STAT3 cooperates with the non-canonical NF-κB signaling to regulate pro-labor genes in the human placenta.
Placenta 2015;
36:581-6. [PMID:
25771405 DOI:
10.1016/j.placenta.2015.02.013]
[Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 02/03/2015] [Accepted: 02/23/2015] [Indexed: 12/30/2022]
Abstract
INTRODUCTION
Our recent studies have shown that constitutively activated non-canonical RelB/NF-κB2 (p52) in the human placenta positively regulates the pro-labor genes CRH and COX-2. STAT3 regulates NF-κB2 (p100) processing to active p52, and in turn, nuclear activation of RelB/p52, by directly binding to p100/p52 in a variety of cancer cells. In the current study, we tested the hypothesis that STAT3 is involved in regulation of pro-labor genes by associating with RelB/p52 heterodimers in the human placenta.
METHODS
We used a variety of techniques including immunohistochemical staining, gene silencing, ectopic expression, chromatin immunoprecipitation, Western blot, RT-qPCR, and immunofluorescence assays in primary culture of cytotrophoblast and placental tissues.
RESULTS
We found that knockdown of STAT3 led to down-regulation of both CRH and COX-2 in a dose-dependent manner. By using chromatin immunoprecipitation, we further showed that interaction of RelB with the CRH or COX-2 gene promoters decreased when STAT3 was depleted. Immunofluorescence demonstrated co-localization of STAT3 with RelB or p100/p52 in both the cytoplasm and nucleus of term cytotrophoblasts.
DISCUSSION
Collectively, these results suggest that STAT3 constitutes part of the RelB/p52-containing activator complex that positively regulates pro-labor genes in the human placenta.
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