METHYLATION PROFILES OF GENOMIC DNA OF MOUSE DEVELOPMENTAL BRAIN DETECTED BY RESTRICTION LANDMARK GENOMIC SCANNING (RLGS) METHOD

Restriction landmark genomic scanning using methylation-sensitive endo nucleases (RLGS-M) is a newly developed powerful method for systematic detection of DNA methylation. Using this method, we scanned mouse bra in genomic DNAs from various developmental stages to detect the transc riptionally active regions. This approach is based on the assumption t hat CpG methylation, particularly of CpG islands, might be associated with gene transcriptional regulation. Genomic DNAs were prepared from telencephalons of 9.5-, 13.5- and 16.5-day embryos, 1- and 10-day neon ates and adults, followed by subjecting them to RLGS-M and comparing t heir patterns with each other or with that of the adult liver. We used NotI as a methylation-sensitive restriction enzyme and surveyed the m ethylation states of 2,600 NotI sites, almost of which should correspo nd to gene loci. Although almost all RLGS spots (98%) were present con stantly at every developmental stages, only a few percent of spots rep roducibly appeared and disappeared at different developmental stages o f the brain (44 spots, 1.7%) and some were tissue-specific (10 spots, 0.7%). These data suggest that DNA methylation associated with gene tr anscription is a well-programmed event during the central nervous syst em (CNS) development. Thus, RLGS-M can offer a means for detecting sys tematically the genes in which the state of DNA methylation changes du ring development of the higher organism.