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1.
Plant Cell ; 23(8): 2924-38, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21862705

RESUMO

During regeneration, differentiated plant cells can be reprogrammed to produce stem cells, a process that requires coordination of cell cycle reactivation with acquisition of other cellular characteristics. However, the factors that coordinate the two functions during reprogramming have not been determined. Here, we report a link between cell cycle reactivation and the acquisition of new cell-type characteristics through the activity of cyclin-dependent kinase A (CDKA) during reprogramming in the moss Physcomitrella patens. Excised gametophore leaf cells of P. patens are readily reprogrammed, initiate tip growth, and form chloronema apical cells with stem cell characteristics at their first cell division. We found that leaf cells facing the cut undergo CDK activation along with induction of a D-type cyclin, tip growth, and transcriptional activation of protonema-specific genes. A DNA synthesis inhibitor, aphidicolin, inhibited cell cycle progression but prevented neither tip growth nor protonemal gene expression, indicating that cell cycle progression is not required for acquisition of protonema cell-type characteristics. By contrast, treatment with a CDK inhibitor or induction of dominant-negative CDKA;1 protein inhibited not only cell cycle progression but also tip growth and protonemal gene expression. These findings indicate that cell cycle progression is coordinated with other cellular changes by the concomitant regulation through CDKA;1.


Assuntos
Bryopsida/fisiologia , Ciclo Celular/fisiologia , Desdiferenciação Celular/fisiologia , Quinases Ciclina-Dependentes/metabolismo , Afidicolina/farmacologia , Sequência de Bases , Bryopsida/citologia , Bryopsida/efeitos dos fármacos , Bryopsida/genética , Ciclo Celular/efeitos dos fármacos , Ciclina D/metabolismo , Quinases Ciclina-Dependentes/antagonistas & inibidores , Quinases Ciclina-Dependentes/genética , DNA de Plantas/química , Inibidores Enzimáticos/farmacologia , Regulação da Expressão Gênica de Plantas/fisiologia , Dados de Sequência Molecular , Mutação , Folhas de Planta/citologia , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/genética , Folhas de Planta/fisiologia , Proteínas de Plantas/antagonistas & inibidores , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Análise de Sequência de DNA , Células-Tronco/fisiologia , Fatores de Tempo , Ativação Transcricional/fisiologia
2.
Life Sci ; 80(6): 592-9, 2007 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-17141277

RESUMO

UNLABELLED: The effect of beta antagonists in the diabetic vascular lesion is controversial. We investigated the effect of celiprolol hydrochloride, a beta1 antagonist and mild beta2 agonist, on the lesions and function in type II male Otsuka Long-Evans Tokushima Fatty (OLETF) diabetic rats. OLETF rats were fed regular chow with or without atenolol (25 mg/kg/day) or celiprolol (100 mg/kg/day) treatment (group DM, no treatment; group DM-a, atenolol treatment; group DM-c, celiprolol treatment), and treatment was continued for 31 days. Separately, normoglycemic control rats, LETO, were prepared as group C. On day 3, endothelial cells of the right internal carotid artery were removed by balloon injury, and the rats were evaluated 4 weeks after balloon injury. The plasma glucose and lipid levels were unchanged throughout the treatment period. Intimal thickening was observed in the right carotid artery in the DM and DM-a groups; however, little thickening was observed in those of DM-c rats. Acetylcholine-induced NO-dependent relaxation in arteries was improved in DM-c rats compared with DM and DM-a rats (maximum relaxation DM 30.8+/-4.5, DM-a 37.4+/-3.9, DM-c 48.8+/-4.6%, *P<0.05 vs. DM for DM-c rats). Tone-related basal NO release and acetylcholine-induced NO-dependent relaxation in the arteries and plasma NO(x) (sum of NO(2)(-) and NO(3)(-)) were greater in DM-c and C groups than in DM and DM-a groups. The serum TNFalpha levels did not increase in DM-c rats compared with those of the DM or DM-a groups, and were comparable with those of group C. CONCLUSION: In conclusion, Celiprolol improves endothelial function in the arteries of OLETF rats, and further restore it 4 weeks after endothelial denudation in the arteries of OLETF rats. NO and O(2)(-) may have a role in the important underlying mechanisms by reducing the TNFalpha levels.


