Non-canonical spatial organization of heterochromatin in mouse preimplantation embryos

Spatial genome organization refers to the arrangement of chromosomes within the nucleus, undergoing significant chromatin remodeling during the early stages of mammalian development. This review explores the mechanisms behind this organization, focusing on heterochromatin and its potential role in regulating embryonic genome expression.

Spatial genome organization refers to the conformation of the chromosomes and their relative positioning within the nucleus. In mammals, fertilization entails intense chromatin remodeling of parental genomes, as well as large-scale structural changes in nuclear organization of the newly formed zygote over the first two cell cleavages. The molecular characteristics, mechanisms and functionality of spatial genome organization during the early steps of development in mice have been extensively studied and will be presented in this review, with a specific focus on heterochromatin. Concomitant with the maturation of genomic architecture, embryonic genome activation occurs in transient waves of transcription. Here, we will also discuss the putative link between heterochromatin organization and regulation of genome expression.