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1.
Mol Cell ; 79(6): 934-949.e14, 2020 09 17.
Artigo em Inglês | MEDLINE | ID: mdl-32822587

RESUMO

Although ADP-ribosylation of histones by PARP-1 has been linked to genotoxic stress responses, its role in physiological processes and gene expression has remained elusive. We found that NAD+-dependent ADP-ribosylation of histone H2B-Glu35 by small nucleolar RNA (snoRNA)-activated PARP-1 inhibits AMP kinase-mediated phosphorylation of adjacent H2B-Ser36, which is required for the proadipogenic gene expression program. The activity of PARP-1 on H2B requires NMNAT-1, a nuclear NAD+ synthase, which directs PARP-1 catalytic activity to Glu and Asp residues. ADP-ribosylation of Glu35 and the subsequent reduction of H2B-Ser36 phosphorylation inhibits the differentiation of adipocyte precursors in cultured cells. Parp1 knockout in preadipocytes in a mouse lineage-tracing genetic model increases adipogenesis, leading to obesity. Collectively, our results demonstrate a functional interplay between H2B-Glu35 ADP-ribosylation and H2B-Ser36 phosphorylation that controls adipogenesis.


Assuntos
ADP-Ribosilação/genética , Adipogenia/genética , Histonas/genética , Poli(ADP-Ribose) Polimerase-1/genética , Adenosina Difosfato Ribose/genética , Adipócitos/metabolismo , Adipócitos/patologia , Animais , Linhagem Celular , Dano ao DNA/genética , Regulação da Expressão Gênica no Desenvolvimento/genética , Camundongos , Fosforilação/genética , RNA Nucleolar Pequeno/genética
2.
PLoS Genet ; 16(8): e1008990, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32810142

RESUMO

The kinetochore, a multi-protein complex assembled on centromeres, is essential to segregate chromosomes during cell division. Deficiencies in kinetochore function can lead to chromosomal instability and aneuploidy-a hallmark of cancer cells. Kinetochore function is controlled by recruitment of regulatory proteins, many of which have been documented, however their function often remains uncharacterized and many are yet to be identified. To identify candidates of kinetochore regulation we used a proteome-wide protein association strategy in budding yeast and detected many proteins that are involved in post-translational modifications such as kinases, phosphatases and histone modifiers. We focused on the Polo-like kinase, Cdc5, and interrogated which cellular components were sensitive to constitutive Cdc5 localization. The kinetochore is particularly sensitive to constitutive Cdc5 kinase activity. Targeting Cdc5 to different kinetochore subcomplexes produced diverse phenotypes, consistent with multiple distinct functions at the kinetochore. We show that targeting Cdc5 to the inner kinetochore, the constitutive centromere-associated network (CCAN), increases the levels of centromeric RNA via an SPT4 dependent mechanism.


Assuntos
Proteínas de Ciclo Celular/genética , Centrômero/genética , Proteínas Nucleares/genética , Proteínas Serina-Treonina Quinases/genética , Proteínas Proto-Oncogênicas/genética , Proteínas de Saccharomyces cerevisiae/genética , Fatores de Elongação da Transcrição/genética , Anáfase/genética , Proteínas Cromossômicas não Histona/genética , Segregação de Cromossomos/genética , Histonas/genética , Humanos , Cinetocoros/metabolismo , Mitose/genética , Fenótipo , Fosforilação/genética , RNA/genética , Saccharomyces cerevisiae/genética
3.
PLoS Genet ; 16(8): e1008988, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32841231

RESUMO

Achieving complete and precise genome duplication requires that each genomic segment be replicated only once per cell division cycle. Protecting large eukaryotic genomes from re-replication requires an overlapping set of molecular mechanisms that prevent the first DNA replication step, the DNA loading of MCM helicase complexes to license replication origins, after S phase begins. Previous reports have defined many such origin licensing inhibition mechanisms, but the temporal relationships among them are not clear, particularly with respect to preventing re-replication in G2 and M phases. Using a combination of mutagenesis, biochemistry, and single cell analyses in human cells, we define a new mechanism that prevents re-replication through hyperphosphorylation of the essential MCM loading protein, Cdt1. We demonstrate that Cyclin A/CDK1 can hyperphosphorylate Cdt1 to inhibit MCM re-loading in G2 phase. The mechanism of inhibition is to block Cdt1 binding to MCM independently of other known Cdt1 inactivation mechanisms such as Cdt1 degradation during S phase or Geminin binding. Moreover, our findings suggest that Cdt1 dephosphorylation at the mitosis-to-G1 phase transition re-activates Cdt1. We propose that multiple distinct, non-redundant licensing inhibition mechanisms act in a series of sequential relays through each cell cycle phase to ensure precise genome duplication.


