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Nature Communications May 2020Mitochondria undergo dynamic fusion/fission, biogenesis and mitophagy in response to stimuli or stresses. Disruption of mitochondrial homeostasis could lead to cell...
Mitochondria undergo dynamic fusion/fission, biogenesis and mitophagy in response to stimuli or stresses. Disruption of mitochondrial homeostasis could lead to cell senescence, although the underlying mechanism remains unclear. We show that deletion of mitochondrial phosphatase PGAM5 leads to accelerated retinal pigment epithelial (RPE) senescence in vitro and in vivo. Mechanistically, PGAM5 is required for mitochondrial fission through dephosphorylating DRP1. PGAM5 deletion leads to increased mitochondrial fusion and decreased mitochondrial turnover. As results, cellular ATP and reactive oxygen species (ROS) levels are elevated, mTOR and IRF/IFN-β signaling pathways are enhanced, leading to cellular senescence. Overexpression of Drp1 K38A or S637A mutant phenocopies or rescues mTOR activation and senescence in PGAM5 cells, respectively. Young but not aging Pgam5 mice are resistant to sodium iodate-induced RPE cell death. Our studies establish a link between defective mitochondrial fission, cellular senescence and age-dependent oxidative stress response, which have implications in age-related diseases.
Topics: Age Factors; Animals; Cell Line; Cellular Senescence; Dynamins; Gene Expression Regulation; Humans; Mice; Mice, Knockout; Mitochondria; Mitochondrial Dynamics; Oxidative Stress; Phosphoprotein Phosphatases; Retinal Pigment Epithelium; Signal Transduction
PubMed: 32439975
DOI: 10.1038/s41467-020-16312-7 -
Autophagy Mar 2020Mitophagy, which is a conserved cellular process for selectively removing damaged or unwanted mitochondria, is critical for mitochondrial quality control and the...
Mitophagy, which is a conserved cellular process for selectively removing damaged or unwanted mitochondria, is critical for mitochondrial quality control and the maintenance of normal cellular physiology. However, the precise mechanisms underlying mitophagy remain largely unknown. Prior studies on mitophagy focused on the events in the mitochondrial outer membrane. PHB2 (prohibitin 2), which is a highly conserved membrane scaffold protein, was recently identified as a novel inner membrane mitophagy receptor that mediates mitophagy. Here, we report a new signaling pathway for PHB2-mediated mitophagy. Upon mitochondrial membrane depolarization or misfolded protein aggregation, PHB2 depletion destabilizes PINK1 in the mitochondria, which blocks the mitochondrial recruitment of PRKN/Parkin, ubiquitin and OPTN (optineurin), leading to an inhibition of mitophagy. In addition, PHB2 overexpression directly induces PRKN recruitment to the mitochondria. Moreover, PHB2-mediated mitophagy is dependent on the mitochondrial inner membrane protease PARL, which interacts with PHB2 and is activated upon PHB2 depletion. Furthermore, PGAM5, which is processed by PARL, participates in PHB2-mediated PINK1 stabilization. Finally, a ligand of PHB proteins that we synthesized, called FL3, was found to strongly inhibit PHB2-mediated mitophagy and to effectively block cancer cell growth and energy production at nanomolar concentrations. Thus, our findings reveal that the PHB2-PARL-PGAM5-PINK1 axis is a novel pathway of PHB2-mediated mitophagy and that targeting PHB2 with the chemical compound FL3 is a promising strategy for cancer therapy.: AIFM1: apoptosis inducing factor mitochondria associated 1; ATP5F1A/ATP5A1: ATP synthase F1 subunit alpha; BAF: bafilomycin A; CALCOCO2/NDP52: calcium binding and coiled-coil domain 2; CCCP: chemical reagent carbonyl cyanide m-chlorophenyl hydrazine; FL3: flavaglines compound 3; HSPD1/HSP60: heat shock protein family D (Hsp60) member 1; LC3B/MAP1LC3B: microtubule associated protein 1 light chain 3 beta; MEF: mouse embryo fibroblasts; MPP: mitochondrial-processing peptidase; MT-CO2/COX2: mitochondrially encoded cytochrome c oxidase II; MTS: mitochondrial targeting sequence; OA: oligomycin and antimycin A; OPTN: optineurin; OTC: ornithine carbamoyltransferase; PARL: presenilin associated rhomboid like; PBS: phosphate-buffered saline; PGAM5: PGAM family member 5, mitochondrial serine/threonine protein phosphatase; PHB: prohibitin; PHB2: prohibitin 2; PINK1: PTEN induced kinase 1; PRKN/Parkin: parkin RBR E3 ubiquitin protein ligase; Roc-A: rocaglamide A; TOMM20: translocase of outer mitochondrial membrane 20; TUBB: tubulin beta class I.
