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1.
Adv Mater ; 34(52): e2200985, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-35820163

RESUMO

The application of wearable devices is promoting the development toward digitization and intelligence in the field of health. However, the current smart devices centered on human health have disadvantages such as weak perception, high interference degree, and unfriendly interaction. Here, an intelligent health agent based on multifunctional fibers, with the characteristics of autonomy, activeness, intelligence, and perceptibility enabling health services, is proposed. According to the requirements for healthcare in the medical field and daily life, four major aspects driven by intelligent agents, including health monitoring, therapy, protection, and minimally invasive surgery, are summarized from the perspectives of materials science, medicine, and computer science. The function of intelligent health agents is realized through multifunctional fibers as sensing units and artificial intelligence technology as a cognitive engine. The structure, characteristics, and performance of fibers and analysis systems and algorithms are reviewed, while discussing future challenges and opportunities in healthcare and medicine. Finally, based on the above four aspects, future scenarios related to health protection of a person's life are presented. Intelligent health agents will have the potential to accelerate the realization of precision medicine and active health.


Assuntos
Inteligência Artificial , Dispositivos Eletrônicos Vestíveis , Humanos , Algoritmos , Inteligência
2.
Invest Ophthalmol Vis Sci ; 63(5): 1, 2022 05 02.
Artigo em Inglês | MEDLINE | ID: mdl-35499835

RESUMO

Purpose: To investigate the phenotypic changes of mature corneal epithelial cells (MCECs) that cocultured with limbal niche cells (LNCs) in three-dimensional Matrigel (3D Matrigel) in vitro. Methods: MCECs were isolated from central corneas, and limbal epithelial progenitor cells (LEPCs) were isolated from limbal segments with Dispase II. LNCs were isolated and cultured from limbal niche using the collagenase A digestion method and identified with PCK/VIM/CD90/CD105/SCF/PDGFRß. MCECs were cultured on 3D Matrigel (50%, v/v) with or without LNCs for 10 days. Expression of CK12 and p63α and clone formation test were used to compare the progenitor phenotypic changes for MCECs before and after induction using LEPCs as control. Results: Homogeneous LNCs were isolated and identified as spindle shape and adherent to a plastic surface coated with 5% Matrigel. Double immunostaining of the fourth-passage LNCs was uniformly PCK-/VIM+/CD90+/CD105+/SCF+/PDGFRß+. Reverse transcription and quantitative real-time polymerase chain reaction (RT-qPCR) revealed the decrease of PCK expression from the second passage and elevation of Vim, CD90, CD105, SCF, and PDGFRß transcripts from the third passage, and the transcription level of Vim, CD90, CD105, SCF, and PDGFRß was elevated statistically in the fourth passage compared to the first passage (P < 0.01). Both immunofluorescence (IF) staining for cross section and cytospin cells demonstrated that MCECs expressed higher CK12 while lower p63α than LEPCs (P < 0.01). Sphere growth formation was noticed as early as 24 hours in the MCEC + LNC group, 48 hours in the LEPC group, and 72 hours in the MCEC group. The diameters of the spheres were the biggest in the MCEC + LNC group (182.24 ± 57.91 µm), smaller in the LEPC group (125.71 ± 41.20 µm), and smallest in the MCEC group (109.39 ± 34.85 µm) by the end of the 10-day culture (P < 0.01). Double immunostaining with CK12/p63α showed that cells in the sphere formed from MCECs expressed CK12 but not p63α; in contrast, some cells in the MCEC + LNC group expressed CK12, but most of them expressed p63α. RT-qPCR revealed a significant reduction of CK12 transcript but elevation of p63α, Oct4, Nanog, Sox2, and SSEA4 (P < 0.05). Holoclone composed of cubic epithelial cells could be generated in the MCEC + LNC group but not in the other two groups. Conclusions: The data shows that human MCEC cell phenotype could be induced to the dedifferentiation stage when cocultured with LNCs in 3D Matrigel that simulated the microenvironment of limbal stem cells in vitro.


