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1.
PLoS One ; 15(12): e0229812, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33315870

RESUMO

Insulin and insulin-like growth factors are longevity determinants that negatively regulate Forkhead box class O (FoxO) transcription factors. In C. elegans mutations that constitutively activate DAF-16, the ortholog of mammalian FoxO3a, extend lifespan by two-fold. While environmental insults induce DAF-16 activity in younger animals, it also becomes activated in an age-dependent manner in the absence of stress, modulating gene expression well into late adulthood. The mechanism by which DAF-16 activity is regulated during aging has not been defined. Since phosphorylation of DAF-16 generally leads to its inhibition, we asked whether phosphatases might be necessary for its increased transcriptional activity in adult C. elegans. We focused on the PP2A/4/6 subfamily of phosphoprotein phosphatases, members of which had been implicated to regulate DAF-16 under low insulin signaling conditions but had not been investigated during aging in wildtype animals. Using reverse genetics, we functionally characterized all C. elegans orthologs of human catalytic, regulatory, and scaffolding subunits of PP2A/4/6 holoenzymes in postreproductive adults. We found that PP2A complex constituents PAA-1 and PPTR-1 regulate DAF-16 transcriptional activity during aging and that they cooperate with the catalytic subunit LET-92 to protect adult animals from ultraviolet radiation. PP4 complex members PPH-4.1/4.2, and SMK-1 also appear to regulate DAF-16 in an age-dependent manner, and together with PPFR-2 they contribute to innate immunity. Interestingly, SUR-6 but no other subunit of the PP2A complex was necessary for the survival of pathogen-infected animals. Finally, we found that PP6 complex constituents PPH-6 and SAPS-1 contribute to host defense during aging, apparently without affecting DAF-16 transcriptional activity. Our studies indicate that a set of PP2A/4/6 complexes protect adult C. elegans from environmental stress, thus preserving healthspan. Therefore, along with their functions in cell division and development, the PP2A/4/6 phosphatases also appear to play critical roles later in life.


Assuntos
Proteínas de Caenorhabditis elegans/metabolismo , Fatores de Transcrição Forkhead/metabolismo , Proteína Fosfatase 2/metabolismo , Estresse Fisiológico/fisiologia , Envelhecimento/metabolismo , Animais , Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/fisiologia , Fatores de Transcrição Forkhead/fisiologia , Longevidade/genética , Fosfoproteínas Fosfatases/metabolismo , Fosforilação , Proteína Fosfatase 2/fisiologia , Transdução de Sinais
2.
Nat Commun ; 11(1): 5043, 2020 10 07.
Artigo em Inglês | MEDLINE | ID: mdl-33028863

RESUMO

Human T-cell lymphotropic virus type 1 (HTLV-1) is a deltaretrovirus and the most oncogenic pathogen. Many of the ~20 million HTLV-1 infected people will develop severe leukaemia or an ALS-like motor disease, unless a therapy becomes available. A key step in the establishment of infection is the integration of viral genetic material into the host genome, catalysed by the retroviral integrase (IN) enzyme. Here, we use X-ray crystallography and single-particle cryo-electron microscopy to determine the structure of the functional deltaretroviral IN assembled on viral DNA ends and bound to the B56γ subunit of its human host factor, protein phosphatase 2 A. The structure reveals a tetrameric IN assembly bound to two molecules of the phosphatase via a conserved short linear motif. Insight into the deltaretroviral intasome and its interaction with the host will be crucial for understanding the pattern of integration events in infected individuals and therefore bears important clinical implications.


Assuntos
Vírus Linfotrópico T Tipo 1 Humano/patogenicidade , Integrases/ultraestrutura , Proteína Fosfatase 2/ultraestrutura , Vírus Linfotrópico T Tipo 1 de Símios/enzimologia , Proteínas Virais/ultraestrutura , Integração Viral , Motivos de Aminoácidos/genética , Clonagem Molecular , Microscopia Crioeletrônica , Cristalografia por Raios X , DNA Viral/metabolismo , DNA Viral/ultraestrutura , Vírus Linfotrópico T Tipo 1 Humano/enzimologia , Vírus Linfotrópico T Tipo 1 Humano/genética , Humanos , Integrases/genética , Integrases/metabolismo , Leucemia-Linfoma de Células T do Adulto/patologia , Leucemia-Linfoma de Células T do Adulto/virologia , Simulação de Acoplamento Molecular , Mutagênese Sítio-Dirigida , Paraparesia Espástica Tropical/patologia , Paraparesia Espástica Tropical/virologia , Multimerização Proteica , Proteína Fosfatase 2/genética , Proteína Fosfatase 2/metabolismo , Estrutura Quaternária de Proteína , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Proteínas Recombinantes/ultraestrutura , Homologia de Sequência de Aminoácidos , Vírus Linfotrópico T Tipo 1 de Símios/genética , Imagem Individual de Molécula , Proteínas Virais/genética , Proteínas Virais/metabolismo
3.
Mol Cell ; 80(2): 345-358.e9, 2020 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-32966759

RESUMO

Efficient release of promoter-proximally paused RNA Pol II into productive elongation is essential for gene expression. Recently, we reported that the Integrator complex can bind paused RNA Pol II and drive premature transcription termination, potently attenuating the activity of target genes. Premature termination requires RNA cleavage by the endonuclease subunit of Integrator, but the roles of other Integrator subunits in gene regulation have yet to be elucidated. Here we report that Integrator subunit 8 (IntS8) is critical for transcription repression and required for association with protein phosphatase 2A (PP2A). We find that Integrator-bound PP2A dephosphorylates the RNA Pol II C-terminal domain and Spt5, preventing the transition to productive elongation. Thus, blocking PP2A association with Integrator stimulates pause release and gene activity. These results reveal a second catalytic function associated with Integrator-mediated transcription termination and indicate that control of productive elongation involves active competition between transcriptional kinases and phosphatases.


