Cytoskeletal involvement in the modulation of cell-cell junctions by the protein kinase inhibitor H-7.
The protein kinase inhibitor H-7 has been shown to block junction dissociation induced by low extracellular calcium in Madin Darby canine kidney epithelial cells (S. Citi, J. Cell Biol. (1992) 117, 169-178). To understand the basis of this effect, we have examined how H-7 affects the organization of junctions and the actin cytoskeleton in different types of epithelial cells in culture. Immunofluorescence microscopy showed that H-7 confers Ca2+ independence on cultured epithelial lens cells, which lack tight junctions and desmosomes but have microfilament-associated adherens junctions. In these cells, H-7 did not protect N-cadherin from trypsin digestion at low extracellular calcium, suggesting that H-7 does not stabilize the 'active' cadherin conformation. In cultured Madin Darby canine kidney cells, H-7 partially prevented the fall in transepithelial resistance induced by cytochalasin D, either alone or in conjunction with calcium chelators. Double-immunofluorescence microscopy showed that H-7 inhibits both the fragmentation of labeling for the tight junction protein cingulin and the condensation of actin into cytoplasmic foci induced by cytochalasin D. Taken together, these observations indicate that H-7 inhibits junction dissociation by affecting the contractility of the adherens junction-associated microfilaments following treatment with calcium chelators or cytochalasin D.
Citi
S
S
Department of Cell Biology and Anatomy, Cornell University Medical School, New York, NY.
Volberg
T
T
Bershadsky
A D
AD
Denisenko
N
N
Geiger
B
B
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000818:Animals; D002450:Cell Communication; D002460:Cell Line; D002478:Cells, Cultured; D002642:Chick Embryo; D003599:Cytoskeleton / Q000187:drug effects*; D004285:Dogs; D005455:Fluorescent Antibody Technique; D017629:Gap Junctions / Q000187:drug effects*; D007546:Isoquinolines / Q000494:pharmacology*; D010879:Piperazines / Q000494:pharmacology*; D047428:Protein Kinase Inhibitors
D007546:Isoquinolines; D010879:Piperazines; D047428:Protein Kinase Inhibitors; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine