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ELife Sep 2023Checkpoint activation after DNA damage causes a transient cell cycle arrest by suppressing cyclin-dependent kinases (CDKs). However, it remains largely elusive how cell...
Checkpoint activation after DNA damage causes a transient cell cycle arrest by suppressing cyclin-dependent kinases (CDKs). However, it remains largely elusive how cell cycle recovery is initiated after DNA damage. In this study, we discovered the upregulated protein level of MASTL kinase hours after DNA damage. MASTL promotes cell cycle progression by preventing PP2A/B55-catalyzed dephosphorylation of CDK substrates. DNA damage-induced MASTL upregulation was caused by decreased protein degradation, and was unique among mitotic kinases. We identified E6AP as the E3 ubiquitin ligase that mediated MASTL degradation. MASTL degradation was inhibited upon DNA damage as a result of the dissociation of E6AP from MASTL. E6AP depletion reduced DNA damage signaling, and promoted cell cycle recovery from the DNA damage checkpoint, in a MASTL-dependent manner. Furthermore, we found that E6AP was phosphorylated at Ser-218 by ATM after DNA damage and that this phosphorylation was required for its dissociation from MASTL, the stabilization of MASTL, and the timely recovery of cell cycle progression. Together, our data revealed that ATM/ATR-dependent signaling, while activating the DNA damage checkpoint, also initiates cell cycle recovery from the arrest. Consequently, this results in a timer-like mechanism that ensures the transient nature of the DNA damage checkpoint.
Topics: Cell Cycle Checkpoints; Cell Cycle; Cell Division; Cyclin-Dependent Kinases; DNA Damage
PubMed: 37672026
DOI: 10.7554/eLife.86976 -
Biomedicine & Pharmacotherapy =... Sep 2023Adenosine is an endogenous nucleoside that regulates many physiological and pathological processes. It is derived from either the intracellular or extracellular... (Review)
Review
Adenosine is an endogenous nucleoside that regulates many physiological and pathological processes. It is derived from either the intracellular or extracellular dephosphorylation of adenosine triphosphate and interacts with cell-surface G-protein-coupled receptors. Adenosine plays a substantial role in protecting against cell damage in areas of increased tissue metabolism and preventing organ dysfunction in pathological states. Targeting adenosine metabolism and receptor signaling may be an effective therapeutic approach for human diseases, including cardiovascular and central nervous system disorders, rheumatoid arthritis, asthma, renal diseases, and cancer. Several lines of evidence have shown that many drugs exert their beneficial effects by modulating adenosine signaling pathways but this knowledge urgently needs to be summarized, and most importantly, actualized. The present review collects pharmaceuticals and pharmacological or diagnostic tools that target adenosine signaling in their primary or secondary mode of action. We overviewed FDA-approved drugs as well as those currently being studied in clinical trials. Among them are already used in clinic A2A adenosine receptor modulators like istradefylline or regadenoson, but also plenty of anti-platelet, anti-inflammatory, or immunosuppressive, and anti-cancer drugs. On the other hand, we investigated dozens of specific adenosine pathway regulators that are tested in clinical trials to treat human infectious and noninfectious diseases. In conclusion, targeting purinergic signaling represents a great therapeutic challenge. The actual knowledge of the involvement of adenosinergic signaling as part of the mechanism of action of old drugs has open a path not only for drug-repurposing but also for new therapeutic strategies.
Topics: Humans; Adenosine; Adenosine Triphosphate; Receptors, Purinergic P1; Cell Membrane; Signal Transduction
PubMed: 37506580
DOI: 10.1016/j.biopha.2023.115184 -
Neurology International Jun 2024The tau protein is a microtubule-associated protein that promotes microtubule stabilization. The phosphorylation of the tau protein has been linked to its dissociation...
The tau protein is a microtubule-associated protein that promotes microtubule stabilization. The phosphorylation of the tau protein has been linked to its dissociation from microtubules. Here, we examined the relationship between neuronal depolarization activity and tau protein phosphorylation by employing model systems in culture as well as in vivo. The KCl-evoked depolarization of cultured neurons has often been used to investigate the effects of neuronal activity. We found dephosphorylation at AT8 sites (S202, T205), T212, AT180 sites (T231, S235), and S396 in KCl-simulated cultured neurons. We also found that the KCl-induced tau protein dephosphorylation increases the level of the tau protein fractionated with stable microtubules. In an in vivo experiment, we demonstrated that the exposure of mice to a new environment activates protein phosphatase 1 in the mouse hippocampus and induces tau protein dephosphorylation. We also found an increased amount of the tau protein in a stable microtubule fraction, suggesting that the dephosphorylation of the tau protein may lead to its increased microtubule association in vivo. These results suggest that the association of microtubules with tau proteins may be regulated by the tau protein phosphorylation status affected by neuronal electrical activity.
