Linker histone H1FOO regulates the chromatin structure in mouse zygotes.

The chromatin structure in one-cell-stage mouse embryos is extremely loose and becomes tighter at the two-cell stage. As linker histones are involved in higher-order chromatin structure, we examined the involvement of the linker histone variant H1foo in the change of chromatin looseness between the one- and two-cell stages. H1foo knockdown causes the chromatin structure to be tighter in the pronucleus and increases deposition of the histone H3 variant H3.1/3.2 in the peripheral region of the pronucleus in one-cell-stage embryos. The decrease in chromatin looseness at the two-cell stage is less after overexpressing H1foo. These results suggest that H1foo is involved in the change in chromatin structure via nuclear deposition of H3 variants between the one- and two-cell stages.