Opioid receptor mu 1 gene, fat intake and obesity in adolescence.

Dietary preference for fat may increase risk for obesity. It is a complex behavior regulated in part by the amygdala, a brain structure involved in reward processing and food behavior, and modulated by genetic factors. Here, we conducted a genome-wide association study (GWAS) to search for gene loci associated with dietary intake of fat, and we tested whether these loci are also associated with adiposity and amygdala volume. We studied 598 adolescents (12-18 years) recruited from the French-Canadian founder population and genotyped them with 530 011 single-nucleotide polymorphisms. Fat intake was assessed with a 24-hour food recall. Adiposity was examined with anthropometry and bioimpedance. Amygdala volume was measured by magnetic resonance imaging. GWAS identified a locus of fat intake in the µ-opioid receptor gene (OPRM1, rs2281617, P=5.2 × 10(-6)), which encodes a receptor expressed in the brain-reward system and shown previously to modulate fat preference in animals. The minor OPRM1 allele appeared to have a 'protective' effect: it was associated with lower fat intake (by 4%) and lower body-fat mass (by ∼2 kg, P=0.02). Consistent with the possible amygdala-mediated inhibition of fat preference, this allele was additionally associated with higher amygdala volume (by 69 mm(3), P=0.02) and, in the carriers of this allele, amygdala volume correlated inversely with fat intake (P=0.02). Finally, OPRM1 was associated with fat intake in an independent sample of 490 young adults. In summary, OPRM1 may modulate dietary intake of fat and hence risk for obesity, and this effect may be modulated by subtle variations in the amygdala volume.

Case report: moderate hemolytic disease of the newborn due to anti-G.

Views expressed in this article are those of the author and do not reflect the official policy or position of the Department of the Navy, Department of Defense, or U.S. Government. The only previously published case of anti-G in a pregnant woman indicated that anti-G alone caused little, if any, fetal or neonatal hemolysis. This report describes an affected fetus with amnionitic fluid OD 450 absorbance values in the moderate zone of the Liley prediction graph who required prolonged phototherapy after birth until day of life 20. Anti-G was identified and anti-C and -D excluded in the mother's serum. In contrast to the previous report, this report shows anti-G alone can cause moderate HDN and that fetal monitoring and treatment may be necessary.

Restoration of interferon responses of adenovirus E1A-expressing HT1080 cell lines by overexpression of p48 protein.

We have previously shown that both alpha interferon (IFN-alpha) and IFN-gamma signaling pathways are blocked in HeLa cells expressing the adenovirus E1A proteins (G. T. Leonard and G. C. Sen, Virology 224:25-33, 1996). Here, we report that in two other E1A-expressing cell lines derived from the HT1080 cells, neither IFN-alpha nor IFN-gamma could induce the transcription of genes containing the IFN-stimulated response element (ISRE). In contrast, IFN-gamma-mediated signaling to the gamma-activated sequence was unimpaired in these cells. This dichotomy was due to a lowered level of functional p48 protein but not of STAT1 protein in the E1A-expressing HT1080 cells. When p48 was overexpressed in those cells by stably transfecting a p48 expression vector, both types of IFN could effectively induce the transcription of ISRE-driven genes. Consequently, IFN-alpha was highly effective in inhibiting the replication of encephelomyocarditis virus in the E1A-expressing cells, which also overexpressed p48. These results reinforce the general conclusion that adenovirus E1A proteins block IFN signaling pathways by lowering the functional levels of one or more components of the trans-acting complexes that activate the transcription of IFN-stimulated genes.

Effects of adenovirus E1A protein on interferon-signaling.

We have previously shown that adenovirus E1A proteins can block interferon-alpha (IFN-alpha)-signalling. In the current study, we examined if the same is true for IFN-gamma signaling. Cotransfection experiments showed that both 289R and 243R forms of E1A could block the expression of an IFN-gamma-inducible reporter gene. Similarly, in an E1A-expressing HeLa cell line IFN-gamma failed to induce the synthesis of IRF-1 mRNA. This failure was due to a block in activation of the crucial trans-acting factor, GAF, which in turn was due to the lack of IFN-gamma-activated tyrosine phosphorylation of the STAT1 alpha protein in E1A-expressing cells. The above defect could be attributed to a reduced level of STAT1 alpha protein. The level of p48 protein, which is required for IFN-alpha signaling, was also lowered. However, the level of lak-1 protein, one of the tyrosine kinases necessary for both IFN-alpha and IFN-gamma signalling, was comparable in the E1A-expressing and the control cells. These results indicate that the observed inhibition of IFN signalling in E1A-expressing cells is a consequence of a lower abundance of the necessary trnas-acting factors.

Transcriptional induction by double-stranded RNA is mediated by interferon-stimulated response elements without activation of interferon-stimulated gene factor 3.

Many genes induced by type I interferons (IFNs) are also induced by double-stranded (ds)RAN. In this study, we investigated the mechanism of this induction process. Using cell lines from which the type I IFN genes have been deleted, we established that induction by dsRNA of the IFN-inducible 561 gene is direct and not mediated by the intermediate synthesis of IFN. Unlike 561 mRNA, the IFN-inducible 6-16 mRNA was induced poorly by dsRNA. Transfection studies demonstrated that the sequence difference between the core IFN-stimulated response elements (ISREs) of these two genes is not responsible for their differential inducibility by dsRNA. A point mutation in the 561 ISRE that abolished its response to IFN-alpha also made it unresponsive to dsRNA, thus demonstrating that the ISRE is the relevant cis-acting element for dsRNA signaling. The roles of different known ISRE-binding protein and tyrosine kinases in transducing the signal elicited by dsRNA were evaluated in genetically altered cell lines. dsRNA failed to induce 561 mRNA in cells expressing an anti-sense RNA for interferon regulatory factor 1, whereas it was induced strongly in cells expressing the corresponding sense mRNA. 561 mRNA was also induced strongly by dsRNA, but not by IFN-alpha, in mutant cell lines that do not express functional tyrosine kinases Tyk2 or JAK1 or ISRE binding protein, p48, or STAT2, all of which are required for IFN-alpha signaling. However, in cells devoid of functional STAT1, which is also required for IFN-alpha signaling, the induction of 561 mRNA by dsRNA was very low. Expression of transfected STAT1 alpha protein, but not of STAT 1beta protein, in these cells greatly enhanced the dsRNA inducibility of the 561 gene. These studies indicated that the major ISRE-mediated signaling pathway used by dsRNA requires interferon regulatory factor 1 and STAT alpha. This pathway, however, does not require the other known cytoplasmic components used for IFN-alpha signaling.