Vinay Choubey ◽  
Akbar Zeb ◽  
Allen Kaasik
Keyword(s):  
Quality Control ◽  
Cell Fate ◽  
Molecular Mechanisms ◽  
Stress Protein ◽  
Antioxidant Defenses ◽  
Control Mechanisms ◽  
Mitochondrial Dna Damage ◽  
Cellular Environment ◽  
Rigorous Research ◽  
Functional Versatility

Mitochondria in the cell are the center for energy production, essential biomolecule synthesis, and cell fate determination. Moreover, the mitochondrial functional versatility enables cells to adapt to the changes in cellular environment and various stresses. In the process of discharging its cellular duties, mitochondria face multiple types of challenges, such as oxidative stress, protein-related challenges (import, folding, and degradation) and mitochondrial DNA damage. They mitigate all these challenges with robust quality control mechanisms which include antioxidant defenses, proteostasis systems (chaperones and proteases) and mitochondrial biogenesis. Failure of these quality control mechanisms leaves mitochondria as terminally damaged, which then have to be promptly cleared from the cells before they become a threat to cell survival. Such damaged mitochondria are degraded by a selective form of autophagy called mitophagy. Rigorous research in the field has identified multiple types of mitophagy processes based on targeting signals on damaged or superfluous mitochondria. In this review, we provide an in-depth overview of mammalian mitophagy and its importance in human health and diseases. We also attempted to highlight the future area of investigation in the field of mitophagy.

scholarly journals The RNA-binding ubiquitin ligase MKRN1 functions in ribosome-associated quality control of poly(A) translation

2019 ◽  
Author(s):  
Andrea Hildebrandt ◽  
Mirko Brüggemann ◽  
Susan Boerner ◽  
Cornelia Rücklé ◽  
Jan Bernhard Heidelberger ◽  
...  
Keyword(s):  
Quality Control ◽  
Ubiquitin Ligase ◽  
Rna Binding ◽  
Mrna Level ◽  
Ring Finger ◽  
Common Source ◽  
Control Mechanisms ◽  
Functional Protein ◽  
Ribosome Stalling ◽  
Translational Regulators

AbstractCells have evolved quality control mechanisms to ensure protein homeostasis by detecting and degrading aberrant mRNAs and proteins. A common source of aberrant mRNAs is premature polyadenylation, which can result in non-functional protein products. Translating ribosomes that encounter poly(A) sequences are terminally stalled, followed by ribosome recycling and decay of the truncated nascent polypeptide via the ribosome-associated quality control (RQC). Here, we demonstrate that the conserved RNA-binding E3 ubiquitin ligase Makorin Ring Finger Protein 1 (MKRN1) promotes ribosome stalling at poly(A) sequences during RQC. We show that MKRN1 interacts with the cytoplasmic poly(A)-binding protein (PABP) and is positioned upstream of poly(A) tails in mRNAs. Ubiquitin remnant profiling uncovers PABP and ribosomal protein RPS10, as well as additional translational regulators as main ubiquitylation substrates of MKRN1. We propose that MKRN1 serves as a first line of poly(A) recognition at the mRNA level to prevent production of erroneous proteins, thus maintaining proteome integrity.

scholarly journals Molecular Mechanisms of the Interaction between the RNA-Binding Protein Nab2 and the Nuclear Basket Protein Mlp1 in mRNA Quality Control

2019 ◽  
Vol 116 (3) ◽  
pp. 203a
Author(s):  
Mohammad Soheilypour ◽  
Mohaddeseh Peyro ◽  
Hengameh Shams ◽  
Stephanie Rider ◽  
Ali R. Kaazempur-Mofrad ◽  
...  
Keyword(s):  
Quality Control ◽  
Molecular Mechanisms ◽  
Rna Binding ◽  
Binding Protein ◽  
Rna Binding Protein

scholarly journals The RNA-binding ubiquitin ligase MKRN1 functions in ribosome-associated quality control of poly(A) translation

2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Andrea Hildebrandt ◽  
Mirko Brüggemann ◽  
Cornelia Rücklé ◽  
Susan Boerner ◽  
Jan B. Heidelberger ◽  
...  
Keyword(s):  
Quality Control ◽  
Ubiquitin Ligase ◽  
Rna Binding ◽  
Ring Finger ◽  
Common Source ◽  
Control Mechanisms ◽  
Dependent Manner ◽  
Functional Protein ◽  
Ribosome Stalling

Abstract Background Cells have evolved quality control mechanisms to ensure protein homeostasis by detecting and degrading aberrant mRNAs and proteins. A common source of aberrant mRNAs is premature polyadenylation, which can result in non-functional protein products. Translating ribosomes that encounter poly(A) sequences are terminally stalled, followed by ribosome recycling and decay of the truncated nascent polypeptide via ribosome-associated quality control. Results Here, we demonstrate that the conserved RNA-binding E3 ubiquitin ligase Makorin Ring Finger Protein 1 (MKRN1) promotes ribosome stalling at poly(A) sequences during ribosome-associated quality control. We show that MKRN1 directly binds to the cytoplasmic poly(A)-binding protein (PABPC1) and associates with polysomes. MKRN1 is positioned upstream of poly(A) tails in mRNAs in a PABPC1-dependent manner. Ubiquitin remnant profiling and in vitro ubiquitylation assays uncover PABPC1 and ribosomal protein RPS10 as direct ubiquitylation substrates of MKRN1. Conclusions We propose that MKRN1 mediates the recognition of poly(A) tails to prevent the production of erroneous proteins from prematurely polyadenylated transcripts, thereby maintaining proteome integrity.

scholarly journals CX-5461 Inhibits Pancreatic Ductal Adenocarcinoma Cell Growth, Migration and Induces DNA Damage

Molecules ◽  
2019 ◽  
Vol 24 (24) ◽  
pp. 4445 ◽  
Author(s):  
Btissame El Hassouni ◽  
Giulia Mantini ◽  
Benoît Immordino ◽  
Godefridus J. Peters ◽  
Elisa Giovannetti
Keyword(s):  
Pancreatic Cancer ◽  
Dna Damage ◽  
Cell Growth ◽  
Cancer Cells ◽  
Ribosome Biogenesis ◽  
Molecular Mechanisms ◽  
Ductal Adenocarcinoma ◽  
Cell Growth And Migration ◽  
Mesenchymal Transition ◽  
Pancreatic Cancer Cells

Background: Inhibition of ribosome biogenesis has recently emerged as a promising strategy for the treatment of metastatic tumors. The RNA polymerase I inhibitor CX-5461 has shown efficacy in a panel of cancer types and is currently being tested in clinical trials. However, further preclinical studies to unravel molecular mechanisms underlying the activity of this drug are warranted. Methods: In this study, we have investigated the effects of CX-5461 on cell growth and migration of pancreatic cancer cells by the sulforhodamine-B and wound healing assay, respectively. Furthermore, we assessed the expression of epithelial-to-mesenchymal transition (EMT) genes by qRT-PCR, while protein expression of DNA damage marker phospho-H2A.X was studied by Western blot and immunofluorescence. Results: CX-5461 inhibits pancreatic cancer cell growth in the nanomolar range and inhibits the migratory capability of the cells. Additionally, CX-5461 induced expression of EMT factor SNAI1 and caused DNA double-strand breaks as measured by increased expression of phospho-H2A.X. Conclusion: This study demonstrated that CX-5461 is active against pancreatic cancer cells and modulation of EMT factors, as well as increased expression of phospho-H2A.X, support further pre-/clinical investigations, including the analyses of these markers.

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