Assuntos
Limbo da Córnea , Diferenciação Celular , Colágeno , Combinação de Medicamentos , Células Epiteliais/metabolismo , Laminina/metabolismo , Proteoglicanas
3.
Macromol Biosci ; 21(2): e2000300, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33205604

RESUMO

Restricted by the difficulty in fabricating scaffolds suitable for cell proliferation, the use of ex vivo expanded limbal stem cell (LSC) for LSC transplantation, an effective treatment method for patients with limb stem cell deficiency (LSCD), is hard to be widely used in clinical practice. To tackle these challenges, a novel electrospun polycaprolactone (PCL)/gelatin nanocomposite is proposed to make 3D scaffolds for limbal niche cells (LNC) proliferation in vitro, which is a milestone in the treatment of diseases such as LSCD. PCL and gelatin in different weight ratios are dissolved in a mixed solvent, and then electrospinning and cross-linking are performed to prepare a scaffold for cell proliferation. The characterizations of the nanocomposites indicate that the gelatin content has a significant effect on its micro-morphology, thermal properties, crystallinity, degradation temperature, hydrophilicity, and mechanical properties. P8G2-C (PCL: gelatin = 80: 20, cross-linked), with smooth fibers and homogeneous pores, has better hydrophilicity, mechanical properties, and flexibility, so it can support LNC as cell proliferation assays revealed. This detailed investigation presented here demonstrates the feasibility of using PCL/gelatin nanocomposites electrospun fiber membranes as a limbus tissue engineering scaffold, which undoubtedly provide a new perspective for the development of tissue engineering field.


Assuntos
Gelatina/farmacologia , Limbo da Córnea/fisiologia , Nanocompostos/química , Poliésteres/farmacologia , Alicerces Teciduais/química , Varredura Diferencial de Calorimetria , Proliferação de Células , Humanos , Células-Tronco/citologia
4.
J Ren Nutr ; 31(6): 620-627, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-33309411

RESUMO

OBJECTIVE: We aimed to evaluate the relationship of plasma 25-hydroxyvitamin D3 (25[OH]D3) with the risk of new-onset proteinuria and examine the possible effect modifiers in patients with hypertension and without chronic kidney disease at baseline. METHODS: This is a post hoc analysis of the renal substudy of the China Stroke Primary Prevention Trial. A total of 1655 patients with hypertension, who had plasma 25(OH)D3 measurements, as well as without proteinuria and with an estimated glomerular filtration rate of ≥60 mL/min/1.73 m2 at baseline, were included in the present study. The main outcome was new-onset proteinuria, defined as a urine dipstick reading of ≥1+ at the exit visit. RESULTS: The mean (standard deviation) 25(OH)D3 level at baseline was 18.6 (7.5) ng/mL. The median follow-up duration was 4.4 years. Overall, there was a significant inverse association between plasma 25(OH)D3 and the risk of new-onset proteinuria (per standard deviation increment; [odds ratio] OR: 0.70; 95% confidence interval [CI]: 0.50, 0.97). Accordingly, when 25(OH)D3 was assessed as quartiles, a significantly lower risk of new-onset proteinuria was found in participants in quartiles 3-4 (≥17.8 ng/mL; OR: 0.45; 95% CI: 0.23, 0.87), compared with those in quartile 1 (<13.1 ng/mL). Furthermore, a stronger inverse relationship of plasma 25(OH)D3 and new-onset proteinuria was observed in nondiabetic participants (per standard deviation increment; OR: 0.57; 95% CI: 0.39, 0.83; vs. diabetics: OR: 1.48; 95% CI: 0.67, 3.28; P for interaction = 0.028). CONCLUSION: There was a significant inverse association between plasma 25(OH)D3 and the risk of proteinuria in patients with hypertension, especially in those without diabetes.


Assuntos
Diabetes Mellitus , Hipertensão , Calcifediol , Taxa de Filtração Glomerular , Humanos , Hipertensão/complicações , Hipertensão/epidemiologia , Proteinúria/complicações , Proteinúria/epidemiologia , Fatores de Risco
5.
ACS Appl Mater Interfaces ; 11(7): 7479-7487, 2019 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-30672685

RESUMO

The severe water contamination caused by oil leakage is calling for low-cost and high-performance absorbent materials for selective oil removal. In this study, a scalable green method was proposed to produce polypropylene (PP)/poly(tetrafluoroethylene) (PTFE) composite foams via conventional processing techniques including twin-screw extrusion and supercritical carbon dioxide foaming. To produce the superhydrophobic foam, micro- and nanosized PTFE particles were melt blended with PP and subsequently foamed. Ascribed to the nanofibrillation of microsized PTFE during processing, the fabricated foam exhibited a special highly porous structure with PTFE nanofibrils and nanoparticles uniformly distributed on the pore surfaces within the PP matrix, which resulted in a remarkably high water contact angle of 156.8° and a low contact angle hysteresis of 1.9°. Unlike traditional surface-modified superhydrophobic absorbers, the foams prepared are entirely superhydrophobic, which means that they remain superhydrophobic when being fractured or cut. Moreover, they are highly durable and maintained the superhydrophobicity when subjected to ultrasonication and mechanical sanding. When used in selective oil absorption, the durable foams exhibited excellent absorption efficiency and high stability in repetitive and long-term use. These advantages make the PP/PTFE foam a promising superabsorbent material for water remediation.