PubMed: 38921953
DOI: 10.3390/neurolint16030049 -
Trends in Plant Science Sep 2023The Salt Overly Sensitive (SOS) pathway plays a central role in plant salinity tolerance. Since the discovery of the SOS pathway, transcriptional and post-translational... (Review)
Review
The Salt Overly Sensitive (SOS) pathway plays a central role in plant salinity tolerance. Since the discovery of the SOS pathway, transcriptional and post-translational regulations of its core components have garnered considerable attention. To date, several proteins that regulate these core components, either positively or negatively at the protein and transcript levels, have been identified. Here, we review recent advances in the understanding of the functional regulation of the core proteins of the SOS pathway and an expanding spectrum of their upstream effectors in plants. Furthermore, we also discuss how these novel regulators act as key signaling nodes of multilayer control of plant development and stress adaptation through modulation of the SOS core proteins at the transcriptional and post-translational levels.
Topics: Salt Tolerance; Arabidopsis Proteins; Plant Proteins; Adaptation, Physiological; Gene Expression Regulation, Plant
PubMed: 37117077
DOI: 10.1016/j.tplants.2023.04.003 -
Biochemical and Biophysical Research... Aug 2023Investigate the role of the Hippo-YAP signaling pathway in radioresistant Nasopharyngeal Carcinoma (NPC).
OBJECTIVES
Investigate the role of the Hippo-YAP signaling pathway in radioresistant Nasopharyngeal Carcinoma (NPC).
METHODS
Establishment of radioresistant CNE-1 cells (CNE-1-RR) by gradually increasing ionizing radiation (IR) doses, and identifying the apoptosis of CNE-1-RR by flow cytometry. We employed immunoblot and immunofluorescence staining to detect the expression of YAP in both CNE-1-RR and control group cells. Moreover, we validated the role of YAP in CNE-1-RR by inhibiting its nuclear translocation.
RESULTS
In contrast to the control group, radioresistant NPC cells demonstrated significant YAP dephosphorylation and nuclear translocation. CNE-1-RR cells exhibited enhanced activation of γ-H2AX (Ser139) upon exposure to IR and greater recruitment of double-strand breaks (DSBs) repair-related proteins. Additionally, inhibiting YAP nuclear translocation in radioresistant CNE-1-RR cells significantly increased their sensitivity to radiotherapy.
CONCLUSIONS
The present investigation has unveiled the intricate mechanisms and physiological roles of YAP in CNE-1-RR cells exhibiting resistance to IR. Based on our findings, it can be inferred that a combinational therapeutic strategy involving radiotherapy and inhibitors that impede the nuclear translocation of YAP holds promising potential for treating radioresistant NPC.
Topics: Humans; Apoptosis; Carcinoma; Cell Line, Tumor; Nasopharyngeal Carcinoma; Nasopharyngeal Neoplasms; Radiation Tolerance; YAP-Signaling Proteins
PubMed: 37290285
DOI: 10.1016/j.bbrc.2023.05.101 -
International Journal of Biological... 2023Numerous mitochondrial abnormalities are reported to result from excessive inflammation during endotoxemia. Prohibitin 2 (PHB2) and phosphoglycerate mutase 5 (Pgam5)...