Assuntos
Proteínas de Drosophila/metabolismo , Proteína Fosfatase 2/metabolismo , Subunidades Proteicas/metabolismo , Terminação da Transcrição Genética , Motivos de Aminoácidos , Sequência de Aminoácidos , Animais , Sequência Conservada , Proteínas de Drosophila/química , Drosophila melanogaster , Regulação da Expressão Gênica , Loci Gênicos , Humanos , Fosforilação , Regiões Promotoras Genéticas , Subunidades Proteicas/química , RNA Polimerase II/química , RNA Polimerase II/metabolismo , Transdução de Sinais , Especificidade por Substrato
4.
PLoS Genet ; 16(8): e1008569, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32810145

RESUMO

Correct bioriented attachment of sister chromatids to the mitotic spindle is essential for chromosome segregation. In budding yeast, the conserved protein shugoshin (Sgo1) contributes to biorientation by recruiting the protein phosphatase PP2A-Rts1 and the condensin complex to centromeres. Using peptide prints, we identified a Serine-Rich Motif (SRM) of Sgo1 that mediates the interaction with condensin and is essential for centromeric condensin recruitment and the establishment of biorientation. We show that the interaction is regulated via phosphorylation within the SRM and we determined the phospho-sites using mass spectrometry. Analysis of the phosphomimic and phosphoresistant mutants revealed that SRM phosphorylation disrupts the shugoshin-condensin interaction. We present evidence that Mps1, a central kinase in the spindle assembly checkpoint, directly phosphorylates Sgo1 within the SRM to regulate the interaction with condensin and thereby condensin localization to centromeres. Our findings identify novel mechanisms that control shugoshin activity at the centromere in budding yeast.


Assuntos
Adenosina Trifosfatases/metabolismo , Centrômero/metabolismo , Proteínas de Ligação a DNA/metabolismo , Complexos Multiproteicos/metabolismo , Proteínas Nucleares/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Motivos de Aminoácidos , Proteínas Nucleares/química , Proteínas Nucleares/genética , Fosforilação , Ligação Proteica , Proteína Fosfatase 2/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Saccharomyces cerevisiae , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/genética
5.
Life Sci ; 260: 118077, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32810509

RESUMO

AIMS: Multiple myeloma (MM) is the second hematological plasma cell malignany and sensitive to fingolimod (FTY720), a novel immunosuppressant. Previous study shows FTY720-induced apoptosis and autophagy can cause cell death in MM cells, however, the high death rate cannot fully be explained. The study aims to investigate further mechanism of how FTY720 kills MM cells. MATERIALS AND METHODS: Experiments are performed on 25 human primary cell samples and two MM cell lines by flow cytometry, fluorescence microscopy, and transmission electron microscopy. Expressions of relative factors are tested by qRT-PCR or western blot. KEY FINDINGS: Ferroptosis-specific inhibitors, deferoxamine mesylate (DFOM) and ferropstatin-1 (Fer-1), reverse FTY720-induced cell death in MM cells. Glutathione peroxidase 4 (GPX4) and soluble carrier family 7 member 11 (SLC7A11), key regulators of ferroptosis, are highly expressed in primary MM cells and can be decreased by FTY720 at the mRNA and protein level in MM cells. In addition, FTY720 induces other characteristic changes of ferroptosis. Furthermore, FTY720 can dephosphorylate AMP-activated protein kinase subunit ɑ (AMPKɑ) at the Thr172 site by activating protein phosphatase 2A (PP2A) and reduce the expression of phosphorylated eukaryotic elongation factor 2 (eEF2), finally cause MM cell death. Using LB-100, a PP2A inhibitor, AICAR, an agonist of AMPK, and bafilomycin A1 (Baf-A1), an autophagy inhibitor, we discover that FTY720 induces ferroptosis and autophagy through the PP2A/AMPK pathway, and ferroptosis and autophagy can reinforce each other. SIGNIFICANCE: These results provide a new perspective on the treatment of MM.


Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Autofagia/efeitos dos fármacos , Ferroptose/efeitos dos fármacos , Cloridrato de Fingolimode/farmacologia , Mieloma Múltiplo/patologia , Proteína Fosfatase 2/metabolismo , Sistema y+ de Transporte de Aminoácidos/efeitos dos fármacos , Sistema y+ de Transporte de Aminoácidos/fisiologia , Antineoplásicos/farmacologia , Linhagem Celular Tumoral , Cicloexilaminas/farmacologia , Desferroxamina/farmacologia , Humanos , Mieloma Múltiplo/tratamento farmacológico , Fenilenodiaminas/farmacologia , Fosfolipídeo Hidroperóxido Glutationa Peroxidase/efeitos dos fármacos , Fosfolipídeo Hidroperóxido Glutationa Peroxidase/fisiologia , Transdução de Sinais/efeitos dos fármacos
6.
Korean J Parasitol ; 58(3): 249-255, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32615738

RESUMO

Toxoplasma gondii, a ubiquitous, intracellular parasite of the phylum Apicomplexa, infects an estimated one-third of the human population as well as a broad range of warm-blooded animals. We have observed that some tyrosine kinase inhibitors suppressed the growth of T. gondii within host ARPE-10 cells. Among them, afatinib, human epithermal growth factor receptor 2 and 4 (HER2/4) inhibitor, may be used as a therapeutic agent for inhibiting parasite growth with minimal adverse effects on host. In this report, we conducted a proteomic analysis to observe changes in host proteins that were altered via infection with T. gondii and the treatment of HER2/4 inhibitors. Secreting proteins were subjected to a procedure of micor basic reverse phase liquid chromatography, nano-liquid chromatography-mass spectrometry, and ingenuity pathway analysis serially. As a result, the expression level of heterogeneous nuclear ribonucleoprotein K, semaphorin 7A, a GPI membrane anchor, serine/threonine-protein phosphatase 2A, and calpain small subunit 1 proteins were significantly changed, and which were confirmed further by western blot analysis. Changes in various proteins, including these 4 proteins, can be used as a basis for explaining the effects of T. gondii infections and HER2/4 inhibitors.


Assuntos
Afatinib/farmacologia , Afatinib/uso terapêutico , Interações Hospedeiro-Parasita , Proteínas/metabolismo , Receptor ErbB-2/antagonistas & inibidores , Toxoplasma/crescimento & desenvolvimento , Toxoplasmose/tratamento farmacológico , Toxoplasmose/metabolismo , Antígenos CD/metabolismo , Western Blotting , Linhagem Celular , Proteínas Ligadas por GPI/metabolismo , Ribonucleoproteínas Nucleares Heterogêneas/metabolismo , Humanos , Proteína Fosfatase 2/metabolismo , Proteômica/métodos , Semaforinas/metabolismo
7.
Nat Commun ; 11(1): 3583, 2020 07 17.
Artigo em Inglês | MEDLINE | ID: mdl-32681005

RESUMO

The phosphatases PP1 and PP2A are responsible for the majority of dephosphorylation reactions on phosphoserine (pSer) and phosphothreonine (pThr), and are involved in virtually all cellular processes and numerous diseases. The catalytic subunits exist in cells in form of holoenzymes, which impart substrate specificity. The contribution of the catalytic subunits to the recognition of substrates is unclear. By developing a phosphopeptide library approach and a phosphoproteomic assay, we demonstrate that the specificity of PP1 and PP2A holoenzymes towards pThr and of PP1 for basic motifs adjacent to the phosphorylation site are due to intrinsic properties of the catalytic subunits. Thus, we dissect this amino acid specificity of the catalytic subunits from the contribution of regulatory proteins. Furthermore, our approach enables discovering a role for PP1 as regulator of the GRB-associated-binding protein 2 (GAB2)/14-3-3 complex. Beyond this, we expect that this approach is broadly applicable to detect enzyme-substrate recognition preferences.


Assuntos
Proteína Fosfatase 1/química , Proteína Fosfatase 1/metabolismo , Proteína Fosfatase 2/química , Proteína Fosfatase 2/metabolismo , Proteínas 14-3-3/genética , Proteínas 14-3-3/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/genética , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Motivos de Aminoácidos , Domínio Catalítico , Holoenzimas/química , Holoenzimas/genética , Holoenzimas/metabolismo , Humanos , Fosforilação , Ligação Proteica , Engenharia de Proteínas , Proteína Fosfatase 1/genética , Proteína Fosfatase 2/genética , Subunidades Proteicas/química , Subunidades Proteicas/genética , Subunidades Proteicas/metabolismo , Especificidade por Substrato
8.
Trends Pharmacol Sci ; 41(9): 595-597, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32624198

RESUMO

In cancer, suppression of protein phosphatases, such as protein phosphatase 2A (PP2A), that normally counteract kinases, contributes to aberrant signaling. Leonard et al. recently demonstrated that a novel small-molecule activator of PP2A, DT-061, selectively stabilizes a specific PP2A holoenzyme responsible for dephosphorylating critical oncogenic targets, including MYC. The 3.6-Å cryo-electron microscopy map of the heterotrimer assembly provides insight into the druggable structure of PP2A, guiding future phosphatase therapeutics.