6.
Fish Shellfish Immunol ; 81: 368-373, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30031065

RESUMO

The antimicrobial peptide (AMP) Pc-pis, a member of Piscidin family from fish with cationic amphipathic structure, has potent, broad-spectrum antimicrobial activity against bacteria, fungi and parasite, and lower hemolytic activity. Here, we reported that Pc-pis had antitumor activity. Pc-pis killed tumor cells including HeLa cells. Previously, it is reported that AMPs bind to the membrane of bacteria to generate the pores to lyse the target cells, and similarly, the cancer cell incorporate phosphatidyl-serine on the outer leaflet of plasma membrane so that amphipathic AMPs can bind to the membrane to kill it. Our data supported that notion because suitable size osmo-protectant PEG4000 prevented HeLa cells from death induced by Pc-pis. Additionally, Fusion protein GFP-Pc-pis accumulated mainly at the nuclear membranes of HeLa cells and positive net charge in modified Pc-pis intensified but negative net charges eliminated this effect. Thus, positively charged residues were important for its affinity to the membrane. Our work will lay the groundwork of the development of Pc-pis antitumor activity.


Assuntos
Peptídeos Catiônicos Antimicrobianos/farmacologia , Antineoplásicos/farmacologia , Proteínas de Peixes/farmacologia , Animais , Peptídeos Catiônicos Antimicrobianos/genética , Sobrevivência Celular/efeitos dos fármacos , Proteínas de Peixes/genética , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/farmacologia , Células HeLa , Humanos , Membrana Nuclear/metabolismo , Perciformes , Proteínas Recombinantes de Fusão/farmacologia
7.
J Biol Chem ; 293(25): 9747-9758, 2018 06 22.
Artigo em Inglês | MEDLINE | ID: mdl-29743236

RESUMO

Resistance to apoptosis and uncontrolled proliferation are two hallmarks of cancer cells. p53 is crucial for apoptosis triggered by a broad range of stresses and a well-known gatekeeper for neoplastic transformation. Here we show that oncogenic IDH1 R132H/R132Q mutants robustly inhibit p53 expression and such an effect is attributed to 2-HG production. Mechanistically, 2-hydroxyglutarate (2-HG) stabilizes hypoxia-inducible factor-2α, which in turn activates the expression of miR-380-5p, a characterized microRNA against p53 expression. Rescue expression of p53 can inhibit the proliferation rate and impair the resistance of apoptosis induced by doxorubicin in IDH1 R132Q mouse embryonic fibroblast cells. Furthermore, p53 protein levels correlates negatively with IDH1 R132H levels in human glioma samples. Our results thus shed a new light on how p53 is down-regulated by 2-HG and suggests that impairment of p53-mediated apoptosis contributes to the tumorigenesis driven by IDH1 mutants.


Assuntos
Arginina/genética , Neoplasias Encefálicas/patologia , Regulação Neoplásica da Expressão Gênica , Glioma/patologia , Isocitrato Desidrogenase/metabolismo , Mutação , Proteína Supressora de Tumor p53/metabolismo , Animais , Arginina/química , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/metabolismo , Carcinogênese , Proliferação de Células , Glioma/genética , Glioma/metabolismo , Glutaratos/farmacologia , Humanos , Isocitrato Desidrogenase/genética , Camundongos , MicroRNAs/genética , Células Tumorais Cultivadas , Proteína Supressora de Tumor p53/genética , Ensaios Antitumorais Modelo de Xenoenxerto
8.
Polymers (Basel) ; 11(1)2018 Dec 23.
Artigo em Inglês | MEDLINE | ID: mdl-30960002

