Cytoskeletal architecture in mouse lung epithelial cells is regulated by protein-kinase C-alpha and calpain II.
Brief exposure to 12-O-tetradecanoylphorbol 13-acetate (TPA) caused a uniformly flattened population of mouse lung epithelial cells to become more heterogeneous; some cells rounded up, and others detached to overlap with flatter cells. Actin stress fiber organization was disrupted, and F-actin accumulated in lemellipodia. Vinculin dissociated from the focal adhesion plaques to diffuse throughout the cytoplasm. Inhibition of protein kinase C (PKC) activity blocked these effects of TPA. After 8 h of TPA exposure, actin filaments reassembled and vinculin again localized to the cell periphery. Calpain inhibition attenuated the decrease of PKC-alpha protein and PKC activity from the membrane fraction, and prevented the redistribution of cytoskeletal elements. Talin immunostaining was widespread throughout control cells but was localized to the periphery 8 h after treatment with TPA or with inhibitors of PKC and calpain. Both vinculin and talin concentrations increased with prolonged TPA treatment. PKC-zeta and calpain II were not appreciably affected by TPA exposure. Translocation of PKC-alpha to the membrane, followed by its calpain-induced downmodulation, is apparently required for the reversible pattern of cytoskeletal changes caused by TPA.
Dwyer-Nield
L D
LD
Department of Pharmaceutical Sciences, School of Pharmacy, University of Colorado Health Sciences Center, Denver 80262, USA.
Miller
A C
AC
Neighbors
B W
BW
Dinsdale
D
D
Malkinson
A M
AM
D000818:Animals; D015153:Blotting, Western; D002154:Calpain / Q000502:physiology*; D003598:Cytoskeletal Proteins / Q000378:metabolism; D003599:Cytoskeleton / Q000502:physiology* / Q000648:ultrastructure*; D004847:Epithelial Cells; D004848:Epithelium / Q000187:drug effects; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000502:physiology*; D008168:Lung / Q000166:cytology* / Q000187:drug effects; D051379:Mice; D008855:Microscopy, Electron, Scanning; D011493:Protein Kinase C / Q000378:metabolism / Q000502:physiology*; D051571:Protein Kinase C-alpha; D016608:Talin / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D003598:Cytoskeletal Proteins; D007527:Isoenzymes; D016608:Talin; C496630:Prkca protein, mouse; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha; D002154:Calpain; D013755:Tetradecanoylphorbol Acetate