Brief Article
Copyright ©2009 The WJG Press and Baishideng. All rights reserved.
World J Gastroenterol. Dec 14, 2009; 15(46): 5821-5826
Published online Dec 14, 2009. doi: 10.3748/wjg.15.5821
Separate basolateral and apical phosphatidylcholine secretion routes in intestinally differentiated tumor cells
Daniel Gotthardt, Annika Braun, Anke Tietje, Karl Heinz Weiss, Robert Ehehalt, Wolfgang R Stremmel
Daniel Gotthardt, Annika Braun, Anke Tietje, Karl Heinz Weiss, Robert Ehehalt, Wolfgang R Stremmel, Department of Gastroenterology, University Hospital Heidelberg, 69120 Heidelberg, Germany
Author contributions: Gotthardt D and Braun A contributed equally to this work, Gotthardt D, Ehehalt R and Stremmel WR designed the research; Gotthardt D, Braun A, Tietje A, Weiss KH performed the research; Gotthardt D, Braun A, Ehehalt R and Stremmel WR analyzed the data; Gotthardt D, Braun A and Stremmel WR wrote the manuscript.
Supported by A Grant From the Dietmar Hopp Foundation (Stremmel WR) and the Post-Doc programme of the Medical Faculty of the University of Heidelberg (Gotthardt D and Braun A)
Correspondence to: Wolfgang R Stremmel, Professor, Department of Gastroenterology, University Hospital Heidelberg, Im Neuenheimer Feld 410, 69120 Heidelberg, Germany. wolfgang_stremmel@med.uni-heidelberg.de
Telephone: +49-6221-568705 Fax: +49-6221-564116
Received: August 4, 2009
Revised: September 14, 2009
Accepted: September 21, 2009
Published online: December 14, 2009
Abstract

AIM: To investigate whether the secretion of phosphatidylcholine (PC) in intestinal mucus occurs by apical secretion or via basolateral excretion and to determine its subsequent passage across the tight junctions to the apical mucus.

METHODS: We addressed this question using the polarized intestinally differentiated tumor cell line CaCo-2 grown on filters to confluence in Transwell culture chambers. The released PC and sphingomyelin (Sph) from apical and basolateral media were analyzed by mass spectrometry.

RESULTS: The secreted PC species were identical in both compartments indicating the same intracellular origin of PC. However, PC secretion into the basolateral compartment was more effective, and the PC:Sph ratio in the basolateral compartment was significantly higher than that in the apical compartment (8.18 ± 1.84 vs 4.31 ± 1.22, P = 0.01). Both pathways were temperature sensitive and were unaltered in the presence of cyclosporine.

CONCLUSION: The data demonstrate the PC secretion capacity of CaCo-2 cells and indicate two separated apical and basolateral release mechanisms.

Keywords: CaCo-2 cells; Epithelial cells; Mass spectrometry; Phosphatidylcholine; Secretion; Sphingomyelin