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1.
Mol Cell Proteomics ; 22(5): 100543, 2023 05.
Artigo em Inglês | MEDLINE | ID: mdl-37030595

RESUMO

Excitotoxicity, a neuronal death process in neurological disorders such as stroke, is initiated by the overstimulation of ionotropic glutamate receptors. Although dysregulation of proteolytic signaling networks is critical for excitotoxicity, the identity of affected proteins and mechanisms by which they induce neuronal cell death remain unclear. To address this, we used quantitative N-terminomics to identify proteins modified by proteolysis in neurons undergoing excitotoxic cell death. We found that most proteolytically processed proteins in excitotoxic neurons are likely substrates of calpains, including key synaptic regulatory proteins such as CRMP2, doublecortin-like kinase I, Src tyrosine kinase and calmodulin-dependent protein kinase IIß (CaMKIIß). Critically, calpain-catalyzed proteolytic processing of these proteins generates stable truncated fragments with altered activities that potentially contribute to neuronal death by perturbing synaptic organization and function. Blocking calpain-mediated proteolysis of one of these proteins, Src, protected against neuronal loss in a rat model of neurotoxicity. Extrapolation of our N-terminomic results led to the discovery that CaMKIIα, an isoform of CaMKIIß, undergoes differential processing in mouse brains under physiological conditions and during ischemic stroke. In summary, by identifying the neuronal proteins undergoing proteolysis during excitotoxicity, our findings offer new insights into excitotoxic neuronal death mechanisms and reveal potential neuroprotective targets for neurological disorders.


Assuntos
Morte Celular , Neurônios , Sinapses , Animais , Masculino , Camundongos , Ratos , Calpaína/metabolismo , Células Cultivadas , Inibidores de Cisteína Proteinase/farmacologia , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Camundongos Endogâmicos C57BL , Proteínas do Tecido Nervoso/metabolismo , Neurônios/patologia , Neurônios/fisiologia , Neuroproteção , Proteoma/análise , Ratos Wistar , Acidente Vascular Cerebral/patologia , Sinapses/patologia , Sinapses/fisiologia
2.
Growth Factors ; 41(2): 82-100, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37229558

RESUMO

Transforming growth factor ß (TGFß) is a multifunctional cytokine, and its signalling responses are exerted via integrated intracellular pathways and complex regulatory mechanisms. Due to its high potency, TGFß signalling is tightly controlled under normal circumstances, while its dysregulation in cancer favours metastasis. The recognised potential of TGFß as a therapeutic target led to emerging development of anti-TGFß reagents with preclinical success, yet these therapeutics failed to recapitulate their efficacy in experimental settings. In this review, possible reasons for this inconsistency are discussed, addressing the knowledge gap between theoretical and actual behaviours of TGFß signalling. Previous studies on oncogenic cells have demonstrated the spatiotemporal heterogeneity of TGFß signalling intensity. Under feedback mechanisms and exosomal ligand recycling, cancer cells may achieve cyclic TGFß signalling to facilitate dissemination and colonisation. This challenges the current presumption of persistently high TGFß signalling in cancer, pointing to a new direction of research on TGFß-targeted therapeutics.


Assuntos
Neoplasias , Fator de Crescimento Transformador beta , Humanos , Fator de Crescimento Transformador beta/metabolismo , Transdução de Sinais , Neoplasias/tratamento farmacológico
3.
EMBO Rep ; 21(1): e47030, 2020 01 07.
Artigo em Inglês | MEDLINE | ID: mdl-31858693

RESUMO

Comment on "USP26 regulates TGF-ß signaling by deubiquitinating and stabilizing SMAD7" by Kit Leng Lui et al.


Assuntos
Glioblastoma , Cisteína Endopeptidases , Humanos , Transdução de Sinais , Proteína Smad7 , Fator de Crescimento Transformador beta
4.
Proteomics ; 21(13-14): e2000221, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33638284