Assuntos
Neoplasias , Proteína Fosfatase 2 , Microscopia Crioeletrônica , Humanos , Neoplasias/tratamento farmacológico , Proteína Fosfatase 2/metabolismo , Transdução de Sinais
9.
Toxicol Lett ; 331: 65-74, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32492475

RESUMO

Although disturbance of the methionine cycle and sequent decrease in hepatic methylation capacity are known to be important factors in the development of alcoholic liver injury, the underlying mechanisms are not fully understood. Here, we investigated the importance of the methylation of protein phosphatase 2A (PP2A) in alcoholic liver disease (ALD). We found that the severity of ethanol-induced liver injury and the extent of demethylation of PP2A catalytic C subunit (PP2Ac) were reduced after treatment with betaine, a methyl donor involved in the methionine-homocysteine cycle. These results suggest that PP2Ac methylation is decreased due to a broad decrease in hepatic methylation capacity after exposure to ethanol. Moreover, we found that the reduction in PP2Ac methylation led to increased degradation of the regulatory Bα subunit, thus promoting the phosphorylation and nuclear exclusion of Forkhead box O1 (FOXO1) and reducing FOXO1 transcriptional activity. Ultimately, the reduced activity of FOXO1 led to increased expression of TXNIP, which caused hepatic lipid accumulation. Our findings suggest that the reduction of PP2A methylation, a result of decrease hepatic methylation capacity, played an important role in ethanol-induced lipid accumulation via down-regulation of PP2A/Bα and FOXO1 phosphorylation.


Assuntos
Etanol/toxicidade , Proteína Forkhead Box O1/metabolismo , Hepatócitos/efeitos dos fármacos , Hepatopatias Alcoólicas/metabolismo , Fígado/efeitos dos fármacos , Proteína Fosfatase 2/metabolismo , Animais , Linhagem Celular , Hepatócitos/metabolismo , Fígado/metabolismo , Fígado/patologia , Hepatopatias Alcoólicas/patologia , Masculino , Metilação , Camundongos , Camundongos Endogâmicos C57BL , Fosforilação
10.
Nat Commun ; 11(1): 3121, 2020 06 19.
Artigo em Inglês | MEDLINE | ID: mdl-32561747

RESUMO

Integration of the reverse-transcribed viral DNA into host chromosomes is a critical step in the life-cycle of retroviruses, including an oncogenic delta(δ)-retrovirus human T-cell leukemia virus type-1 (HTLV-1). Retroviral integrase forms a higher order nucleoprotein assembly (intasome) to catalyze the integration reaction, in which the roles of host factors remain poorly understood. Here, we use cryo-electron microscopy to visualize the HTLV-1 intasome at 3.7-Šresolution. The structure together with functional analyses reveal that the B56γ (B'γ) subunit of an essential host enzyme, protein phosphatase 2 A (PP2A), is repurposed as an integral component of the intasome to mediate HTLV-1 integration. Our studies reveal a key host-virus interaction underlying the replication of an important human pathogen and highlight divergent integration strategies of retroviruses.


Assuntos
Interações Hospedeiro-Patógeno/genética , Vírus Linfotrópico T Tipo 1 Humano/genética , Integrases/metabolismo , Proteína Fosfatase 2/genética , Proteínas Virais/metabolismo , Integração Viral/genética , Microscopia Crioeletrônica , DNA Viral/metabolismo , Células HEK293 , Vírus Linfotrópico T Tipo 1 Humano/enzimologia , Humanos , Integrases/ultraestrutura , Modelos Moleculares , Mutação Puntual , Ligação Proteica/genética , Proteína Fosfatase 2/metabolismo , Proteína Fosfatase 2/ultraestrutura , Proteínas Virais/ultraestrutura
11.
Proc Natl Acad Sci U S A ; 117(23): 13127-13137, 2020 06 09.
Artigo em Inglês | MEDLINE | ID: mdl-32434921

RESUMO

Stomatal guard cells control gas exchange that allows plant photosynthesis but limits water loss from plants to the environment. In Arabidopsis, stomatal development is mainly controlled by a signaling pathway comprising peptide ligands, membrane receptors, a mitogen-activated protein kinase (MAPK) cascade, and a set of transcription factors. The initiation of the stomatal lineage requires the activity of the bHLH transcription factor SPEECHLESS (SPCH) with its partners. Multiple kinases were found to regulate SPCH protein stability and function through phosphorylation, yet no antagonistic protein phosphatase activities have been identified. Here, we identify the conserved PP2A phosphatases as positive regulators of Arabidopsis stomatal development. We show that mutations in genes encoding PP2A subunits result in lowered stomatal production in Arabidopsis Genetic analyses place the PP2A function upstream of SPCH. Pharmacological treatments support a role for PP2A in promoting SPCH protein stability. We further find that SPCH directly binds to the PP2A-A subunits in vitro. In plants, nonphosphorylatable SPCH proteins are less affected by PP2A activity levels. Thus, our research suggests that PP2A may function to regulate the phosphorylation status of the master transcription factor SPCH in stomatal development.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/fisiologia , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Regulação da Expressão Gênica de Plantas/fisiologia , Estômatos de Plantas/crescimento & desenvolvimento , Proteína Fosfatase 2/metabolismo , Proteínas de Arabidopsis/antagonistas & inibidores , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/isolamento & purificação , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Mutação , Fosforilação/fisiologia , Estômatos de Plantas/efeitos dos fármacos , Plantas Geneticamente Modificadas , Proteína Fosfatase 2/antagonistas & inibidores , Proteína Fosfatase 2/genética , Proteína Fosfatase 2/isolamento & purificação , Estabilidade Proteica/efeitos dos fármacos , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Tabaco/genética
12.
J Virol ; 94(14)2020 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-32404521

