The effect of maternal arginine supplementation on the development of the thermogenic program in the ovine fetus

Brown adipose tissue (BAT) is a specialised fat store that is metabolised by the newborn lamb to ensure effective adaptation to the cold challenge of the extra-uterine environment. Increasing BAT reserves therefore has the potential to increase neonatal thermogenesis and survival. It is established that arginine supplementation can increase fetal BAT stores but the biological mechanisms involved are unclear. The objective of this study was to test the hypothesis that increased fetal BAT stores resulting from maternal arginine supplementation is mediated by activation of the thermogenic program. Brown adipose tissue was collected from fetuses of ewes supplemented with arginine from 100 to 140 days of gestation. Increased peri-renal fat stores in fetuses from arginine-supplemented ewes was associated with an increase in uncoupling protein 1 (UCP-1) and PRD1-BF-1-RIZ1 homologous domain containing protein-16 expression, but not proliferator-activated receptor gamma or proliferator-activated receptor gamma-co-activator-1α in BAT. The activity of UCP-1 is regulated by hormones including cortisol and thyroid hormones. Cortisol level in fetuses from supplemented sheep was 68% greater than those from control ewes, indicating that cortisol may control upregulation of UCP-1 expression in the ovine neonate. The DNA and RNA concentration in BAT of both groups suggest that increased peri-renal fat stores is not associated with an increase in cell number or number of ribosomes, but rather an increase in the size of individual fat cells. Collectively, these results indicate that maternal arginine supplementation during mid to late gestation improved the thermoregulatory ability of lambs and this could potentially increase their survival in early life.

Binding of octamer factors to the murine IL-5 CLE0 in primary T-cells and a T-cell line

Interleukin-5 (IL-5) is an inducible T-cell derived cytokine with remarkable specificity for the eosinophil lineage. It is controlled at the level of transcription and regulation of the gene is an obvious target for therapy of eosinophil-dependent allergic disorders such as asthma, eczema and rhinitis. Using a T-cell line and primary T-cells we have shown for the first time that the Oct1 and Oct2 transcription factors combine to form a complex with the functionally critical murine IL-5 cis-regulatory element, conserved lymphokine element 0 (CLE0), and contribute to positive regulation of the gene. These results show the increasingly important role of octamer factors in regulation of the IL-5 gene.

Binding of octamer factors to a novel 3'-positive regulatory element in the mouse interleukin-5 gene

The development of eosinophilia is regulated by interleukin (IL)-5. The biological specificity of eosinophilia suggests a tight and independent regulation of IL-5 expression. A number of regulatory regions in the 5'-end of the IL-5 gene have been described; many of them are involved in the regulation of other genes, and it is not clear how the specific expression of IL-5 is regulated. In this study, we report the finding of a novel 3'-regulatory element. Data base analysis of a 2-kilobase fragment of the 3'-end of the mouse IL-5 gene revealed the presence of a 40-base pair-long repetitive sequence that consists of four direct repeats of ATGAATGA distributed in a symmetrical manner. This sequence, named mouse downstream regulatory element-1 (mDRE1), was shown to be protected in DNase I footprinting assays in vitro. Electrophoretic mobility shift assays using specific antibodies identified the transcription factors Oct-1 and Oct-2 as responsible for the formation of the specific complexes with mDRE1 and nuclear extracts from both EL4 and primary T-cells. Competition electrophoretic mobility shift assays with oligonucleotides containing different numbers of ATGAATGA repeats showed that Oct-1 and Oct-2 bind to different motifs in the mDRE1 sequence. Deletion of mDRE1 from a 9.5-kilobase IL-5 gene construct significantly decreased the expression of the luciferase reporter gene, suggesting that it plays a positive role in the expression of the IL-5 gene.