Glucocorticoids are vital for life and regulate an array of physiological functions by binding to the ubiquitously expressed glucocorticoid receptor (GR, also known as NR3C1). Previous studies demonstrate striking breed differences in plasma cortisol levels in pigs. However, investigation into the breed-dependent GR transcriptional regulation is hampered by lacking porcine GR promoter information. In this study, we sequenced 5.3 kb upstream of the translation start codon of the porcine GR gene, and identified seven alternative 5′-untranslated exons 1–4, 1–5, 1–6, 1–7, 1–8, 1–9,10 and 1–11. Among all these mRNA variants, exons 1–4 and 1–5, as well as the total GR were expressed significantly (P<0.05) higher in the liver of newborn piglets of Large White (LW) compared with Erhualian, a Chinese indigenous breed. Overall level of CpG methylation in the region flanking exons 1–4 and 1–5 did not show breed difference. However, nuclear content of Sp1, p-CREB and GR in the liver was significantly (P<0.05) higher in LW piglets, associated with enhanced binding of p-CREB, and higher level of histone H3 acetylation in 1–4 and 1–5 promoters. In contrast, GR binding to promoters of exons 1–4 and 1–5 was significantly diminished in LW piglets, implicating the presence of negative GREs. These results indicate that the difference in the hepatic expression of GR transcript variants between two breeds of pigs is determined, at least partly, by the disparity in the binding of transcription factors and the enrichment of histone H3 acetylation to the promoters.

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Maternal protein restriction diminishes placental 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) activity and causes fetal growth restriction in mammals. However, it is unknown whether such effect was caused directly by nutrient deficiency, or indirectly through the mediation of maternal hormones. In the present study, a human placental cell line (BeWo) was cultured in F12K as control and F12 as low amino acids (LAA) media for 48 h to investigate the effects of amino acids deficiency on 11β-HSD2 expression and activity. Despite a significant up-regulation of 11β-HSD2 mRNA expression in LAA cells, 11β-HSD2 activity and protein content were decreased by 38 and 54%, respectively (P<0.05), indicating a mechanism of post-transcriptional regulation. Among 5 miRNAs targeting 11β-HSD2, miR-498 was expressed significantly higher in LAA cells. Leptin concentration was significantly lower (P<0.01) in LAA medium. The mRNA expression of both isoforms of leptin receptor was significantly higher in LAA cells, although no difference was detected at protein level. To further clarify whether leptin is involved in mediating the effect of LAA on 11β-HSD2 activity, leptin was supplemented to LAA medium, whereas three specific inhibitors of leptin signaling pathways, WP1066 for JAK-STAT, PD98059 for MAPK and LY294002 for PI3K, respectively were added to control medium. Leptin restored the diminished 11β-HSD2 activity in LAA cells, whereas WP1066 (5 nM) and PD98059 (50 nM) significantly decreased 11β-HSD2 activity in control cells. In conclusion, the present results indicate that LAA diminishes 11β-HSD2 expression and activity in BeWo cells through leptin-activated JAK-STAT and MAPK pathways.

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