Topics: HCT116 Cells; HeLa Cells; Humans; Ligands; Metalloproteases; Microtubule-Associated Proteins; Mitochondria; Mitochondrial Proteins; Mitophagy; Phosphoprotein Phosphatases; Prohibitins; Protein Binding; Protein Kinases; Protein Stability; Repressor Proteins; Signal Transduction; Ubiquitin-Protein Ligases
PubMed: 31177901
DOI: 10.1080/15548627.2019.1628520 -
Pharmacology & Therapeutics Nov 2020Protein phosphatases and kinases control multiple cellular events including proliferation, differentiation, and stress responses through regulating reversible protein... (Review)
Review
Protein phosphatases and kinases control multiple cellular events including proliferation, differentiation, and stress responses through regulating reversible protein phosphorylation, the most important post-translational modification. Members of metal-dependent protein phosphatase (PPM) family, also known as PP2C phosphatases, are Ser/Thr phosphatases that bind manganese/magnesium ions (Mn/Mg) in their active center and function as single subunit enzymes. In mammals, there are 20 isoforms of PPM phosphatases: PPM1A, PPM1B, PPM1D, PPM1E, PPM1F, PPM1G, PPM1H, PPM1J, PPM1K, PPM1L, PPM1M, PPM1N, ILKAP, PDP1, PDP2, PHLPP1, PHLPP2, PP2D1, PPTC7, and TAB1, whereas there are only 8 in yeast. Phylogenetic analysis of the DNA sequences of vertebrate PPM isoforms revealed that they can be divided into 12 different classes: PPM1A/PPM1B/PPM1N, PPM1D, PPM1E/PPM1F, PPM1G, PPM1H/PPM1J/PPM1M, PPM1K, PPM1L, ILKAP, PDP1/PDP2, PP2D1/PHLPP1/PHLPP2, TAB1, and PPTC7. PPM-family members have a conserved catalytic core region, which contains the metal-chelating residues. The different isoforms also have isoform specific regions within their catalytic core domain and terminal domains, and these regions may be involved in substrate recognition and/or functional regulation of the phosphatases. The twenty mammalian PPM phosphatases are involved in regulating diverse cellular functions, such as cell cycle control, cell differentiation, immune responses, and cell metabolism. Mutation, overexpression, or deletion of the PPM phosphatase gene results in abnormal cellular responses, which lead to various human diseases. This review focuses on the structures and biological functions of the PPM-phosphatase family and their associated diseases. The development of specific inhibitors against the PPM phosphatase family as a therapeutic strategy will also be discussed.
