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1.
PLoS Biol ; 18(8): e3000820, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32866173

RESUMO

Mutations in the gene encoding the microtubule-severing protein spastin (spastic paraplegia 4 [SPG4]) cause hereditary spastic paraplegia (HSP), associated with neurodegeneration, spasticity, and motor impairment. Complicated forms (complicated HSP [cHSP]) further include cognitive deficits and dementia; however, the etiology and dysfunctional mechanisms of cHSP have remained unknown. Here, we report specific working and associative memory deficits upon spastin depletion in mice. Loss of spastin-mediated severing leads to reduced synapse numbers, accompanied by lower miniature excitatory postsynaptic current (mEPSC) frequencies. At the subcellular level, mutant neurons are characterized by longer microtubules with increased tubulin polyglutamylation levels. Notably, these conditions reduce kinesin-microtubule binding, impair the processivity of kinesin family protein (KIF) 5, and reduce the delivery of presynaptic vesicles and postsynaptic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors. Rescue experiments confirm the specificity of these results by showing that wild-type spastin, but not the severing-deficient and disease-associated K388R mutant, normalizes the effects at the synaptic, microtubule, and transport levels. In addition, short hairpin RNA (shRNA)-mediated reduction of tubulin polyglutamylation on spastin knockout background normalizes KIF5 transport deficits and attenuates the loss of excitatory synapses. Our data provide a mechanism that connects spastin dysfunction with the regulation of kinesin-mediated cargo transport, synapse integrity, and cognition.


Assuntos
Ácido Glutâmico/metabolismo , Cinesina/metabolismo , Transtornos da Memória/metabolismo , Transtornos da Memória/fisiopatologia , Memória de Curto Prazo , Neurônios/metabolismo , Espastina/deficiência , Tubulina (Proteína)/metabolismo , Potenciais de Ação , Animais , Membrana Celular/metabolismo , Espinhas Dendríticas/metabolismo , Espinhas Dendríticas/ultraestrutura , Potenciais Pós-Sinápticos Excitadores , Hipocampo/patologia , Hipocampo/fisiopatologia , Camundongos Knockout , Microtúbulos/metabolismo , Microtúbulos/ultraestrutura , Atividade Motora , Neurônios/patologia , Neurônios/ultraestrutura , Transporte Proteico , Espastina/metabolismo , Sinapses/metabolismo , Sinapses/ultraestrutura , Vesículas Sinápticas/metabolismo
2.
PLoS Comput Biol ; 16(9): e1008132, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32877399

RESUMO

Tubulin dimers associate longitudinally and laterally to form metastable microtubules (MTs). MT disassembly is preceded by subtle structural changes in tubulin fueled by GTP hydrolysis. These changes render the MT lattice unstable, but it is unclear exactly how they affect lattice energetics and strain. We performed long-time atomistic simulations to interrogate the impacts of GTP hydrolysis on tubulin lattice conformation, lateral inter-dimer interactions, and (non-)local lateral coordination of dimer motions. The simulations suggest that most of the hydrolysis energy is stored in the lattice in the form of longitudinal strain. While not significantly affecting lateral bond stability, the stored elastic energy results in more strongly confined and correlated dynamics of GDP-tubulins, thereby entropically destabilizing the MT lattice.


Assuntos
Microtúbulos , Tubulina (Proteína) , Guanosina Trifosfato/química , Guanosina Trifosfato/metabolismo , Hidrólise , Microtúbulos/química , Microtúbulos/metabolismo , Microtúbulos/fisiologia , Simulação de Dinâmica Molecular , Conformação Proteica , Termodinâmica , Tubulina (Proteína)/química , Tubulina (Proteína)/metabolismo , Tubulina (Proteína)/fisiologia
3.
Life Sci ; 258: 118238, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32791146

RESUMO

AIM: To rationally-design, synthesize, characterize, biologically evaluate, and to elucidate the anticancer mechanism of action of a novel analogue of noscapine, N-propargyl noscapine (NPN), as a potential drug candidate against triple-negative breast cancer (TNBC). MATERIALS AND METHODS: After the synthesis and IR, 1H, 13C NMR and mass spectral characterization of NPN, its antiproliferative efficacy against different cancer cell lines was investigated using Sulforhodamine B assay. Cell cycle progression was analysed using flow cytometry. The drug-tubulin interactions were studied using tryptophan-quenching assay, ANS-binding assay, and colchicine-binding assay. Immunofluorescence imaging was used to examine the effect of NPN on cellular microtubules. Levels of reactive oxygen species (ROS), loss of mitochondrial membrane potential (MMP), and cell death were studied by staining the cells with DCFDA, Rhodamine 123, and acridine orange/ethidium bromide, respectively. KEY FINDINGS: NPN strongly inhibited the viability (IC50, 1.35 ± 0.2 µM) and clonogenicity (IC50, 0.56 ± 0.06 µM) of the TNBC cell line, MDA-MB-231, with robust G2/M arrest. In vitro, the drug bound to tubulin and disrupted the latter's structural integrity and promoted colchicine binding to tubulin. NPN triggered an unusual form of microtubule disruption in cells, repressed recovery of cold-depolymerized cellular microtubules and suppressed their dynamicity. These effects on microtubules were facilitated by elevated levels of ROS and loss of MMP. SIGNIFICANCE: NPN can be explored further as a chemotherapeutic agent against TNBC.


