Molecular mechanisms underlying the origin of human imprinting disorders

In our laboratory we study the factors controlling epigenetic reprogramming in gametes and pre-implantation embryo development and the role they have in the etiology of human imprinting disorders. In particular, we are interested in understanding what is the role of maternal-effect genes in the origin of the DNA methylation abnormalities that alter the expression of imprinted genes in the Beckwith-Wiedemann syndrome (BWS) and Silver-Russell syndrome (SRS) that are rare congenital growth disorders.

Our experimental strategy is based on a transgenic mouse model carrying a missense variant of the PADI6 gene that was previously associated with BWS. We generate mouse embryos by in vitro fertilization (IVF) and analyse them during pre-implantation stages by employing transcriptomic and epigenomic technologies.     

• Development and analysis of a mouse model of human imprinting disorder

Because of lack of proper cellular systems and developmental contexts for molecular studies, very little is known about the mechanisms underlying the origin of the genomic imprinting defects of the patients affected by BWS and SRS. Therefore, we developed a novel transgenic mouse line, in which the P620A variant of the Padi6 gene was introduced. A similar variant was found in the mother of two children with BWS and Multi-Locus Imprinting Disturbance (MLID). Padi6 is a maternal-effect gene and its protein product is expressed specifically in oocytes and is necessary for storing proteins needed for early embryo development. We found that when oocytes derived from homozygous Padi6-P620A mice were fertilized with wildtype sperm, most of the obtained embryos stopped their development at the 2-cell stage and showed incomplete DNA demethylation, down-regulation of zygotic genome activation (ZGA) genes and up-regulation of maternal-decay genes. We did not see imprinting defects in the matPadi6-P620A 2-cell embryos. However, we found that the DNMT1 cofactor UHRF1 was severely down-regulated, suggesting that mutant embryos possibly surviving the 2-cell stage could show defective DNA methylation maintenance. To test this hypothesis, we are currently analysing the rare mutant embryos reaching the stage of blastocyst.

Effect of PADI6-associated protein depletion in mouse oocyte and early embryo

1. Giaccari C, Cecere F, Argenziano L, Pagano A, Galvao A, Acampora D, Rossi G, Hay Mele B, Acurzio B, Coonrod S, Cubellis MV, Cerrato F, Andrews S, Cecconi S, Kelsey G, Riccio A. A maternal-effect Padi6 variant causes nuclear and cytoplasmic abnormalities in oocytes, as well as failure of epigenetic reprogramming and zygotic genome activation in embryos. Genes Dev. 2024 Mar 22;38(3-4):131-150. doi: 10.1101/gad.351238.123.
2. Giaccari C, Cecere F, Argenziano L, Pagano A, Riccio A. New insights into oocyte cytoplasmic lattice-associated proteins. Trends Genet. 2024 Oct;40(10):880-890. doi: 10.1016/j.tig.2024.06.002. Epub 2024 Jul 1.
3. Cecere F, Relator R, Levy M, Verma A, McConkey H, Mele BH, Pignata L, Giaccari C, D’Angelo E, Saha S, Saadat A, Sparago A, Angelini C, Cerrato F, Sadikovic B, Riccio A.Identification of genetic and non-genetic modifiers of genomic imprinting through screening of imprinted DMR methylation in humans. Epigenetics Chromatin. 2025 Jul 24;18(1):47. doi: 10.1186/s13072-025-00612-7.
4. Cecere F, Pignata L, D’Angelo E, Giaccari C, Saadat A, Sparago A, Angelini C, Hay Mele B, Mussa A, Ferrero GB, Scarano G, Gori G, Di Maria E, Romano C, Tarani L, Piscopo C, Scala I, Tenorio JA, Lapunzina P, Cerrato F, Riccio A. Highly variable genomic methylation in the Beckwith-Wiedemann syndrome associated with multi-locus imprinting disturbances. Clin Epigenetics. 2025 Oct 3;17(1):160. doi: 10.1186/s13148-025-01971-4.