摘要
AIM:To investigate whether the secretion of phospha-tidylcholine(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 po-larized 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 compart-ment was more effective,and the PC:Sph ratio in the ba-solateral compartment was signif icantly 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 secre-tion capacity of CaCo-2 cells and indicate two sepa-rated apical and basolateral release mechanisms.
AIM: To investigate whether the secretion of phospha- tidylcholine (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.
基金
Supported by A Grant From the Dietmar Hopp Foundation (Stremmel WR)
the Post-Doc programme of the Medical Faculty of the University of Heidelberg (Gotthardt D and Braun A)