RESUMO

Epithelial-mesenchymal transition (EMT) describes an evolutionary conserved morphogenic process defined by loss of epithelial characteristics and acquisition of mesenchymal phenotype, and altered patterns of intercellular communication, leading to functional changes in cell migration and invasion. In this regard, we have previously reported that oncogenic H-Ras induced EMT in Madin-Darby Canine Kidney (MDCK) cells (21D1 cells) trigger changes in the protein distribution pattern in cells, exosomes, and soluble protein factors (secretome) which modulate the tumor microenvironment. Here, we report that shed microvesicles (also termed microparticles/ectosomes) secreted from MDCK cells following oncogenic H-Ras-induced EMT (21D1-sMVs) are biochemically distinct from exosomes and parental MDCK-sMVs. The protein spectra of RNA-binding proteins and mitochondrial proteins in 21D1-sMVs differ profoundly compared to those of exosomes, likewise proteins associated with suppression of anoikis. We show that 21D1-sMVs promote cell migration, confer anchorage-independent growth, and induce EMT in parental MDCK cells. An unexpected and novel finding was the selective sorting of tissue transglutaminase-2 (TGM2) into 21D1-sMVs; there was no evidence of TGM2 in MDCK-sMVs. Prior treatment of 21D1-sMVs with neutralizing anti-TGM2 or anti-FN1 antibodies attenuates the invasive capability of fibroblasts. These finding suggest that microvesicle-associated TGM2 may play an important contributory role in the EMT process and warrants further investigation.


Assuntos
Micropartículas Derivadas de Células , Transição Epitelial-Mesenquimal , Animais , Cães , Proteínas de Ligação ao GTP , Células Madin Darby de Rim Canino , Proteínas Mitocondriais , Proteína 2 Glutamina gama-Glutamiltransferase , Proteínas de Ligação a RNA , Transglutaminases
5.
Mol Cancer ; 20(1): 154, 2021 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-34852849

RESUMO

To identify novel cancer therapies, the tumor microenvironment (TME) has received a lot of attention in recent years in particular with the advent of clinical successes achieved by targeting immune checkpoint inhibitors (ICIs). The TME consists of multiple cell types that are embedded in the extracellular matrix (ECM), including immune cells, endothelial cells and cancer associated fibroblasts (CAFs), which communicate with cancer cells and each other during tumor progression. CAFs are a dominant and heterogeneous cell type within the TME with a pivotal role in controlling cancer cell invasion and metastasis, immune evasion, angiogenesis and chemotherapy resistance. CAFs mediate their effects in part by remodeling the ECM and by secreting soluble factors and extracellular vesicles. Exosomes are a subtype of extracellular vesicles (EVs), which contain various biomolecules such as nucleic acids, lipids, and proteins. The biomolecules in exosomes can be transmitted from one to another cell, and thereby affect the behavior of the receiving cell. As exosomes are also present in circulation, their contents can also be explored as biomarkers for the diagnosis and prognosis of cancer patients. In this review, we concentrate on the role of CAFs-derived exosomes in the communication between CAFs and cancer cells and other cells of the TME. First, we introduce the multiple roles of CAFs in tumorigenesis. Thereafter, we discuss the ways CAFs communicate with cancer cells and interplay with other cells of the TME, and focus in particular on the role of exosomes. Then, we elaborate on the mechanisms by which CAFs-derived exosomes contribute to cancer progression, as well as and the clinical impact of exosomes. We conclude by discussing aspects of exosomes that deserve further investigation, including emerging insights into making treatment with immune checkpoint inhibitor blockade more efficient.


Assuntos
Fibroblastos Associados a Câncer/metabolismo , Exossomos/metabolismo , Neoplasias/metabolismo , Neoplasias/patologia , Microambiente Tumoral , Animais , Biomarcadores , Comunicação Celular , Transformação Celular Neoplásica/genética , Transformação Celular Neoplásica/metabolismo , Gerenciamento Clínico , Progressão da Doença , Desenvolvimento de Medicamentos , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Resistencia a Medicamentos Antineoplásicos/genética , Metabolismo Energético , Matriz Extracelular/metabolismo , Vesículas Extracelulares/metabolismo , Fibroblastos , Humanos , Junções Intercelulares/metabolismo , Modelos Biológicos , Terapia de Alvo Molecular , Neoplasias/tratamento farmacológico , Neoplasias/etiologia
6.
Arch Virol ; 166(1): 291-294, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33057930

RESUMO

Here, we report the molecular characterization of a novel partitivirus from Phomopsis vexans strain PvHZ002, a plant-pathogenic fungus infecting eggplant. The virus was designated "Phomopsis vexans partitivirus 1" (PvPV1). PvPV1 contains two dsRNA segments, dsRNA1 and dsRNA2, which are 1,662 bp and 1,628 bp long, respectively. Each segment contains a single open reading frame, putatively encoding RNA-dependent RNA polymerase (dsRNA 1) and capsid protein (dsRNA 2). A homology search and phylogenetic analysis showed that PvPV1 clustered with viruses of the genus Deltapartitivirus of the family Partitiviridae.


