Project description:Intrauterine growth restriction (IUGR) increases susceptibility to age-related diseases including type 2 diabetes (T2DM), and is associated with permanent and progressive changes in gene expression and epigenetic regulation. We studied cytosine methylation throughout the genome in pancreatic islets from a rat model of uteroplacental insufficiency, providing a novel and detailed assessment of the genomic distribution and locus-specific patterns of DNA methylation in normal islets as well as the changes that occur as a consequence of IUGR. Utilizing a high throughput approach to study DNA methylation at almost 1 million unique sites throughout the genome, we found ~1,400 changes in methylation (IUGR compared to control) with an estimated false discovery rate of 4.2%. These epigenetic differences were observed in IUGR male rats at 7 weeks of age, preceding the development of diabetes in this model. Therefore, these epigenetic differences represent candidates for mediating the pathogenesis of metabolic disease that occurs later in life in these animals. Moreover, many of the changes we identify are located near genes that regulate processes known to be abnormal in IUGR islets, such as vascularization, Î²-cell proliferation, insulin secretion, and cell death. Consistent changes in mRNA expression were identified at some of the epigenetically-dysregulated genes including Fgfr1, Gch1, Pcsk5, and Vgf. Globally, epigenetic dysregulation occurred preferentially at conserved intergenic sequences, which are candidate cis-regulatory elements driving differential expression of nearby genes. These results provide insights into the complex developmental consequences of IUGR, and suggest that changes in DNA methylation could mediate a constellation of changes in both gene expression and pancreatic islet development and function, with relevance to T2DM. Direct comparison of DNA methylation in 8 samples consisting of isolated, pooled pancreatic islets from 7-week-old male offspring belonging to 4 IUGR and 4 control litters (Sprague-Dawley rats). Each microarray consists of a two-color comparison of a methylation-sensitive representation of the genome (HpaII) with an internal methylation-insensitive control/reference (MspI).

Project description:The global prevalence of type 2 diabetes (T2D) is increasing, and it is contributing to the susceptibility to diabetes and its related epidemic in offspring. Although the impacts of paternal T2D on metabolism of offspring have been well established, the exact molecular and mechanistic basis that mediates these impacts remains largely unclear. Here we show that paternal T2D increases the susceptibility to diabetes in offspring through the gametic epigenetic alterations. Paternal T2D led to glucose intolerance and insulin resistance in offspring. Relative to controls, offspring of T2D fathers exhibited altered gene expression patterns in the pancreatic islets, with downregulation of several genes involved in glucose metabolism and insulin signaling pathway. Epigenomic profiling of offspring pancreatic islets revealed numerous changes in cytosine methylation depending on paternal T2D, including reproducible changes in methylation over several insulin signaling genes. Paternal T2D altered overall methylome patterns in sperm, with a large portion of differentially methylated genes overlapped with that of pancreatic islets in offspring. Our study revealed, for the first time, that T2D can be inherited transgenerationally through the mammalian germline by an epigenetic manner. For all comparisons shown, male F0 founders were weaned from mothers at 3 weeks of age, and sibling males were put into cages with high-fat diet (33% energy as fat) or control diet until 12 weeks of age, at which point mice fed with HFD were injected intraperitoneally with a low dose of STZ and kept on the same diet for 4 weeks. Fasting blood glucose was examined each week post-STZ for 4 weeks, and only glucose level at 7~11 mM was considered as type 2 diabetes. Females were always raised on standard diet. At 16 weeks, male F0 founders were mated with females. After 1 or 2 days, males were removed, and pregnant females were left alone until their litters were 3 weeks of age. Note that we always used virgin females to avoid confounding effects brought about by the females. At 3 weeks of age a portion of the offspring were sacrificed and islets were generated, each from an independent father.Samples from six control and six paternal type 2 diabetes offspring were chosen for microarray analysis.

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Homo sapiens

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