Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 5 de 5
Filtrar
Mais filtros

Base de dados
Tipo de documento
Intervalo de ano de publicação
1.
Exp Eye Res ; 145: 317-326, 2016 04.
Artigo em Inglês | MEDLINE | ID: mdl-26706283

RESUMO

Norrin is an angiogenic signaling molecule that activates canonical Wnt/ß-catenin signaling, and is involved in capillary formation in retina and brain. Moreover, Norrin induces vascular repair following an oxygen-induced retinopathy (OIR), the model of retinopathy of prematurity in mice. Since insulin-like growth factor (IGF)-1 is a very potent angiogenic molecule, we investigated if IGF-1 is a downstream mediator of Norrin's angiogenic properties. In retinae of transgenic mice with an ocular overexpression of Norrin (ßB1-Norrin), we found at postnatal day (P)11 a significant increase of IGF-1 mRNA compared to wild-type littermates. In addition, after treatment of cultured Müller cells or dermal microvascular endothelial cells with Norrin we observed an increase of IGF-1 and its mRNA, an effect that could be blocked with DKK-1, an inhibitor of Wnt/ß-catenin signaling. When OIR was induced, the expression of IGF-1 was significantly suppressed in both transgenic ßB1-Norrin mice and wild-type littermates when compared to wild-type animals that were housed in room air. Furthermore, at P13, one day after the mice had returned to normoxic conditions, IGF-1 levels were significantly higher in transgenic mice compared to wild-type littermates. Finally, after intravitreal injections of inhibitory α-IGF-1 antibodies at P12 or at P12 and P14, the Norrin-mediated vascular repair was significantly attenuated. We conclude that Norrin induces the expression of IGF-1 via an activation of the Wnt/ß-catenin signaling pathway, an effect that significantly contributes to the protective effects of Norrin against an OIR.


Assuntos
Proteínas do Olho/fisiologia , Fator de Crescimento Insulin-Like I/metabolismo , Proteínas do Tecido Nervoso/fisiologia , Neovascularização Retiniana/metabolismo , Animais , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Modelos Animais de Doenças , Células Endoteliais/efeitos dos fármacos , Células Endoteliais/metabolismo , Células Ependimogliais/efeitos dos fármacos , Células Ependimogliais/metabolismo , Proteínas do Olho/farmacologia , Humanos , Fator de Crescimento Insulin-Like I/antagonistas & inibidores , Camundongos , Camundongos Transgênicos , Proteínas do Tecido Nervoso/farmacologia , Oxigênio/efeitos adversos , RNA Mensageiro/metabolismo , Ratos , Ratos Wistar , Neovascularização Retiniana/etiologia , Via de Sinalização Wnt/fisiologia
2.
Cell Tissue Res ; 358(2): 567-83, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25096716

RESUMO

Optineurin, a cytosolic protein associated with the actin cytoskeleton, microtubules, and the Golgi complex, appears to have an important function in neurons, as mutations in its gene are causative for neurodegenerative diseases such as primary open-angle glaucoma and amyotrophic lateral sclerosis. Here, we report that optineurin is localized in podocytes of the kidney and induced upon injury following treatment with puromycin aminonucleoside. In cultured human podocytes, optineurin localizes to the Golgi complex. Optineurin depletion by RNA interference causes Golgi fragmentation. Moreover, if the Golgi complex is fragmented following microtubule destabilization induced by nocodazole treatment, optineurin dissociates from Golgi vesicles. Furthermore, optineurin colocalizes with vinculin-labeled focal contacts of cultured podocytes and with lysosome-like structures. Optineurin is essential for the survival of cultured podocytes, as optineurin depletion causes cell death. Thus, optineurin appears to play an important role in the maintenance of the podocyte Golgi complex and in the trafficking of vesicles to focal contacts and lysosomes.