Assuntos
Replicação do DNA/genética , Genoma Humano/genética , Origem de Replicação/genética , Duplicações Segmentares Genômicas/genética , Proteína Quinase CDC2/genética , Proteínas de Ciclo Celular/genética , Ciclina A/genética , Fase G2/genética , Geminina/genética , Genes Duplicados/genética , Células HEK293 , Humanos , Proteínas de Manutenção de Minicromossomo/genética , Fosforilação/genética , Fase S/genética
4.
PLoS Genet ; 16(8): e1008996, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32841242

RESUMO

The utilization of different carbon sources in filamentous fungi underlies a complex regulatory network governed by signaling events of different protein kinase pathways, including the high osmolarity glycerol (HOG) and protein kinase A (PKA) pathways. This work unraveled cross-talk events between these pathways in governing the utilization of preferred (glucose) and non-preferred (xylan, xylose) carbon sources in the reference fungus Aspergillus nidulans. An initial screening of a library of 103 non-essential protein kinase (NPK) deletion strains identified several mitogen-activated protein kinases (MAPKs) to be important for carbon catabolite repression (CCR). We selected the MAPKs Ste7, MpkB, and PbsA for further characterization and show that they are pivotal for HOG pathway activation, PKA activity, CCR via regulation of CreA cellular localization and protein accumulation, as well as for hydrolytic enzyme secretion. Protein-protein interaction studies show that Ste7, MpkB, and PbsA are part of the same protein complex that regulates CreA cellular localization in the presence of xylan and that this complex dissociates upon the addition of glucose, thus allowing CCR to proceed. Glycogen synthase kinase (GSK) A was also identified as part of this protein complex and shown to potentially phosphorylate two serine residues of the HOG MAPKK PbsA. This work shows that carbon source utilization is subject to cross-talk regulation by protein kinases of different signaling pathways. Furthermore, this study provides a model where the correct integration of PKA, HOG, and GSK signaling events are required for the utilization of different carbon sources.


Assuntos
Proteínas Quinases Dependentes de AMP Cíclico/genética , Glucose/metabolismo , Quinases da Glicogênio Sintase/genética , Proteínas Quinases Ativadas por Mitógeno/genética , Aspergillus nidulans/enzimologia , Repressão Catabólica/genética , Fungos/genética , Fungos/metabolismo , Glicerol/metabolismo , Concentração Osmolar , Fosforilação/genética , Mapas de Interação de Proteínas/genética , Proteínas Repressoras/genética , Xilose/metabolismo
5.
PLoS Genet ; 16(7): e1008610, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32716926

RESUMO

Two-component systems and phosphorelays play central roles in the ability of bacteria to rapidly respond to changing environments. In E. coli and related enterobacteria, the complex Rcs phosphorelay is a critical player in the bacterial response to antimicrobial peptides, beta-lactam antibiotics, and other disruptions at the cell surface. The Rcs system is unusual in that an inner membrane protein, IgaA, is essential due to its negative regulation of the RcsC/RcsD/RcsB phosphorelay. While it is known that IgaA transduces signals from the outer membrane lipoprotein RcsF, how it interacts with the phosphorelay has remained unknown. Here we performed in vivo interaction assays and genetic dissection of the critical proteins and found that IgaA interacts with the phosphorelay protein RcsD, and that this interaction is necessary for regulation. Interactions between IgaA and RcsD within their respective periplasmic domains of these two proteins anchor repression of signaling. However, the signaling response depends on a second interaction between cytoplasmic loop 1 of IgaA and a truncated Per-Arndt-Sim (PAS-like) domain in RcsD. A single point mutation in the PAS-like domain increased interactions between the two proteins and blocked induction of the phosphorelay. IgaA may regulate RcsC, the histidine kinase that initiates phosphotransfer through the phosphorelay, indirectly, via its contacts with RcsD. Unlike RcsD, and unlike many other histidine kinases, the periplasmic domain of RcsC is dispensable for the response to signals that induce the Rcs phosphorelay system. The multiple contacts between IgaA and RcsD constitute a poised sensing system, preventing potentially toxic over-activation of this phosphorelay while enabling it to rapidly and quantitatively respond to signals.


Assuntos
Proteínas de Escherichia coli/genética , Proteínas de Membrana/genética , Fosfoproteínas/genética , Fosfotransferases/genética , Escherichia coli/genética , Regulação Bacteriana da Expressão Gênica/genética , Complexos Multienzimáticos/genética , Fosforilação/genética , Transporte Proteico/genética , Salmonella typhimurium/genética , Transdução de Sinais/genética
6.
Proc Natl Acad Sci U S A ; 117(27): 15809-15817, 2020 07 07.
Artigo em Inglês | MEDLINE | ID: mdl-32571924

RESUMO

Src family kinase Lck plays critical roles during T cell development and activation, as it phosphorylates the TCR/CD3 complex to initiate TCR signaling. Lck is present either in coreceptor-bound or coreceptor-unbound (free) forms, and we here present evidence that the two pools of Lck have different molecular properties. We discovered that the free Lck fraction exhibited higher mobility than CD8α-bound Lck in OT-I T hybridoma cells. The free Lck pool showed more activating Y394 phosphorylation than the coreceptor-bound Lck pool. Consistent with this, free Lck also had higher kinase activity, and free Lck mediated higher T cell activation as compared to coreceptor-bound Lck. Furthermore, the coreceptor-Lck coupling was independent of TCR activation. These findings give insights into the initiation of TCR signaling, suggesting that changes in coreceptor-Lck coupling constitute a mechanism for regulation of T cell sensitivity.


