Tracking mobilization uncovers an evolutionarily conserved mechanism in suppressing transpositions during somatic development

Transposon mobilizations could cause gene mutations and even genomic instability, whose aberrant activation is tightly linked with cancer, neurodegenerative disorder and other pathologies. However, the precise suppression mechanisms of transposon mobilizations during somatic development throughout evolution remain largely obscure. Here, by spatiotemporally monitoring transpositions with single-cell resolution, we determined a highly conserved mechanism in suppressing transposon mobilizations. We identified that Cramp1 safeguards the genomic integrity in both Drosophila hindgut regeneration and mouse embryonic erythropoiesis through silencing transposon mobility. Cramp1 is characterized as a major hallmark that specifically binds to the DNA sequences of histone gene cluster to initiate transcription of linker histone H1, which subsequently promotes H3K36me2-established heterochromatin for transposon silencing. Our finding highlights that with the endless arms race between hosts and transposons during evolution, the core mechanisms will also evolve to suppress transposon mobilizations during somatic development. One-sentence abstractCramp1 plays an evolutionarily conserved role in specifically initiating linker histone H1 transcription and triggering H1-H3K36me2-established heterochromatin to suppress transposon mobilizations and maintain genome integrity during somatic development.