RESUMO

UNC5B is a dependence receptor that promotes survival in the presence of its ligand, netrin-1, while inducing cell death in its absence. The receptor has an important role in the development of the nervous and vascular systems. It is also involved in the normal turnover of intestinal epithelium. Netrin-1 and UNC5B are deregulated in multiple cancers, including colorectal, neuroblastoma, and breast tumors. However, the detailed mechanism of UNC5B function is not fully understood. We have utilized the murine polyomavirus small T antigen (PyST) as a tool to study UNC5B-mediated apoptosis. PyST is known to induce mitotic arrest followed by extensive cell death in mammalian cells. Our results show that the expression of PyST increases mRNA levels of UNC5B by approximately 3-fold in osteosarcoma cells (U2OS) and also stabilizes UNC5B at the posttranslational level. Furthermore, UNC5B is upregulated predominantly in those cells that undergo mitotic arrest upon PyST expression. Interestingly, although its expression was previously reported to be regulated by p53, our data show that the increase in UNC5B levels by PyST is p53 independent. The posttranslational stabilization of UNC5B by PyST is regulated by the interaction of PyST with PP2A. We also show that netrin-1 expression, which is known to inhibit UNC5B apoptotic activity, promotes survival of PyST-expressing cells. Our results thus suggest an important role of UNC5B in small-T antigen-induced mitotic catastrophe that also requires PP2A.IMPORTANCE UNC5B, PP2A, and netrin-1 are deregulated in a variety of cancers. UNC5B and PP2A are regarded as tumor suppressors, as they promote apoptosis and are deleted or mutated in many cancers. In contrast, netrin-1 promotes survival by inhibiting dependence receptors, including UNC5B, and is upregulated in many cancers. Here, we show that UNC5B-mediated apoptosis can occur independently of p53 but in a PP2A-dependent manner. A substantial percentage of cancers arise due to p53 mutations and are insensitive to chemotherapeutic treatments that activate p53. Unexpectedly, treatment of cancers having functional p53 with many conventional drugs leads to the upregulation of netrin-1 through activated p53, which is counterintuitive. Therefore, understanding the p53-independent mechanisms of the netrin-UNC5B axis, such as those involving PP2A, assumes greater clinical significance. Anticancer strategies utilizing anti-netrin-1 antibody treatment are already in clinical trials.


Assuntos
Antígenos Virais de Tumores/metabolismo , Apoptose , Receptores de Netrina/metabolismo , Polyomavirus/metabolismo , Proteína Fosfatase 2/metabolismo , Células A549 , Animais , Antígenos Virais de Tumores/genética , Células HeLa , Humanos , Camundongos , Receptores de Netrina/genética , Polyomavirus/genética , Proteína Fosfatase 2/genética
13.
Nat Cell Biol ; 22(4): 389-400, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32231305

RESUMO

In mouse embryonic stem cells (mESCs), chemical blockade of Gsk3α/ß and Mek1/2 (2i) instructs a self-renewing ground state whose endogenous inducers are unknown. Here we show that the axon guidance cue Netrin-1 promotes naive pluripotency by triggering profound signalling, transcriptomic and epigenetic changes in mESCs. Furthermore, we demonstrate that Netrin-1 can substitute for blockade of Gsk3α/ß and Mek1/2 to sustain self-renewal of mESCs in combination with leukaemia inhibitory factor and regulates the formation of the mouse pluripotent blastocyst. Mechanistically, we reveal how Netrin-1 and the balance of its receptors Neo1 and Unc5B co-regulate Wnt and MAPK pathways in both mouse and human ESCs. Netrin-1 induces Fak kinase to inactivate Gsk3α/ß and stabilize ß-catenin while increasing the phosphatase activity of a Ppp2r2c-containing Pp2a complex to reduce Erk1/2 activity. Collectively, this work identifies Netrin-1 as a regulator of pluripotency and reveals that it mediates different effects in mESCs depending on its receptor dosage, opening perspectives for balancing self-renewal and lineage commitment.


Assuntos
Regulação da Expressão Gênica no Desenvolvimento , Proteínas do Tecido Nervoso/genética , Receptores de Netrina/genética , Netrina-1/genética , Receptores de Superfície Celular/genética , Via de Sinalização Wnt/genética , Animais , Linhagem Celular , Embrião de Mamíferos , MAP Quinases Reguladas por Sinal Extracelular/genética , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Quinase 1 de Adesão Focal/genética , Quinase 1 de Adesão Focal/metabolismo , Glicogênio Sintase Quinase 3 beta/antagonistas & inibidores , Glicogênio Sintase Quinase 3 beta/genética , Glicogênio Sintase Quinase 3 beta/metabolismo , Humanos , Isoenzimas/antagonistas & inibidores , Isoenzimas/genética , Isoenzimas/metabolismo , Fator Inibidor de Leucemia/genética , Fator Inibidor de Leucemia/metabolismo , MAP Quinase Quinase 1/antagonistas & inibidores , MAP Quinase Quinase 1/genética , MAP Quinase Quinase 1/metabolismo , MAP Quinase Quinase 2/antagonistas & inibidores , MAP Quinase Quinase 2/genética , MAP Quinase Quinase 2/metabolismo , Masculino , Camundongos , Camundongos Knockout , Camundongos SCID , Células-Tronco Embrionárias Murinas/citologia , Células-Tronco Embrionárias Murinas/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Receptores de Netrina/metabolismo , Netrina-1/metabolismo , Células-Tronco Pluripotentes/citologia , Células-Tronco Pluripotentes/metabolismo , Proteína Fosfatase 2/genética , Proteína Fosfatase 2/metabolismo , Receptores de Superfície Celular/metabolismo , beta Catenina/genética , beta Catenina/metabolismo
14.
Am J Physiol Gastrointest Liver Physiol ; 318(6): G1000-G1012, 2020 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-32308041

