Extra-cellular matrix proteins induce re-distribution of a-actinin-1 and a-actinin-4 in A431 cells

• Alpha-actinins are actin-binding proteins of non-muscle cells, which can participate in the regulation of transcription factor activity. We describe the distribution of a-actinin-1 and -4 depending on different actin cytoskeleton formed as a result of cell adhesion to extracellular matrix proteins, such as fibronectin and laminin 2/4. Immunofluorescent studies show a difference in the distribution of a-actinin and -4. Both isoforms localise along stress-fibres, but a-actinin-1 localises in the perinuclear region more abundantly than a-actinin-4. Western blot analysis demonstrated existence of truncated forms of both isoforms. Truncated a-actinin-1 appears in cells spread on fibronectin or laminin. Cell spreading also correlated with more tight association of a-actinin-4 with chromatin. Basing on our previous finding of an interaction of a-actinin-4 with p65 subunit of the NF-?B, we checked the possible influence of immobilised ligands on its redistribution in nuclear complexes containing p65. a-Actinin-4 seems to be present in some but not all nuclear complexes containing p65. Immobilised ligands may affect the interaction of a-actinin-4/p65 complexes with chromatin. The data suggest that adhesion to extra-cellular matrix may interfere in cellular reactions mediated by a-actinin-1 and -4. © 2007 International Federation for Cell Biology.

Nyckelord

a-Actinin-1

a-Actinin-4

Actin cytoskeleton

Extra-cellular matrix

NF-?B

MEDICINE

MEDICIN

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