RESUMO

In this study, the flexural behavior and fracture mechanisms of short carbon fiber reinforced polyether-ether-ketone (SCFR/PEEK) composites at various ambient temperatures were investigated. First, the crystallinity and glass transition temperature (Tg) of PEEK and SCFR/PEEK were analyzed by differential scanning calorimetry analysis and dynamic mechanical analysis tests, respectively. The addition of SCFs increases the Tg but does not change the crystallinity of the PEEK matrix. Then, the three-point flexural tests of PEEK and SCFR/PEEK were performed over the temperature range of 20 to 235 °C, and the temperature-dependencies of the flexural properties of PEEK and SCFR/PEEK were discussed in detail. Finally, the microstructure of SCFR/PEEK was observed using a digital microscope and scanning electron microscope. The results show that the tension crack occurs first, and the crack extends upward leading to the shear crack and compression crack at room temperature. The fracture of SCFR/PEEK is mainly due to the extraction and rupture of SCFs. At high temperatures (above Tg), the tension crack and compression crack both occur, and the strong ductility of the matrix prevents the generation of shear crack. The fracture of SCFR/PEEK is mainly due to the rotation and extraction of SCFs, while the SCFs rupture plays a minor role.

9.
Cell Rep ; 19(2): 389-400, 2017 04 11.
Artigo em Inglês | MEDLINE | ID: mdl-28402860

RESUMO

Two hallmarks of cancer cells are their resistance to apoptosis and ability to thrive despite reduced levels of vital serum components. c-jun N-terminal kinase (JNK) activation is crucial for apoptosis triggered by serum starvation (SS), and isocitrate dehydrogenase 1 (IDH1) mutations are tumorigenic, in part, because they produce the abnormal metabolite 2-hydroxyglutarate (2-HG). However, it is unknown whether 2-HG-induced tumorigenesis is partially due to JNK inhibition and thus defective SS-induced apoptosis. We show here, using IDH1-R132Q knockin mutant mouse cells, that 2-HG inhibits JNK activation induced only by SS and not by UV or doxorubicin, and thus can block apoptosis. Upon SS, Cdc42 normally disrupts mixed lineage kinase 3's (MLK3's) auto-inhibition, triggering the MLK3-MKK4/7-JNK-Bim apoptotic cascade. 2-HG binds to Cdc42 and abolishes its association with MLK3, inactivating MLK3 and apoptosis. Allograft tumor assays in mice demonstrate that this mechanism contributes to tumorigenesis driven by mutant IDH1, a result confirmed by detection of JNK inactivation in human gliomas harboring IDH1-R132H mutations.


Assuntos
Apoptose/genética , Carcinogênese/genética , Glioma/genética , Isocitrato Desidrogenase/genética , MAP Quinase Quinase 4/biossíntese , Animais , Linhagem Celular Tumoral , Meios de Cultura Livres de Soro , Regulação Neoplásica da Expressão Gênica , Glioma/metabolismo , Glioma/patologia , Glutaratos/metabolismo , Humanos , MAP Quinase Quinase 4/genética , Sistema de Sinalização das MAP Quinases/genética , Camundongos , Ensaios Antitumorais Modelo de Xenoenxerto
10.
Nat Commun ; 8: 13732, 2017 01 05.
Artigo em Inglês | MEDLINE | ID: mdl-28054552

RESUMO

It is well known that c-Src has important roles in tumorigenesis. However, it remains unclear whether c-Src contributes to metabolic reprogramming. Here we find that c-Src can interact with and phosphorylate hexokinases HK1 and HK2, the rate-limiting enzymes in glycolysis. Tyrosine phosphorylation dramatically increases their catalytic activity and thus enhances glycolysis. Mechanistically, c-Src phosphorylation of HK1 at Tyr732 robustly decreases its Km and increases its Vmax by disrupting its dimer formation. Mutation in c-Src phosphorylation site of either HK1 or HK2 remarkably abrogates the stimulating effects of c-Src on glycolysis, cell proliferation, migration, invasion, tumorigenesis and metastasis. Due to its lower Km for glucose, HK1 rather than HK2 is required for tumour cell survival when glucose is scarce. Importantly, HK1-Y732 phosphorylation level remarkably correlates with the incidence and metastasis of various clinical cancers and may serve as a marker to predict metastasis risk of primary cancers.


