KEGG(Kyoto Encyclopedia of Genes and Genomes)〔和文〕 (特集 ゲノム医学の現在と未来--基礎と臨床) -- (データベース)

The obesity epidemic has forced us to evaluate the role of inflammation in the health complications of obesity. This has led to a convergence of the fields of immunology and nutrient physiology and the understanding that they are inextricably linked. The reframing of obesity as an inflammatory condition has had a wide impact on our conceptualization of obesity-associated diseases. In this Review, we highlight the cellular and molecular mechanisms at play in the generation of obesity-induced inflammation. We also emphasize how defining the immune regulation in metabolic tissues has broadened the understanding of the diversity of inflammatory responses.

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Inflammatory links between obesity and metabolic disease.

Despite the success of genome-wide association studies (GWASs) in identifying loci associated with common diseases, a substantial proportion of the causality remains unexplained. Recent advances in genomic technologies have placed us in a position to initiate large-scale studies of human disease-associated epigenetic variation, specifically variation in DNA methylation. Such epigenome-wide association studies (EWASs) present novel opportunities but also create new challenges that are not encountered in GWASs. We discuss EWAS design, cohort and sample selections, statistical significance and power, confounding factors and follow-up studies. We also discuss how integration of EWASs with GWASs can help to dissect complex GWAS haplotypes for functional analysis.

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Epigenome-wide association studies for common human diseases

Paternally Induced Transgenerational Environmental Reprogramming of Metabolic Gene Expression in Mammals

Using olfactory molecular specificity, we examined the inheritance of parental traumatic exposure, a phenomenon that has been frequently observed, but not understood. We subjected F0 mice to odor fear conditioning before conception and found that subsequently conceived F1 and F2 generations had an increased behavioral sensitivity to the F0-conditioned odor, but not to other odors. When an odor (acetophenone) that activates a known odorant receptor ( Olfr151) was used to condition F0 mice, the behavioral sensitivity of the F1 and F2 generations to acetophenone was complemented by an enhanced neuroanatomical representation of the Olfr151 pathway. Bisulfite sequencing of sperm DNA from conditioned F0 males and F1 naive offspring revealed CpG hypomethylation in the Olfr151 gene. In addition, in vitro fertilization, F2 inheritance and cross-fostering revealed that these transgenerational effects are inherited via parental gametes. Our findings provide a framework for addressing how environmental information may be inherited transgenerationally at behavioral, neuroanatomical and epigenetic levels.

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Parental olfactory experience influences behavior and neural structure in subsequent generations

Childhood obesity and diabetes are closely related to these conditions in either parent, but how the father contributes is unclear. A study in rats shows that normal females mated with obese, glucose-intolerant fathers on a high-fat diet produce female offspring who develop glucose intolerance due to impaired insulin secretion and pancreatic function. This is the first report in any species that a father's diet can initiate progression to diabetes in his offspring. The work highlights a novel role for environmentally induced paternal factors in influencing metabolic disease in offspring and in the growing epidemics of obesity and diabetes. Here it is shown that the consumption of a high-fat diet by male rats has an intergenerational effect: it leads to the dysfunction of pancreatic β-cells in female offspring. Relative to controls, these offspring showed an early onset of impaired insulin secretion and glucose tolerance, which worsened with time. The results add to our understanding of the complex genetic and environmental factors that are leading to the global epidemic of obesity and type 2 diabetes. The global prevalence of obesity is increasing across most ages in both sexes. This is contributing to the early emergence of type 2 diabetes and its related epidemic1,2. Having either parent obese is an independent risk factor for childhood obesity3. Although the detrimental impacts of diet-induced maternal obesity on adiposity and metabolism in offspring are well established4, the extent of any contribution of obese fathers is unclear, particularly the role of non-genetic factors in the causal pathway. Here we show that paternal high-fat-diet (HFD) exposure programs β-cell ‘dysfunction’ in rat F1 female offspring. Chronic HFD consumption in Sprague–Dawley fathers induced increased body weight, adiposity, impaired glucose tolerance and insulin sensitivity. Relative to controls, their female offspring had an early onset of impaired insulin secretion and glucose tolerance that worsened with time, and normal adiposity. Paternal HFD altered the expression of 642 pancreatic islet genes in adult female offspring (P < 0.01); genes belonged to 13 functional clusters, including cation and ATP binding, cytoskeleton and intracellular transport. Broader pathway analysis of 2,492 genes differentially expressed (P < 0.05) demonstrated involvement of calcium-, MAPK- and Wnt-signalling pathways, apoptosis and the cell cycle. Hypomethylation of the Il13ra2 gene, which showed the highest fold difference in expression (1.76-fold increase), was demonstrated. This is the first report in mammals of non-genetic, intergenerational transmission of metabolic sequelae of a HFD from father to offspring.

Chronic high-fat diet in fathers programs β-cell dysfunction in female rat offspring

We previously showed that paternal high-fat diet (HFD) consumption programs β-cell dysfunction in female rat offspring, together with transcriptome alterations in islets. Here we investigated the retroperitoneal white adipose tissue (RpWAT) transcriptome using gene and pathway enrichment and pathway analysis to determine whether commonly affected network topologies exist between these two metabolically related tissues. In RpWAT, 5108 genes were differentially expressed due to a paternal HFD; the top 5 significantly enriched networks identified by pathway analysis in offspring of HFD fathers compared with those of fathers fed control diet were: mitochondrial and cellular response to stress, telomerase signaling, cell death and survival, cell cycle, cellular growth and proliferation, and cancer. A total of 187 adipose olfactory receptor genes were down-regulated. Interrogation against the islet transcriptome identified specific gene networks and pathways, including olfactory receptor genes that were similarly affected in both tissues (411 common genes, P<0.05). In particular, we highlight a common molecular network, cell cycle and cancer, with the same hub gene, Myc, suggesting early onset developmental changes that persist, shared responses to programmed systemic factors, or crosstalk between tissues. Thus, paternal HFD consumption triggers unique gene signatures, consistent with premature aging and chronic degenerative disorders, in both RpWAT and pancreatic islets of daughters.

Paternal high-fat diet consumption induces common changes in the transcriptomes of retroperitoneal adipose and pancreatic islet tissues in female rat offspring

Paternal high fat diet (HFD) consumption triggers unique gene signatures, consistent with premature aging and chronic degenerative disorders, in both white adipose tissue (RpWAT) and pancreatic islets of daughters. In addition to published data in Nature, 2010, 467, 963–966 (GSE: 19877, islet) and FASEB J 2014, 28, 1830–1841 (GSE: 33551, RpWAT), we describe here additional details on systems-based approaches and analysis to develop our observations. Our data provides a resource for exploring the complex molecular mechanisms that underlie intergenerational transmission of obesity.

Gene expression in rat models for inter-generational transmission of islet dysfunction and obesity.

The invention relates to determining risk factors for metabolic disease, especially diabetes and related diseases, to screening compounds for therapeutic activity, and to therapeutic or dietetic intervention in metabolic disease, especially diabetes and related disease.

Sheau-Fang Ng

Papers

Chronic high-fat diet in fathers programs β-cell dysfunction in female rat offspring

Paternal high-fat diet consumption induces common changes in the transcriptomes of retroperitoneal adipose and pancreatic islet tissues in female rat offspring

Gene expression in rat models for inter-generational transmission of islet dysfunction and obesity.

Inheritance of metabolic dysfunction