Assuntos
Proteína Tirosina Quinase p56(lck) Linfócito-Específica/genética , Receptores de Antígenos de Linfócitos T alfa-beta/genética , Linfócitos T/metabolismo , Quinases da Família src/genética , Animais , Linfócitos T CD8-Positivos/imunologia , Diferenciação Celular/genética , Hibridomas/imunologia , Ativação Linfocitária/genética , Proteína Tirosina Quinase p56(lck) Linfócito-Específica/imunologia , Camundongos , Fosforilação/genética , Ligação Proteica/genética , Complexo Receptor-CD3 de Antígeno de Linfócitos T/genética , Complexo Receptor-CD3 de Antígeno de Linfócitos T/imunologia , Transdução de Sinais , Linfócitos T/imunologia
7.
Proc Natl Acad Sci U S A ; 117(27): 15666-15672, 2020 07 07.
Artigo em Inglês | MEDLINE | ID: mdl-32571956

RESUMO

Muscle contraction depends on the cyclical interaction of myosin and actin filaments. Therefore, it is important to understand the mechanisms of polymerization and depolymerization of muscle myosins. Muscle myosin 2 monomers exist in two states: one with a folded tail that interacts with the heads (10S) and one with an unfolded tail (6S). It has been thought that only unfolded monomers assemble into bipolar and side-polar (smooth muscle myosin) filaments. We now show by electron microscopy that, after 4 s of polymerization in vitro in both the presence (smooth muscle myosin) and absence of ATP, skeletal, cardiac, and smooth muscle myosins form tail-folded monomers without tail-head interaction, tail-folded antiparallel dimers, tail-folded antiparallel tetramers, unfolded bipolar tetramers, and small filaments. After 4 h, the myosins form thick bipolar and, for smooth muscle myosin, side-polar filaments. Nonphosphorylated smooth muscle myosin polymerizes in the presence of ATP but with a higher critical concentration than in the absence of ATP and forms only bipolar filaments with bare zones. Partial depolymerization in vitro of nonphosphorylated smooth muscle myosin filaments by the addition of MgATP is the reverse of polymerization.


Assuntos
Citoesqueleto de Actina/química , Miosina Tipo II/química , Miosinas/química , Miosinas de Músculo Liso/química , Citoesqueleto de Actina/genética , Citoesqueleto de Actina/ultraestrutura , Animais , Galinhas , Microscopia Eletrônica , Miosina Tipo II/genética , Miosina Tipo II/ultraestrutura , Miosinas/genética , Miosinas/ultraestrutura , Fosforilação/genética , Polimerização , Conformação Proteica , Dobramento de Proteína , Multimerização Proteica/genética , Desdobramento de Proteína , Miosinas de Músculo Liso/genética , Miosinas de Músculo Liso/ultraestrutura
8.
Immunol Med ; 43(3): 121-129, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32546118

RESUMO

The roles of interleukin-22 (IL-22) in carcinogenesis have been proposed in various neoplasms. Increased expression of IL-22 has been observed in oral squamous cell carcinoma (OSCC) lesions as well as in other cancers. OSCC is still associated with poor prognosis and a high mortality rate because of its invasiveness and frequent lymph node metastasis. In the present study, we investigated the effects of IL-22 on OSCC cells. The human OSCC cell lines Ca9-22 and SAS were stimulated with IL-22 (1-10 ng/mL), and their migration abilities were examined using a cell scratch assay. A Matrigel invasion assay was performed to evaluate the invasion abilities of OSCC cells. Signal transducer and activator of transcription 3 (STAT3) phosphorylation, matrix metalloproteinase (MMP) and epithelial-mesenchymal transition (EMT)-related genes and proteins were also examined. IL-22 treatment promoted the migration and invasion abilities of OSCC cells without increasing their viability. IL-22 stimulation also induced STAT3 phosphorylation, MMP-9 activity and EMT-related genes and proteins. Our findings suggest that IL-22 has possible roles in the development of OSCC.


Assuntos
Carcinoma de Células Escamosas/patologia , Movimento Celular/efeitos dos fármacos , Interleucinas/efeitos adversos , Interleucinas/fisiologia , Neoplasias Bucais/patologia , Carcinoma de Células Escamosas/genética , Carcinoma de Células Escamosas/metabolismo , Linhagem Celular Tumoral , Transição Epitelial-Mesenquimal/efeitos dos fármacos , Transição Epitelial-Mesenquimal/genética , Expressão Gênica/efeitos dos fármacos , Expressão Gênica/genética , Humanos , Metástase Linfática/genética , Metaloproteinase 9 da Matriz/genética , Metaloproteinase 9 da Matriz/metabolismo , Neoplasias Bucais/genética , Neoplasias Bucais/metabolismo , Invasividade Neoplásica/genética , Fosforilação/genética , Fator de Transcrição STAT3/genética , Fator de Transcrição STAT3/metabolismo
9.
Gene ; 755: 144883, 2020 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-32565321

RESUMO

The anti-anti-sigma factor BldG has a pleiotropic function in Streptomyces coelicolor A3(2), regulating both morphological and physiological differentiation. Together with the anti-sigma factor UshX, it participates in a partner-switching activation of the sigma factor σH, which has a dual role in the osmotic stress response and morphological differentiation in S. coelicolor A3(2). In addition to UshX, BldG also interacts with the anti-sigma factor ApgA, although no target sigma factor has yet been identified. However, neither UshX nor ApgA phosphorylates BldG. This phosphorylation is provided by the anti-sigma factor RsfA, which is specific for the late developmental sigma factor σF. However, BldG is phosphorylated in the rsfA mutant, suggesting that some other anti-sigma factors containing HATPase_c kinase domain are capable to phosphorylate BldG in vivo. Bacterial two-hybrid system (BACTH) was therefore used to investigate the interactions of all suitable anti-sigma factors of S. coelicolor A3(2) with BldG. At least 15 anti-sigma factors were found to interact with BldG. These interactions were confirmed by native PAGE. In addition to RsfA, BldG is specifically phosphorylated on the conserved phosphorylation Ser57 residue by at least seven additional anti-sigma factors. However, only one of them, SCO7328, has been shown to interact with three sigma factors, σG, σK and σM. A mutant with deleted SCO7328 gene was prepared in S. coelicolor A3(2), however, no specific function of SCO7328 in growth, differentiation or stress response could be attributed to this anti-sigma factor. These results suggest that BldG is specifically phosphorylated by several anti-sigma factors and it plays a role in the regulation of several sigma factors in S. coelicolor A3(2). This suggests a complex regulation of the stress response and differentiation in S. coelicolor A3(2) through this pleiotropic anti-sigma factor.