Topics: Animals; Drug Development; Enzyme Inhibitors; Gene Expression Regulation; Humans; Metals; Mutation; Phosphoprotein Phosphatases
PubMed: 32650009
DOI: 10.1016/j.pharmthera.2020.107622 -
European Journal of Cell Biology Jan 2021In response to mitochondrial damage, mitochondria activate mitochondrial dynamics to maintain normal functions, and an imbalance in mitochondrial dynamics triggers... (Review)
Review
In response to mitochondrial damage, mitochondria activate mitochondrial dynamics to maintain normal functions, and an imbalance in mitochondrial dynamics triggers multiple programmed cell death processes. Recent studies have shown that phosphoglycerate mutase 5 (PGAM5) is associated with mitochondrial damage. PGAM5 activates mitochondrial biogenesis and mitophagy to promote a cellular compensatory response when mitochondria are mildly damaged, whereas severe damage to mitochondria leads to PGAM5 inducing excessive mitochondria fission, disruption to mitochondrial movement, and amplification of apoptosis, necroptosis and mitophagic death signals, which eventually evoke cell death. PGAM5 functions mainly through protein-protein interactions and specific Ser/Thr/His protein phosphatase activity. PGAM5 is also regulated by mitochondrial proteases. Detection of PGAM5 and its interacting protein partners should enable a more accurate evaluation of mitochondrial damage and a more precise method for the diagnosis and treatment of diseases.
Topics: Apoptosis; Humans; Mitochondrial Dynamics; Mitochondrial Proteins; Mitophagy; Necroptosis; Phosphoprotein Phosphatases
PubMed: 33370650
DOI: 10.1016/j.ejcb.2020.151144 -
Nature Cell Biology Dec 2020The Hippo pathway plays critical roles in cell growth, differentiation, organ development and tissue homeostasis, whereas its dysregulation can lead to tumorigenesis....
The Hippo pathway plays critical roles in cell growth, differentiation, organ development and tissue homeostasis, whereas its dysregulation can lead to tumorigenesis. YAP and TAZ are transcription co-activators and represent the main downstream effectors of the Hippo pathway. Here, we show that heat stress induces a strong and rapid YAP dephosphorylation and activation. The effect of heat shock on YAP is dominant to other signals known to modulate the Hippo pathway. Heat shock inhibits LATS kinase by promoting HSP90-dependent LATS interaction with and inactivation by protein phosphatase 5. Heat shock also induces LATS ubiquitination and degradation. YAP and TAZ are crucial for cellular heat shock responses, including the heat shock transcriptome and cell viability. This study uncovers previously unknown mechanisms of Hippo regulation by heat shock, as well as physiological functions of YAP, in the heat stress response. Our observations also reveal a potential combinational therapy involving hyperthermia and targeting of the Hippo pathway.
Topics: A549 Cells; Adaptor Proteins, Signal Transducing; Animals; Cell Cycle Proteins; Cell Line, Tumor; Cell Survival; Female; Gene Expression Profiling; HEK293 Cells; Heat-Shock Response; Humans; Mice; Mice, Inbred BALB C; Mice, Nude; NIH 3T3 Cells; Nuclear Proteins; Phosphoprotein Phosphatases; Phosphorylation; Protein Serine-Threonine Kinases; Signal Transduction; Trans-Activators; Transcription Factors; Transcriptional Coactivator with PDZ-Binding Motif Proteins; Transcriptome; YAP-Signaling Proteins
PubMed: 33199845
DOI: 10.1038/s41556-020-00602-9 -
Immunity Jul 2020Psoriasis is a chronic inflammatory disease whose etiology is multifactorial. The contributions of cellular metabolism to psoriasis are unclear. Here, we report that...
Psoriasis is a chronic inflammatory disease whose etiology is multifactorial. The contributions of cellular metabolism to psoriasis are unclear. Here, we report that interleukin-17 (IL-17) downregulated Protein Phosphatase 6 (PP6) in psoriatic keratinocytes, causing phosphorylation and activation of the transcription factor C/EBP-β and subsequent generation of arginase-1. Mice lacking Pp6 in keratinocytes were predisposed to psoriasis-like skin inflammation. Accumulation of arginase-1 in Pp6-deficient keratinocytes drove polyamine production from the urea cycle. Polyamines protected self-RNA released by psoriatic keratinocytes from degradation and facilitated the endocytosis of self-RNA by myeloid dendritic cells to promote toll-like receptor-7 (TLR7)-dependent RNA sensing and IL-6 production. An arginase inhibitor improved skin inflammation in murine and non-human primate models of psoriasis. Our findings suggest that urea cycle hyperreactivity and excessive polyamine generation in psoriatic keratinocytes promote self-RNA sensation and PP6 deregulation in keratinocytes is a pivotal event that amplifies the inflammatory circuits in psoriasis.
