May 7, 1999

Complement-mediated injury reversibly disrupts glomerular epithelial cell actin microfilaments and focal adhesions

Kidney International
P S TophamD J Salant

Abstract

Foot process effacement and condensation of the glomerular epithelial cell (GEC) cytoskeleton are manifestations of passive Heymann nephritis, a model of complement-mediated membranous nephropathy. To study the effects of complement on the actin cytoskeleton in this model, we have used an in vitro system in which GECs are sublethally injured using a combination of complement-fixing anti-Fx1A IgG and human serum as a source of complement. We examined the effects of this injury on the organization of the cytoskeleton and focal contacts using immunohistology and immunochemistry. By immunofluorescence, sublethal complement-mediated injury was accompanied by a loss of actin stress fibers and focal contacts but retention of matrix-associated integrins. Full recovery was seen after 18 hours. Western blot analysis showed no change in the cellular content of the focal contact proteins. Inhibition of the calcium-dependent protease calpain did not prevent injury. In addition, cycloheximide during recovery did not inhibit the reassembly of stress fibers or focal contacts. Injury was associated with a reduction in tyrosine phosphorylation of paxillin and a currently unidentified 200 kDa protein, but inhibition of tyrosine phosphatase activi...Continue Reading

  • References18
  • Citations45

References

  • References18
  • Citations45

Citations

Mentioned in this Paper

Complement Membrane Attack Complex
Immunofluorescence Assay
Calcium [EPC]
Calcium
Isovinculin
Isoactin
Integrin alpha3beta1
Actins
Laminin Receptor
Protein Synthesis Inhibitors

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