Blood, Vol. 95 No. 2 (January 15), 2000:
pp. 721-723
BRIEF REPORT
Apo-transferrin is internalized and routed differently from
Fe-transferrin by Caco-2 cells: a confocal microscopy study of
vesicular transport in intestinal cells
Xavier Alvarez-Hernandez,
Margaret Smith, and
Jonathan Glass
From the Department of Medicine and Feist-Weiller Cancer Center,
Louisiana State University Medical Center, Shreveport, LA 71130.
Caco-2 cells grown as monolayers on porous membranes in bicameral
chambers have been used to study the transport of Fe from the apical
(lumenal) chamber to the basal (serosal) chamber. The transport of Fe
is stimulated by the presence of either apo-transferrin (apo-Tf) or
ferri-transferrin (Fe-Tf) in the basal chamber with the stimulation
occurring at much lower concentrations of apo-Tf than
Fe-Tf. To further explore the involvement of Tf in Fe transport across the basal surface, laser scanning confocal microscopy
with 3-dimensional reconstruction of the confocal images was used
to visualize the internalization of Texas Red-labeled apo-Tf and Bodipy-labeled Fe-Tf from the basal chamber. These studies show that
apo-Tf was readily internalized and routed preferentially to a
perinuclear region of the Caco-2 cells while internalized Fe-Tf stayed
preferentially below the nuclei. These findings suggest that intestinal
cells have a specialized mechanism to recognize and sort apo-Tf.
