Incorporation of cholesterol in sphingomyelin-phosphatidylcholine vesicles has profound effects on detergent-induced phase transitions

Antonio Moschetta, Peter M. Frederik, Piero Portincasa, Gerard P. VanBerge-Henegouwen, Karel J. Van Erpecum

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

Vesicle micelle transitions are important phenomena during bile formation and intestinal lipid processing. The hepatocyte canalicular membrane outer leaflet contains appreciable amounts of phosphatidylcholine (PC) and sphingomyelin (SM), and both phospholipids are found in the human diet. Dietary SM enrichment inhibits intestinal cholesterol absorption. We therefore studied detergent-induced vesicle micelle transitions in SM-PC vesicles. Phase transitions were evaluated by spectrophotometry and cryotransmission electron microscopy (cryo-TEM) after addition of taurocholate (3-7 mM) to SM-PC vesicles (4 mM phospholipid, SM/PC 40%/60%, without or with 1.6 mM cholesterol). After addition of excess (5-7 mM) taurocholate, SM-PC vesicles were more sensitive to micellization than PC vesicles. As shown by sequential cryo-TEM, addition of equimolar (4 mM) taurocholate to SM-PC vesicles induced formation of open vesicles, then (at the absorbance peak) fusion of bilayer fragments into large open structures (around 200 nm diameter) coexisting with some multilamellar or fused vesicles and thread-like micelles and, finally, transformation into an uniform picture with long thread-like micelles. Incorporation of cholesterol in the SM/PC bilayer changed initial vesicular shape from spherical into ellipsoid and profoundly increased detergent resistance. Disk-like micelles and multilamellar vesicles, and then extremely large vesicular structures, were observed by sequential cryo-TEM under these circumstances, with persistently increased absorbance values by spectrophotometry. These findings may be relevant for bile formation and intestinal lipid processing. Inhibition of intestinal cholesterol absorption by dietary SM enrichment may relate to high resistance against bile salt-induced micellization of intestinal lipids in presence of the sphingolipid.

Original languageEnglish (US)
Pages (from-to)1046-1053
Number of pages8
JournalJournal of Lipid Research
Volume43
Issue number7
DOIs
StatePublished - 2002

Fingerprint

Sphingomyelins
Phase Transition
Phosphatidylcholines
Detergents
Phase transitions
Cholesterol
Micelles
Taurocholic Acid
Electron microscopy
Electron Microscopy
Micellization
Spectrophotometry
Intestinal Absorption
Lipids
Bile
Phospholipids
Dietary Cholesterol
Sphingolipids
Nutrition
Processing

Keywords

  • Micelles
  • Spectrophotometry
  • Taurocholate

ASJC Scopus subject areas

  • Endocrinology

Cite this

Incorporation of cholesterol in sphingomyelin-phosphatidylcholine vesicles has profound effects on detergent-induced phase transitions. / Moschetta, Antonio; Frederik, Peter M.; Portincasa, Piero; VanBerge-Henegouwen, Gerard P.; Van Erpecum, Karel J.

In: Journal of Lipid Research, Vol. 43, No. 7, 2002, p. 1046-1053.

Research output: Contribution to journalArticle

Moschetta, Antonio ; Frederik, Peter M. ; Portincasa, Piero ; VanBerge-Henegouwen, Gerard P. ; Van Erpecum, Karel J. / Incorporation of cholesterol in sphingomyelin-phosphatidylcholine vesicles has profound effects on detergent-induced phase transitions. In: Journal of Lipid Research. 2002 ; Vol. 43, No. 7. pp. 1046-1053.
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