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Am J Physiol Endocrinol Metab. 2013 Jul 1;305(1):E1-14. doi: 10.1152/ajpendo.00076.2013. Epub 2013 Apr 30.

Early growth response protein-1 mediates lipotoxicity-associated placental inflammation: role in maternal obesity.

Author information

1
Arkansas Children's Nutrition Center, Little Rock, AR 72202, USA.

Abstract

Obesity is associated with low-grade chronic inflammation, which contributes to cellular dysfunction promoting metabolic disease. Obesity during pregnancy leads to a proinflammatory milieu in the placenta; however, the underlying causes for obesity-induced placental inflammation remain unclear. Here, we examine the mechanisms by which saturated fatty acids and inflammatory cytokines induce inflammation in placental trophoblasts. We conducted global transcriptomic profiling in BeWo cells following palmitate and/or TNFα treatment and gene/protein expression analyses of MAPK pathways and characterized downstream transcription factors directly regulating inflammatory cytokines. Microarray analysis revealed increased expression of genes regulating inflammation, stress response, and immediate early response in cytotrophoblasts in response to palmitic acid (PA), TNFα, or a combination of both (PA + TNFα). Both gene ontology and gene set enrichment analysis revealed MAPK and EGR-1 signaling to be upregulated in BeWo cells, which was confirmed via immunoblotting. Importantly, activation of JNK signaling was necessary for increased proinflammatory cytokine (IL-6, TNFα, and IL-8) and EGR1 mRNA. Consistent with the requirement of JNK signaling, ChIP analysis confirmed the recruitment of c-Jun and other MAPK-responsive immediate early factors on the EGR1 promoter. Moreover, recruitment of EGR-1 on cytokine promoters (IL-6, TNFα, and IL-8) and an impaired proinflammatory response following knockdown of EGR-1 suggested it as a central component of the mechanism facilitating inflammatory gene expression. Finally, akin to in vitro findings, term placenta from obese women also had both increased JNK and p38 signaling and greater EGR-1 protein relative to lean women. Our results demonstrate that lipotoxic insults induce inflammation in placental cells via activation of JNK/EGR-1 signaling.

TRIAL REGISTRATION:

ClinicalTrials.gov NCT01104454.

KEYWORDS:

developmental programming; early growth response protein-1; fatty acids; gestational obesity; mitogen-activated protein kinase

PMID:
23632636
PMCID:
PMC4116409
DOI:
10.1152/ajpendo.00076.2013
[Indexed for MEDLINE]
Free PMC Article

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