Lipid deprivation increases surfactant phosphatidylcholine synthesis via a sterol-sensitive regulatory element within the CTP: Phosphocholine cytidylyltransferase promoter

Rama K. Mallampalli, Alan J. Ryan, James L. Carroll, Timothy F. Osborne, Christie P. Thomas

Research output: Contribution to journalArticlepeer-review

Abstract

Lipid-deprived mice increase alveolar surfactant disaturated phosphatidylcholine (DSPtdCho) synthesis compared with mice fed a standard diet by increasing expression of CTP:phosphocholine cytidylyltransferase (CCT), the rate-limiting enzyme for DSPtdCho synthesis. We previously observed that lipid deprivation increases mRNA synthesis for CCT [Ryan, McCoy, Mathur, Field and Mallampalli (2000) J. Lipid Res. 41, 1268-1277]. To evaluate regulatory mechanisms for this gene, we cloned the proximal ∼ 1900 bp of the 5′ flanking sequence of the murine CCT gene, coupled this to a luciferase reporter, and examined transcriptional regulation in a murine alveolar epithelial type II cell line (MLE- 12). The core promoter was localized to a region between - 169 and + 71 bp, which exhibited strong basal activity comparable with the simian virus 40 promoter. The full-length construct, from - 1867 to + 71, was induced 2-3-fold when cells were cultured in lipoprotein-deficient serum (LPDS), similar to the level of induction of the endogenous CCT gene. By deletional analysis the sterol regulatory element (SRE) was localized within a 240 bp region. LPDS activation of the CCT promoter was abolished by mutation of this SRE, and gel mobility-shift assays demonstrated specific binding of recombinant SRE-binding protein to this element within the CCT promoter. These observations indicate that sterol-regulated expression of CCT is mediated by an SRE within its 5′ flanking region.

Original languageEnglish (US)
Pages (from-to)81-88
Number of pages8
JournalBiochemical Journal
Volume362
Issue number1
DOIs
StatePublished - Feb 15 2002
Externally publishedYes

Keywords

  • Cholesterol
  • Lipoproteins
  • Sterol regulatory element
  • Transcription

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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