Antioxidant Signaling Involving the Microtubule Motor KIF12 Is an Intracellular Target of Nutrition Excess in Beta Cells

SummaryBeta cell injury due to oxidative stress is a typical etiology of diabetes caused by nutritional excess, but its precise mechanism remains largely elusive. Here, we demonstrate that the microtubule motor KIF12 mediates an antioxidant cascade in beta cells as an intracellular target of excess fat intake or “lipotoxicity.” KIF12 knockout mice suffer from hypoinsulinemic glucose intolerance due to increased beta cell oxidative stress. Using this model, we identified an antioxidant signaling cascade involving KIF12 as a scaffold for the transcription factor Sp1. The stabilization of nascent Sp1 appeared to be essential for proper peroxisomal function by enhancing Hsc70 expression, and the pharmacological induction of Hsc70 expression with teprenone counteracted the oxidative stress. Because KIF12 is transcriptionally downregulated by chronic exposure to fatty acids, this antioxidant cascade involving KIF12 and Hsc70 is proposed to be a critical target of nutritional excess in beta cells in diabetes

L1 Mosaicism in Mammals:Extent, Effects, and Evolution

The retrotransposon LINE-1 (long interspersed element 1, L1) is a transposable element that has extensively colonized the mammalian germline. L1 retrotransposition can also occur in somatic cells, causing genomic mosaicism, as well as in cancer. However, the extent of L1-driven mosaicism arising during ontogenesis is unclear. We discuss here recent experimental data which, at a minimum, fully substantiate L1 mosaicism in early embryonic development and neural cells, including post-mitotic neurons. We also consider the possible biological impact of somatic L1 insertions in neurons, the existence of donor L1s that are highly active (‘hot’) in specific spatiotemporal niches, and the evolutionary selection of donor L1s driving neuronal mosaicism

Estimating RNA editing efficiency of five editing sites in the serotonin 2C receptor by pyrosequencing

Accumulating evidence suggests that altered RNA editing of the serotonin 2C receptor (HTR2C) is involved in the pathophysiology of mental disorders and the action of antidepressants. Estimating RNA editing of HTR2C in various samples is a first step to understanding its pathophysiological roles. Here, we developed a high-throughput quantification method of RNA editing efficiency by pyrosequencing. By optimizing the dispensation order, the RNA editing efficiency of all five RNA editing sites including consecutively ordered sites in HTR2C was obtained. More importantly, our method made it possible to determine the content of partial HTR2C isoforms, which enabled us to monitor possible functional changes of HTR2C. This method was validated in both oligonucleotide and RT-PCR product templates, and showed good correlation with conventional cloning-sequencing analysis. Our method could be a valuable tool in the rapid assessment of RNA editing status, including assessment of natural variations, alterations in disease tissues, and responses to drugs

A systematic evaluation of whole genome amplification of bisulfite-modified DNA

<p>Abstract</p> <p>Background</p> <p>Studying DNA methylation profiles in detail should be the first step in epigenetic research. Although sodium bisulfite modification of genomic DNA is the gold standard method for DNA methylation analysis, this method results in the loss of the majority of the DNA material. Whole genome amplification (WGA) of bisulfite-modified DNA is expected to provide a rich source of materials, but its validity has not been thoroughly evaluated. In this study, we evaluated the extent of biased amplification in the WGA of bisulfite-modified DNA and the reproducibility of independent WGA reactions. We performed the multiple displacement amplification-based WGA separately three times. Each experiment included two reactions using 10 or 50 ng of bisulfite-modified DNA as template. DNA methylation levels were compared between WGA products and original bisulfite-modified DNA at about 450,000 CpG sites.</p> <p>Results</p> <p>Using a sufficient amount of bisulfite-modified DNA for WGA was critical for downstream application. The considerable deviations from original bisulfite-modified DNA were found in the middle range of DNA methylation levels. Distribution of hyper- and hypomethylation were equal, which suggested that the deviation at each CpG site occurred randomly. Averaging the data from independently amplified WGA products dramatically improved the overall quality.</p> <p>Conclusions</p> <p>WGA of bisulfite-modified DNA could be a valuable tool for epigenetic research, but careful experimental design and data interpretation are required.</p

Comprehensive survey of CNVs influencing gene expression in the human brain and its implications for pathophysiology

Copy number variations (CNVs) contribute to neuropsychiatric diseases, which may be partly mediated by their effects on gene expression. However, few studies have assessed the influence of CNVs on gene expression in the brain. The objective was to perform an unbiased comprehensive survey of influence of CNVs on gene expression in human brain tissues. CNV regions (CNVRs) were identified in 72 individuals (23 schizophrenia, 23 bipolar disorder and 26 controls). Significant associations between the CNVRs and gene expression levels were observed for 583 CNVR-expression probe pairs (293 unique eCNVRs and 429 unique transcripts), after corrections for multiple testing and controlling the effect of the number of subjects with CNVRs by label swapping permutations. These CNVRs affecting gene expression (eCNVRs) were significantly enriched for rare/low frequency (p=1.087×10-10) and gene-harboring CNVRs (p=1.4×10-6). Transcripts overlapping CNVRs were significantly enriched for glutathione metabolism and oxidative stress only for cases but not for controls. Moreover, 72 (24.6%) of eCNVRs were located within the chromosomal aberration regions implicated in psychiatric-disorders: 16p11.2, 1q21.1, 22q11.2, 3q29, 15q11.2, 17q12 and 16p13.1. These results shed light on the mechanism of how CNVs confer a risk for psychiatric disorders

Quantification of cytosine modifications in the aged mouse brain

Abstract Quantifying cytosine modifications in various brain regions provides important insights into the gene expression regulation and pathophysiology of neuropsychiatric disorders. In this study, we quantified 5‐methylcytosine (5‐mC), 5‐hydroxymethylation (5‐hmC), and 5‐formylcytosine (5‐fC) levels in five brain regions (the frontal lobe, cerebral cortical region without frontal lobe, hippocampus, basal ganglia, and the cerebellum) and the heart at three developmental periods (12, 48, and 101 weeks). We observed significant regional variations in cytosine modification. Notably, regional variations were generally maintained throughout development, suggesting that epigenetic regulation is unique to each brain region and remains relatively stable with age. The 5‐mC and 5‐hmC levels were positively correlated, although the extent of the correlations seemed to differ in different brain regions. On the contrary, 5‐fC levels did not correlate with 5‐mC or 5‐hmC levels. Additionally, we observed an age‐dependent decrease in 5‐fC levels in the basal ganglia, suggesting a unique epigenetic regulation mechanism. Further high‐resolution studies using animal models of neuropsychiatric disorders as well as postmortem brain evaluation are warranted