Assuntos
Proliferação de Células/fisiologia , Morfinanos/metabolismo , Noscapina/análogos & derivados , Noscapina/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Tubulina (Proteína)/metabolismo , Células A549 , Animais , Proliferação de Células/efeitos dos fármacos , Chlorocebus aethiops , Relação Dose-Resposta a Droga , Humanos , Células MCF-7 , Morfinanos/farmacologia , Noscapina/farmacologia , Células Vero
4.
PLoS Pathog ; 16(8): e1008710, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32817722

RESUMO

Rice stripe virus (RSV, genus Tenuivirus, family Phenuiviridae) is the causal agent of rice stripe disease transmitted by the small brown planthopper (SBPH, Laodelphax striatellus) in a persistent propagative manner. The midgut and salivary glands of SBPH are the first and last barriers to the viral circulation and transmission processes, respectively; however, the precise mechanisms used by RSV to cross these organs and transmit to rice plants have not been fully elucidated. We obtained the full-length cDNA sequence of L. striatellus α-tubulin 2 (LsTUB) and found that RSV infection increased the level of LsTUB in vivo. Furthermore, LsTUB was shown to co-localize with RSV nonstructural protein 3 (NS3) in vivo and bound NS3 at positions 74-76 and 80-82 in vitro. Transient gene silencing of LsTUB expression caused a significant reduction in detectable RSV loads and viral NS3 expression levels, but had no effect on NS3 silencing suppressor activity and viral replication in insect cells. However, suppression of LsTUB attenuated viral spread in the bodies of SBPHs and decreased RSV transmission rates to rice plants. Electrical penetration graphs (EPG) showed that LsTUB knockdown by RNAi did not impact SBPH feeding; therefore, the reduction in RSV transmission rates was likely caused by a decrease in viral loads inside the planthopper. These findings suggest that LsTUB mediates the passage of RSV through midgut and salivary glands and leads to successful horizontal transmission.


Assuntos
Hemípteros/metabolismo , Proteínas de Insetos/metabolismo , Insetos Vetores/metabolismo , Oryza/virologia , Doenças das Plantas/virologia , Tenuivirus/fisiologia , Tubulina (Proteína)/metabolismo , Animais , Sistema Digestório/metabolismo , Sistema Digestório/virologia , Hemípteros/genética , Hemípteros/virologia , Proteínas de Insetos/genética , Insetos Vetores/genética , Insetos Vetores/virologia , Glândulas Salivares/metabolismo , Glândulas Salivares/virologia , Tubulina (Proteína)/genética
5.
Mol Cell ; 79(1): 180-190.e4, 2020 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-32619468

RESUMO

Rigosertib is a styryl benzyl sulfone that inhibits growth of tumor cells and acts as a RAS mimetic by binding to Ras binding domains of RAS effectors. A recent study attributed rigosertib's mechanism of action to microtubule binding. In that study, rigosertib was obtained from a commercial vendor. We compared the purity of clinical-grade and commercially sourced rigosertib and found that commercially sourced rigosertib contains approximately 5% ON01500, a potent inhibitor of tubulin polymerization. Clinical-grade rigosertib, which is free of this impurity, does not exhibit tubulin-binding activity. Cell lines expressing mutant ß-tubulin have also been reported to be resistant to rigosertib. However, our study showed that these cells failed to proliferate in the presence of rigosertib at concentrations that are lethal to wild-type cells. Rigosertib induced a senescence-like phenotype in the small percentage of surviving cells, which could be incorrectly scored as resistant using short-term cultures.


Assuntos
Antineoplásicos/farmacologia , Proliferação de Células , Glicina/análogos & derivados , Neoplasias Pulmonares/patologia , Sulfonas/farmacologia , Tubulina (Proteína)/metabolismo , Contaminação de Medicamentos , Resistencia a Medicamentos Antineoplásicos , Glicina/farmacologia , Humanos , Neoplasias Pulmonares/tratamento farmacológico , Neoplasias Pulmonares/metabolismo , Mutação , Tubulina (Proteína)/química , Tubulina (Proteína)/genética , Células Tumorais Cultivadas
6.
Mol Cell ; 79(1): 191-198.e3, 2020 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-32619469

RESUMO

We recently used CRISPRi/a-based chemical-genetic screens and cell biological, biochemical, and structural assays to determine that rigosertib, an anti-cancer agent in phase III clinical trials, kills cancer cells by destabilizing microtubules. Reddy and co-workers (Baker et al., 2020, this issue of Molecular Cell) suggest that a contaminating degradation product in commercial formulations of rigosertib is responsible for the microtubule-destabilizing activity. Here, we demonstrate that cells treated with pharmaceutical-grade rigosertib (>99.9% purity) or commercially obtained rigosertib have qualitatively indistinguishable phenotypes across multiple assays. The two formulations have indistinguishable chemical-genetic interactions with genes that modulate microtubule stability, both destabilize microtubules in cells and in vitro, and expression of a rationally designed tubulin mutant with a mutation in the rigosertib binding site (L240F TUBB) allows cells to proliferate in the presence of either formulation. Importantly, the specificity of the L240F TUBB mutant for microtubule-destabilizing agents has been confirmed independently. Thus, rigosertib kills cancer cells by destabilizing microtubules, in agreement with our original findings.