Assuntos
Fator sigma/genética , Streptomyces coelicolor/imunologia , Streptomyces coelicolor/metabolismo , Sequência de Aminoácidos/genética , Anticorpos Anti-Idiotípicos/imunologia , Anticorpos Anti-Idiotípicos/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Sequência de Bases/genética , Regulação Bacteriana da Expressão Gênica/genética , Pleiotropia Genética/genética , Fosforilação/genética , Fosfotransferases/metabolismo , Regiões Promotoras Genéticas/genética , Fator sigma/imunologia , Fator sigma/metabolismo , Streptomyces/genética , Streptomyces coelicolor/genética , Transcrição Genética/genética
10.
PLoS One ; 15(6): e0234011, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32484825

RESUMO

The tomato AGC protein kinase Adi3 is a Ser/Thr kinase that functions as a negative regulator of programmed cell death through cell death suppression (CDS) activity in the nucleus. In this study, to understand the mechanism of Adi3 CDS, peptide microarrays containing random Ser- and Thr-peptide phosphorylation substrates were used to screen for downstream phosphorylation substrates. In the microarray phosphorylation assay, Adi3 showed promiscuous kinase activity more toward Ser-peptides compared to Thr-peptides, and a preference for aromatic and cyclic amino acids on both Ser- and Thr-peptides was seen. The 63 highest phosphorylated peptide sequences from the Ser-peptide microarray were selected as queries for a BLAST search against the tomato proteome. As a result, 294 candidate nuclear Adi3 substrates were selected and categorized based on their functions. Many of these proteins were classified as DNA/RNA polymerases or regulators involved in transcription and translation events. The list of potential Adi3 substrates was narrowed to eleven and four candidates were tested for phosphorylation by Adi3. Two of these candidates, RNA polymerase II 2nd largest subunit (RPB2) and the pathogen defense related transcription factor Pti5, were confirmed as Adi3 phosphorylation substrates by in vitro kinase assays. Using a mutational approach two residues, Thr675 and Thr676, were identified as Adi3 phosphorylation sites on RPB2. This study provides the foundation for understanding Adi3 CDS mechanisms in the nucleus as well as other cellular functions.


Assuntos
Morte Celular/genética , Peptídeos/genética , Células Vegetais/metabolismo , Proteínas de Plantas/genética , Sequência de Aminoácidos , Núcleo Celular/genética , Lycopersicon esculentum/genética , Lycopersicon esculentum/metabolismo , Análise em Microsséries , Mutação/genética , Fosforilação/genética , Proteínas Quinases/genética
11.
Hum Cell ; 33(3): 801-809, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32388810

RESUMO

Endometrial cancer (EC) is one of the most common cancers among females worldwide. Advanced stage patients of EC have poor prognosis. Inevitable side effects and treatment tolerance of chemotherapy for EC remain to be addressed. Our results in this study showed that EC cells with higher tumor necrosis factor receptor-associated factor 4 (TRAF4) expression have lower sensitivity to poly ADP-ribose polymerase 1 (PARP1) inhibitors. Upon TRAF4 knockdown, the colony numbers of EC cells were markedly down-regulated, and the markers of DNA double-strand breakage were significantly up-regulated after the treatment of olaparib, a PARP1 inhibitor. TRAF4 knockdown reduced the phosphorylation of protein kinase B (Akt), promoted DNA double-strand breakage, and decreased levels of DNA repair related proteins, including phosphorylated-DNA-dependent protein kinase (p-DNA-PK) and RAD51 recombinase (RAD51). In addition, TRAF4's effect on the sensitivity of EC cells to olaparib was further found to be mainly mediated by Akt phosphorylation. Moreover, in vivo results showed that TRAF4 knockdown enhanced the sensitivity of EC to PARP1 inhibitors using a mouse xenograft model. Collectively, our data suggest that combined application of TRAF4 knockdown and PARP1 inhibition can be used as a promising strategy for synthetic lethality in EC treatment.


