Identification and characterization of rodent ABCA1 in isolated type II pneumocytes

Anna E. Bortnick, Elda Favari, Jian Qin Tao, Omar L. Francone, Muredach Reilly, Yuzhen Zhang, George H. Rothblat, Sandra R. Bates

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46 Scopus citations

Abstract

ATP-binding cassette transporter A1 (ABCA1) promotes transfer of cholesterol and phospholipid from cells to lipid-free serum apolipoproteins. ABCA1 mRNA and protein expression in primary cultures of rodent type II cells was sensitive to upregulation with 5 μM 9-cis-retinoic acid (9cRA) and 6.2 μM 22-hydroxycholesterol (22-OH). The increase in ABCA1 protein levels was time dependent and was maximal after 16 h of exposure to 9cRA + 22-OH. Inducible ABCA1 was also found in transformed cell lines of lung origin: WI38/VA13, A549, and NIH-H441 cells. Stimulation of ABCA1 in rat type II cells by 9cRA + 22-OH resulted in a four- or fivefold enhancement of efflux of radioactive phospholipid or cholesterol, respectively, from the pneumocytes to apolipoprotein AI (apo AI), whereas cAMP (0.3 mM) had no effect. ABCA1-mediated lipid efflux to apo AI was independent of the surfactant secretion pathway, inasmuch as upregulation of ABCA1 resulted in a reduction of secretagogue-stimulated surfactant phospholipid release. These studies demonstrate the presence of functional ABCA1 in type II cells from the lung.

Original languageEnglish (US)
Pages (from-to)L869-L878
JournalAmerican Journal of Physiology - Lung Cellular and Molecular Physiology
Volume285
Issue number4 29-4
StatePublished - Oct 1 2003

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Keywords

  • Cholesterol
  • Lung
  • Phospholipid
  • Reverse cholesterol transport
  • Surfactant secretion

ASJC Scopus subject areas

  • Physiology
  • Pulmonary and Respiratory Medicine
  • Physiology (medical)
  • Cell Biology

Cite this

Bortnick, A. E., Favari, E., Tao, J. Q., Francone, O. L., Reilly, M., Zhang, Y., Rothblat, G. H., & Bates, S. R. (2003). Identification and characterization of rodent ABCA1 in isolated type II pneumocytes. American Journal of Physiology - Lung Cellular and Molecular Physiology, 285(4 29-4), L869-L878.