Assuntos
Micovírus/genética , Genoma Viral/genética , Phomopsis/virologia , Vírus de RNA/genética , Sequência de Aminoácidos , Sequência de Bases , Proteínas do Capsídeo/genética , Filogenia , Doenças das Plantas/virologia , RNA de Cadeia Dupla/genética , RNA Polimerase Dependente de RNA/genética , Solanum melongena/virologia
7.
J Cell Mol Med ; 23(8): 5576-5587, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31211499

RESUMO

Obstructive nephropathy is the end result of a variety of diseases that block drainage from the kidney(s). Transforming growth factor-ß1 (TGF-ß1)/Smad3-driven renal fibrosis is the common pathogenesis of obstructive nephropathy. In this study, we identified petchiether A (petA), a novel small-molecule meroterpenoid from Ganoderma, as a potential inhibitor of TGF-ß1-induced Smad3 phosphorylation. The obstructive nephropathy was induced by unilateral ureteral obstruction (UUO) in mice. Mice received an intraperitoneal injection of petA/vehicle before and after UUO or sham operation. An in vivo study revealed that petA protected against renal inflammation and fibrosis by reducing the infiltration of macrophages, inhibiting the expression of proinflammatory cytokines (interleukin-1ß and tumour necrosis factor-α) and reducing extracellular matrix deposition (α-smooth muscle actin, collagen I and fibronectin) in the obstructed kidney of UUO mice; these changes were associated with suppression of Smad3 and NF-κB p65 phosphorylation. Petchiether A inhibited Smad3 phosphorylation in vitro and down-regulated the expression of the fibrotic marker collagen I in TGF-ß1-treated renal epithelial cells. Further, we found that petA dose-dependently suppressed Smad3-responsive promoter activity, indicating that petA inhibits gene expression downstream of the TGF-ß/Smad3 signalling pathway. In conclusion, our findings suggest that petA protects against renal inflammation and fibrosis by selectively inhibiting TGF-ß/Smad3 signalling.


Assuntos
Nefropatias/tratamento farmacológico , Nefropatias/metabolismo , NF-kappa B/metabolismo , Transdução de Sinais , Proteína Smad3/metabolismo , Terpenos/uso terapêutico , Fator de Crescimento Transformador beta/metabolismo , Actinas/metabolismo , Animais , Linhagem Celular , Colágeno/metabolismo , Fibronectinas/metabolismo , Fibrose , Humanos , Inflamação/patologia , Rim/lesões , Rim/patologia , Nefropatias/patologia , Masculino , Camundongos Endogâmicos C57BL , Fosforilação , Terpenos/química , Terpenos/farmacologia , Terpenos/toxicidade , Obstrução Ureteral/tratamento farmacológico , Obstrução Ureteral/patologia
8.
Breast Cancer Res ; 21(1): 109, 2019 09 18.
Artigo em Inglês | MEDLINE | ID: mdl-31533776