Numerous mitochondrial abnormalities are reported to result from excessive inflammation during endotoxemia. Prohibitin 2 (PHB2) and phosphoglycerate mutase 5 (Pgam5) have been associated with altered mitochondrial homeostasis in several cardiovascular diseases; however, their role in endotoxemia-related myocardial dysfunction has not been explored. Our experiments were aimed to evaluate the potential contribution of Pgam5 and PHB2 to endotoxemia-induced mitochondrial dysfunction in cardiomyocytes, with a focus on two endogenous protective programs that sustain mitochondrial integrity, namely mitophagy and the mitochondrial unfolded protein response (UPR). We found that PHB2 transgenic mice are resistant to endotoxemia-mediated myocardial depression and mitochondrial damage. Our assays indicated that PHB2 overexpression activates mitophagy and the UPR, which maintains mitochondrial metabolism, prevents oxidative stress injury, and enhances cardiomyocyte viability. Molecular analyses further showed that Pgam5 binds to and dephosphorylates PHB2, resulting in cytosolic translocation of mitochondrial PHB2. Silencing of Pgam5 or transfection of a phosphorylated PHB2 mutant in mouse HL-1 cardiomyocytes prevented the loss of mitochondrially-localized PHB2 and activated mitophagy and UPR in the presence of LPS. Notably, cardiomyocyte-specific deletion of Pgam5 attenuated LPS-mediated myocardial dysfunction and preserved cardiomyocyte viability. These findings suggest that Pgam5/PHB2 signaling and mitophagy/UPR are potential targets for the treatment of endotoxemia-related cardiac dysfunction.
Topics: Animals; Mice; Endotoxemia; Lipopolysaccharides; Mitophagy; Phosphoprotein Phosphatases; Prohibitins; Unfolded Protein Response
PubMed: 37781037
DOI: 10.7150/ijbs.85767 -
Circulation Research Jan 2024Cardiac hypertrophy is an intermediate stage in the development of heart failure. The structural and functional processes occurring in cardiac hypertrophy include...
BACKGROUND
Cardiac hypertrophy is an intermediate stage in the development of heart failure. The structural and functional processes occurring in cardiac hypertrophy include extensive gene reprogramming, which is dependent on epigenetic regulation and chromatin remodeling. However, the chromatin remodelers and their regulatory functions involved in the pathogenesis of cardiac hypertrophy are not well characterized.
METHODS
Protein interaction was determined by immunoprecipitation assay in primary cardiomyocytes and mouse cardiac samples subjected or not to transverse aortic constriction for 1 week. Chromatin immunoprecipitation and DNA sequencing (ChIP-seq) experiments were performed on the chromatin of adult mouse cardiomyocytes.
RESULTS
We report that the calcium-activated protein phosphatase CaN (calcineurin), its endogenous inhibitory protein carabin, the STK24 (STE20-like protein kinase 3), and the histone monomethyltransferase, MLL3 (mixed lineage leukemia 3) form altogether a macromolecular complex at the chromatin of cardiomyocytes. Under basal conditions, carabin prevents CaN activation while the serine/threonine kinase STK24 maintains MLL3 inactive via phosphorylation. After 1 week of transverse aortic constriction, both carabin and STK24 are released from the CaN-MLL3 complex leading to the activation of CaN, dephosphorylation of MLL3, and in turn, histone H3 lysine 4 monomethylation. Selective cardiac MLL3 knockdown mitigates hypertrophy, and chromatin immunoprecipitation and DNA sequencing analysis demonstrates that MLL3 is de novo recruited at the transcriptional start site of genes implicated in cardiomyopathy in stress conditions. We also show that CaN and MLL3 colocalize at chromatin and that CaN activates MLL3 histone methyl transferase activity at distal intergenic regions under hypertrophic conditions.
CONCLUSIONS
Our study reveals an unsuspected epigenetic mechanism of CaN that directly regulates MLL3 histone methyl transferase activity to promote cardiac remodeling.
Topics: Animals; Mice; Calcineurin; Cardiomegaly; Chromatin; Epigenesis, Genetic; Histones; Myocytes, Cardiac; Transferases; Ventricular Remodeling
PubMed: 38084599
DOI: 10.1161/CIRCRESAHA.123.323458 -
Biochimica Et Biophysica Acta.... Oct 2023The senescence of bone marrow mesenchymal stem cells (BMSCs) is the basis of senile osteoporosis (SOP). Targeting BMSCs senescence is of paramount importance for...
