@article{FehrholzSeidenspinnerKunzmann2017,
  author    = {Fehrholz, Markus and Seidenspinner, Silvia and Kunzmann, Steffen},
  title     = {Expression of surfactant protein B is dependent on cell density in H441 lung epithelial cells},
  series = {PLoS ONE},
  volume    = {12},
  journal   = {PLoS ONE},
  number    = {9},
  doi       = {10.1371/journal.pone.0184556},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-158291},
  pages     = {e0184556},
  year      = {2017},
  abstract  = {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.},
  language  = {en}
}
@article{FehrholzChristianPKunzmann2014,
  author    = {Fehrholz, Markus and Christian P., Speer and Kunzmann, Steffen},
  title     = {Caffeine and Rolipram Affect Smad Signalling and TGFβ1 Stimulated CTGF and Transgelin Expression in Lung Epithelial Cells},
  series = {PLoS One},
  volume    = {9},
  journal   = {PLoS One},
  number    = {5},
  doi       = {10.1371/journal.pone.0097357},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-118406},
  pages     = {e97357},
  year      = {2014},
  abstract  = {Caffeine administration is an important part of the therapeutic treatment of bronchopulmonary dysplasia (BPD) in preterm infants. However, caffeine mediated effects on airway remodelling are still undefined. The TGF-β/Smad signalling pathway is one of the key pathways involved in airway remodelling. Connective tissue growth factor (CTGF), a downstream mediator of TGF-β, and transgelin, a binding and stabilising protein of the cytoskeleton, are both regulated by TGF-b1 and play an important role in airway remodelling. Both have also been implicated in the pathogenesis of BPD. The aim of the present study was to clarify whether caffeine, an unspecific phosphodiesterase (PDE) inhibitor, and rolipram, a prototypical PDE-4 selective inhibitor, were both able to affect TGF-β1-induced Smad signalling and CTGF/transgelin expression in lung epithelial cells. Furthermore, the effect of transgelin knock-down on Smad signalling was studied. The pharmacological effect of caffeine and rolipram on Smad signalling was investigated by means of a luciferase assay via transfection of a TGFβ1- inducible reporter plasmid in A549 cells. The regulation of CTGF and transgelin expression by caffeine and rolipram were studied by promoter analysis, real-time PCR and Western blot. Endogenous transgelin expression was down-regulated by lentiviral transduction mediating transgelin-specific shRNA expression. The addition of caffeine and rolipram inhibited TGFβ1 induced reporter gene activity in a concentration-related manner. They also antagonized the TGF-b1 induced upregulation of CTGF and transgelin on the promoter-, the mRNA-, and the protein-level. Functional analysis showed that transgelin silencing reduced TGF-β1 induced Smad-signalling and CTGF induction in lung epithelial cells. The present study highlights possible new molecular mechanisms of caffeine and rolipram including an inhibition of Smad signalling and of TGF-β1 regulated genes involved in airway remodelling. An understanding of these mechanisms might help to explain the protective effects of caffeine in prevention of BPD and suggests rolipram to be a potent replacement for caffeine.},
  language  = {en}
}