AJP - Lung Cellular and Molecular Physiology, Vol 267, Issue 1 16-L24, Copyright © 1994 by American Physiological Society
3'-untranslated region of SP-B mRNA mediates inhibitory effects of TPA and TNF-alpha on SP-B expression
G. S. Pryhuber, S. L. Church, T. Kroft, A. Panchal and J. A. Whitsett
Division of Pulmonary Biology, Children's Hospital Medical Center, Cincinnati, Ohio 45229-3039.
Surfactant protein-B (SP-B) is a small hydrophobic polypeptide that
enhances spreading and stability of surfactant phospholipids in the
alveolus of the lung. Decreased expression of SP-B is associated with
respiratory failure in premature infants and in adult patients with acute
respiratory distress syndrome (ARDS). Tumor necrosis factor-alpha
(TNF-alpha) and 12-O-tetradecanoylphorbol-13 acetate (TPA) cause ARDS-like
lung injury in vivo. Inhibitory effects of TPA and TNF-alpha on SP-B mRNA
expression in vitro were mediated by decreased SP-B mRNA stability rather
than by decreased rate of SP-B gene transcription. In the present study, a
human pulmonary adenocarcinoma cell line, NCI H441-4, was stably
transfected with expression vectors consisting of the thymidine kinase (TK)
promotor and human growth hormone (hGH) gene, in which the hGH
3'-untranslated region (3'-UTR) was replaced by the 2.0-kb human SP-B cDNA
[pTKGH(SP-B2.0)] or the 837-bp human SP-B 3'-UTR [pTKGH(SP-B.837)]. The
mRNAs and cellular growth hormone protein generated from the chimeric
TKGH(SP-B2.0) and TKGH(SP-B.837) genes were each inhibited by approximately
50% by TPA and TNF-alpha. Dexamethasone decreased the inhibitory effects of
TPA and TNF-alpha. The inhibition of steady-state hGH-SP-B mRNA by TPA and
TNF-alpha was mediated by a cis-active element located in the 3-UTR region
of SP-B mRNA.