Assuntos
Antineoplásicos/farmacologia , Proliferação de Células , Glicina/análogos & derivados , Microtúbulos/efeitos dos fármacos , Neoplasias/patologia , Preparações Farmacêuticas/metabolismo , Sulfonas/farmacologia , Tubulina (Proteína)/metabolismo , Células Cultivadas , Cristalografia por Raios X , Contaminação de Medicamentos , Glicina/farmacologia , Humanos , Mutação , Neoplasias/tratamento farmacológico , Neoplasias/metabolismo , Preparações Farmacêuticas/química , Conformação Proteica , Tubulina (Proteína)/química , Tubulina (Proteína)/genética
7.
Nat Commun ; 11(1): 3765, 2020 07 28.
Artigo em Inglês | MEDLINE | ID: mdl-32724196

RESUMO

Microtubules are dynamic tubulin polymers responsible for many cellular processes, including the capture and segregation of chromosomes during mitosis. In contrast to textbook models of tubulin self-assembly, we have recently demonstrated that microtubules elongate by addition of bent guanosine triphosphate tubulin to the tips of curving protofilaments. Here we explore this mechanism of microtubule growth using Brownian dynamics modeling and electron cryotomography. The previously described flaring shapes of growing microtubule tips are remarkably consistent under various assembly conditions, including different tubulin concentrations, the presence or absence of a polymerization catalyst or tubulin-binding drugs. Simulations indicate that development of substantial forces during microtubule growth and shortening requires a high activation energy barrier in lateral tubulin-tubulin interactions. Modeling offers a mechanism to explain kinetochore coupling to growing microtubule tips under assisting force, and it predicts a load-dependent acceleration of microtubule assembly, providing a role for the flared morphology of growing microtubule ends.


Assuntos
Microtúbulos/metabolismo , Modelos Biológicos , Tubulina (Proteína)/metabolismo , Animais , Microscopia Crioeletrônica , Tomografia com Microscopia Eletrônica , Microtúbulos/efeitos dos fármacos , Microtúbulos/ultraestrutura , Simulação de Dinâmica Molecular , Polimerização/efeitos dos fármacos , Suínos , Tubulina (Proteína)/isolamento & purificação , Tubulina (Proteína)/ultraestrutura , Moduladores de Tubulina/farmacologia
8.
Chem Biol Interact ; 327: 109186, 2020 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-32590071

RESUMO

In this study, we scrutinized the anticancer effects of FB-15 on human gastric carcinoma MGC-803 cells in vitro and vivo, and its preliminary effect on tubulin and HIF-1α. We confirmed that FB-15 not only inhibited the proliferation of a large number of cells in a concentration and time-dependent manner but also inhibited proliferation of a single cell to form clones. FB-15 manifested little cytotoxicity for normal stomach cells GES-1. The flow cytometry analysis displayed that FB-15 induced apoptosis MGC-803 cells and mainly arrested cells in the S phase in a concentration-dependent manner. The results of the wound healing assay indicated that FB-15 suppressed cell migration. Furthermore, the western blotting showed that FB-15 down-regulated the expression of ß3-tubulin and HIF-1α, consistent with Immunohistochemical assay. The binding modes of FB-15 with tubulin were clarified by molecular docking. FB-15 significantly suppressed the growth of MGC-803 gastric cancer tumors. The inhibitory effect of FB-15 on tumor growth was superior to 5-Fu. Taken together, these results provided evidence for FB-15 to be used as an effective anticancer drug candidate for gastric cancer.


Assuntos
Antineoplásicos/uso terapêutico , Benzimidazóis/uso terapêutico , Metabolismo Energético/efeitos dos fármacos , Flavonoides/uso terapêutico , Neoplasias Gástricas/tratamento farmacológico , Animais , Antineoplásicos/metabolismo , Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Benzimidazóis/metabolismo , Benzimidazóis/farmacologia , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Flavonoides/metabolismo , Flavonoides/farmacologia , Humanos , Camundongos Endogâmicos BALB C , Camundongos Nus , Simulação de Acoplamento Molecular , Ligação Proteica , Pontos de Checagem da Fase S do Ciclo Celular/efeitos dos fármacos , Neoplasias Gástricas/patologia , Tubulina (Proteína)/metabolismo , Ensaios Antitumorais Modelo de Xenoenxerto
9.
Chem Biol Interact ; 325: 109109, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32376239