Assuntos
Antagonistas de Receptores Adrenérgicos beta 1 , Agonistas de Receptores Adrenérgicos beta 2 , Celiprolol/uso terapêutico , Diabetes Mellitus Experimental/complicações , Diabetes Mellitus Tipo 2/complicações , Endotélio Vascular/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Animais , Aorta Abdominal/metabolismo , Aterosclerose/metabolismo , Aterosclerose/prevenção & controle , Pressão Sanguínea/efeitos dos fármacos , Peso Corporal/efeitos dos fármacos , Celiprolol/farmacologia , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Angiopatias Diabéticas/metabolismo , Angiopatias Diabéticas/prevenção & controle , Masculino , Nitratos/sangue , Óxido Nítrico/metabolismo , Nitritos/sangue , Ratos , Ratos Long-Evans , Superóxidos/metabolismo
3.
J Pharmacol Exp Ther ; 320(2): 591-8, 2007 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-17082313

RESUMO

In postmenopausal women, the risk of diabetic cardiovascular disease drastically increases compared with that of men or premenopausal women. However, the mechanism of this phenomenon has not yet been clarified. We hypothesized that the beneficial effects of estrogen on endothelial function may be relevant to protection against hyperglycemia-induced vascular derangement. Bovine aortic endothelial cells were incubated for 72 h in the presence and absence of the physiological concentration of 17beta-estradiol (17beta-E2) under normal and high-glucose conditions. The presence of 17beta-E2 significantly counteracted the reduction in basal nitric oxide production under high-glucose conditions. This finding was associated with the recovery of endothelial nitric-oxide synthase (eNOS) protein expression, tetrahydrobiopterin (BH4) levels, and the activity and gene expression of GTP cyclohydrolase I (GTPCH-I), a rate-limiting enzyme for BH4 synthesis. Both the gene transfer of estrogen receptor alpha using adenovirus and treatment with the protein kinase C inhibitor bisindolylmaleimide I significantly enhanced the effects of 17beta-E2 treatment under high-glucose conditions, whereas these effects were abolished by the estrogen receptor antagonist ICI 182,780 (faslodex). Transfection of small-interfering RNA targeting eNOS resulted in a marked reduction in GTPCH-I mRNA under both normal and high-glucose conditions, but this reduction was strongly reversed by 17beta-E2. These results suggest that the activation of ERalpha with 17beta-E2 can counteract high-glucose-induced down-regulation of eNOS and GTPCH-I in endothelial cells. Therefore, estrogen deficiency may result in an exaggeration of hyperglycemia-induced endothelial dysfunction, leading to the development of cardiovascular disease in postmenopausal diabetic women.


Assuntos
Doenças Cardiovasculares/etiologia , Complicações do Diabetes/etiologia , Estradiol/farmacologia , GTP Cicloidrolase/antagonistas & inibidores , Hiperglicemia/metabolismo , Óxido Nítrico Sintase Tipo III/antagonistas & inibidores , Animais , Biopterinas/análogos & derivados , Biopterinas/sangue , Bovinos , Células Cultivadas , Regulação para Baixo , Células Endoteliais/enzimologia , Receptor alfa de Estrogênio/fisiologia , Feminino , Nitritos/metabolismo , Pós-Menopausa , Proteína Quinase C/fisiologia , RNA Interferente Pequeno/farmacologia
4.
Am J Physiol Heart Circ Physiol ; 293(1): H790-7, 2007 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-17449545

