Transcriptional repression of the CTP:phosphocholine cytidylyltransferase gene by sphingosine

Biochem J. 2004 Sep 1;382(Pt 2):741-50. doi: 10.1042/BJ20040105.

Abstract

We examined the effects of the bioactive lipid, sphingosine, on the expression of the rate-limiting enzyme involved in surfactant phosphatidylcholine synthesis, CCTalpha (CTP:phosphocholine cytidylyltransferase alpha). Sphingosine decreased phosphatidylcholine synthesis by inhibiting CCT activity in primary alveolar type II epithelia. Sphingosine decreased CCTalpha protein and mRNA levels by approx. 50% compared with control. The bioactive lipid did not alter CCTalpha mRNA stability, but significantly inhibited its transcriptional rate. In murine lung epithelia, sphingosine selectively reduced CCTalpha promoter-reporter activity when transfected with a 2 kb CCTalpha promoter/luciferase gene construct. Sphingosine also decreased transgene expression in murine type II epithelia isolated from CCTalpha promoter-reporter transgenic mice harbouring this 2 kb proximal 5'-flanking sequence. Deletional analysis revealed that sphingosine responsiveness was mapped to a negative regulatory element contained within 814 bp upstream of the coding region. The results indicate that bioactive sphingolipid metabolites suppress surfactant lipid synthesis by inhibiting gene transcription of a key surfactant biosynthetic enzyme.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Choline-Phosphate Cytidylyltransferase / genetics*
  • Enzyme Induction / drug effects
  • Enzyme Induction / genetics
  • Epithelial Cells / enzymology
  • Gene Expression Regulation, Enzymologic / drug effects*
  • Gene Expression Regulation, Enzymologic / genetics
  • Mice
  • Pulmonary Alveoli / cytology
  • Pulmonary Alveoli / enzymology
  • RNA, Messenger / biosynthesis
  • RNA, Messenger / metabolism
  • Rats
  • Respiratory Mucosa / cytology
  • Respiratory Mucosa / enzymology
  • Sphingosine / pharmacology*
  • Transcription, Genetic / drug effects*
  • Transcription, Genetic / genetics

Substances

  • RNA, Messenger
  • Choline-Phosphate Cytidylyltransferase
  • Sphingosine