RESUMO

A series of 10 natural and semisynthetic flavonoids (1 to 10) were obtained from Gardenia oudiepe (Rubiaceae), an endemic plant from New Caledonia. Most of them were polymethoxylated flavones (PMFs) of rare occurrence. After a cell viability screening test, PMFs 2 and 3 showed significant cytotoxic activity against A2058 human melanoma cells (IC50 = 3.92 and 8.18 µM, respectively) and were selected for in-depth pharmacological assays. Both compounds inhibited cell migration and induced apoptosis and cell cycle arrest after 72h of treatment. Immunofluorescence assays indicated that these outcomes were possibly related to the induction of cytoskeleton disruption associated to actin and tubulin depolymerization. These data were confirmed by molecular docking studies, which showed a good interaction between PMFs 2 and 3 and tubulin, particularly at the colchicine binding site. As A2058 are considered as chemoresistant to conventional chemotherapy, compounds 2 and 3 (½IC50) were associated to clinically-used antimelanoma drugs (vemurafenib and dacarbazine) and combined therapies efficacy was assessed by the MTT assay. PMFs 2 restored the sensitivity of A2058 cells to dacarbazine treatment (IC50 = 49.38 µM vs. >100 µM). Taken together, these data suggest that PMFs from G. oudiepe could be potential leaders for the design of new antimelanoma drugs.


Assuntos
Apoptose/efeitos dos fármacos , Citoesqueleto/efeitos dos fármacos , Flavonas/farmacologia , Gardenia/química , Melanoma/patologia , Mutação , Proteínas Proto-Oncogênicas B-raf/genética , Antineoplásicos/farmacologia , Caspase 3/metabolismo , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Citoesqueleto/metabolismo , Sinergismo Farmacológico , Ativação Enzimática/efeitos dos fármacos , Flavonas/química , Flavonas/metabolismo , Humanos , Simulação de Acoplamento Molecular , Conformação Proteica , Relação Estrutura-Atividade , Tubulina (Proteína)/química , Tubulina (Proteína)/metabolismo
10.
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
11.
Chem Biol Interact ; 323: 109063, 2020 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-32224134

RESUMO

Exposure to TiO2 NPs induces several cellular alterations after NPs uptake including disruption of cytoskeleton that is crucial for lung physiology but is not considered as a footprint of cell damage. We aimed to investigate cytoskeleton disturbances and the impact on cell migration induced by an acute TiO2 NPs exposure (24 h) and the recovery capability after 6 days of NPs-free treatment, which allowed investigating if cytoskeleton damage was reversible. Exposure to TiO2 NPs (10 µg/cm2) for 24 h induced a decrease 20.2% and 25.1% in tubulin and actin polymerization. Exposure to TiO2 NPs (10 µg/cm2) for 24 h followed by 6 days of NPs-free had a decrease of 26.6% and 21.3% in tubulin and actin polymerization, respectively. The sustained exposure for 7 days to 1 µg/cm2 and 10 µg/cm2 induced a decrease of 22.4% and 30.7% of tubulin polymerization respectively, and 28.7% and 46.2% in actin polymerization. In addition, 24 h followed 6 days of NPs-free exposure of TiO2 NPs (1 µg/cm2 and 10 µg/cm2) decreased cell migration 40.7% and 59.2%, respectively. Cells exposed (10 µg/cm2) for 7 days had a decrease of 65.5% in cell migration. Ki67, protein surfactant B (SFTPB) and matrix metalloprotease 2 (MMP2) were analyzed as genes related to lung epithelial function. The results showed a 20% of Ki67 upregulation in cells exposed for 24 h to 10 µg/cm2 TiO2 NPs while a downregulation of 20% and 25.8% in cells exposed to 1 µg/cm2 and 10 µg/cm2 for 24 h followed by 6 days of NPs-free exposure. Exposure to 1 µg/cm2 and 10 µg/cm2 for 24 h and 7 days upregulates SFTPB expression in 53% and 59% respectively, MMP2 expression remain unchanged. In conclusion, exposure of TiO2 NPs affected cytoskeleton of lung epithelial cells irreversibly but this damage was not cumulative.


Assuntos
Citoesqueleto/patologia , Células Epiteliais/patologia , Pulmão/patologia , Nanopartículas/toxicidade , Titânio/toxicidade , Células A549 , Actinas/metabolismo , Movimento Celular/efeitos dos fármacos , Tamanho Celular , Sobrevivência Celular/efeitos dos fármacos , Citoesqueleto/efeitos dos fármacos , Endocitose , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/ultraestrutura , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Antígeno Ki-67/metabolismo , Metaloproteinase 2 da Matriz/metabolismo , Nanopartículas/ultraestrutura , Polimerização , Precursores de Proteínas/metabolismo , Proteínas Associadas a Surfactantes Pulmonares/metabolismo , Tubulina (Proteína)/metabolismo
12.
Toxicol Appl Pharmacol ; 396: 115001, 2020 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-32277947

