Nuclear factor kappa B (NF-κB) transcriptionally regulates several genes involved in initiating uterine contractions. A key factor controlling NF-κB activity is its translocation to the nucleus. In myometrial smooth muscle cells (MSMCs), this translocation can be stimulated by the inflammatory molecule lipopolysaccharide (LPS) or by blocking the potassium calcium-activated channel subfamily M alpha 1 (KCNMA1 or BKCa) with paxilline (PAX). Here, we sought to determine the mechanism by which blocking BKCa causes NF-κB-p65 translocation to the nucleus in MSMCs. We show that LPS- and PAX-induced NF-κB-p65 translocation are similar in that neither depends on several mitogen-activated protein kinase pathways, but both require increased intracellular calcium (Ca2+). However, the nuclear transport inhibitor wheat germ agglutinin prevented NF-κB-p65 nuclear translocation in response to LPS but not in response to PAX. Blocking BKCa located on the plasma membrane resulted in a transient NF-κB-p65 nuclear translocation that was not sufficient to induce expression of its transcriptional target, suggesting a role for intracellular BKCa. We report that BKCa also localizes to the nucleus and that blocking nuclear BKCa results in an increase in nuclear Ca2+ in MSMCs. Together, these data suggest that BKCa localized on the nuclear membrane plays a key role in regulating nuclear Ca2+ and NF-κB-p65 nuclear translocation in MSMCs. Summary Sentence Blocking of BK channels by paxilline in myometrial smooth muscle cells increases nuclear calcium levels and translocation of NF-κB-p65.
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15 November 2021
Blocking the BKCa channel induces NF-κB nuclear translocation by increasing nuclear calcium concentration
Lindsey N. Kent,
Youe Li,
Monali Wakle-Prabagaran,
Mashal Z. Naqvi,
Sophia G. Weil,
Sarah K. England
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Biology of Reproduction
Vol. 106 • No. 3
March 2022
Vol. 106 • No. 3
March 2022
BK channel
calcium
myometrium
NF-κB