Epigenetic mark sequence of the H19 gene in human sperm

We have investigated the epigenetic mark in the human H19 gene. The H19 pro moter is methylation-free in human sperm. but it is methylated in the pater nally derived allele of most adult tissues. Consequently, the H19 gene is e xclusively transcribed from the maternal allele. It was demonstrated that t he differentially methylated region (DMR) located 2 kb upstream From mouse H19 is essential for the imprinting of H19. A 39 bp sequence in DMR has a h igh degree of similarity between humans, mice and rats. The highly conserve d 15 bp core region of the consensus sequence contains four methylatable si tes, and thus has been proposed as a potential imprinting mark region. In t his study, fine epigenetic sequencing analysis was performed on the sperm D NA in comparison with other adult organs. Interestingly, the conserved sequ ence of the potential mark region was methylated in almost all the sperm ge nomes analyzed. Furthermore, the single dinucleotide CpG, whose methylation affects the accessibility of the element to CTCF, was methylated in the co nserved core in the human sperm. These results suggest that the human core sequences may act as an imprinting center in the reciprocal monoallelic exp ression of H19. (C) 2001 Elsevier Science B.V. All rights reserved.