title: Hypomethylation and genome instability in the germline of exposed parents and their progeny is associated with altered miRNA expression.
abstract: Recent studies suggest that transgenerational genome instability may be epigenetic in nature and mediated via altered DNA methylation and microRNAome. Here, we investigated the nature and mechanisms underlying the disruption of DNA methylation and microRNA expression status in the germline and progeny of exposed parents. We have found that paternal irradiation leads to upregulation of the miR-29 family in the exposed male germline, which causes decreased expression of de novo methyltransferase, DNA methyltransferase 3a, and profound hypomethylation of long interspersed nuclear elements 1 (LINE1) and short interspersed nuclear elements B2 (SINE B2). Epigenetic changes in the male germline further resulted in deleterious effects in the somatic thymus tissue from the progeny of exposed animals, including hypomethylation of LINE1 and SINE B2. Hypomethylation of LINE1 and SINE B2 in the thymus tissue from the progeny was associated with a significant decrease in the levels of lymphoid-specific helicase (LSH) that is crucial for the maintenance of methylation and silencing of repetitive elements. Furthermore, we noted a significant upregulation of miR-468 that targets LSH and leads to its decreased expression in thymus in the progeny of exposed parents. We suggest that miR-468-mediated suppression of LSH leads to aberrant methylation of LINE1 and SINE B2. In summary, altered microRNAome and hypomethylation of retroelements constitute deleterious effects that may significantly influence genome stability of the parental germline and consequently cause genome instability in the progeny.
authors: Department of Biological Sciences, University of Lethbridge, 4401 University of Lethbridge, Alberta, Canada T1K 3M4.
authors: Jody N
authors: JN
authors: Filkowski
authors: Yaroslav
authors: Y
authors: Ilnytskyy
authors: Jan
authors: J
authors: Tamminga
authors: Igor
authors: I
authors: Koturbash
authors: Andrey
authors: A
authors: Golubov
authors: Tetyana
authors: T
authors: Bagnyukova
authors: Igor P
authors: IP
authors: Pogribny
authors: Olga
authors: O
authors: Kovalchuk
mesh_terms: D000818:Animals; D015153:Blotting, Western; D019175:DNA Methylation; D000090205:DNA Methyltransferase 3A; D044127:Epigenesis, Genetic; D005260:Female; D042822:Genomic Instability; D005854:Germ Cells; D020084:Long Interspersed Nucleotide Elements; D008297:Male; D018811:Maternal Exposure; D051379:Mice; D035683:MicroRNAs / Q000235:genetics*; D041681:NIH 3T3 Cells; D010290:Parents; D018812:Paternal Exposure
chemical_list: C000715535:Dnmt3a protein, mouse; D035683:MicroRNAs; D000090205:DNA Methyltransferase 3A