Assuntos
Carcinogênese , Hexoquinase/metabolismo , Metástase Neoplásica , Neoplasias/patologia , Proteínas Proto-Oncogênicas pp60(c-src)/metabolismo , Animais , Linhagem Celular Tumoral , Proliferação de Células , Ativação Enzimática , Glucose/metabolismo , Glucose-6-Fosfato/metabolismo , Glicólise , Xenoenxertos , Humanos , Cinética , Masculino , Redes e Vias Metabólicas , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Fosforilação , Ligação Proteica , Tirosina/metabolismo
11.
Biochem Biophys Res Commun ; 463(3): 275-9, 2015 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-26009488

RESUMO

Clnk, as a third member of the Blnk/SLP-76 adapter family, is involved in the positive regulation of immunoreceptor signaling. Here we provide findings that Clnk may be is required for TNF induced cell death, it functions downstream of RIP3 and promotes TNF- induced ROS generation and MLKL tetramer formation and subsequent necrosis of L929 cells. Therefore, Clnk, as an adaptor protein, may take part in the other cellular processes.


Assuntos
Proteínas de Transporte/imunologia , Fibrossarcoma/imunologia , Espécies Reativas de Oxigênio/imunologia , Fator de Necrose Tumoral alfa/imunologia , Proteínas Adaptadoras de Transdução de Sinal , Animais , Morte Celular , Linhagem Celular Tumoral , Fibrossarcoma/patologia , Células HeLa , Humanos , Camundongos , Necrose/imunologia , Proteínas Quinases/química , Proteínas Quinases/imunologia , Multimerização Proteica , Proteína Serina-Treonina Quinases de Interação com Receptores/imunologia , Transdução de Sinais
12.
Mol Biol Cell ; 18(11): 4681-9, 2007 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-17855512

RESUMO

Mitochondrial adenine nucleotide translocase (ANT) is believed to be a component or a regulatory component of the mitochondrial permeability transition pore (mtPTP), which controls mitochondrial permeability transition during apoptosis. However, the role of ANT in apoptosis is still uncertain, because hepatocytes isolated from ANT knockout and wild-type mice are equally sensitive to TNF- and Fas-induced apoptosis. In a screen for genes required for tumor necrosis factor alpha (TNF-alpha)-induced apoptosis in MCF-7 human breast cancer cells using retrovirus insertion-mediated random mutagenesis, we discovered that the ANT3 gene is involved in TNF-alpha-induced cell death in MCF-7 cells. We further found that ANT3 is selectively required for TNF- and oxidative stress-induced cell death in MCF-7 cells, but it is dispensable for cell death induced by several other inducers. This data supplements previous data obtained from ANT knockout studies, indicating that ANT is involved in some apoptotic processes. We found that the resistance to TNF-alpha-induced apoptosis observed in ANT3 mutant (ANT3(mut)) cells is associated with a deficiency in the regulation of the mitochondrial membrane potential and cytochrome c release. It is not related to intracellular ATP levels or survival pathways, supporting a previous model in which ANT regulates mtPTP. Our study provides genetic evidence supporting a role of ANT in apoptosis and suggests that the involvement of ANT in cell death is cell type- and stimulus-dependent.


Assuntos
Translocador 3 do Nucleotídeo Adenina/metabolismo , Apoptose/efeitos dos fármacos , Fator de Necrose Tumoral alfa/farmacologia , Translocador 3 do Nucleotídeo Adenina/genética , Trifosfato de Adenosina/metabolismo , Linhagem Celular Tumoral , Citocromos c/metabolismo , Humanos , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Mutação/genética , Estresse Oxidativo , Espécies Reativas de Oxigênio/metabolismo
13.
Proc Natl Acad Sci U S A ; 103(6): 1840-5, 2006 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-16446438

RESUMO

Nod1, a cytosolic protein that senses meso-diaminopimelic acid-containing ligands derived from peptidoglycan, plays a role in host responses to invasive bacteria. Here we describe a function for Nod1, whereby it controls tumor formation. Cell lines derived from the human breast cancer epithelial cell line MCF-7 were used in a severe combined immune deficiency (SCID) mouse xenograft model to characterize a pathway linking Nod1 to the growth of estrogen-sensitive tumors. In MCF-7 cells, the absence of Nod1 correlates with tumor growth, an increased sensitivity to estrogen-induced cell proliferation, and a failure to undergo Nod1-dependent apoptosis. Conversely, overexpression of Nod1 in MCF-7 cells results in inhibition of estrogen-dependent tumor growth and reduction of estrogen-induced proliferative responses in vitro.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Neoplasias/metabolismo , Neoplasias/patologia , Proteínas Adaptadoras de Transdução de Sinal/genética , Animais , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Humanos , Camundongos , Camundongos SCID , Neoplasias/genética , Proteína Adaptadora de Sinalização NOD1 , Fator de Necrose Tumoral alfa/farmacologia , Ensaios Antitumorais Modelo de Xenoenxerto
14.
Mol Cell Biol ; 25(15): 6673-81, 2005 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16024802

RESUMO

Tumor necrosis factor (TNF) alpha is a cytokine capable of inducing caspase-dependent (apoptotic) cell death in some cells and caspase-independent (necrosis-like) cell death in others. Here, using a mutagenesis screen for genes critical in TNF-induced death in L929 cells, we have found that H-ferritin deficiency is responsible for TNF resistance in a mutant line and that, upon treatment with TNF, this line fails to elevate levels of labile iron pool (LIP), critical for TNF-induced reactive oxygen species (ROS) production and ROS-dependent cell death. Since we found that TNF-induced LIP in L929 cells is primarily furnished by intracellular storage iron, the lesser induction of LIP in H-ferritin-deficient cells results from a reduction of intracellular iron storage caused by less H-ferritin. Different from some other cell lines, the H-ferritin gene in L929 cells is not TNF inducible; however, when H-ferritin is expressed in L929 cells under a TNF-inducible system, the TNF-induced LIP and subsequent ROS production and cell death were all prevented. Thus, LIP is a common denominator of ferritin both in the enhancement of cell death by basal steady-state H-ferritin and in protection against cell death by induced H-ferritin, thereby acting as a key determinant of TNF-induced cell death.


Assuntos
Apoptose/fisiologia , Ferritinas/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Animais , Apoptose/efeitos dos fármacos , Sequência de Bases , Linhagem Celular , Desferroxamina/farmacologia , Relação Dose-Resposta a Droga , Ferritinas/genética , Ferro/metabolismo , Quelantes de Ferro/farmacologia , Camundongos , Dados de Sequência Molecular , Mutação , NF-kappa B/metabolismo , Espécies Reativas de Oxigênio/metabolismo
15.
J Cell Sci ; 117(Pt 20): 4673-80, 2004 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-15371523

RESUMO

Tumor necrosis factor (TNF)-alpha induces caspase-independent cell death in the fibrosarcoma cell line L929. This cell death has a necrotic phenotype and is dependent on production of reactive oxygen species (ROS) in the mitochondria. To identify genes involved in this TNF-induced, ROS-dependent cell death pathway, we utilized retrovirus insertion-mediated random mutagenesis to generate TNF-resistant L929 cell lines and we subsequently identified genes whose mutations are responsible for the TNF-resistant phenotype. In one such resistant line, beta-actin was disrupted by viral insertion, and subsequent reconstitution of beta-actin expression levels in the mutant line Actin(mut) restored its sensitivity to TNF. Resistance to TNF in Actin(mut) cells is signal specific since the sensitivity to other death stimuli is either unchanged or even increased. Comparable NF-kappaB activation and p38 phosphorylation in TNF-treated wild-type and Actin(mut) cells also indicates that reduced expression of actin only selectively blocked some of the TNF-induced cellular changes. Actin cleavage involved in apoptosis does not occur in TNF-treated L929 cell death, as in HeLa cells. Consistent over-expression of a caspase-cleaved product, a 15 kDa actin fragment, had no effect on TNF-induced necrosis of L929 cell. By contrast, TNF-induced mitochondria clustering and ROS production were dramatically reduced in Actin(mut) cells, indicating that actin-deficiency-mediated TNF resistance is most likely due to impaired mitochondrial responses to TNF stimulation. Our findings suggest that a full complement of actin is required for transduction of a cell death signal to mitochondria in TNF-treated L929 cells.


Assuntos
Actinas/metabolismo , Caspases/metabolismo , Morte Celular/genética , Mitocôndrias/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Fator de Necrose Tumoral alfa/farmacologia , Actinas/genética , Animais , Morte Celular/fisiologia , Linhagem Celular , Ativação Enzimática , Humanos , Camundongos , Mitocôndrias/metabolismo , Mutação , NF-kappa B/metabolismo , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Transdução de Sinais/fisiologia , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismo
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