Assuntos
Neoplasias do Endométrio/tratamento farmacológico , Neoplasias do Endométrio/genética , Técnicas de Silenciamento de Genes , Ftalazinas/farmacologia , Ftalazinas/uso terapêutico , Piperazinas/farmacologia , Piperazinas/uso terapêutico , Poli(ADP-Ribose) Polimerase-1/antagonistas & inibidores , Animais , Antineoplásicos/efeitos adversos , Antineoplásicos/uso terapêutico , Quebras de DNA de Cadeia Dupla , Modelos Animais de Doenças , Neoplasias do Endométrio/patologia , Feminino , Expressão Gênica , Humanos , Camundongos , Terapia de Alvo Molecular , Fosforilação/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , Fator 4 Associado a Receptor de TNF/genética , Fator 4 Associado a Receptor de TNF/metabolismo , Células Tumorais Cultivadas
12.
RNA ; 26(9): 1143-1159, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32404348

RESUMO

Tob2, an anti-proliferative protein, promotes deadenylation through recruiting Caf1 deadenylase to the mRNA poly(A) tail by simultaneously interacting with both Caf1 and poly(A)-binding protein (PABP). Previously, we found that changes in Tob2 phosphorylation can alter its PABP-binding ability and deadenylation-promoting function. However, it remained unknown regarding the relevant kinase(s). Moreover, it was unclear whether Tob2 phosphorylation modulates the transcriptome and whether the phosphorylation is linked to Tob2's anti-proliferative function. In this study, we found that c-Jun amino-terminal kinase (JNK) increases phosphorylation of Tob2 at many Ser/Thr sites in the intrinsically disordered region (IDR) that contains two separate PABP-interacting PAM2 motifs. JNK-induced phosphorylation or phosphomimetic mutations at these sites weaken the Tob2-PABP interaction. In contrast, JNK-independent phosphorylation of Tob2 at serine 254 (S254) greatly enhances Tob2 interaction with PABP and its ability to promote deadenylation. We discovered that both PAM2 motifs are required for Tob2 to display these features. Combining mass spectrometry analysis, poly(A) size-distribution profiling, transcriptome-wide mRNA turnover analyses, and cell proliferation assays, we found that the phosphomimetic mutation at S254 (S254D) enhances Tob2's association with PABP, leading to accelerated deadenylation and decay of mRNAs globally. Moreover, the Tob2-S254D mutant accelerates the decay of many transcripts coding for cell cycle related proteins and enhances anti-proliferation function. Our findings reveal a novel mechanism by which Ccr4-Not complex is recruited by Tob2 to the mRNA 3' poly(A)-PABP complex in a phosphorylation dependent manner to promote rapid deadenylation and decay across the transcriptome, eliciting transcriptome reprogramming and suppressed cell proliferation.


Assuntos
Proteínas de Ciclo Celular/genética , Proliferação de Células/genética , Fosforilação/genética , RNA Mensageiro/genética , Transcriptoma/genética , Linhagem Celular , Células HEK293 , Humanos , Poli A/genética , Proteínas de Ligação a Poli(A)/genética , Poliadenilação/genética , Estabilidade de RNA/genética
13.
mSphere ; 5(3)2020 05 20.
Artigo em Inglês | MEDLINE | ID: mdl-32434842

RESUMO

The control of the virulence response regulator and sensor (CovR-CovS) two-component regulatory system in group A Streptococcus (GAS) strains regulates more than 15% of gene expression and has critical roles in invasive GAS infection. The membrane-embedded CovS has kinase and phosphatase activities, and both are required for modulating the phosphorylation level of CovR. Regulator of Cov (RocA) is a positive regulator of covR and also been shown to be a pseudokinase that interacts with CovS to enhance the phosphorylation level of CovR; however, how RocA modulates the activity of CovS has not been determined conclusively. Although the phosphorylation level of CovR was decreased in the rocA mutant in the exponential phase, the present study shows that phosphorylated CovR in the rocA mutant increased to levels similar to those in the wild-type strain in the stationary phase of growth. In addition, acidic stress, which is generally present in the stationary phase, enhanced the phosphorylation level of CovR in the rocA mutant. The phosphorylation levels of CovR in the CovS phosphatase-inactivated mutant and its rocA mutant were similar under acidic stress and Mg2+ (the signal that inhibits CovS phosphatase activity) treatments, suggesting that the phosphatase activity, but not the kinase activity, of CovS is required for RocA to modulate CovR phosphorylation. The phosphorylation level of CovR is crucial for GAS strains to regulate virulence factor expression; therefore, the growth phase- and pH-dependent RocA activity would contribute significantly to GAS pathogenesis.IMPORTANCE The emergence of invasive group A streptococcal infections has been reported worldwide. Clinical isolates that have spontaneous mutations or a truncated allele of the rocA gene (e.g., emm3-type isolates) are considered to be more virulent than isolates with the intact rocA gene (e.g., emm1-type isolates). RocA is a positive regulator of covR and has been shown to enhance the phosphorylation level of intracellular CovR regulator through the functional CovS protein. CovS is the membrane-embedded sensor and modulates the phosphorylation level of CovR by its kinase and phosphatase activities. The present study shows that the enhancement of CovR phosphorylation is mediated via the repression of CovS's phosphatase activity by RocA. In addition, we found that RocA acts dominantly on modulating CovR phosphorylation under neutral pH conditions and in the exponential phase of growth. The phosphorylation level of CovR is crucial for group A Streptococcus species to regulate virulence factor expression and is highly related to bacterial invasiveness; therefore, growth phase- and pH-dependent RocA activity and the sequence polymorphisms of rocA gene would contribute significantly to bacterial phenotype variations and pathogenesis.


