Altered membrane-cytoskeleton linkage and membrane blebbing in energy-depleted renal proximal tubular cells.
The effects of energy depletion on two membrane-cytoskeletal linker proteins (ezrin and myosin-1 beta) and membrane bleb formation were studied in isolated rabbit proximal tubule cells. Measurements of cytoskeletal-membrane interactions by using the laser optic trap method revealed a stronger association of control tubule membrane with the apical cytoskeleton compared with the basal cytoskeleton. Energy depletion weakened the apical membrane-cytoskeleton interactions to a greater degree. Biochemical studies demonstrated that energy depletion altered both ezrin and myosin-1 beta. The salt-insensitive ezrin fraction dissociated from the cytoskeleton; myosin-1beta redistributed from the peripheral cytoskeleton to a perinuclear/nuclear complex. These changes in ezrin and myosin-1 beta and the weakening of the membrane-cytoskeleton interactions correlated with the release of brush-border membrane blebs observed by differential interference contrast microscopy. Permeability of membrane blebs was also evaluated during energy depletion and indicated an increased permeabilization of basal blebs to 3-kDa dextrans. These results support the hypothesis that alterations in membrane-cytoskeleton linkers facilitate the formation and detachment of blebs by weakening membrane-cytoskeleton interactions.
Department of Life Sciences, Indiana State University, Terre Haute, 47809, USA. Lschen@scifac.indstate.edu
J
J
Chen
M C
MC
Wagner
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002458:Cell Fractionation; D002462:Cell Membrane / Q000378:metabolism*; D002463:Cell Membrane Permeability / Q000187:drug effects / Q000502:physiology; D002467:Cell Nucleus / Q000378:metabolism; D003598:Cytoskeletal Proteins; D003599:Cytoskeleton / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D003911:Dextrans / Q000493:pharmacokinetics; D004734:Energy Metabolism / Q000187:drug effects / Q000502:physiology*; D005260:Female; D006801:Humans; D007511:Ischemia / Q000378:metabolism*; D007687:Kidney Tubules, Proximal / Q000378:metabolism* / Q000648:ultrastructure; D008854:Microscopy, Electron; D008871:Microvilli / Q000378:metabolism / Q000648:ultrastructure; D009218:Myosins / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D011817:Rabbits; D012492:Salts; D012995:Solubility; D000099149:Ezrin
D000255:Adenosine Triphosphate; D002118:Calcium; D003598:Cytoskeletal Proteins; D003911:Dextrans; D009218:Myosins; D010750:Phosphoproteins; D012492:Salts; D000099149:Ezrin