Topics: 3T3 Cells; Animals; Arginase; Arginine; Autoantigens; CCAAT-Enhancer-Binding Protein-beta; Cell Line; Dendritic Cells; Disease Models, Animal; HEK293 Cells; HaCaT Cells; Humans; Interleukin-17; Keratinocytes; Macaca fascicularis; Membrane Glycoproteins; Mice; Mice, Inbred C57BL; Phosphoprotein Phosphatases; Phosphorylation; Polyamines; Psoriasis; RNA; Skin; Toll-Like Receptor 7
PubMed: 32553276
DOI: 10.1016/j.immuni.2020.06.004 -
Kidney International Aug 2022Energy metabolism is crucial in maintaining cellular homeostasis and adapting to stimuli for tubular cells. However, the underlying mechanisms remain largely unknown....
Energy metabolism is crucial in maintaining cellular homeostasis and adapting to stimuli for tubular cells. However, the underlying mechanisms remain largely unknown. Here, we report that PP2Acα was upregulated in damaged tubular cells from patients and animal models with acute or chronic kidney injury. Using in vitro and in vivo model, we demonstrated that PP2Acα induction in damaged tubular cells suppresses fatty acid oxidation and promotes glycolysis, leading to cell death and fibrosis. Mechanistically, we revealed that PP2Acα dephosphorylates ACC through interaction with B56δ, leading to the regulation of fatty acid oxidation. Furthermore, PP2Acα also dephosphorylates p-Glut1 (Thr478) and suppresses Trim21-mediated Glut1 ubiquitination and degradation, leading to the promotion of glucose intake and glycolysis. Thus, this study adds new insight into the tubular cell metabolic alterations in kidney diseases. PP2Acα may be a promising therapeutic target for kidney injury.
Topics: Animals; Fatty Acids; Glucose Transporter Type 1; Glycolysis; Kidney; Phosphoprotein Phosphatases
PubMed: 35483524
DOI: 10.1016/j.kint.2022.03.024 -
Redox Biology Jan 2021The death of cardiomyocytes either through apoptosis or necroptosis is the pathological feature of cardiac ischemia-reperfusion (I/R) injury. Phosphoglycerate mutase 5...
The death of cardiomyocytes either through apoptosis or necroptosis is the pathological feature of cardiac ischemia-reperfusion (I/R) injury. Phosphoglycerate mutase 5 (PGAM5), a mitochondrially-localized serine/threonine-protein phosphatase, functions as a novel inducer of necroptosis. However, intense debate exists regarding the effect of PGAM5 on I/R-related cardiomyocyte death. Using cardiac-specific PGAM5 knockout (PGAM5) mice, we comprehensively investigated the precise contribution and molecular mechanism of PGAM5 in cardiomyocyte death. Our data showed that both PGAM5 transcription and expression were upregulated in reperfused myocardium. Genetic ablation of PGAM5 suppressed I/R-mediated necroptosis but failed to prevent apoptosis activation, a result that went along with improved heart function and decreased inflammation response. Regardless of PGAM5 status, mitophagy-related cell death was not apparent following I/R. Under physiological conditions, PGAM5 overexpression in primary cardiomyocytes was sufficient to induce cardiomyocyte necroptosis rather than apoptosis. At the sub-cellular levels, PGAM5 deficiency increased mitochondrial DNA copy number and transcript levels, normalized mitochondrial respiration, repressed mitochondrial ROS production, and prevented abnormal mPTP opening upon I/R. Molecular investigation demonstrated that PGAM5 deletion interrupted I/R-mediated Drp dephosphorylation but failed to abolish I/R-induce Drp1 phosphorylation, resulting in partial inhibition of mitochondrial fission. In addition, declining Mfn2 and OPA1 levels were restored in PGAM5 cardiomyocytes following I/R. Nevertheless, PGAM5 depletion did not rescue suppressed mitophagy upon I/R injury. In conclusion, our results provide an insight into the specific role and working mechanism of PGAM5 in driving cardiomyocyte necroptosis through imposing mitochondrial quality control in cardiac I/R injury.
