The choline-depleted type II pneumocyte. A model for investigating the synthesis of surfactant lipids

M. M. Anceschi, G. C. Di Renzo, M. D. Venincasa, J. E. Bleasdale

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

When type II pneumocytes from adult rats were maintained in a medium that lacked choline, the incorporation of [14C]glycerol into phosphatidylcholine was not greatly diminished during the period that the cells displayed characteristics of type II pneumocytes. Cells that were maintained in choline-free medium that contained choline oxidase and catalase, however, became depleted of choline and subsequent synthesis of phosphatidylcholine by these cells was responsive to choline in the extracellular medium. Incorporation of [14C]glycerol into phosphatidylcholine by choline-depleted cells was stimulated maximally (approx. 6-fold) by extracellular choline at a concentration (0.05 mM) that also supported the greatest incorporation into phosphatidylglycerol. The incorporation of [14C]glycerol into other glycerophospholipids by choline-depleted cells was not increased by extracellular choline. When cells were incubated in the presence of [3H]cytidine, the choline-dependent stimulation of the synthesis of phosphatidylcholine and phosphatidylglycerol was accompanied by an increased recovery of [3H]CMP. This increased recovery of [3H]CMP reflected an increase in the intracellular amount of CMP from 48±9 to 76±16 pmol/106 cells. Choline-depleted cells that were exposed to [3H]choline contained [3H]CDP-choline as the principal water-soluble choline derivative. As the extracellular concentration of choline was increased, however, the amount of 3H in phosphocholine greatly exceeded that in all other water-soluble derivatives. Choline-depletion of cells resulted in an increase in the specific activity of CTP:phosphocholine cytidylyltransferase in cell homogenates (from 0.40±0.15 to 1.31±0.20 nmol.min-1.mg of protein-1). These data are indicative that the biosynthesis of phosphatidylcholine is integrated with that of phosphatidylglycerol and are consistent with the proposed involvement of CMP in this integration. The choline-depleted type II pneumonocyte provides a new model for investigating the regulation of CTP:phosphocholine cytidylyltransferase activity.

Original languageEnglish (US)
Pages (from-to)253-262
Number of pages10
JournalBiochemical Journal
Volume224
Issue number1
DOIs
StatePublished - Jan 1 1984

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Alveolar Epithelial Cells
Choline
Surface-Active Agents
Lipids
Phosphatidylcholines
Cytidine Monophosphate
Phosphatidylglycerols
Choline-Phosphate Cytidylyltransferase
Glycerol
choline oxidase
Cytidine Diphosphate Choline
Derivatives
Recovery
Cytidine
Phosphorylcholine
Water
Biosynthesis
Catalase

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

The choline-depleted type II pneumocyte. A model for investigating the synthesis of surfactant lipids. / Anceschi, M. M.; Di Renzo, G. C.; Venincasa, M. D.; Bleasdale, J. E.

In: Biochemical Journal, Vol. 224, No. 1, 01.01.1984, p. 253-262.

Research output: Contribution to journalArticle

Anceschi, M. M. ; Di Renzo, G. C. ; Venincasa, M. D. ; Bleasdale, J. E. / The choline-depleted type II pneumocyte. A model for investigating the synthesis of surfactant lipids. In: Biochemical Journal. 1984 ; Vol. 224, No. 1. pp. 253-262.
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abstract = "When type II pneumocytes from adult rats were maintained in a medium that lacked choline, the incorporation of [14C]glycerol into phosphatidylcholine was not greatly diminished during the period that the cells displayed characteristics of type II pneumocytes. Cells that were maintained in choline-free medium that contained choline oxidase and catalase, however, became depleted of choline and subsequent synthesis of phosphatidylcholine by these cells was responsive to choline in the extracellular medium. Incorporation of [14C]glycerol into phosphatidylcholine by choline-depleted cells was stimulated maximally (approx. 6-fold) by extracellular choline at a concentration (0.05 mM) that also supported the greatest incorporation into phosphatidylglycerol. The incorporation of [14C]glycerol into other glycerophospholipids by choline-depleted cells was not increased by extracellular choline. When cells were incubated in the presence of [3H]cytidine, the choline-dependent stimulation of the synthesis of phosphatidylcholine and phosphatidylglycerol was accompanied by an increased recovery of [3H]CMP. This increased recovery of [3H]CMP reflected an increase in the intracellular amount of CMP from 48±9 to 76±16 pmol/106 cells. Choline-depleted cells that were exposed to [3H]choline contained [3H]CDP-choline as the principal water-soluble choline derivative. As the extracellular concentration of choline was increased, however, the amount of 3H in phosphocholine greatly exceeded that in all other water-soluble derivatives. Choline-depletion of cells resulted in an increase in the specific activity of CTP:phosphocholine cytidylyltransferase in cell homogenates (from 0.40±0.15 to 1.31±0.20 nmol.min-1.mg of protein-1). These data are indicative that the biosynthesis of phosphatidylcholine is integrated with that of phosphatidylglycerol and are consistent with the proposed involvement of CMP in this integration. The choline-depleted type II pneumonocyte provides a new model for investigating the regulation of CTP:phosphocholine cytidylyltransferase activity.",
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