RESUMO

Mebendazole (MBZ) is a tubulin-suppressive antihelmintic agent with low toxicity, which has been repurposed to treat different types of tumors. Chemoresistance is quite common in refractory or relapsed T cell acute lymphoblastic leukemia (T-ALL), which leads to dismal chances of recovery. In this study, MBZ was found to suppress the proliferation and reduce the viability of T-ALL cell line, CCRF-CEM, and its chemoresistant derivative, CEM/C1, at nanomolar concentrations. The inhibitive effects were found to be dose-dependent and not to be affected by the chemoresistance of CEM/C1 cells. Cell cycle arrest, caspase 3/7 activation and tubulin disruption were found in the MBZ-treated T-ALL cells. Notch1 signaling, which is often aberrantly activated in T-ALL cells, was showed to be suppressed by MBZ treatments. MBZ administration in murine T-ALL models also suppressed the growth of CEM/C1 cells, indicating that MBZ may be developed as a therapeutic agent for chemoresistant T-ALLs. The mRNA levels of the Notch1 and Hes1 were also confirmed to be suppressed by MBZ in vivo, which was consistent with the in vitro observations. This study demonstrated, for the first time, that MBZ could inhibit chemoresistant T-ALL cells both in vitro and in vivo, and the Notch1 signaling pathway was suppressed by MBZ treatment.


Assuntos
Antineoplásicos/uso terapêutico , Mebendazol/uso terapêutico , Leucemia-Linfoma Linfoblástico de Células T Precursoras/tratamento farmacológico , Moduladores de Tubulina/uso terapêutico , Animais , Western Blotting , Caspase 3/metabolismo , Caspase 7/metabolismo , Ciclo Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Resistencia a Medicamentos Antineoplásicos , Humanos , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Transplante de Neoplasias , Receptor Notch1/metabolismo , Tubulina (Proteína)/metabolismo
13.
PLoS One ; 15(4): e0228771, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32255788

RESUMO

Hyperphosphorylated tau protein is a pathological hallmark of numerous neurodegenerative diseases and the level of tau pathology is correlated with the degree of cognitive impairment. Tau hyper-phosphorylation is thought to be an early initiating event in the cascade leading to tau toxicity and neuronal death. Inhibition of tau phosphorylation therefore represents an attractive therapeutic strategy. However, the widespread expression of most kinases and promiscuity of their substrates, along with poor selectivity of most kinase inhibitors, have resulted in systemic toxicities that have limited the advancement of tau kinase inhibitors into the clinic. We therefore focused on the CNS-specific tau kinase, TTBK1, and investigated whether selective inhibition of this kinase could represent a viable approach to targeting tau phosphorylation in disease. In the current study, we demonstrate that TTBK1 regulates tau phosphorylation using overexpression or knockdown of this kinase in heterologous cells and primary neurons. Importantly, we find that TTBK1-specific phosphorylation of tau leads to a loss of normal protein function including a decrease in tau-tubulin binding and deficits in tubulin polymerization. We then describe the use of a novel, selective small molecule antagonist, BIIB-TTBK1i, to study the acute effects of TTBK1 inhibition on tau phosphorylation in vivo. We demonstrate substantial lowering of tau phosphorylation at multiple sites implicated in disease, suggesting that TTBK1 inhibitors may represent an exciting new approach in the search for neurodegenerative disease therapies.


Assuntos
Doenças do Sistema Nervoso Central/enzimologia , Doenças do Sistema Nervoso Central/patologia , Sistema Nervoso Central/enzimologia , Sistema Nervoso Central/patologia , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Proteínas tau/metabolismo , Animais , Células Cultivadas , Masculino , Camundongos Endogâmicos C57BL , Microtúbulos/efeitos dos fármacos , Microtúbulos/metabolismo , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Neurônios/patologia , Especificidade de Órgãos , Fosforilação/efeitos dos fármacos , Polimerização , Ligação Proteica/efeitos dos fármacos , Inibidores de Proteínas Quinases/química , Inibidores de Proteínas Quinases/farmacologia , Proteínas Serina-Treonina Quinases/metabolismo , Bibliotecas de Moléculas Pequenas/farmacologia , Tubulina (Proteína)/metabolismo
14.
PLoS One ; 15(4): e0231352, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32275729

RESUMO

We report the formation of spherulites from droplets of highly concentrated tubulin solution via nucleation and subsequent polymerization to microtubules (MTs) under water evaporation by heating. Radial alignment of MTs in the spherulites was confirmed by the optical properties of the spherulites observed using polarized optical microscopy and fluorescence microscopy. Temperature and concentration of tubulins were found as important parameters to control the spherulite pattern formation of MTs where evaporation plays a significant role. The alignment of MTs was regulated reversibly by temperature induced polymerization and depolymerization of tubulins. The formation of the MTs patterns was also confirmed at the molecular level from the small angle X-ray measurements. This work provides a simple method for obtaining radially aligned arrays of MTs.


