PARENT SESSION
GENE REGULATION AND FUNCTION IN THE REPRODUCTIVE AXIS
Kent
7:30 AM-10:00 AM

(371) THE ACQUISITION OF PATERNAL-SPECIFIC METHYLATION IMPRINTS DURING GAMETOGENESIS.

Davis, Tamara¹, Arnaudo, Anna¹, Naik, Snehal¹, ¹ Department of Biology, Bryn Mawr, PA

ABSTRACT- Genomic imprinting is a mammalian-specific form of gene regulation that results in the preferential expression of one parental allele. To achieve parent of origin-specific expression, the parental alleles must be distinguished from each other in somatic tissues. This imprinting mark must be passed from parent to offspring via the germ cells, suggesting that the parent-specific imprinting mark is established during germ cell development. To date, the best candidate for the imprinting mark is the differential methylation of cytosine residues in cytosine-guanine dinucleotides. The focus of our research has been to analyze the establishment of methylation at paternally-methylated imprinted loci during male gametogenesis. Analysis of the imprinted H19 gene in mouse has demonstrated that the paternal-specific methylation inherited from sperm is erased in male germ cells by 13.5 days post coitum (dpc). While the paternal H19 allele reacquires methylation by 15.5 dpc, methylation is first observed on the maternal allele in spermatogonia at 6 days post partum. We hypothesize that the differential acquisition of methylation reflects an underlying difference in chromatin structure. We are interested in determining if temporal changes in the methylation status of other imprinted genes are similar to those we have observed for H19. To address this question, we are currently analyzing two imprinted genes: p57 and gtl2. p57 is located in the same cluster of imprinted genes as H19 on mouse distal chromosome 7. In contrast, gtl2 is located on mouse chromosome 12, but shares other features with H19. H19 and gtl2 both encode untranslated RNAs and are the downstream component of a reciprocally imprinted pair of genes. We are currently investigating regions of differential methylation within p57 and gtl2. Our results will indicate if the temporal acquisition of methylation at imprinted loci is globally regulated or is unique for each imprinted gene. We will present our analysis of imprinted gene methylation status during male germ cell development.

KEY WORDS: imprinting, gametogenesis, methylation