Effects of TNF-alpha and phorbol ester on human surfactant protein and MnSOD gene transcription in vitro.
Tumor necrosis factor-alpha (TNF-alpha) and the phorbol ester, 12-O-tetradecanoyl-phorbol-13-acetate (TPA) decrease the synthesis of surfactant proteins association with decreased SP-A and SP-B mRNA. Nuclear run-on assays were utilized to test whether the inhibitory effects of TNF-alpha and TPA were associated with changes in surfactant protein gene transcription. SP-A gene transcription was inhibited by both TNF-alpha and TPA as assessed by nuclear run-on assays. Inhibitory effects of both agents on SP-A gene transcription were readily detected within 6 h after exposure and persisted for 24 h. While TNF-alpha and TPA decreased cellular SP-B mRNA content, transcription of the SP-B gene was not influenced by these agents. In contrast to the inhibitory effects of TPA and TNF-alpha on SP-A and SP-B mRNAs, steady-state mRNA and rate of transcription of human manganese superoxide dismutase (MnSOD) were increased by both agents. The time course and extent of increased MnSOD gene transcription by TNF-alpha and TPA were distinct. Transcription of the human beta-actin gene was not altered by either agent. The inhibitory effects of TPA and TNF-alpha on SP-A expression in pulmonary adenocarcinoma cells are associated with the inhibition of SP-A gene transcription. Loss of SP-B mRNA was not accompanied by decreased SP-B gene transcription. Actinomycin D blocked the inhibitory effects of TNF-alpha and TPA on SP-A and SP-B mRNA, supporting a role for posttranscriptional events in the modulation of the expression of the surfactant proteins SP-A and SP-B.
Whitsett
J A
JA
Division of Pulmonary Biology, Children's Hospital Medical Center, Cincinnati, Ohio 45229.
Clark
J C
JC
Wispé
J R
JR
Pryhuber
G S
GS
D000230:Adenocarcinoma; D015152:Blotting, Northern; D002460:Cell Line; D002467:Cell Nucleus / Q000187:drug effects / Q000502:physiology*; D003001:Cloning, Molecular; D004273:DNA, Neoplasm / Q000235:genetics / Q000302:isolation & purification; D003609:Dactinomycin / Q000494:pharmacology; D005796:Genes / Q000187:drug effects; D006801:Humans; D007527:Isoenzymes / Q000235:genetics*; D007700:Kinetics; D008175:Lung Neoplasms; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013482:Superoxide Dismutase / Q000235:genetics*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D014158:Transcription, Genetic / Q000187:drug effects*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D004273:DNA, Neoplasm; D007527:Isoenzymes; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D003609:Dactinomycin; D013482:Superoxide Dismutase; D013755:Tetradecanoylphorbol Acetate