Assuntos
Microtúbulos/química , Tubulina (Proteína)/química , Animais , Temperatura Alta , Microtúbulos/metabolismo , Polimerização , Suínos , Tubulina (Proteína)/metabolismo , Volatilização , Água/química
15.
PLoS One ; 15(4): e0230814, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32251425

RESUMO

Microtubules are a major cytoskeletal component of neurites, and the regulation of microtubule stability is essential for neurite morphogenesis. ßPix (ARHGEF7) is a guanine nucleotide exchange factor for the small GTPases Rac1 and Cdc42, which modulate the organization of actin filaments and microtubules. ßPix is expressed as alternatively spliced variants, including the ubiquitous isoform ßPix-a and the neuronal isoforms ßPix-b and ßPix-d, but the function of the neuronal isoforms remains unclear. Here, we reveal the novel role of ßPix neuronal isoforms in regulating tubulin acetylation and neurite outgrowth. At DIV4, hippocampal neurons cultured from ßPix neuronal isoform knockout (ßPix-NIKO) mice exhibit defects in neurite morphology and tubulin acetylation, a type of tubulin modification which often labels stable microtubules. Treating ßPix-NIKO neurons with paclitaxel, which stabilizes the microtubules, or reintroducing either neuronal ßPix isoform to the KO neurons overcomes the impairment in neurite morphology and tubulin acetylation, suggesting that neuronal ßPix isoforms may promote microtubule stabilization during neurite development. ßPix-NIKO neurons also exhibit lower phosphorylation levels for Stathmin1, a microtubule-destabilizing protein, at Ser16. Expressing either ßPix neuronal isoform in the ßPix-NIKO neurons restores Stathmin1 phosphorylation levels, with ßPix-d having a greater effect than ßPix-b. Furthermore, we find that the recovery of neurite length and Stathmin1 phosphorylation via ßPix-d expression requires PAK kinase activity. Taken together, our study demonstrates that ßPix-d regulates the phosphorylation of Stathmin1 in a PAK-dependent manner and that neuronal ßPix isoforms promote tubulin acetylation and neurite morphogenesis during neuronal development.


Assuntos
Crescimento Neuronal/fisiologia , Fatores de Troca de Nucleotídeo Guanina Rho/metabolismo , Transdução de Sinais/fisiologia , Estatmina/metabolismo , Tubulina (Proteína)/metabolismo , Quinases Ativadas por p21/metabolismo , Proteínas rac1 de Ligação ao GTP/metabolismo , Acetilação , Citoesqueleto de Actina/metabolismo , Animais , Proteínas de Ciclo Celular/metabolismo , Células Cultivadas , Feminino , Hipocampo/metabolismo , Hipocampo/fisiologia , Masculino , Camundongos , Camundongos Knockout , Microtúbulos/metabolismo , Neuritos/metabolismo , Neuritos/fisiologia , Neurônios/metabolismo , Neurônios/fisiologia , Fosforilação/fisiologia , Isoformas de Proteínas/metabolismo , Isoformas de Proteínas/fisiologia
16.
Mol Pharmacol ; 97(6): 409-422, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32241960

RESUMO

The microtubule-binding taxanes, docetaxel and cabazitaxel, are administered intravenously for the treatment of castration-resistant prostate cancer (CRPC) as the oral administration of these drugs is largely hampered by their low and highly variable bioavailabilities. Using a simple, rapid, and environmentally friendly microwave-assisted protocol, we have synthesized a number of 3,5-bis(styryl)pyrazoles 2a-l, thus allowing for their screening for antiproliferative activity in the androgen-independent PC3 prostate cancer cell line. Surprisingly, two of these structurally simple 3,5-bis(styryl)pyrazoles (2a and 2l) had concentrations which gave 50% of the maximal inhibition of cell proliferation (GI50) in the low micromolar range in the PC3 cell line and were thus selected for extensive further biologic evaluation (apoptosis and cell cycle analysis, and effects on tubulin and microtubules). Our findings from these studies show that 3,5-bis[(1E)-2(2,6-dichlorophenyl)ethenyl]-1H-pyrazole 2l 1) caused significant effects on the cell cycle in PC3 cells, with the vast majority of treated cells in the G2/M phase (89%); 2) induces cell death in PC3 cells even after the removal of the compound; 3) binds to tubulin [dissociation constant (Kd) 0.4 ± 0.1 µM] and inhibits tubulin polymerization in vitro; 4) had no effect upon the polymerization of the bacterial cell division protein FtsZ (a homolog of tubulin); 5) is competitive with paclitaxel for binding to tubulin but not with vinblastine, crocin, or colchicine; and 6) leads to microtubule depolymerization in PC3 cells. Taken together, these results suggest that 3,5-bis(styryl)pyrazoles warrant further investigation as lead compounds for the treatment of CRPC. SIGNIFICANCE STATEMENT: The taxanes are important components of prostate cancer chemotherapy regimens, but their oral administration is hampered by very low and highly variable oral bioavailabilities resulting from their poor absorption, poor solubility, high first-pass metabolism, and efficient efflux by P-glycoprotein. New chemical entities for the treatment of prostate cancer are thus required, and we report here the synthesis and investigation of the mechanism of action of some bis(styryl)pyrazoles, demonstrating their potential as lead compounds for the treatment of prostate cancer.