Assuntos
Proteínas de Bactérias/metabolismo , Histidina Quinase/metabolismo , Proteínas Repressoras/metabolismo , Streptococcus pyogenes/patogenicidade , Transativadores/metabolismo , Regulação Bacteriana da Expressão Gênica/genética , Humanos , Monoéster Fosfórico Hidrolases/metabolismo , Fosforilação/genética , Infecções Estreptocócicas/patologia , Streptococcus pyogenes/genética , Transativadores/genética
14.
PLoS One ; 15(4): e0231739, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32352989

RESUMO

OBJECTIVES: We previously reported microvascular leakage resulting from fibrinogen-γ chain C-terminal products (γC) occurred via a RhoA-dependent mechanism. The objective of this study was to further elucidate the signaling mechanism by which γC induces endothelial hyperpermeability. Since it is known that γC binds and activates endothelial αvß3, a transmembrane integrin receptor involved in intracellular signaling mediated by the tyrosine kinases FAK and Src, we hypothesized that γC alters endothelial barrier function by activating the FAK-Src pathway leading to junction dissociation and RhoA driven cytoskeletal stress-fiber formation. METHODS AND RESULTS: Using intravital microscopy of rat mesenteric microvessels, we show increased extravasation of plasma protein (albumin) resulting from γC administration. In addition, capillary fluid filtration coefficient (Kfc) indicated γC-induced elevated lung vascular permeability. Furthermore, γC decreased transendothelial barrier resistance in a time-dependent and dose-related fashion in cultured rat lung microvascular endothelial cells (RLMVECs), accompanied by increased FAK/Src phosphorylation detection by western blot. Experiments with pharmacological inhibition or gene silencing of FAK showed significantly reduced γC-induced albumin and fluid leakage across microvessels, stress-fiber formation, VE-cadherin tyrosine phosphorylation, and improved γC-induced endothelial barrier dysfunction, indicating the involvement of FAK in γC mediated hyperpermeability. Comparable results were found when Src was targeted in a similar manner, however inhibition of FAK prevented Src activation, suggesting that FAK is upstream of Src in γC-mediated hyperpermeability. In addition, γC-induced cytoskeletal stress-fiber formation was attenuated during inhibition or silencing of these tyrosine kinases, concomitantly with RhoA inhibition. CONCLUSION: The FAK-Src pathway contributes to γC-induced microvascular barrier dysfunction, junction protein phosphorylation and disorganization in a manner that involves RhoA and stress-fiber formation.


Assuntos
Permeabilidade Capilar/fisiologia , Quinase 1 de Adesão Focal/metabolismo , Hemorragia/patologia , Microvasos/patologia , Quinases da Família src/metabolismo , Animais , Permeabilidade Capilar/efeitos dos fármacos , Linhagem Celular , Modelos Animais de Doenças , Células Endoteliais/efeitos dos fármacos , Células Endoteliais/patologia , Endotélio Vascular/citologia , Endotélio Vascular/efeitos dos fármacos , Endotélio Vascular/patologia , Fibrinogênio/toxicidade , Quinase 1 de Adesão Focal/antagonistas & inibidores , Quinase 1 de Adesão Focal/genética , Hemorragia/induzido quimicamente , Humanos , Microscopia Intravital , Pulmão/irrigação sanguínea , Masculino , Mesentério/irrigação sanguínea , Mesentério/diagnóstico por imagem , Microvasos/efeitos dos fármacos , Fosforilação/efeitos dos fármacos , Fosforilação/genética , RNA Interferente Pequeno/metabolismo , Ratos , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética , Proteínas rho de Ligação ao GTP/metabolismo , Quinases da Família src/genética
15.
J Vis Exp ; (159)2020 05 08.
Artigo em Inglês | MEDLINE | ID: mdl-32449708

RESUMO

Polynucleotide kinases (PNKs) are enzymes that catalyze the phosphorylation of the 5' hydroxyl end of DNA and RNA oligonucleotides. The activity of PNKs can be quantified using direct or indirect approaches. Presented here is a direct, in vitro approach to measure PNK activity that relies on a fluorescently-labeled oligonucleotide substrate and polyacrylamide gel electrophoresis. This approach provides resolution of the phosphorylated products while avoiding the use of radiolabeled substrates. The protocol details how to set up the phosphorylation reaction, prepare and run large polyacrylamide gels, and quantify the reaction products. The most technically challenging part of this assay is pouring and running the large polyacrylamide gels; thus, important details to overcome common difficulties are provided. This protocol was optimized for Grc3, a PNK that assembles into an obligate pre-ribosomal RNA processing complex with its binding partner, the Las1 nuclease. However, this protocol can be adapted to measure the activity of other PNK enzymes. Moreover, this assay can also be modified to determine the effects of different components of the reaction, such as the nucleoside triphosphate, metal ions, and oligonucleotides.


Assuntos
Bioensaio/métodos , Nucleotídeos/metabolismo , Fosforilação/genética
16.
Nucleic Acids Res ; 48(12): 6775-6787, 2020 07 09.
Artigo em Inglês | MEDLINE | ID: mdl-32453417

RESUMO

Cell growth requires a high level of protein synthesis and oncogenic pathways stimulate cell proliferation and ribosome biogenesis. Less is known about how cells respond to dysfunctional mRNA translation and how this feeds back into growth regulatory pathways. The Epstein-Barr virus (EBV)-encoded EBNA1 causes mRNA translation stress in cis that activates PI3Kδ. This leads to the stabilization of MDM2, induces MDM2's binding to the E2F1 mRNA and promotes E2F1 translation. The MDM2 serine 166 regulates the interaction with the E2F1 mRNA and deletion of MDM2 C-terminal RING domain results in a constitutive E2F1 mRNA binding. Phosphorylation on serine 395 following DNA damage instead regulates p53 mRNA binding to its RING domain and prevents the E2F1 mRNA interaction. The p14Arf tumour suppressor binds MDM2 and in addition to preventing degradation of the p53 protein it also prevents the E2F1 mRNA interaction. The data illustrate how two MDM2 domains selectively bind specific mRNAs in response to cellular conditions to promote, or suppress, cell growth and how p14Arf coordinates MDM2's activity towards p53 and E2F1. The data also show how EBV via EBNA1-induced mRNA translation stress targets the E2F1 and the MDM2 - p53 pathway.