RESUMO

Trypsinogen activation is the hallmark of acute pancreatitis (AP) independent of intra-acinar NF-κB activation and inflammation. We previously found that dopamine (DA) receptor 2 (DRD2) activation controls inflammation during AP via PP2A-dependent NF-κB activation. In this study, we sought to examine whether DRD2 signaling mediates trypsinogen activation and the underlying mechanisms. Pancreatic acinar cells were stimulated with cholecystokinin-8 in vitro. AP was induced by intraperitoneal injections of caerulein and LPS or l-arginine. Pancreatitis severity was assessed biochemically and histologically. We found that activation of DRD2 by quinpirole, a potent DRD2 agonist, resulted in the reduction of trypsinogen activation and the upregulation of HSP70 in vitro and in vivo. Mechanistically, we found that quinpirole induced dephosphorylation of heat shock factor 1 (HSF1), a master transcription factor of HSP70, leading to increased nuclear translocation of HSF1 in a PP2A-dependent pathway. Furthermore, DRD2 activation restored lysosomal pH and, therefore, maintained lysosomal cathepsin B activity in a HSP70-dependent manner. VER155008, a potent HSP70 antagonist, abolished the protective effects observed with DRD2 activation in vitro and in two experimental models of AP. Our data showed that besides controlling NF-κB activation, DRD2 activation prevented trypsinogen activation during acute pancreatitis via PP2A-dependent upregulation of HSP70 and further support that DRD2 agonist could be a promising therapeutic strategy for treating AP.NEW & NOTEWORTHY The current study demonstrated that activation of DRD2 by quinpirole protects against trypsinogen activation in the in vitro and in vivo setting of acute pancreatitis by upregulating HSP70 and restoring lysosomal degradation via a PP2A-dependent manner, therefore leading to reduced pancreatic injury. These findings provide a new mechanistic insight on the protective effect of DRD2 activation in acute pancreatitis.


Assuntos
Proteínas de Choque Térmico HSP72/metabolismo , Pancreatite/tratamento farmacológico , Quimpirol/farmacologia , Receptores de Dopamina D2/agonistas , Tripsinogênio/metabolismo , Animais , Ceruletídeo/farmacologia , Agonistas de Dopamina/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Proteínas de Choque Térmico HSP72/genética , Fatores de Transcrição de Choque Térmico/genética , Fatores de Transcrição de Choque Térmico/metabolismo , Lisossomos , Camundongos , Camundongos Endogâmicos C57BL , Pâncreas/citologia , Pancreatite/metabolismo , Fosforilação , Proteína Fosfatase 2/metabolismo , Regulação para Cima
15.
Nat Commun ; 11(1): 1819, 2020 04 14.
Artigo em Inglês | MEDLINE | ID: mdl-32286328

RESUMO

The BRCA2 tumor suppressor protein is involved in the maintenance of genome integrity through its role in homologous recombination. In mitosis, BRCA2 is phosphorylated by Polo-like kinase 1 (PLK1). Here we describe how this phosphorylation contributes to the control of mitosis. We identify a conserved phosphorylation site at T207 of BRCA2 that constitutes a bona fide docking site for PLK1 and is phosphorylated in mitotic cells. We show that BRCA2 bound to PLK1 forms a complex with the phosphatase PP2A and phosphorylated-BUBR1. Reducing BRCA2 binding to PLK1, as observed in BRCA2 breast cancer variants S206C and T207A, alters the tetrameric complex resulting in unstable kinetochore-microtubule interactions, misaligned chromosomes, faulty chromosome segregation and aneuploidy. We thus reveal a role of BRCA2 in the alignment of chromosomes, distinct from its DNA repair function, with important consequences on chromosome stability. These findings may explain in part the aneuploidy observed in BRCA2-mutated tumors.


Assuntos
Proteína BRCA2/metabolismo , Proteínas de Ciclo Celular/metabolismo , Cromossomos Humanos/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Aneuploidia , Neoplasias da Mama/genética , Segregação de Cromossomos , Feminino , Variação Genética , Células HeLa , Recombinação Homóloga , Humanos , Cinética , Cinetocoros , Mitose , Simulação de Acoplamento Molecular , Fosforilação , Fosfosserina/metabolismo , Fosfotreonina/metabolismo , Ligação Proteica , Proteína Fosfatase 2/metabolismo
16.
Proc Natl Acad Sci U S A ; 117(17): 9292-9301, 2020 04 28.
Artigo em Inglês | MEDLINE | ID: mdl-32277029

