Respiratory syncytial virus infection alters surfactant protein A expression in human pulmonary epithelial cells by reducing translation efficiency.
Am J Physiol Lung Cell Mol Physiol
; 297(4): L559-67, 2009 Oct.
Article
em En
| MEDLINE
| ID: mdl-19525387
ABSTRACT
Infection of neonatal lung by respiratory syncytial virus (RSV) is a common cause of respiratory dysfunction. Lung alveolar type II and bronchiolar epithelial (Clara) cells secrete surfactant protein A (SP-A), a collectin that is an important component of the pulmonary innate immune system. SP-A binds to the virus, targeting the infectious agent for clearance by host defense mechanisms. We have previously shown that while the steady-state level of SP-A mRNA increases approximately threefold after RSV infection, steady-state levels of cellular and secreted SP-A protein decrease 40-60% in human type II cells in primary culture, suggesting a mechanism where the virus alters components of the innate immune response in infected cells. In these studies, we find that changes in SP-A mRNA and protein levels in RSV-infected NCI-H441 cells (a bronchiolar epithelial cell line) recapitulate the results in SP-A expression observed in primary lung cells. While SP-A protein is normally ubiquitinated, there is no change in the level of SP-A protein ubiquitination or proteasome activity during RSV infection, suggesting that the reduced levels of SP-A protein are not due to degradation by activated proteasomes. SP-A mRNA is appropriately processed and exported from the nucleus to the cytoplasm during RSV infection. As evidenced by polysome analysis of SP-A mRNA and pulse-chase analysis of newly synthesized SP-A protein, we find a decrease in translational efficiency that is specific for SP-A mRNA. Therefore, the decrease in SP-A protein levels observed after RSV infection of pulmonary bronchiolar epithelial cells results from a mechanism that affects SP-A mRNA translation efficiency.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Biossíntese de Proteínas
/
RNA Mensageiro
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Infecções por Vírus Respiratório Sincicial
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Proteína A Associada a Surfactante Pulmonar
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Células Epiteliais
/
Pulmão
Limite:
Humans
Idioma:
En
Revista:
Am J Physiol Lung Cell Mol Physiol
Assunto da revista:
BIOLOGIA MOLECULAR
/
FISIOLOGIA
Ano de publicação:
2009
Tipo de documento:
Article
País de afiliação:
Estados Unidos