Assuntos
Antineoplásicos/uso terapêutico , Chumbo/uso terapêutico , Neoplasias de Próstata Resistentes à Castração/tratamento farmacológico , Pirazóis/uso terapêutico , Tubulina (Proteína)/metabolismo , Antineoplásicos/síntese química , Antineoplásicos/química , Apoptose/efeitos dos fármacos , Sítios de Ligação , Ciclo Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Ensaios de Seleção de Medicamentos Antitumorais , Estabilidade de Medicamentos , Humanos , Chumbo/química , Masculino , Microtúbulos/efeitos dos fármacos , Modelos Moleculares , Células PC-3 , Pirazóis/síntese química , Pirazóis/química
17.
Proc Natl Acad Sci U S A ; 117(16): 8876-8883, 2020 04 21.
Artigo em Inglês | MEDLINE | ID: mdl-32245812

RESUMO

Microtubules (MTs) are essential components of the eukaryotic cytoskeleton that serve as "highways" for intracellular trafficking. In addition to the well-known active transport of cargo by motor proteins, many MT-binding proteins seem to adopt diffusional motility as a transportation mechanism. However, because of the limited spatial resolution of current experimental techniques, the detailed mechanism of protein diffusion has not been elucidated. In particular, the precise role of tubulin tails and tail modifications in the diffusion process is unclear. Here, using coarse-grained molecular dynamics simulations validated against atomistic simulations, we explore the molecular mechanism of protein diffusion along MTs. We found that electrostatic interactions play a central role in protein diffusion; the disordered tubulin tails enhance affinity but slow down diffusion, and diffusion occurs in discrete steps. While diffusion along wild-type MT is performed in steps of dimeric tubulin, the removal of the tails results in a step of monomeric tubulin. We found that the energy barrier for diffusion is larger when diffusion on MTs is mediated primarily by the MT tails rather than the MT body. In addition, globular proteins (EB1 and PRC1) diffuse more slowly than an intrinsically disordered protein (Tau) on MTs. Finally, we found that polyglutamylation and polyglycylation of tubulin tails lead to slower protein diffusion along MTs, although polyglycylation leads to faster diffusion across MT protofilaments. Taken together, our results explain experimentally observed data and shed light on the roles played by disordered tubulin tails and tail modifications in the molecular mechanism of protein diffusion along MTs.


Assuntos
Difusão Facilitada/fisiologia , Microtúbulos/metabolismo , Tubulina (Proteína)/metabolismo , Proteínas de Ciclo Celular/metabolismo , Humanos , Proteínas Associadas aos Microtúbulos/metabolismo , Simulação de Dinâmica Molecular , Processamento de Proteína Pós-Traducional/fisiologia , Eletricidade Estática , Proteínas tau/metabolismo
18.
J Neurosci ; 40(20): 4033-4041, 2020 05 13.
Artigo em Inglês | MEDLINE | ID: mdl-32284336

RESUMO

Cytoskeletal proteins and post-translational modifications play a role in mood disorders. Post-translational modifications of tubulin also alter microtubule dynamics. Furthermore, tubulin interacts closely with Gαs, the G-protein responsible for activation of adenylyl cyclase. Postmortem tissue derived from depressed suicide brain showed increased Gαs in lipid-raft domains compared with normal subjects. Gαs, when ensconced in lipid rafts, couples less effectively with adenylyl cyclase to produce cAMP, and this is reversed by antidepressant treatment. A recent in vitro study demonstrated that tubulin anchors Gαs to lipid rafts and that increased tubulin acetylation (due to HDAC6 inhibition) and antidepressant treatment decreased the proportion of Gαs complexed with tubulin. This suggested that deacetylated-tubulin might be more prevalent in depression. This study examined tubulin acetylation in whole-tissue homogenate, plasma membrane, and lipid-raft membrane domains in tissue from normal control subjects, depressed suicides, and depressed nonsuicides (human males/females). While tissue homogenate showed no changes in tubulin acetylation between control, depressed suicides, and depressed nonsuicides, plasma membrane-associated tubulin showed significant decreases in acetylation from depressed suicides and depressed nonsuicides compared with controls. No change was seen in expression of the enzymes responsible for tubulin acetylation or deacetylation. These data suggest that, during depression, membrane-localized tubulin maintains a lower acetylation state, permitting increased sequestration of Gαs in lipid-raft domains, where it is less likely to couple to adenylyl cyclase for cAMP production. Thus, membrane tubulin may play a role in mood disorders, which could be exploited for diagnosis and treatment.SIGNIFICANCE STATEMENT There is little understanding about the molecular mechanisms involved in the development of depression and, in severe cases, suicide. Evidence for the role of microtubule modifications in progression of depressive disorders is emerging. These postmortem data provide strong evidence for membrane tubulin modification leading to reduced efficacy of the G protein, Gαs, in depression. This study reveals a direct link between decreased tubulin acetylation in human depression and the increased localization of Gαs in lipid-raft domains responsible for attenuated cAMP signaling. The evidence presented here suggest a novel diagnostic and therapeutic locus for depression.