RESUMO

In insects, 20-hydroxyecdysone (20E) limits the growth period by triggering developmental transitions; 20E also modulates the growth rate by antagonizing insulin/insulin-like growth factor signaling (IIS). Previous work has shown that 20E cross-talks with IIS, but the underlying molecular mechanisms are not fully understood. Here we found that, in both the silkworm Bombyx mori and the fruit fly Drosophila melanogaster, 20E antagonized IIS through the AMP-activated protein kinase (AMPK)-protein phosphatase 2A (PP2A) axis in the fat body and suppressed the growth rate. During Bombyx larval molt or Drosophila pupariation, high levels of 20E activate AMPK, a molecular sensor that maintains energy homeostasis in the insect fat body. In turn, AMPK activates PP2A, which further dephosphorylates insulin receptor and protein kinase B (AKT), thus inhibiting IIS. Activation of the AMPK-PP2A axis and inhibition of IIS in the Drosophila fat body reduced food consumption, resulting in the restriction of growth rate and body weight. Overall, our study revealed an important mechanism by which 20E antagonizes IIS in the insect fat body to restrict the larval growth rate, thereby expanding our understanding of the comprehensive regulatory mechanisms of final body size in animals.


Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Tamanho Corporal/fisiologia , Proteína Fosfatase 2/metabolismo , Animais , Bombyx/crescimento & desenvolvimento , Bombyx/metabolismo , Drosophila/crescimento & desenvolvimento , Drosophila/metabolismo , Ecdisterona/metabolismo , Corpo Adiposo/metabolismo , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Proteínas de Insetos/genética , Insetos/crescimento & desenvolvimento , Insetos/metabolismo , Insulina/metabolismo , Larva/crescimento & desenvolvimento , Receptor de Insulina/metabolismo , Transdução de Sinais/efeitos dos fármacos , Somatomedinas/metabolismo
17.
Toxicology ; 438: 152442, 2020 05 30.
Artigo em Inglês | MEDLINE | ID: mdl-32278051

RESUMO

Bisphenol A (BPA) is a well-known endocrine disruptor used to manufacture polycarbonate plastics and epoxy resins. BPA exposure especially occupational perinatal exposure to has been linked to numerous adverse effects for the offspring. Available data have shown that perinatal exposure to BPA contributes to neurodegenerative pathological changes; however, the potential mechanisms remain unclear. This study attempted to investigate the long-term consequences of perinatal exposure to BPA on the offspring mouse brain. The pregnant mice were given either a vehicle control or BPA (2, 10, 100 µg/kg/d) from day 6 of gestation until weaning (P6-PND21, foetal and neonatal exposure). At 3, 6 and 9 months of age, the neurotoxic effects in the offspring in each group were investigated. We found that the spine density but not the dendritic branches in the hippocampus were noticeably reduced at 6 and 9 months of age. Meanwhile, p-Tau, the characteristic protein for tauopathy, was dramatically increased in both the hippocampus and cortex at 3-9 months of age. Mechanically, the balance of kinase and protein phosphatase, which plays critical roles in p-Tau regulation, was disturbed. It indicated that GSK3ß and CDK5, two critical kinases, were activated in most of the BPA perinatal exposure group, while protein phosphatase 2A (PP2A), one of the important phosphatases, regulated p-Tau expression through its demethylation, methylation and phosphorylation. Taken together, the present study may be translatable to the human occupational BPA exposure due to a similar exposure level. BPA perinatal exposure causes long-term adverse effects on the mouse brain and may be a risk factor for tauopathies, and the CDK5/GSK3ß/PP2A axis might be a promising therapeutic target for BPA-induced neurodegenerative pathological changes.


Assuntos
Compostos Benzidrílicos/toxicidade , Córtex Cerebral/efeitos dos fármacos , Quinase 5 Dependente de Ciclina/metabolismo , Disruptores Endócrinos/toxicidade , Glicogênio Sintase Quinase 3 beta/metabolismo , Hipocampo/efeitos dos fármacos , Síndromes Neurotóxicas/etiologia , Fenóis/toxicidade , Efeitos Tardios da Exposição Pré-Natal , Proteína Fosfatase 2/metabolismo , Proteínas tau/metabolismo , Animais , Córtex Cerebral/enzimologia , Córtex Cerebral/patologia , Espinhas Dendríticas/efeitos dos fármacos , Espinhas Dendríticas/enzimologia , Espinhas Dendríticas/patologia , Feminino , Idade Gestacional , Hipocampo/enzimologia , Hipocampo/patologia , Masculino , Exposição Materna , Camundongos Endogâmicos C57BL , Síndromes Neurotóxicas/enzimologia , Síndromes Neurotóxicas/patologia , Fosforilação , Gravidez
18.
J Neurosci ; 40(14): 2808-2816, 2020 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-32111696