Topics: Animals; Heart; Mice; Mice, Knockout; Mitochondria; Mitochondrial Dynamics; Mitophagy; Phosphoprotein Phosphatases; Reperfusion Injury
PubMed: 33166869
DOI: 10.1016/j.redox.2020.101777 -
Nature Cell Biology Nov 2022Tumour cells exhibit greater metabolic plasticity than normal cells and possess selective advantages for survival and proliferation with unclearly defined mechanisms....
Tumour cells exhibit greater metabolic plasticity than normal cells and possess selective advantages for survival and proliferation with unclearly defined mechanisms. Here we demonstrate that glucose deprivation in normal hepatocytes induces PERK-mediated fructose-1,6-bisphosphatase 1 (FBP1) S170 phosphorylation, which converts the FBP1 tetramer to monomers and exposes its nuclear localization signal for nuclear translocation. Importantly, nuclear FBP1 binds PPARα and functions as a protein phosphatase that dephosphorylates histone H3T11 and suppresses PPARα-mediated β-oxidation gene expression. In contrast, FBP1 S124 is O-GlcNAcylated by overexpressed O-linked N-acetylglucosamine transferase in hepatocellular carcinoma cells, leading to inhibition of FBP1 S170 phosphorylation and enhancement of β-oxidation for tumour growth. In addition, FBP1 S170 phosphorylation inversely correlates with β-oxidation gene expression in hepatocellular carcinoma specimens and patient survival duration. These findings highlight the differential role of FBP1 in gene regulation in normal and tumour cells through direct chromatin modulation and underscore the inactivation of its protein phosphatase function in tumour growth.
Topics: Humans; Carcinoma, Hepatocellular; Histones; Fructose-Bisphosphatase; PPAR alpha; Fructose; Liver Neoplasms; Transcription, Genetic; Phosphoprotein Phosphatases
PubMed: 36266488
DOI: 10.1038/s41556-022-01009-4 -
Molecular Plant May 2023Pattern-triggered immunity (PTI) and effector-triggered immunity (ETI) are required for host defense against pathogens. Although PTI and ETI are intimately connected,...
Pattern-triggered immunity (PTI) and effector-triggered immunity (ETI) are required for host defense against pathogens. Although PTI and ETI are intimately connected, the underlying molecular mechanisms remain elusive. In this study, we demonstrate that flg22 priming attenuates Pseudomonas syringae pv. tomato DC3000 (Pst) AvrRpt2-induced hypersensitive cell death, resistance, and biomass reduction in Arabidopsis. Mitogen-activated protein kinases (MAPKs) are key signaling regulators of PTI and ETI. The absence of MPK3 and MPK6 significantly reduces pre-PTI-mediated ETI suppression (PES). We found that MPK3/MPK6 interact with and phosphorylate the downstream transcription factor WRKY18, which regulates the expression of AP2C1 and PP2C5, two genes encoding protein phosphatases. Furthermore, we observed that the PTI-suppressed ETI-triggered cell death, MAPK activation, and growth retardation are significantly attenuated in wrky18/40/60 and ap2c1 pp2c5 mutants. Taken together, our results suggest that the MPK3/MPK6-WRKYs-PP2Cs module underlies PES and is essential for the maintenance of plant fitness during ETI.
Topics: Arabidopsis Proteins; Mitogen-Activated Protein Kinases; Arabidopsis; Signal Transduction; Plant Development; Plant Immunity; Gene Expression Regulation, Plant; Pseudomonas syringae; Phosphoprotein Phosphatases
PubMed: 37041748
DOI: 10.1016/j.molp.2023.04.004