TY - JOUR
T1 - Filipin and digitonin studies of cell membrane changes during junction breakdown in the dystrophic rat retinal pigment epithelium
AU - Caldwell, Ruth B.
N1 - Funding Information:
ACKNOWLEDGEMENTS The excellent technical assistance of Ms. S. M. Slapnick and Mr. D. Lum and the helpful suggestions of Drs. B. J. McLaughlin, B. I. Tarnowski and N. G. F. Cooper are gratefully acknowledged. This work was supported by NIH Grant EY04618.
PY - 1987
Y1 - 1987
N2 - We have previously found that a breakdown of tight junctions in retinal pigment epithelial cells of Royal College of Surgeons' rats is associated with a redistribution of intramembrane particles and Na-K-ATPase activity. Changes in the lipid and sterol composition of membranes can alter their fluidity, permeability and enzyme activity, and may contribute to changes in cell barrier function in the dystrophic epithelium. We have now used filipin and digitonin, which bind to membrane sterols and produce membrane deformations recognizable by freeze-fracture and thin-section electron microscopy, to study the distribution of cholesterol and related 3-B-hydroxysterols in the dystrophic epithelium. The results of these studies show that in the normal pigment epithelium and prior to tight junction breakdown in the dystrophic epithelium, filipinand digitoninsterol complexes are rare in the membranes between tight junctions and adhering junctions, and in areas of attachment between the plasma membrane and basal lamina. Complexes are more numerous in the basal infoldings, and most densely packed in the lateral and apical microvillous membranes. During junction breakdown, complexes increase substantially in apical, basal, junctional, and nuclear membranes. Later, after the junctions disappear, complexes decrease. These results indicate that alterations in the expression of membrane sterols accompany the changes in structure and function of tight junctions in the dystrophic retinal pigment epithelium.
AB - We have previously found that a breakdown of tight junctions in retinal pigment epithelial cells of Royal College of Surgeons' rats is associated with a redistribution of intramembrane particles and Na-K-ATPase activity. Changes in the lipid and sterol composition of membranes can alter their fluidity, permeability and enzyme activity, and may contribute to changes in cell barrier function in the dystrophic epithelium. We have now used filipin and digitonin, which bind to membrane sterols and produce membrane deformations recognizable by freeze-fracture and thin-section electron microscopy, to study the distribution of cholesterol and related 3-B-hydroxysterols in the dystrophic epithelium. The results of these studies show that in the normal pigment epithelium and prior to tight junction breakdown in the dystrophic epithelium, filipinand digitoninsterol complexes are rare in the membranes between tight junctions and adhering junctions, and in areas of attachment between the plasma membrane and basal lamina. Complexes are more numerous in the basal infoldings, and most densely packed in the lateral and apical microvillous membranes. During junction breakdown, complexes increase substantially in apical, basal, junctional, and nuclear membranes. Later, after the junctions disappear, complexes decrease. These results indicate that alterations in the expression of membrane sterols accompany the changes in structure and function of tight junctions in the dystrophic retinal pigment epithelium.
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U2 - 10.3109/02713688709025208
DO - 10.3109/02713688709025208
M3 - Article
C2 - 3581872
AN - SCOPUS:0023155173
SN - 0271-3683
VL - 6
SP - 515
EP - 526
JO - Current Eye Research
JF - Current Eye Research
IS - 3
ER -