RESUMO

Addictive drugs usurp the brain's intrinsic mechanism for reward, leading to compulsive and destructive behaviors. In the ventral tegmental area (VTA), the center of the brain's reward circuit, GABAergic neurons control the excitability of dopamine (DA) projection neurons and are the site of initial psychostimulant-dependent changes in signaling. Previous work established that cocaine/methamphetamine exposure increases protein phosphatase 2A (PP2A) activity, which dephosphorylates the GABABR2 subunit, promotes internalization of the GABAB receptor (GABABR) and leads to smaller GABABR-activated G-protein-gated inwardly rectifying potassium (GIRK) currents in VTA GABA neurons. How the actions of PP2A become selective for a particular signaling pathway is poorly understood. Here, we demonstrate that PP2A can associate directly with a short peptide sequence in the C terminal domain of the GABABR1 subunit, and that GABABRs and PP2A are in close proximity in rodent neurons (mouse/rat; mixed sexes). We show that this PP2A-GABABR interaction can be regulated by intracellular Ca2+ Finally, a peptide that potentially reduces recruitment of PP2A to GABABRs and thereby limits receptor dephosphorylation increases the magnitude of baclofen-induced GIRK currents. Thus, limiting PP2A-dependent dephosphorylation of GABABRs may be a useful strategy to increase receptor signaling for treating diseases.SIGNIFICANCE STATEMENT Dysregulation of GABAB receptors (GABABRs) underlies altered neurotransmission in many neurological disorders. Protein phosphatase 2A (PP2A) is involved in dephosphorylating and subsequent internalization of GABABRs in models of addiction and depression. Here, we provide new evidence that PP2A B55 regulatory subunit interacts directly with a small region of the C-terminal domain of the GABABR1 subunit, and that this interaction is sensitive to intracellular Ca2+ We demonstrate that a short peptide corresponding to the PP2A interaction site on GABABR1 competes for PP2A binding, enhances phosphorylation GABABR2 S783, and affects functional signaling through GIRK channels. Our study highlights how targeting PP2A dependent dephosphorylation of GABABRs may provide a specific strategy to modulate GABABR signaling in disease conditions.


Assuntos
Neurônios/metabolismo , Proteína Fosfatase 2/metabolismo , Receptores de GABA-B/metabolismo , Transdução de Sinais/fisiologia , Animais , Encéfalo/metabolismo , Feminino , Canais de Potássio Corretores do Fluxo de Internalização Acoplados a Proteínas G/metabolismo , Células HEK293 , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Fosforilação , Ratos , Transmissão Sináptica/fisiologia
19.
In Vivo ; 34(2): 601-608, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32111759

RESUMO

BACKGROUND/AIM: Nuclear factor kappa B (NF-kB) signalling including the RelA subunit is activated upon fibroblast growth factor (FGF) stimulation. A clear understanding of the mechanisms underlying this action will provide insights into molecular targeting therapy. Furthermore, protein phosphatase 2A (PP2A) is involved in RelA dephosphorylation, but little is known about the underlying mechanism. MATERIALS AND METHODS: Because the regulatory subunits of PP2A drive NF-kB signalling via RelA, we used qRT-PCR and immunoblot analysis to investigate the expression of these subunits in MC3T3-E1 cells. We examined weather FGF2 interacts with NF-kB using immunocytochemistry (IC), immunoprecipitation (IP), and pull-down assay (PD) using recombinant proteins. RESULTS: PR55ß expression was increased, whereas activated RelA was dephosphorylated upon FGF2 stimulation. Further, the interaction of PR55ß with RelA was confirmed by IC, IP, and PD. CONCLUSION: FGF2-induced PR55ß directly interacts with RelA and regulates NF-kB signalling.


Assuntos
NF-kappa B/metabolismo , Osteoblastos/metabolismo , Proteína Fosfatase 2/metabolismo , Transdução de Sinais , Fator de Transcrição RelA/metabolismo , Animais , Linhagem Celular , Fator 2 de Crescimento de Fibroblastos/farmacologia , Humanos , Camundongos , Modelos Biológicos , Osteoblastos/efeitos dos fármacos , Fosforilação , Ligação Proteica
20.
Biochem Biophys Res Commun ; 526(1): 1-7, 2020 05 21.
Artigo em Inglês | MEDLINE | ID: mdl-32192773

RESUMO

The mechanisms underlying the initiation and proliferation of liver regeneration (LR) has been extensively studied using the partial hepatectomy (PHx) model, while little is known about the termination of LR. PP2Acα (protein phosphatase 2 A catalytic subunit α isoform) is the catalytic subunit of protein phosphatase 2 A (PP2A), accounting for most of intracellular serine/threonine phosphatase activity. We have previously observed that termination of LR delayed in PP2Acα liver-specific knockout (LKO) mice after PHx. In our study, we used phospho explorer antibody array analysis to screen the potential phosphorylation targets of PP2Acα, and PP2Acα had a great influence on the hepatic phosphoproteomic signaling in the termination of LR after PHx. We then tested the phosphorylation changes and metabolic function of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase-2 (PFKFB2), an isoform of the key glycolytic enzyme PFKFB, which was significantly regulated by PP2Acα knockout. PP2Acα knockout enhanced glycolysis in vivo and in vitro, while adenoviral-mediated RNAi of PFKFB2 reversed the extension of postoperative liver regeneration in KO mice along with the downregulation of glycolysis. Therefore, we demonstrated that PP2Acα liver-specific knockout regulated the hepatocytes glycolysis via activating PFKFB2, thus enhancing liver regeneration during the termination stage.


Assuntos
Glicólise , Regeneração Hepática , Fosfofrutoquinase-2/metabolismo , Proteína Fosfatase 2/metabolismo , Animais , Movimento Celular , Proliferação de Células , Regulação para Baixo , Camundongos Knockout , Neovascularização Fisiológica , Especificidade de Órgãos , Fosforilação , Fosfosserina/metabolismo , Regulação para Cima
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