Assuntos
Complexo de Golgi/metabolismo , Podócitos/metabolismo , Podócitos/ultraestrutura , Fator de Transcrição TFIIIA/metabolismo , Citoesqueleto de Actina/metabolismo , Animais , Apoptose , Proteínas de Ciclo Celular , Linhagem Celular , Sobrevivência Celular , Adesões Focais/metabolismo , Complexo de Golgi/ultraestrutura , Humanos , Lisossomos/metabolismo , Masculino , Proteínas de Membrana Transportadoras , Microtúbulos/metabolismo , Nefrose/metabolismo , Nefrose/patologia , Podócitos/patologia , Ligação Proteica , Transporte Proteico , Puromicina Aminonucleosídeo , Interferência de RNA , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ratos Sprague-Dawley , Frações Subcelulares/metabolismo , Fator de Transcrição TFIIIA/deficiência , Fator de Transcrição TFIIIA/genética , Regulação para Cima , Fator A de Crescimento do Endotélio Vascular/metabolismo
3.
Histochem Cell Biol ; 136(3): 301-19, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21814837

RESUMO

Structural changes of podocytes and retraction of their foot processes are a critical factor in the pathogenesis of minimal change nephritis and glomerulosclerosis. Here we tested, if connective tissue growth factor (CTGF) is involved in podocyte injury during acute and chronic puromycin aminonucleoside nephrosis (PAN) as animal models of minimal change nephritis, and focal segmental glomerulosclerosis, respectively. Rats were treated once (acute PAN) or for 13 weeks (chronic PAN). In both experimental conditions, CTGF and its mRNA were found to be highly upregulated in podocytes. The upregulation correlated with onset and duration of proteinuria in acute PAN, and glomerulosclerosis and high expression of glomerular fibronectin, and collagens I, III, and IV in chronic PAN. In vitro, treatment of podocytes with recombinant CTGF increased amount and density of actin stress fibers, the expression of actin-associated molecules such as podocalyxin, synaptopodin, ezrin, and actinin-4, and activation of focal adhesion kinase (FAK) and extracellular signal-regulated kinase (ERK). Moreover, we observed increased podocyte expression of mRNA for transforming growth factor (TGF)-ß2, TGF-ß receptor II, fibronectin, and collagens I, III, and IV. Treatment of cultured podocytes with puromycin aminonucleoside resulted in loss of actin stress fibers and cell death, effects that were partially prevented when CTGF was added to the culture medium. Depletion of CTGF mRNA in cultured podocytes by RNA interference reduced both the number of actin stress fibers and the expression of actin-associated molecules. We propose that the expression of CTGF is acutely upregulated in podocytes as part of a cellular attempt to repair structural changes of the actin cytoskeleton. When the damaging effects on podocyte structure and function persist chronically, continuous CTGF expression in podocytes is a critical factor that promotes progressive accumulation of glomerular extracellular matrix and glomerulosclerosis.


Assuntos
Citoesqueleto de Actina/metabolismo , Fator de Crescimento do Tecido Conjuntivo/metabolismo , Matriz Extracelular/metabolismo , Glomerulosclerose Segmentar e Focal/metabolismo , Nefrose Lipoide/metabolismo , Podócitos/metabolismo , Animais , Morte Celular , Células Cultivadas , Fator de Crescimento do Tecido Conjuntivo/genética , Glomerulosclerose Segmentar e Focal/induzido quimicamente , Glomerulosclerose Segmentar e Focal/patologia , Humanos , Glomérulos Renais/metabolismo , Masculino , Nefrose Lipoide/induzido quimicamente , Nefrose Lipoide/patologia , Podócitos/patologia , Proteinúria/induzido quimicamente , Proteinúria/metabolismo , Puromicina Aminonucleosídeo , Interferência de RNA , RNA Mensageiro/metabolismo , Ratos , Ratos Wistar , Transfecção , Regulação para Cima
4.
Sci Rep ; 7(1): 14274, 2017 10 27.
Artigo em Inglês | MEDLINE | ID: mdl-29079753