Assuntos
Citoesqueleto/metabolismo , Depressão/metabolismo , Desacetilase 6 de Histona/metabolismo , Córtex Pré-Frontal/metabolismo , Tubulina (Proteína)/metabolismo , Acetilação , Adenilil Ciclases/metabolismo , Adolescente , Adulto , Idoso , Membrana Celular/metabolismo , AMP Cíclico/biossíntese , Feminino , Humanos , Masculino , Microdomínios da Membrana/metabolismo , Pessoa de Meia-Idade , Mudanças Depois da Morte , Suicídio , Adulto Jovem
19.
Am J Physiol Lung Cell Mol Physiol ; 318(6): L1145-L1157, 2020 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-32267731

RESUMO

We have demonstrated previously that intracellular transport is impaired in cystic fibrosis (CF) epithelial cells. This impairment is related to both growth and inflammatory regulation in CF cell and animal models. Understanding how transport in CF cells is regulated and identifying means to manipulate that regulation are key to identifying new therapies that can address key CF phenotypes. It was hypothesized that resveratrol could replicate these benefits since it interfaces with multiple pathways identified to affect microtubule regulation in CF. It was found that resveratrol treatment significantly restored intracellular transport as determined by monitoring both cholesterol distribution and the distribution of rab7-positive organelles in CF cells. This restoration of intracellular transport is due to correction of both microtubule formation rates and microtubule acetylation in cultured CF cell models and primary nasal epithelial cells. Mechanistically, the effect of resveratrol on microtubule regulation and intracellular transport was dependent on peroxisome proliferator-activated receptor-γ signaling and its ability to act as a pan-histone deacetylase (HDAC) inhibitor. Resveratrol represents a candidate compound with known anti-inflammatory properties that can restore both microtubule formation and acetylation in CF epithelial cells.


Assuntos
Fibrose Cística/patologia , Células Epiteliais/metabolismo , Células Epiteliais/patologia , Espaço Intracelular/metabolismo , Resveratrol/farmacologia , 1-Metil-3-Isobutilxantina/farmacologia , Acetilação/efeitos dos fármacos , Transporte Biológico/efeitos dos fármacos , Carbazóis/farmacologia , Células Cultivadas , Colesterol/metabolismo , Regulador de Condutância Transmembrana em Fibrose Cística/metabolismo , Humanos , Espaço Intracelular/efeitos dos fármacos , Microtúbulos/efeitos dos fármacos , Microtúbulos/metabolismo , Nariz/patologia , PPAR gama/antagonistas & inibidores , PPAR gama/metabolismo , Inibidores de Fosfodiesterase/farmacologia , Resorcinóis/farmacologia , Transdução de Sinais/efeitos dos fármacos , Sirtuínas/metabolismo , Estilbenos/farmacologia , Tubulina (Proteína)/metabolismo
20.
Int Heart J ; 61(2): 355-363, 2020 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-32173700

RESUMO

Heart failure (HF) is a disease with high morbidity and mortality. In patients with HF, decreased cardiac output and blood redistribution results in decreased intestinal perfusion and destruction of intestinal barrier. Microorganisms and endotoxins can migrate into the blood circulation, aggravating systemic inflammation and HF. Trimethylamine N-oxide (TMAO) is highly closed to the occurrence of HF. However, the exact mechanism between TMAO and HF remains unclear.To investigate the role of TMAO in transverse-tubule (T-tubule) in the cultured cardiomyocytes.T-tubule imaging and analysis detected T-tubule network in cardiomyocytes. Ca2+ handling dysfunction was identified by confocal Ca2+ imaging. Tubulin densification and polymerization were assessed by western blot and immunofluorescent staining of cardiomyocytes.TMAO induced T-tubule network damage in cardiomyocytes and Ca2+ handling dysfunction in cardiomyocytes under the TMAO stress via promoting tubulin densification and polymerization and therefore Junctophilin-2 (JPH2) redistribution. Mice treated with TMAO represented cardiac dysfunction and T-tubule network disorganization.TMAO impairs cardiac function via the promotion of tubulin polymerization, subsequent translocation of JPH2, and T-tubule remodeling, which provides a novel mechanism for the relationship between HF and elevated TMAO.


Assuntos
Insuficiência Cardíaca/metabolismo , Metilaminas/toxicidade , Microtúbulos/metabolismo , Miócitos Cardíacos/metabolismo , Animais , Cálcio/metabolismo , Células Cultivadas , Acoplamento Excitação-Contração , Insuficiência Cardíaca/etiologia , Masculino , Proteínas de Membrana/metabolismo , Camundongos Endogâmicos C57BL , Microtúbulos/efeitos dos fármacos , Miócitos Cardíacos/efeitos dos fármacos , Tubulina (Proteína)/metabolismo
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