Oncostatina M, através da ativação de Shc1, é uma indutora da expressão de RANKL e diferenciação de osteoclastos mais potente do que o Fator Inibidor de Leucemia
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Data
2020-02-05
Autores
Marcelino, Thaís Floriano
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Reações inflamatórias crônicas próximas ao tecido ósseo geralmente levam à perda de estrutura tecidual, como no caso da artrite reumatoide e periodontite. Inúmeras citocinas foram identificadas como participantes do processo de modelação do tecido ósseo em condições inflamatórias, atuando diretamente em receptores presentes nas células ósseas. Citocinas da família gp130 (glicoproteína 130) são capazes de modular a formação de osteoclastos, bem como a sua atividade. Os membros dessa família sinalizam através da dimerização de receptores com a subunidade gp130 e caracteristicamente ativam STAT3 e MAPK. A Oncostatina M (OSM) é uma citocina única dentro da família gp130 já que seu receptor (OSMR) recruta a proteína adaptadora Shc1. Neste trabalho avaliamos o papel de Shc1 na reabsorção óssea induzida por OSM. Osteoblastos foram tratados com OSM e a ativação de Shc1 e STAT3 foi avaliada por PCR quantitativa e western blot. Para determinar a importância de Shc1 e STAT3 no aumento da expressão de RANKL e formação de osteoclastos induzida por OSM, utilizamos siRNA específico para Shc1 e STAT3 para silenciar esse mRNA e consequentemente reduzir os níveis destas proteínas. Os efeitos de OSM foram comparados aos de LIF (Fator Inibidor de Leucemia), por se tratar da citocina mais próxima a OSM dentro da família gp130. O tratamento de osteoblastos com OSM, mas não LIF, induziu aumento da expressão de mRNA e da fosforilação de Shc1. O silenciamento de Shc1 reduziu efeito indutor de OSM sobre a ativação de STAT3 e expressão de RANKL. O silenciamento de STAT3 não afetou a ativação de Shc1, mas suprimiu o aumento da expressão de RANKL induzida por OSM. Em co-culturas de osteoblastos e macrófagos OSM estimula a formação de osteoclastos, e o silenciamento de Shc1 ou STAT3 bloqueou esse efeito. Em osteoblastos da calvaria e células derivadas da medula óssea, OSM é um indutor mais potente do que LIF da reabsorção óssea e da formação de osteoclastos, respectivamente. Em conclusão, a proteína Shc1 é crucial para os efeitos de OSM na diferenciação de osteoclastos e reabsorção óssea. Esse mecanismo é dependente da fosforilação de ERK e STAT3.
Chronic inflammation near to bone tissue often lead to loss of tissue structure, as in the case of rheumatoid arthritis and periodontitis. Countless cytokines have been identified as participants in the process of bone tissue modeling under inflammatory conditions, acting directly on receptors present in bone cells. Cytokines of the gp130 (glycoprotein 130) can beable to modulate osteoclast formation as well as its activity. Members of this family signals through receptors dimerizing with the gp130 subunit and typically activates STAT3 and MAPK. Oncostatin M (OSM) is a unique cytokine within the gp130 family since receptor (OSMR) recruits the adapter protein Shc1. We have evaluated the role of Shc1 for OSM-induced bone resorption. Osteoblasts were treated with OSM and Shc1 and STAT3 activations were analyzed by quantitative PCR and western blot. To determine the role of Shc1 and STAT3 for OSM-induced RANKL expression and osteoclast formation we used siRNA targeting Shc1 and STAT3 to knock-down this mRNA and consequently reduce the proteins levels. The effects of OSM were compared to those of LIF (Leukemia Inhibitor Factor) because it is the closest cytokine to OSM within the gp130 family. Treatment of osteoblasts with OSM, but not LIF, induced increased mRNA expression and phosphorylation of Shc1. Silencing of STAT3 did not affect Shc1 activation, but suppressed OSM-induced increase in RANKL expression. In co-cultures of osteoblasts and macrophages OSM stimulates osteoclast formation, and silencing of Shc1 or STAT3 blocked this effect. In calvarial osteoblasts and bone marrow cells, respectively, OSM is a more potent inducer than LIF of bone resorption and osteoclast formation. In conclusion, the protein Shc1 is crucial for effects by OSM on osteoclasts differentiation and bone resorption. This mechanism is dependent of the phosphorylation of ERK and STAT3.
Chronic inflammation near to bone tissue often lead to loss of tissue structure, as in the case of rheumatoid arthritis and periodontitis. Countless cytokines have been identified as participants in the process of bone tissue modeling under inflammatory conditions, acting directly on receptors present in bone cells. Cytokines of the gp130 (glycoprotein 130) can beable to modulate osteoclast formation as well as its activity. Members of this family signals through receptors dimerizing with the gp130 subunit and typically activates STAT3 and MAPK. Oncostatin M (OSM) is a unique cytokine within the gp130 family since receptor (OSMR) recruits the adapter protein Shc1. We have evaluated the role of Shc1 for OSM-induced bone resorption. Osteoblasts were treated with OSM and Shc1 and STAT3 activations were analyzed by quantitative PCR and western blot. To determine the role of Shc1 and STAT3 for OSM-induced RANKL expression and osteoclast formation we used siRNA targeting Shc1 and STAT3 to knock-down this mRNA and consequently reduce the proteins levels. The effects of OSM were compared to those of LIF (Leukemia Inhibitor Factor) because it is the closest cytokine to OSM within the gp130 family. Treatment of osteoblasts with OSM, but not LIF, induced increased mRNA expression and phosphorylation of Shc1. Silencing of STAT3 did not affect Shc1 activation, but suppressed OSM-induced increase in RANKL expression. In co-cultures of osteoblasts and macrophages OSM stimulates osteoclast formation, and silencing of Shc1 or STAT3 blocked this effect. In calvarial osteoblasts and bone marrow cells, respectively, OSM is a more potent inducer than LIF of bone resorption and osteoclast formation. In conclusion, the protein Shc1 is crucial for effects by OSM on osteoclasts differentiation and bone resorption. This mechanism is dependent of the phosphorylation of ERK and STAT3.
Descrição
Palavras-chave
Oncostatina M, Fator Inibidor de Leucemia., Ligante RANK, Proteína 1 de Transformação que Contém Domínio 2 de Homologia de Src., Osteoclastos