The senescence of bone marrow mesenchymal stem cells (BMSCs) is the basis of senile osteoporosis (SOP). Targeting BMSCs senescence is of paramount importance for developing anti-osteoporotic strategy. In this study, we found that protein tyrosine phosphatase 1B (PTP1B), an enzyme responsible for tyrosine dephosphorylation, was significantly upregulated in BMSCs and femurs with advancing chronological age. Therefore, the potential role of PTP1B in BMSCs senescence and senile osteoporosis was studied. Firstly, significantly upregulated PTP1B expression along with impaired osteogenic differentiation capacity was observed in D-galactose (D-gal)-induced BMSCs and naturally-aged BMSCs. Furthermore, PTP1B silencing could effectively alleviate senescence, improve mitochondrial dysfunction, and restore osteogenic differentiation in aged BMSCs, which was attributable to enhanced mitophagy mediated by PKM2/AMPK pathway. In addition, hydroxychloroquine (HCQ), an autophagy inhibitor, significantly reversed the protective effects from PTP1B knockdown. In SOP animal model, transplantation of LV-transfected D-gal-induced BMSCs harvested double protective effects, including increased bone formation and reduced osteoclastogenesis. Similarly, HCQ treatment remarkably suppressed osteogenesis of LV-transfected D-gal-induced BMSCs in vivo. Taken together, our data demonstrated that PTP1B silencing protects against BMSCs senescence and mitigates SOP via activating AMPK-mediated mitophagy. Targeting PTP1B may represent a promising interventional strategy to attenuate SOP.
Topics: Animals; Osteogenesis; AMP-Activated Protein Kinases; Mitophagy; Phosphoric Monoester Hydrolases; Mesenchymal Stem Cells; Osteoporosis
PubMed: 37385514
DOI: 10.1016/j.bbadis.2023.166795 -
International Journal of Molecular... Dec 2023The regulation of protein kinases by dephosphorylation is a key mechanism that defines the activity of immune cells. A balanced process of the... (Review)
Review
The regulation of protein kinases by dephosphorylation is a key mechanism that defines the activity of immune cells. A balanced process of the phosphorylation/dephosphorylation of key protein kinases by dual-specificity phosphatases is required for the realization of the antitumor immune response. The family of dual-specificity phosphatases is represented by several isoforms found in both resting and activated macrophages. The main substrate of dual-specificity phosphatases are three components of mitogen-activated kinase signaling cascades: the extracellular signal-regulated kinase ERK1/2, p38, and Janus kinase family. The results of the study of model tumor-associated macrophages supported the assumption of the crucial role of dual-specificity phosphatases in the formation and determination of the outcome of the immune response against tumor cells through the selective suppression of mitogen-activated kinase signaling cascades. Since mitogen-activated kinases mostly activate the production of pro-inflammatory mediators and the antitumor function of macrophages, the excess activity of dual-specificity phosphatases suppresses the ability of tumor-associated macrophages to activate the antitumor immune response. Nowadays, the fundamental research in tumor immunology is focused on the search for novel molecular targets to activate the antitumor immune response. However, to date, dual-specificity phosphatases received limited discussion as key targets of the immune system to activate the antitumor immune response. This review discusses the importance of dual-specificity phosphatases as key regulators of the tumor-associated macrophage function.
Topics: Dual-Specificity Phosphatases; Mitogen-Activated Protein Kinases; Phosphoprotein Phosphatases; Tumor-Associated Macrophages; Protein Tyrosine Phosphatases; Mitogens; Phosphorylation; Protein Kinases; p38 Mitogen-Activated Protein Kinases; Dual Specificity Phosphatase 1
PubMed: 38139370
DOI: 10.3390/ijms242417542 -
Cell Death & Disease Sep 2023Phosphorylation of IRF3 is critical to induce type I interferon (IFN-I) production in antiviral innate response. Here we report that lysine methyltransferase SMYD2...
Phosphorylation of IRF3 is critical to induce type I interferon (IFN-I) production in antiviral innate response. Here we report that lysine methyltransferase SMYD2 inhibits the expressions of IFN-I and proinflammatory cytokines in macrophages upon viral infections. The Smyd2-deficient mice are more resistant to viral infection by producing more IFN-I and proinflammatory cytokines. Mechanistically, SMYD2 inhibits IRF3 phosphorylation in macrophages in response to viral infection independent of its methyltransferase activity. We found that SMYD2 interacts with the DNA-binding domain (DBD) and IRF association domain (IAD) domains of IRF3 by its insertion SET domain (SETi) and could recruit phosphatase PP1α to enhance its interaction with IRF3, which leads to decreased phosphorylation of IRF3 in the antiviral innate response. Our study identifies SMYD2 as a negative regulator of IFN-I production against virus infection. The new way of regulating IRF3 phosphorylation will provide insight into the understanding of IFN-I production in the innate response and possible intervention of the related immune disorders.
Topics: Animals; Mice; Antiviral Agents; Lysine; Immunity, Innate; Interferons; Cytokines; Antibodies; Methyltransferases
PubMed: 37673879
DOI: 10.1038/s41419-023-06118-y