Differential methylation of the gene encoding myo -inositol 3-phosphate synthase ( Isyna1 ) in rat tissues

Abstract

Aims Myo-inositol levels are frequently altered in several brain disorders. Myo-inositol 3-phosphate synthase, encoded by the Isyna1 gene, catalyzes the synthesis of myo-inositol in cells. Very little is known about the mechanisms regulating Isyna1 expression in brain and other tissues. In this study, we have examined the role of DNA methylation in regulating Isyna1 expression in rat tissues. Materials & methods Transfection analysis using in vitro methylated promoter constructs, Southern blot analysis of genomic DNA from various tissues digested with a methylation-sensitive enzyme and CpG methylation profiling of genomic DNA from different tissues were used to determine differential methylation of Isyna1 in tissues. Transfection analysis using plasmids harboring mutated CpG residues in the 5’-upstream region of Isyna1 was used to identify critical residues mediating promoter activity. Results The −700 bp to −500 bp region (region 1) of Isyna1 exhibited increased methylation in brain cortex compared with other tissues; it also exhibited sex-specific methylation differences between matched male and female brain cortices. Mutation analysis identified one CpG residue in region 1 necessary for promoter activity in neuronal cells. A tissue-specific differentially methylated region (T-DMR) was found to be localized between +450 bp and +650 bp (region 3). This DMR was comparatively highly methylated in spleen, moderately methylated in brain cortex and poorly methylated in testis, consistent with mRNA levels observed in these tissues. Conclusion Rat Isyna1 exhibits tissue-specific DNA methylation. Brain DNA was uniquely methylated in the 5’-upstream region and displayed gender specificity. A T-DMR was identified within the gene body of Isyna1. These findings suggest that Isyna1 is regulated, in part, by DNA methylation and that significant alterations in methylation patterns during development could have a major impact on inositol phosphate synthase expression in later life.

Epigenetic Regulation of Sox4 during Palate Development

“…These data provide support for the hypothesis that the decrease in Sox4 mRNA levels observed in the secondary palate from GD12 to GD13 (Table 1) was functionally correlated with the pronounced increases in methylation of CpG83 and CpG85. The methylation status of CpG residues 40–53 and 86–89 (Figure 4) could not be analyzed in this study, because these regions were presumably too degenerate to be amplified by PCR after bisulfite modification, a problem frequently encountered in bisulfite sequencing [35]. …”

Transcriptomic and Epigenetic Changes in the Hypothalamus Are Involved in an Increased Susceptibility to a High-Fat-Sucrose Diet in Prenatally Stressed Female Rats

“…Significant methylation levels are classically categorized as highly methylated (methylation levels more than 60%), moderately methylated (30–60%) and poorly methylated (less than 30%) [43]. However, recent data suggest that DNA methylation is not only involved in cellular differentiation, but it also participates in modulation of genome function in response to signals from physical, biological and social environments [44].…”

Dual function of MIPS1 as a metabolic enzyme and transcriptional regulator

“…On the contrary, inositol tetrakisphosphate (IP 4 ) and inositol pentakisphosphate (IP 5 ) stimulate nucleosome mobilization catalyzed by SWI/SNF complex (15). In mammals, the gene encoding MIPS is regulated by DNA methylation (16). Hence, chromatin remodeling appears to be a widespread mechanism regulating MIPS expression in many eukaryotes, and similar mechanisms may operate in plants.…”