RESUMO

BACKGROUND: Bone morphogenetic proteins (BMPs) have been reported to maintain epithelial integrity and to antagonize the transforming growth factor ß (TGFß)-induced epithelial to mesenchymal transition. The expression of soluble BMP antagonists is dysregulated in cancers and interrupts proper BMP signaling in breast cancer. METHODS: In this study, we mined the prognostic role of BMP antagonists GREMLIN 1 (GREM1) in primary breast cancer tissues using in-house and publicly available datasets. We determined which cells express GREM1 RNA using in situ hybridization (ISH) on a breast cancer tissue microarray. The effects of Grem1 on the properties of breast cancer cells were assessed by measuring the mesenchymal/stem cell marker expression and functional cell-based assays for stemness and invasion. The role of Grem1 in breast cancer-associated fibroblast (CAF) activation was measured by analyzing the expression of fibroblast markers, phalloidin staining, and collagen contraction assays. The role of Grem1 in CAF-induced breast cancer cell intravasation and extravasation was studied by utilizing xenograft zebrafish breast cancer (co-) injection models. RESULTS: Expression analysis of clinical breast cancer datasets revealed that high expression of GREM1 in breast cancer stroma is correlated with a poor prognosis regardless of the molecular subtype. The large majority of human breast cancer cell lines did not express GREM1 in vitro, but breast CAFs did express GREM1 both in vitro and in vivo. Transforming growth factor ß (TGFß) secreted by breast cancer cells, and also inflammatory cytokines, stimulated GREM1 expression in CAFs. Grem1 abrogated bone morphogenetic protein (BMP)/SMAD signaling in breast cancer cells and promoted their mesenchymal phenotype, stemness, and invasion. Moreover, Grem1 production by CAFs strongly promoted the fibrogenic activation of CAFs and promoted breast cancer cell intravasation and extravasation in co-injection xenograft zebrafish models. CONCLUSIONS: Our results demonstrated that Grem1 is a pivotal factor in the reciprocal interplay between breast cancer cells and CAFs, which promotes cancer cell invasion. Targeting Grem1 could be beneficial in the treatment of breast cancer patients with high Grem1 expression.


Assuntos
Proteínas Morfogenéticas Ósseas/antagonistas & inibidores , Neoplasias da Mama/patologia , Fibroblastos Associados a Câncer/metabolismo , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Animais , Proteínas Morfogenéticas Ósseas/metabolismo , Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Fibroblastos Associados a Câncer/patologia , Linhagem Celular Tumoral , Meios de Cultivo Condicionados/metabolismo , Citocinas/metabolismo , Progressão da Doença , Transição Epitelial-Mesenquimal , Feminino , Expressão Gênica , Humanos , Peptídeos e Proteínas de Sinalização Intercelular/genética , Neoplasias Mamárias Experimentais , Invasividade Neoplásica , Células-Tronco Neoplásicas/patologia , Fosforilação , Prognóstico , Transdução de Sinais , Proteínas Smad/metabolismo , Fator de Crescimento Transformador beta/antagonistas & inibidores , Fator de Crescimento Transformador beta/metabolismo , Peixe-Zebra
9.
Arch Virol ; 164(11): 2859-2863, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31385115

RESUMO

In this study, we report the molecular characterization of a novel mycovirus in a phytopathogenic fungus of the species Colletotrichum gloeosporioides, which we named "Colletotrichum gloeosporioides RNA virus 1" (CgRV1). The virus has a dsRNA genome of 2,975 bp and possesses two non-overlapping open reading frames (ORFs 1 and 2). The smaller ORF1 encodes a protein of unknown function, and the larger ORF2 encodes the RNA-dependent RNA polymerase (RdRp). Phylogenetic analysis based on the RdRp sequence showed that CgRV1 clustered with and is closely related to unclassified mycoviruses that are distinct from members of the family Partitiviridae.


Assuntos
Colletotrichum/virologia , Micovírus/genética , Genoma Viral/genética , Vírus não Classificados/genética , Sequência de Aminoácidos , Micovírus/isolamento & purificação , Fases de Leitura Aberta/genética , Doenças das Plantas/microbiologia , RNA Viral/genética , Vírus não Classificados/isolamento & purificação
10.
Arch Virol ; 164(10): 2631-2635, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31367950

RESUMO

In this study, a novel mycovirus designed Colletotrichum gloeosporioides ourmia-like virus 1 (CgOLV1) was isolated from a filamentous phytopathogenic fungus, Colletotrichum gloeosporioides. The virus has a genome of 2,516 nucleotides and contains a large open reading frame (ORF) encoding an RNA-dependent RNA polymerase (RdRp). Phylogenetic analysis indicated that CgOLV1 is located in the ourmia-like mycovirus clade, whose members are related to plant ourmiaviruses. To the best of our knowledge, this is the first report of an ourmia-like mycovirus in C. gloeosporioides.