RESUMO

Norrin is a secreted signaling molecule activating the Wnt/ß-catenin pathway. Since Norrin protects retinal neurons from experimental acute injury, we were interested to learn if Norrin attenuates chronic damage of retinal ganglion cells (RGC) and their axons in a mouse model of glaucoma. Transgenic mice overexpressing Norrin in the retina (Pax6-Norrin) were generated and crossed with DBA/2J mice with hereditary glaucoma and optic nerve axonal degeneration. One-year old DBA/2J/Pax6-Norrin animals had significantly more surviving optic nerve axons than their DBA/2J littermates. The protective effect correlated with an increase in insulin-like growth factor (IGF)-1 mRNA and an enhanced Akt phosphorylation in DBA/2J/Pax6-Norrin mice. Both mouse strains developed an increase in intraocular pressure during the second half of the first year and marked degenerative changes in chamber angle, ciliary body and iris structure. The degenerations were slightly attenuated in the chamber angle of DBA/2J/Pax6-Norrin mice, which showed a ß-catenin increase in the trabecular meshwork. We conclude that high levels of Norrin and the subsequent constitutive activation of Wnt/ß-catenin signaling in RGC protect from glaucomatous axonal damage via IGF-1 causing increased activity of PI3K-Akt signaling. Our results identify components of a protective signaling network preventing degeneration of optic nerve axons in glaucoma.


Assuntos
Axônios/patologia , Proteínas do Olho/metabolismo , Glaucoma/metabolismo , Glaucoma/patologia , Proteínas do Tecido Nervoso/metabolismo , Nervo Óptico/patologia , Animais , Modelos Animais de Doenças , Fator de Crescimento Insulin-Like I/metabolismo , Camundongos , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Células Ganglionares da Retina/metabolismo , Células Ganglionares da Retina/patologia , Transdução de Sinais
5.
PLoS One ; 9(4): e95546, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24751879

RESUMO

Wnt/ß-catenin signaling induced by the Norrin/Frizzled-4 pathway has been shown to improve capillary repair following oxygen induced retinopathy (OIR) in the mouse, a model for retinopathy of prematurity. Here we investigated if treatment with the monovalent cation lithium that has been shown to augment Wnt/ß-catenin signaling in vitro and in vivo has similar effects. In cultured human microvascular endothelial cells, LiCl as well as SB 216763, another small molecule that activates Wnt/ß-catenin signaling, induced proliferation, survival and migration, which are all common parameters for angiogenic properties in vitro. Moreover, treatment with both agents caused an increase in the levels of ß-catenin and their translocation to nuclei while quercetin, an inhibitor of Wnt/ß-catenin signaling, completely blocked the effects of LiCl on proliferation. In mice with OIR, intraperitonal or intravitreal treatment with LiCl markedly increased the retinal levels of ß-catenin, but did not improve capillary repair. In contrast, repair was significantly improved following intravitreal treatment with Norrin. The effects of LiCl on HDMEC in vitro have minor relevance for OIR in vivo, and the influence of the Norrin/Frizzled-4 pathway on capillary repair in OIR is not reproducible upon enhancing Wnt/ß-catenin signaling by LiCl treatment strongly indicating the presence of additional and essential mechanisms.


Assuntos
Cloreto de Lítio/farmacologia , Neovascularização Fisiológica/efeitos dos fármacos , Animais , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Derme/irrigação sanguínea , Células Endoteliais/citologia , Células Endoteliais/efeitos dos fármacos , Células Endoteliais/metabolismo , Proteínas do Olho/metabolismo , Humanos , Indóis/farmacologia , Injeções Intraperitoneais , Cloreto de Lítio/administração & dosagem , Maleimidas/farmacologia , Camundongos , Microvasos/citologia , Proteínas do Tecido Nervoso/metabolismo , Oxigênio , Retina/efeitos dos fármacos , Retina/metabolismo , Retina/patologia , Fator A de Crescimento do Endotélio Vascular/metabolismo , Via de Sinalização Wnt/efeitos dos fármacos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA