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Abstract : During the cortical development, cells in the brain acquire somatic mutations that can be implicated in various neurodevelopmental disorders. There is increasing evidence that brain somatic mutations lead to sporadic form of epileptic disorders with previously unknown etiology. In particular, malformation of cortical developments (MCD), ganglioglioma (GG) associated with intractable epilepsy and non-lesional focal epilepsy (NLFE) are known to be attributable to brain somatic mutations in mTOR pathway genes and others. In order to identify such somatic mutations presenting as low-level in epileptic brain tissues, the mutated cells should be enriched and sequenced with high-depth coverage. Nevertheless, there are a lot of technical limitations to accurately detect low-level of somatic mutations. Also, it is important to validate whether identified somatic mutations are truly causative for epileptic seizures or not. Furthermore, it will be necessary to understand the molecular mechanism of how brain somatic mutations disturb neuronal circuitry since epilepsy is a typical example of neural network disorder. In this review, we overview current genetic techniques and experimental tools in neuroscience that can address the existence and significance of brain somatic mutations in epileptic disorders as well as their effect on neuronal circuitry.

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Abstract : Intrinsically disordered proteins (IDPs) are highly unorthodox proteins that do not form three-dimensional structures under physiological conditions. The discovery of IDPs has destroyed the classical structure-function paradigm in protein science, 3-D structure = function, because IDPs even without well-folded 3-D structures are still capable of performing important biological functions and furthermore are associated with fatal diseases such as cancers, neurodegenerative diseases and viral pandemics. Pre-structured motifs (PreSMos) refer to transient local secondary structural elements present in the target-unbound state of IDPs. During the last two decades PreSMos have been steadily acknowledged as the critical determinants for target binding in dozens of IDPs. To date, the PreSMo concept provides the most convincing structural rationale explaining the IDP-target binding behavior at an atomic resolution. Here we present a brief developmental history of PreSMos and describe their common characteristics. We also provide a list of newly discovered PreSMos along with their functional relevance.

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Abstract : Insulin resistance is closely associated with metabolic diseases such as type 2 diabetes, dyslipidemia, hypertension and atherosclerosis. Thiazolidinediones (TZDs) have been developed to ameliorate insulin resistance by activation of peroxisome proliferator-activated receptor (PPAR) γ. Although TZDs are synthetic ligands for PPARγ, metabolic outcomes of each TZD are different. Moreover, there are lack of head-to-head comparative studies among TZDs in the aspect of metabolic outcomes. In this study, we analyzed the effects of three TZDs, including lobeglitazone (Lobe), rosiglitazone (Rosi), and pioglitazone (Pio) on metabolic and thermogenic regulation. In adipocytes, Lobe more potently stimulated adipogenesis and insulin-dependent glucose uptake than Rosi and Pio. In the presence of pro-inflammatory stimuli, Lobe efficiently suppressed expressions of pro-inflammatory genes in macrophages and adipocytes. In obese and diabetic db/db mice, Lobe effectively promoted insulin-stimulated glucose uptake and suppressed pro-inflammatory responses in epididymal white adipose tissue (EAT), leading to improve glucose intolerance. Compared to other two TZDs, Lobe enhanced beige adipocyte formation and thermogenic gene expression in inguinal white adipose tissue (IAT) of lean mice, which would be attributable to cold-induced thermogenesis. Collectively, these comparison data suggest that Lobe could relieve insulin resistance and enhance thermogenesis at low-concentration conditions where Rosi and Pio are less effective.

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Abstract : In pancreatic β cells, glucose stimulates the biosynthesis of insulin at transcriptional and post-transcriptional levels. The RNA-binding protein, polypyrimidine tract-binding protein 1 (PTBP1), also named hnRNP I, acts as a critical mediator of insulin biosynthesis through binding to the pyrimidine-rich region in the 3’-untranslated region (UTR) of insulin mRNA. However, the underlying mechanism that regulates its expression in β cells is unclear. Here, we report that glucose induces the expression of PTBP1 via the insulin receptor (IR) signaling pathway in β cells. PTBP1 is present in β cells of both mouse and monkey, where its levels are increased by glucose and insulin, but not by insulin-like growth factor 1. PTBP1 levels in immortalized β cells established from wild-type (βIRWT) mice are higher than levels in β cells established from IR-null (βIRKO) mice, and ectopic re-expression of IR-WT in βIRKO cells restored PTBP1 levels. However, PTBP1 levels were not altered in βIRKO cells transfected with IR-3YA, in which the Tyr1158/1162/1163 residues are substituted with Ala. Consistently, treatment with glucose or insulin elevated PTBP1 levels in βIRWT cells, but not in βIRKO cells. In addition, silencing Akt significantly lowered PTBP1 levels. Thus, our results identify insulin as a pivotal mediator of glucose-induced PTBP1 expression in pancreatic β cells.

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Abstract : The CRISPR-Cas system is a well-established RNA-guided DNA editing technique widely used to modify genomic DNA sequences. I used the CRISPR-Cas9 system to change the second and third nucleotides of the triplet TCT of human TNSFSF9 in HepG2 cells to TAG to create an amber stop codon. The TCT triplet is the codon for Ser at the 172^nd position of TNSFSF9. The two substituted nucleotides, AG, were confirmed by DNA sequencing of the PCR product followed by PCR amplification of the genomic TNFSF9 gene. Interestingly, sequencing of the cDNA of transcripts of the edited TNFSF9 gene revealed that the TAG had been re-edited to the wild type triplet TCT, and 1 or 2 bases just before the triplet had been deleted. These observations indicate that CRISPR-Cas9-mediated editing of bases in target genomic DNA can be followed by spontaneous re-editing (correcting) of the bases during transcription.

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Abstract : Ethylene regulates numerous aspects of plant growth and development. Multiple external and internal factors coordinate ethylene production in plant tissues. Transcriptional and post-translational regulations of ACC synthases (ACSs), which are key enzymes mediating a rate-limiting step in ethylene biosynthesis have been well characterized. However, the regulation and physiological roles of ACC oxidases (ACOs) that catalyze the final step of ethylene biosynthesis are largely unknown in Arabidopsis. Here, we show that Arabidopsis ACO1 exhibits a tissue-specific expression pattern that is regulated by multiple signals, and plays roles in the lateral root development in Arabidopsis. Histochemical analysis of the ACO1 promoter indicated that ACO1 expression was largely modulated by light and plant hormones in a tissue-specific manner. We demonstrated that point mutations in two E-box motifs on the ACO1 promoter reduce the light-regulated expression patterns of ACO1. The aco1-1 mutant showed reduced ethylene production in root tips compared to wild-type. In addition, aco1-1 displayed altered lateral root formation. Our results suggest that Arabidopsis ACO1 integrates various signals into the ethylene biosynthesis that is required for ACO1’s intrinsic roles in root physiology.