Assuntos
Fator de Transcrição E2F1/genética , Neoplasias/genética , Proteínas Proto-Oncogênicas c-mdm2/genética , Proteína Supressora de Tumor p53/genética , Carcinogênese/genética , Ciclo Celular/genética , Proliferação de Células/genética , Dano ao DNA/genética , Genes Supressores de Tumor , Herpesvirus Humano 4/genética , Humanos , Neoplasias/virologia , Oncogenes/genética , Fosforilação/genética , Domínios Proteicos/genética , Proteínas com Motivo de Reconhecimento de RNA/genética , RNA Mensageiro/genética , Proteína Supressora de Tumor p14ARF/genética
17.
Life Sci ; 253: 117740, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32376265

RESUMO

AIMS: Annexin A2 (ANXA2) is closely associated with tumor malignancy and its N-terminus includes a vital domain for its function. The aims are to explore the correlation between the sites (Tyr23, Ser1, Ser11 and Ser25) in the domain and its roles. MAIN METHODS: We re-expressed ANXA2 with mutated sites in ANXA2-deleted human colonic adenocarcinoma cell line caco2 (ANXA2-/-caco2). A series of analyses were used to determine the correlation of each site with ANXA2 activation, cell malignancy enhancement and motility-associated microstructural development. Bioinformatics and luciferase reporter assays were employed to validate ANXA2-targeted miRNAs. KEY FINDINGS: The in vitro results showed that all single and multiple mutations of the ANXA2 N-terminal sites inhibited ANXA2 phosphorylation at different levels and subsequently inhibited the proliferation, motility, and polymerization of F-actin and ß-tubulin in caco2 cells. Motility-associated microstructures were significantly remodeled when these sites were mutated. The forced expression of miR-206 significantly suppressed the proliferation, motility and epithelial-mesenchymal transition (EMT) of caco2 cells. The in vivo results showed that all the ANXA2 N-terminal site mutations and forced expression of miR-206 significantly inhibited tumor growth. Overall, this study demonstrated that the sites of the ANXA2 N-terminus, especially Tyr23, play crucial roles in maintaining the high malignancy of colonic adenocarcinoma. Furthermore, miR-206 targets ANXA2 and plays a role as a cancer suppressor in colonic adenocarcinoma. SIGNIFICANCE: Our study provided evidence that further elucidates the molecular mechanism of ANXA2 and its roles in colonic adenocarcinoma and suggested potential targets of ANXA2 for colonic adenocarcinoma therapy by using miR-206 as a novel strategy.


Assuntos
Adenocarcinoma/patologia , Anexina A2/genética , Neoplasias do Colo/patologia , MicroRNAs/genética , Actinas/metabolismo , Adenocarcinoma/genética , Animais , Células CACO-2 , Movimento Celular/genética , Proliferação de Células/genética , Neoplasias do Colo/genética , Transição Epitelial-Mesenquimal/genética , Humanos , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Fosforilação/genética , Tubulina (Proteína)/metabolismo , Ensaios Antitumorais Modelo de Xenoenxerto
18.
PLoS One ; 15(5): e0227786, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32433703

RESUMO

Homeostasis is an essential concept to understand the stability of organisms and their adaptive behaviors when coping with external and internal assaults. Many hormones that take part in homeostatic control come in antagonistic pairs, such as glucagon and insulin reflecting the inflow and outflow compensatory mechanisms to control a certain internal variable, such as blood sugar levels. By including negative feedback loops homeostatic controllers can exhibit oscillations with characteristic frequencies. In this paper we demonstrate the associated frequency changes in homeostatic systems when individual controllers -in a set of interlocked feedback loops- gain control in response to environmental changes. Taking p53 as an example, we show how Per2, ATM and Mdm2 feedback loops -interlocked with p53- gain individual control in dependence to the level of DNA damage, and how each of these controllers provide certain functionalities in their regulation of p53. In unstressed cells, the circadian regulator Per2 ensures a basic p53 level to allow its rapid up-regulation in case of DNA damage. When DNA damage occurs the ATM controller increases the level of p53 and defends it towards uncontrolled degradation, which despite DNA damage, would drive p53 to lower values and p53 dysfunction. Mdm2 on its side keeps p53 at a high but sub-apoptotic level to avoid premature apoptosis. However, with on-going DNA damage the Mdm2 set-point is increased by HSP90 and other p53 stabilizers leading finally to apoptosis. An emergent aspect of p53 upregulation during cell stress is the coordinated inhibition of ubiquitin-independent and ubiquitin-dependent degradation reactions. Whether oscillations serve a function or are merely a by-product of the controllers are discussed in view of the finding that homeostatic control of p53, as indicated above, does in principle not require oscillatory homeostats.


