Surfactant protein C: hormonal control of SP-C mRNA levels in vitro.
We have studied hormonal regulation of the surfactant protein C (SP-C) in fetal 18-dah rat lung explants. SP-C mRNA was detected in Northern blots with a specific rat SP-C cDNA probe and quantified by densitometry. Treatment of the explants with dexamethasone resulted in a dose-dependent increase of the SP-C mRNA level. Transcriptional assays have shown that the regulation of SP-C mRNA by dexamethasone involves a transcriptional step. Administration of the cAMP analogues, 8-bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP) or dibutyryl adenosine 3',5'-cyclic monophosphate (DBcAMP), produced a dose-dependent increase of SP-C mRNA levels, with maximum stimulation observed at 200 microM. The thyroid hormone T3 had no effect on SP-C mRNA levels, whether administered alone or in combination with dexamethasone. Variation in the effects of the above hormones on three surfactant protein mRNAs, SP-A, SP-B and SP-C, indicates that the hormonal regulation of the surfactant proteins is a complex process and that each gene is, in part, differentially regulated.
Veletza
S V
SV
Department of Pediatrics, Harvard Medical School, Boston, Massachusetts 02115.
Nichols
K V
KV
Gross
I
I
Lu
H
H
Dynia
D W
DW
Floros
J
J
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology*; D000704:Analysis of Variance; D000818:Animals; D001483:Base Sequence; D003994:Bucladesine / Q000494:pharmacology*; D002467:Cell Nucleus / Q000187:drug effects / Q000502:physiology*; D003001:Cloning, Molecular; D003907:Dexamethasone / Q000494:pharmacology*; D005333:Fetus; D015723:Gene Library; D006801:Humans; D007700:Kinetics; D008168:Lung / Q000187:drug effects / Q000502:physiology*; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D009924:Organ Culture Techniques; D011510:Proteolipids / Q000235:genetics* / Q000378:metabolism; D011663:Pulmonary Surfactants / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D014158:Transcription, Genetic / Q000187:drug effects*
D015345:Oligonucleotide Probes; D011510:Proteolipids; D011663:Pulmonary Surfactants; D012333:RNA, Messenger; D015124:8-Bromo Cyclic Adenosine Monophosphate; D003994:Bucladesine; D003907:Dexamethasone