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Articles by K. Rokutan
Total Records ( 2 ) for K. Rokutan
  Y Yamamoto , T Tanahashi , T Kawai , S Chikahisa , S Katsuura , K Nishida , S Teshima Kondo , H Sei and K. Rokutan
 

Caloric restriction (CR) is an effective method for prevention of age-associated diseases as well as overweight and obesity; however, there is controversy regarding the effects of dieting regimens on behavior. In this study, we investigated two different dieting regimens: repeated fasting and refeeding (RFR) and daily feeding of half the amount of food consumed by RFR mice (CR). CR and RFR mice had an approximate 20% reduction in food intake compared with control mice. Open field, light-dark transition, elevated plus maze, and forced swimming tests indicated that CR, but not RFR, reduced anxiety- and depressive-like behaviors, with a reduction peak on day 8. Using a mouse whole genome microarray, we analyzed gene expression in the prefrontal cortex, amygdala, and hypothalamus. In addition to the CR-responsive genes commonly modified by RFR and CR, each regimen differentially changed the expression of distinct genes in each region. The most profound change was observed in the amygdalas of CR mice: 884 genes were specifically upregulated. Ingenuity pathway analysis revealed that these 884 genes significantly modified nine canonical pathways in the amygdala. -Adrenergic and dopamine receptor signalings were the two top-scoring pathways. Quantitative RT-PCR confirmed the upregulation of six genes in these pathways. Western blotting confirmed that CR specifically increased dopamine- and cAMP-regulated phosphoprotein (Darpp-32), a key regulator of dopamine receptor signaling, in the amygdala. Our results suggest that CR may change behavior through altered gene expression.

  K Takeo , T Kawai , K Nishida , K Masuda , S Teshima Kondo , T Tanahashi and K. Rokutan
 

The tra2β gene encoding an alternative splicing regulator, transformer 2-β (Tra2β), generates five alternative splice variant transcripts (tra2β15). Functionally active, full-length Tra2β is encoded by tra2β1 isoform. Expression and physiological significance of the other isoforms, particularly tra2β4, are not fully understood. Rat gastric mucosa constitutively expressed tra2β1 isoform and specifically generated tra2β4 isoform that includes premature termination codon-containing exon 2, when exposed to restraint and water immersion stress. Treatment of a gastric cancer cell line (AGS) with arsenite (100 µM) preferentially generated tra2β4 isoform and caused translocation of Tra2β from the nucleus to the cytoplasm in association with enhanced phosphorylation during the initial 4–6 h (acute phase). Following the acute phase, AGS cells continued upregulated tra2β1 mRNA expression, and higher amounts of Tra2β were reaccumulated in their nuclei. Treatment with small interference RNAs targeting up-frameshift-1 or transfection of a plasmid containing tra2β1 cDNA did not induce tra2β4 isoform expression and did not modify the arsenite-induced expression of this isoform, suggesting that neither the nonsense-mediated mRNA decay nor the autoregulatory control by excess amounts of Tra2β participated in the tra2β4 isoform generation. Knockdown of Tra2β facilitated skipping of the central variable region of the CD44 gene and suppressed cell growth. In contrast, overexpression of Tra2β stimulated combinatorial inclusion of multiple variable exons in the region and cell growth. The similar skipping and inclusion of the variable region were observed in arsenite-treated cells. Our results suggest that Tra2β may regulate cellular oxidative response by changing alternative splicing of distinct genes including CD44.

 
 
 
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