Assuntos
Colletotrichum/virologia , Micovírus/classificação , Micovírus/isolamento & purificação , Filogenia , Micovírus/genética , Genoma Viral , Fases de Leitura Aberta , Doenças das Plantas/microbiologia , RNA Polimerase Dependente de RNA/genética , Análise de Sequência de DNA
11.
Cell Commun Signal ; 16(1): 10, 2018 03 13.
Artigo em Inglês | MEDLINE | ID: mdl-29534718

RESUMO

BACKGROUND: Transformation by oncogene Ras overcomes TGF-ß mediated growth inhibition in epithelial cells. However, it cooperates with each other to mediate epithelial to mesenchymal transition (EMT). The mechanism of how these two pathways interact with each other is controversial. METHODS: Molecular techniques were used to engineer expression plasmids for Ras, SPRY, TGF-ß receptors, type I and II and ubiquitin. Immunoprecipitation and western blots were employed to determine protein-protein interactions, preotein levels, protein phosphorylation while immunofluorecesent staining for molecular co-localization. TGF-ß signalling activities is also determined by its luciferase reporter assay. Trans-well assays were used to measure cell migration and invasion. RESULTS: Ras interacts with the SPSB1's SPRY domain to enhance TGF-ß signaling. Ras interacts and colocalizes with the TGF-ß type II receptor's (TßRII) negative regulator SPSB1 on the cell membrane, consequently promoting SPSB1 protein degradation via enhanced mono- and di-ubiquitination. Reduced SPSB1 levels result in the stablization of TßRII, in turn the increase of receptor levels significantly enhance Smad2/3 phosphorylation and signaling. Importantly, forced expression of SPSB1 in Ras transformed cells suppresses TGF-ß signaling and its mediated migration and invasion. CONCLUSION: Ras positively cooperates with TGF-ß signaling by reducing the cellular protein levels of TßRII negative regualtor SPSB1.


Assuntos
Proteínas Supressoras da Sinalização de Citocina/metabolismo , Fator de Crescimento Transformador beta/metabolismo , Proteínas ras/metabolismo , Animais , Domínio B30.2-SPRY , Movimento Celular/efeitos dos fármacos , Cicloeximida/farmacologia , Cães , Regulação para Baixo/efeitos dos fármacos , Células HEK293 , Humanos , Leupeptinas/farmacologia , Células Madin Darby de Rim Canino , Mutagênese Sítio-Dirigida , Fosforilação/efeitos dos fármacos , Ligação Proteica , Receptor do Fator de Crescimento Transformador beta Tipo II/metabolismo , Transdução de Sinais/efeitos dos fármacos , Proteína Smad2/metabolismo , Proteínas Supressoras da Sinalização de Citocina/química , Proteínas Supressoras da Sinalização de Citocina/genética , Fator de Crescimento Transformador beta/genética , Fator de Crescimento Transformador beta/farmacologia , Ubiquitinação , Proteínas ras/genética
12.
Arch Virol ; 163(4): 1091-1095, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29302791

RESUMO

We report the molecular attributes of a novel bisegmented double-stranded RNA (dsRNA) virus, designated "Nigrospora oryzae partitivirus 1" (NoPV1), from a phytopathogenic fungus Nigrospora oryzae. The genome of NoPV1 contains two dsRNA segments (dsRNA1 and 2), 1875 bp and 1601 bp in length, respectively. dsRNA1 and -2 both have a single open reading frame encoding the RNA-dependent RNA polymerase and coat protein, respectively. NoPV1 has a high degree of sequence identity to members of genus Gammapartitivirus in the family Partitiviridae. This is the first report of a mycovirus in the family Partitiviridae that infects N. oryzae.


Assuntos
Ascomicetos/virologia , Micovírus/genética , Genoma Viral , Filogenia , Vírus de RNA/genética , RNA Polimerase Dependente de RNA/genética , Sequência de Aminoácidos , Sequência de Bases , Proteínas do Capsídeo/genética , Micovírus/classificação , Micovírus/isolamento & purificação , Expressão Gênica , Oryza/microbiologia , Doenças das Plantas/microbiologia , Vírus de RNA/classificação , Vírus de RNA/isolamento & purificação , RNA de Cadeia Dupla/genética , RNA Viral/genética , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos
13.
Biochem J ; 474(1): 21-45, 2017 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-28008089