Assuntos
Retroalimentação Fisiológica , Homeostase/genética , Modelos Teóricos , Proteína Supressora de Tumor p53/genética , Apoptose/genética , Proteínas Mutadas de Ataxia Telangiectasia/genética , Ritmo Circadiano/genética , Dano ao DNA/genética , Regulação da Expressão Gênica/genética , Humanos , Proteínas Circadianas Period/genética , Fosforilação/genética , Proteínas Proto-Oncogênicas c-mdm2/genética , Ubiquitina/genética
19.
Proc Natl Acad Sci U S A ; 117(16): 9042-9053, 2020 04 21.
Artigo em Inglês | MEDLINE | ID: mdl-32241891

RESUMO

RNA has been proposed as an important scaffolding factor in the nucleus, aiding protein complex assembly in the dense intracellular milieu. Architectural contributions of RNA to cytosolic signaling pathways, however, remain largely unknown. Here, we devised a multidimensional gradient approach, which systematically locates RNA components within cellular protein networks. Among a subset of noncoding RNAs (ncRNAs) cosedimenting with the ubiquitin-proteasome system, our approach unveiled ncRNA MaIL1 as a critical structural component of the Toll-like receptor 4 (TLR4) immune signal transduction pathway. RNA affinity antisense purification-mass spectrometry (RAP-MS) revealed MaIL1 binding to optineurin (OPTN), a ubiquitin-adapter platforming TBK1 kinase. MaIL1 binding stabilized OPTN, and consequently, loss of MaIL1 blunted OPTN aggregation, TBK1-dependent IRF3 phosphorylation, and type I interferon (IFN) gene transcription downstream of TLR4. MaIL1 expression was elevated in patients with active pulmonary infection and was highly correlated with IFN levels in bronchoalveolar lavage fluid. Our study uncovers MaIL1 as an integral RNA component of the TLR4-TRIF pathway and predicts further RNAs to be required for assembly and progression of cytosolic signaling networks in mammalian cells.


Assuntos
Proteínas de Ciclo Celular/metabolismo , Interferon Tipo I/genética , Proteínas de Membrana Transportadoras/metabolismo , RNA não Traduzido/metabolismo , Infecções Respiratórias/imunologia , Receptor 4 Toll-Like/metabolismo , Proteínas Adaptadoras de Transporte Vesicular/metabolismo , Adulto , Idoso , Buffy Coat/citologia , Líquido da Lavagem Broncoalveolar/imunologia , Feminino , Regulação da Expressão Gênica/imunologia , Técnicas de Silenciamento de Genes , Humanos , Fator Regulador 3 de Interferon/metabolismo , Interferon Tipo I/sangue , Interferon Tipo I/imunologia , Macrófagos , Masculino , Pessoa de Meia-Idade , Fosforilação/genética , Cultura Primária de Células , Estabilidade Proteica , Proteínas Serina-Treonina Quinases/metabolismo , RNA não Traduzido/sangue , RNA não Traduzido/genética , RNA-Seq , Infecções Respiratórias/sangue , Infecções Respiratórias/microbiologia , Transdução de Sinais/genética , Transdução de Sinais/imunologia , Adulto Jovem
20.
Invest Ophthalmol Vis Sci ; 61(4): 44, 2020 04 09.
Artigo em Inglês | MEDLINE | ID: mdl-32343785

RESUMO

Purpose: To determine how visual cortex plasticity changes after monocular deprivation (MD) in mice and whether conventional protein kinase C gamma (cPKCγ) plays a role in visual cortex plasticity. Methods: cPKCγ membrane translocation levels were quantified by using immunoblotting to explore the effects of MD on cPKCγ activation. Electrophysiology was used to record field excitatory postsynaptic potential (fEPSP) amplitude with the goal of observing changes in visual cortex plasticity after MD. Immunoblotting was also used to determine the phosphorylation levels of GluR1 at Ser831. Light transmission was analyzed using electroretinography to examine the effects of MD and cPKCγ on mouse retinal function. Results: Membrane translocation levels of cPKCγ significantly increased in the contralateral visual cortex of MD mice compared to wild-type (WT) mice (P < 0.001). In the contralateral visual cortex, long-term potentiation (LTP) and the phosphorylation levels of GluR1 at Ser 831 were increased in cPKCγ+/+ mice after MD. Interestingly, these levels could be downregulated by cPKCγ knockout compared to cPKCγ+/++MD mice (P < 0.001). Compared to the right eyes of WT mice, the amplitudes of a-waves and b-waves declined in deprived right eyes of mice after MD (P < 0.001). There were no significant differences when comparing cPKCγ+/+ and cPKCγ-/- mice with MD. Conclusions: cPKCγ participates in the plasticity of the visual cortex after MD, which is characterized by increased LTP in the contralateral visual cortex, which may be a result of cPKCγ-mediated phosphorylation of GluR1 at Ser 831.


Assuntos
Plasticidade Neuronal , Proteína Quinase C/genética , Receptores de AMPA/genética , Privação Sensorial , Visão Monocular/fisiologia , Análise de Variância , Animais , Modelos Animais de Doenças , Eletrorretinografia , Feminino , Imunofluorescência , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fosforilação/genética , Proteína Quinase C-épsilon/genética , Distribuição Aleatória , Transmissão Sináptica , Córtex Visual/fisiologia , Vias Visuais/fisiologia
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