α-ACTININ-4 AND p65/ReIA SUBUNIT OF NF-κÂ
TRANSCRIPTION FACTOR ARE CO-LOCALIZED AND MIGRATE TOGETHER INTO THE NUCLEUS IN EGF-STIMULATED A431 CELL
V. N. Babakov,1 D. E. Bobkov,1 O. A. Petukhova,1
L. V. Turoverova,1 I. V. Kropacheva,1
E. P. Podolskaya,2 G. P. Pinaev 1, *
1 Institute of Cytology RAS, St. Petersburg, and
2 Institute for Analytical Instrumentation, RAS, St. Petersburg, Russia;
* e-mail: pinaev@mail.cytspb.rssi.ru
The NF-κB/Rel family of transcription factors in mammalian cells regulates inducible transcription of a large
number of genes in response to diverse stimuli. Despite a great number of publications on this subject, little is known about precise
NF-κB localization in the cytoplasm. As previously demonstrated, in normal rat fibroblast and human epidermoid carcinoma A431 cells
p65/RelA subunit of NF-κB is co-localized in the cytoplasm with actin structures. However, the mechanism of NF-κB interaction with actin
remains unclear. We have investigated localization of p65/RelA subunit NF-κB and α-actinin isoforms during cell activation by epidermal
growth factor (EGF). Using con-focal microscopy, we have shown that α-actinin-4 and p65/RelA subunit of NF-κB transcription factor are
co-localized in A431 cells. Cell treatment with EGF leads to translocation of the proteins to membrane ruffles, and eventually to
migration into the nucleus. Pretreatment of A431 cells with cytochalasin D or wortmannin prior to EGF treatment increases p65/RelA and
α-actinin-4 accumulation in nuclear extracts. Co-localization of α-actinin-4 with p65/RelA subunit of NF-κB was found in nuclei isolated
from stimulated cells. These results support the notion that actin cytoskeleton reorganization and α-actinin-4 are involved in NF-κB
signaling.
Key words: NF-kappaB, transcription factor, α-actinin-4, actin cytoskeleton, cytochalasin D,
wortmannin, A431 cells
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