RESUMO

The long-term benefits of nitroglycerin therapy are limited by tolerance development. Understanding the precise nature of mechanisms underlying nitroglycerin-induced endothelial cell dysfunction may provide new strategies to prevent tolerance development. In this line, we tested interventions to prevent endothelial dysfunction in the setting of nitrate tolerance. When bovine aortic endothelial cells (BAECs) were continuously treated with nitric oxide (NO) donors, including nitroglycerin, over 2-3 days, basal production of nitrite and nitrate (NO(x)) was diminished. The diminished basal NO(x) levels were mitigated by intermittent treatment allowing an 8-h daily nitrate-free interval during the 2- to 3-day treatment period. Addition of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor apocynin restored the basal levels of NO(x) that were decreased by continuous nitroglycerin treatment of BAECs. Apocynin caused significant improvement of increased mRNA and protein levels of endothelial nitric oxide synthase (eNOS) in BAECs given nitroglycerin continuously over the treatment period. Apocynin also reduced endothelial production of reactive oxygen species (ROS) after continuous nitroglycerin treatment. These results showed an essential similarity to the effects of a nitrate-free interval. Application of the NOS inhibitor N(omega)-nitro- l-arginine methyl ester caused a recovery effect on basal NO(x) and eNOS expression but was without effect on ROS levels in continuously NO donor-treated BAECs. In conclusion, the present study characterized abnormal features and functions of endothelial cells following continuous NO donor application. We suggest that inhibition of NADPH oxidase, by preventing NO donor-induced endothelial dysfunction, may represent a potential therapeutic strategy that confers protection from nitrate tolerance development.


Assuntos
Acetofenonas/administração & dosagem , Células Endoteliais/efeitos dos fármacos , Células Endoteliais/metabolismo , NADPH Oxidases/antagonistas & inibidores , Nitratos/metabolismo , Doadores de Óxido Nítrico/administração & dosagem , Espécies Reativas de Oxigênio/metabolismo , Animais , Bovinos , Células Cultivadas , Relação Dose-Resposta a Droga , Combinação de Medicamentos , Tolerância a Medicamentos/fisiologia , Inibidores Enzimáticos/administração & dosagem
5.
Proc Natl Acad Sci U S A ; 103(45): 17018-23, 2006 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-17075048

RESUMO

Senescence may contribute to the pathogenesis of atherosclerosis. Although the bioavailability of nitric oxide (NO) is limited in senescence, the effect of NO on senescence and its relationship to cardiovascular risk factors have not been investigated fully. We studied these factors by investigating senescence-associated beta-galactosidase (SA-beta-gal) and human telomerase activity in human umbilical venous endothelial cells (HUVECs). Treatment with NO donor (Z)-1-[2-(2-aminoethyl)-N-(2-aminoethyl)amino]diazen-1-ium-1,2-diolate (DETA-NO) and transfection with endothelial NO synthase (eNOS) into HUVECs each decreased the number of SA-beta-gal positive cells and increased telomerase activity. The NOS inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME) abolished the effect of eNOS transfection. The physiological concentration of 17beta-estradiol activated hTERT, decreased SA-beta-gal-positive cells, and caused cell proliferation. However, ICI 182780, an estrogen receptor-specific antagonist, and L-NAME each inhibited these effects. Finally, we investigated the effect of NO bioavailability on high glucose-promoted cellular senescence of HUVECs. Inhibition by eNOS transfection of this cellular senescence under high glucose conditions was less pronounced. Treatment with L-arginine or L-citrulline of eNOS-transfected cells partially inhibited, and combination of L-arginine and L-citrulline with antioxidants strongly prevented, high glucose-induced cellular senescence. These data demonstrate that NO can prevent endothelial senescence, thereby contributing to the anti-senile action of estrogen. The ingestion of NO-boosting substances, including L-arginine, L-citrulline, and antioxidants, can delay endothelial senescence under high glucose. We suggest that the delay in endothelial senescence through NO and/or eNOS activation may have clinical utility in the treatment of atherosclerosis in the elderly.


Assuntos
Senescência Celular/efeitos dos fármacos , Células Endoteliais/citologia , Células Endoteliais/efeitos dos fármacos , Óxido Nítrico/farmacologia , Aterosclerose/etiologia , Aterosclerose/metabolismo , Aterosclerose/patologia , Aterosclerose/prevenção & controle , Células Cultivadas , Angiopatias Diabéticas/etiologia , Angiopatias Diabéticas/metabolismo , Angiopatias Diabéticas/patologia , Angiopatias Diabéticas/prevenção & controle , Células Endoteliais/metabolismo , Feminino , Humanos , Menopausa , Óxido Nítrico/metabolismo , Óxido Nítrico Sintase Tipo III/genética , Espécies Reativas de Oxigênio/metabolismo , Telomerase/metabolismo , Transfecção
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