AJP - Lung Cellular and Molecular Physiology, Vol 269, Issue 2 241-L247, Copyright © 1995 by American Physiological Society
Correlation of expression of transcription factor C/EBP alpha and surfactant protein genes in lung cells
F. Li, E. Rosenberg, C. I. Smith, K. Notarfrancesco, S. R. Reisher, H. Shuman and S. I. Feinstein
Institute for Environmental Medicine, University of Pennsylvania School of Medicine, Philadelphia 19104, USA.
C/EBP alpha is a transcription factor which can stimulate expression of
genes in lipid-metabolizing epithelial cells. We have detected an increase
in mRNA for C/EBP alpha in lungs of fetal rats between days 18 and 20 of
gestation, correlating with events occurring during the maturation of the
surfactant system, such as an increase in the amount of surfactant protein
A mRNA. We have found that C/EBP alpha mRNA levels are substantially
enriched in type II alveolar epithelial cells purified from adult lung and
that the C/EBP alpha protein is present in type II cell nuclei. When the
type II cells are removed from the lung and purified, the protein is
rapidly lost. However, both surfactant protein gene expression and C/EBP
alpha reappear when cells are plated on Matrigel. Levels of C/EBP alpha
mRNA from purified cells decline much more slowly than the protein and are
still detectable 48 h after cells have been plated on standard tissue
culture plastic. We have also detected the C/EBP alpha protein in nuclear
extracts of NCI-H441, a lung-derived cell line that expresses surfactant
proteins A and B, but not in A549, a lung-derived cell line which does not
express the surfactant proteins. Our data suggest that C/EBP alpha is
involved in the development and maintenance of the surfactant system in
lung type II cells.