RESUMO

Cell-cell communication is critical across an assortment of physiological and pathological processes. Extracellular vesicles (EVs) represent an integral facet of intercellular communication largely through the transfer of functional cargo such as proteins, messenger RNAs (mRNAs), microRNA (miRNAs), DNAs and lipids. EVs, especially exosomes and shed microvesicles, represent an important delivery medium in the tumour micro-environment through the reciprocal dissemination of signals between cancer and resident stromal cells to facilitate tumorigenesis and metastasis. An important step of the metastatic cascade is the reprogramming of cancer cells from an epithelial to mesenchymal phenotype (epithelial-mesenchymal transition, EMT), which is associated with increased aggressiveness, invasiveness and metastatic potential. There is now increasing evidence demonstrating that EVs released by cells undergoing EMT are reprogrammed (protein and RNA content) during this process. This review summarises current knowledge of EV-mediated functional transfer of proteins and RNA species (mRNA, miRNA, long non-coding RNA) between cells in cancer biology and the EMT process. An in-depth understanding of EVs associated with EMT, with emphasis on molecular composition (proteins and RNA species), will provide fundamental insights into cancer biology.


Assuntos
Micropartículas Derivadas de Células/metabolismo , DNA de Neoplasias/metabolismo , Transição Epitelial-Mesenquimal , Lipídeos , Neoplasias/metabolismo , RNA Neoplásico/metabolismo , Animais , Micropartículas Derivadas de Células/genética , Micropartículas Derivadas de Células/patologia , DNA de Neoplasias/genética , Humanos , MicroRNAs/genética , MicroRNAs/metabolismo , Neoplasias/genética , Neoplasias/patologia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA Neoplásico/genética
14.
Semin Cell Dev Biol ; 40: 60-71, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25721809

RESUMO

Epithelial-mesenchymal transition (EMT) is a highly conserved process defined by the loss of epithelial characteristics, and acquisition of the mesenchymal phenotype. In addition to its central role in development, EMT has been implicated as a cellular process during tumourigenesis which facilitates tumour cell invasion and metastasis. The EMT process has been largely defined by signal transduction networks and transcriptional factors that activate mesenchymal-associated gene expression. Knowledge of secretome components that influence EMT including secreted proteins/peptides and membrane-derived extracellular vesicles (EVs) (i.e., exosomes) has emerged. Here we review EV cargo associated with inducing the hallmarks of EMT and cancer progression, modulators of cell transformation, invasion/migration, angiogenesis, and components involved in establishing the metastatic niche.


Assuntos
Transição Epitelial-Mesenquimal , Exossomos/metabolismo , Neoplasias/patologia , Animais , Transformação Celular Neoplásica , Humanos , Neoplasias/metabolismo
15.
Growth Factors ; 35(2-3): 100-124, 2017 06.
Artigo em Inglês | MEDLINE | ID: mdl-28948853

RESUMO

Mathematical models for TGF-ß and IL-6 signalling have been linked, providing a platform for analyzing the crosstalk between the systems. An integrated IL-6:TGF-ß model was developed via a reduced set of reaction equations which incorporate both feedback loops and appropriate time-delays for transcription and translation processes. The model simulates stable, robust and realistic responses to both ligands. Pulsatile (multiple pulses) inputs for both TGF-ß and IL-6 have been simulated to investigate the effects of each ligand on the sensitivity, equilibrium and dynamic responses of the integrated signalling system. In our simulations the crosstalk between constant IL-6 and TGF-ß signalling via SMAD7 does not appear to be sufficient to render the cells resistant to TGF-ß inhibition. However, the simulations predict that pulsatile IL-6 stimulation would increase SMAD7 levels substantially and consequentially, lead to resistance to TGF-ß. The model also allows the prediction of the integrated signalling pathway responses to the mutation of key components, e.g. Gp130 F/F.


Assuntos
Interleucina-6/metabolismo , Modelos Teóricos , Transdução de Sinais , Fator de Crescimento Transformador beta/metabolismo , Animais , Células Cultivadas , Camundongos , Proteína Smad7/metabolismo
16.
Cell Commun Signal ; 15(1): 29, 2017 08 07.
Artigo em Inglês | MEDLINE | ID: mdl-28784162

