Background: Expression of surfactant protein (SP)-B, which assures the structural stability of the pulmonary surfactant film, is influenced by various stimuli, including glucocorticoids; however, the role that cell-cell contact plays in SP-B transcription remains unknown. The aim of the current study was to investigate the impact of cell-cell contact on SP-B mRNA and mature SP-B expression in the lung epithelial cell line H441.
Methods: Different quantities of H441 cells per growth area were either left untreated or incubated with dexamethasone. The expression of SP-B, SP-B transcription factors, and tight junction proteins were determined by qPCR and immunoblotting. The influence of cell density on SP-B mRNA stability was investigated using the transcription inhibitor actinomycin D.
Results: SP-B mRNA and mature SP-B expression levels were significantly elevated in untreated and dexamethasone-treated H441 cells with increasing cell density. High cell density as a sole stimulus was found to barely have an impact on SP-B transcription factor and tight junction mRNA levels, while its stimulatory ability on SP-B mRNA expression could be mimicked using SP-B-negative cells. SP-B mRNA stability was significantly increased in high-density cells, but not by dexamethasone alone.
Conclusion: SP-B expression in H441 cells is dependent on cell-cell contact, which increases mRNA stability and thereby potentiates the glucocorticoid-mediated induction of transcription. Loss of cell integrity might contribute to reduced SP-B secretion in damaged lung cells via downregulation of SP-B transcription. Cell density-mediated effects should thus receive greater attention in future cell culture-based research.
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Environ Sci Technol
July 2024
Radiation Biology & Health Sciences Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India.
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The Ritchie Centre, Hudson Institute of Medical Research, Clayton, Victoria, Australia.
Extremely preterm infants are often exposed to long durations of mechanical ventilation to facilitate gas exchange, resulting in ventilation-induced lung injury (VILI). New lung protective strategies utilizing noninvasive ventilation or low tidal volumes are now common but have not reduced rates of bronchopulmonary dysplasia. We aimed to determine the effect of 24 h of low tidal volume ventilation on the immature lung by ventilating preterm fetal sheep in utero.
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Department of Pediatrics, The First Affiliated Hospital of Air Force Military Medical University, Xi'an, China.
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February 2024
Paris-Saclay University, UVSQ, UFR-SVS, UMR1198-BREED-RHuMA, 2 avenue de la source de la Bièvre, 78180, Montigny le Bretonneux, France; Poissy St Germain Hospital, Neonatal Intensive Care Unit, Poissy, France. Electronic address:
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April 2023
Research and Innovation Unit, Health University of Applied Sciences Tyrol/FH Gesundheit Tirol, 6020 Innsbruck, Austria.
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