RESUMO

BACKGROUND: C-terminal Src kinase (Csk) and Csk-homologous kinase (Chk) are the major endogenous inhibitors of Src-family kinases (SFKs). They employ two mechanisms to inhibit SFKs. First, they phosphorylate the C-terminal tail tyrosine which stabilizes SFKs in a closed inactive conformation by engaging the SH2 domain in cis. Second, they employ a non-catalytic inhibitory mechanism involving direct binding of Csk and Chk to the active forms of SFKs that is independent of phosphorylation of their C-terminal tail. Csk and Chk are co-expressed in many cell types. Contributions of the two mechanisms towards the inhibitory activity of Csk and Chk are not fully clear. Furthermore, the determinants in Csk and Chk governing their inhibition of SFKs by the non-catalytic inhibitory mechanism are yet to be defined. METHODS: We determined the contributions of the two mechanisms towards the inhibitory activity of Csk and Chk both in vitro and in transduced colorectal cancer cells. Specifically, we assayed the catalytic activities of Csk and Chk in phosphorylating a specific peptide substrate and a recombinant SFK member Src. We employed surface plasmon resonance spectroscopy to measure the kinetic parameters of binding of Csk, Chk and their mutants to a constitutively active mutant of the SFK member Hck. Finally, we determined the effects of expression of recombinant Chk on anchorage-independent growth and SFK catalytic activity in Chk-deficient colorectal cancer cells. RESULTS: Our results revealed Csk as a robust enzyme catalysing phosphorylation of the C-terminal tail tyrosine of SFKs but a weak non-catalytic inhibitor of SFKs. In contrast, Chk is a poor catalyst of SFK tail phosphorylation but binds SFKs with high affinity, enabling it to efficiently inhibit SFKs with the non-catalytic inhibitory mechanism both in vitro and in transduced colorectal cancer cells. Further analyses mapped some of the determinants governing this non-catalytic inhibitory mechanism of Chk to its kinase domain. CONCLUSIONS: SFKs are activated by different upstream signals to adopt multiple active conformations in cells. SFKs adopting these conformations can effectively be constrained by the two complementary inhibitory mechanisms of Csk and Chk. Furthermore, the lack of this non-catalytic inhibitory mechanism accounts for SFK overactivation in the Chk-deficient colorectal cancer cells.


Assuntos
Proteínas Proto-Oncogênicas pp60(c-src)/metabolismo , Sítios de Ligação , Linhagem Celular Tumoral , Células HEK293 , Humanos , Mutação , Fosforilação , Ligação Proteica , Domínios Proteicos , Processamento de Proteína Pós-Traducional , Proteínas Proto-Oncogênicas pp60(c-src)/química , Proteínas Proto-Oncogênicas pp60(c-src)/genética , Tirosina/química
17.
Int J Mol Sci ; 18(5)2017 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-28467379

RESUMO

Ustilaginoidea virens, the causal agent of rice false smut, is one of the most devastating grain diseases that causes loss of yield in most rice-growing areas worldwide. In this study, we performed a dsRNA screen to isolate mycoviruses from 35 U. virens strains. The results revealed that 34 of the tested isolates were infected by various dsRNA elements, displaying highly viral diversity and mixed infections. We characterized a 5.3 kbp dsRNA from a typical isolate containing dsRNA segments with sizes ranging from 0.5 to 5.3 kbp. Sequence analysis of its genomic properties indicated that it is a novel victorivirus, named Ustilaginoidea virens RNA virus 5 (UvRV5), that belongs to the family Totiviridae. RT-PCR detection was performed and indicated that not all the dsRNA bands that were 5.3 kbp in size contained UvRV5. Moreover, the genetic relatedness of all the U. virens strains was estimated according to phylogenetic analysis of the partial intergenic spacer region (IGS) sequences. However, concordance was not found between the dsRNA profiles and the IGS-based genetic relatedness of their host fungi.


Assuntos
Micovírus/genética , Interações Hospedeiro-Patógeno/genética , Hypocreales/genética , Hypocreales/virologia , Oryza/microbiologia , Doenças das Plantas/microbiologia , Totiviridae/genética , Patrimônio Genético , Genoma Fúngico , Genoma Viral , Filogenia , RNA de Cadeia Dupla/isolamento & purificação , Análise de Sequência de RNA
18.
J Biol Chem ; 290(29): 17894-17908, 2015 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-26032413

RESUMO

Appropriate cellular signaling is essential to control cell proliferation, differentiation, and cell death. Aberrant signaling can have devastating consequences and lead to disease states, including cancer. The transforming growth factor-ß (TGF-ß) signaling pathway is a prominent signaling pathway that has been tightly regulated in normal cells, whereas its deregulation strongly correlates with the progression of human cancers. The regulation of the TGF-ß signaling pathway involves a variety of physiological regulators. Many of these molecules act to alter the activity of Smad proteins. In contrast, the number of molecules known to affect the TGF-ß signaling pathway at the receptor level is relatively low, and there are no known direct modulators for the TGF-ß type II receptor (TßRII). Here we identify SPSB1 (a Spry domain-containing Socs box protein) as a novel regulator of the TGF-ß signaling pathway. SPSB1 negatively regulates the TGF-ß signaling pathway through its interaction with both endogenous and overexpressed TßRII (and not TßRI) via its Spry domain. As such, TßRII and SPSB1 co-localize on the cell membrane. SPSB1 maintains TßRII at a low level by enhancing the ubiquitination levels and degradation rates of TßRII through its Socs box. More importantly, silencing SPSB1 by siRNA results in enhanced TGF-ß signaling and migration and invasion of tumor cells.


Assuntos
Proteínas Serina-Treonina Quinases/metabolismo , Receptores de Fatores de Crescimento Transformadores beta/metabolismo , Transdução de Sinais , Proteínas Supressoras da Sinalização de Citocina/metabolismo , Fator de Crescimento Transformador beta/metabolismo , Animais , Linhagem Celular , Linhagem Celular Tumoral , Movimento Celular , Inativação Gênica , Células HEK293 , Humanos , Camundongos , Células NIH 3T3 , Invasividade Neoplásica/genética , Invasividade Neoplásica/patologia , Neoplasias/genética , Neoplasias/metabolismo , Neoplasias/patologia , Mapas de Interação de Proteínas , Proteínas Serina-Treonina Quinases/análise , Receptor do Fator de Crescimento Transformador beta Tipo II , Receptores de Fatores de Crescimento Transformadores beta/análise , Proteínas Supressoras da Sinalização de Citocina/análise , Proteínas Supressoras da Sinalização de Citocina/genética , Ativação Transcricional , Ubiquitinação
19.
Arch Virol ; 161(3): 725-9, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26650038

RESUMO

Here, we report a novel virus isolated from rice blast fungus, Magnaporthe oryzae, an important plant pathogen. This virus has an RNA genome of 3246 nucleotides. Its genome possesses two in-frame open reading frames (ORFs). The smaller ORF1 encodes a protein with significant similarity to a protein encoded by the ssRNA mycovirus Diaporthe ambigua RNA virus 1 (DaRV1). The larger ORF2 encodes a protein with similarity to RNA-dependent RNA polymerases (RdRp) of DaRV1 and other plant viruses of the family Tombusviridae. In silico analysis and comparisons with DaRV1 genome expression suggest that ORF2 is translated via a readthrough mechanism together with ORF1. Based upon results of this study, this virus, for which the provisional name Magnaporthe oryzae virus A (MoVA) is proposed, belongs to a new virus species. Furthermore, MoVA along with DaRV1 belong to a new taxon of mycoviruses that are evolutionarily related to plant viruses belonging to the family Tombusviridae.


Assuntos
Magnaporthe/virologia , Vírus de RNA/classificação , Vírus de RNA/isolamento & purificação , Tombusviridae/genética , Análise por Conglomerados , Dados de Sequência Molecular , Fases de Leitura Aberta , Oryza/microbiologia , Filogenia , Doenças das Plantas/microbiologia , Vírus de RNA/genética , RNA Viral/genética , Análise de Sequência de DNA , Homologia de Sequência
20.
Virus Genes ; 52(1): 156-9, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26757943

RESUMO

Nigrospora oryzae is a worldwide phytopathogenic fungus that can infect many plant host species. In this study, complete sequence of a novel mycovirus from N. oryzae was reported. The viral genome is 5100 base pairs in length and possesses two overlapping open reading frames (ORFs). The two ORFs potentially encode proteins that showed significant similarity to the capsid protein and RNA-dependent RNA polymerase, in the family Totiviridae, respectively. Phylogenetic tree showed that this novel mycovirus is a new member of the genus Victorivirus in the family Totiviridae. We here designated the virus as Nigrospora oryzae victorivirus 1 (NoRV1), the first putative victorivirus identified in N. oryzae.


Assuntos
Ascomicetos/virologia , Totiviridae/classificação , Totiviridae/isolamento & purificação , Sequência de Aminoácidos , Dados de Sequência Molecular , Filogenia , Alinhamento de Sequência , Proteínas Virais/química , Proteínas Virais/genética
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